Article

The Assessment of First Metatarsal Rotation in the Normal Adult Population Using Weightbearing Computed Tomography

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Abstract

Background The importance of the rotational profile of the first metatarsal is increasingly recognized in the surgical planning of hallux valgus. However, rotation in the normal population has only been measured in small series. We aimed to identify the normal range of first metatarsal rotation in a large series using weightbearing computed tomography (WBCT). Methods WBCT scans were retrospectively analyzed for 182 normal feet (91 patients). Hallux valgus angle, intermetatarsal angle, anteroposterior/lateral talus–first metatarsal angle, calcaneal pitch, and hindfoot alignment angle were measured using digitally reconstructed radiographs. Patients with abnormal values for any of these measures and those with concomitant pathology, previous surgery, or hallux rigidus were excluded. Final assessment was performed on 126 feet. Metatarsal pronation (MPA) and α angles were measured on standardized coronal computed tomography slices. Pronation was recorded as positive. Intraobserver and interobserver reliability were assessed using intraclass correlation coefficients (ICCs). Results Mean MPA was 5.5 ± 5.1 (range, –6 to 25) degrees, and mean α angle was 6.9 ± 5.5 (range, –5 to 22) degrees. When considering the normal range as within 2 standard deviations of the mean, the normal range identified was −5 to 16 degrees for MPA and −4 to 18 degrees for α angle. Interobserver and intraobserver reliability were excellent for both MPA (ICC = 0.80 and 0.97, respectively) and α angle (ICC = 0.83 and 0.95, respectively). There was a moderate positive correlation between MPA and α angle (Pearson coefficient 0.68, P < .001). Conclusion Metatarsal rotation is variable in normal feet. Normal MPA can be defined as less than 16 degrees, and normal α angle can be defined as less than 18 degrees. Both MPA and α angle are reproducible methods for assessing rotation. Further work is needed to evaluate these angles in patients with deformity and to determine their significance when planning surgical correction of hallux valgus. Level of Evidence Level III, retrospective comparative study.

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... 8 With advances in 3-dimensional imaging, there has been renewed interest in a third plane of the deformity; rotation of the first metatarsal in the coronal plane has been termed metatarsal pronation and has been implicated as an important factor for the development of hallux valgus deformities. [5][6][7]10 It has been shown that there are significantly higher levels of first metatarsal pronation in feet with hallux valgus deformity as compared to controls. 3 Further, it has been shown that correction of pronation in hallux valgus results in significantly improved PROMIS physical function scales and reduced recurrence rates compared to no correction of rotation in the coronal plane. 1 Therefore, addressing first metatarsal pronation is an area of topical interest as it may improve outcomes in operative correction of hallux valgus. ...
... Identifying a normal range as within 2 SDs of the mean, normal values of MPA and α angle were defined as <16 and <18 degrees, respectively. 6 The relatively large range of rotation seen prompts the question as to whether side-to-side comparison may be more appropriate in determining abnormal pronation for an individual, rather than comparing to a population mean. Further, when planning operative correction, it may be more appropriate to restore the rotation to a value that is normal for that patient, rather than to a population average. ...
... This study was a single-center, retrospective analysis of data collected as part of routine clinical care. This was an extension of the article published by Najefi et al, 6 "The Assessment of First Metatarsal Rotation in the Normal Adult Population Using Weightbearing Computed Tomography," with additional analysis performed on the same patient cohort. All the same protocols and procedures were followed, including compliance with the ethical standards of the institutional research committee and the 1964 Declaration of Helsinki, and its later amendments. ...
Article
Background A previous study defined the normal first metatarsal pronation angle (MPA) as <16 degrees and normal α angle as <18 degrees. The primary purpose of this study was to assess the side-to-side variation in first metatarsal pronation between feet in normal individuals. Methods MPA and α angles were measured on standardized coronal weightbearing computed tomography slices. Paired t tests were used to test significance of mean side-to-side differences in a population of 63 normal, asymptomatic individuals. Results The mean side-to-side difference in first metatarsal pronation was 4.3 degrees (95% CI 3.3, 5.2 degrees) for MPA and 4.9 degrees (95% CI 3.8, 6.0 degrees) for α angle. The normative range for side-to-side difference was calculated as 12 degrees for MPA and 14 degrees for α angle, as defined by 2 SDs from the mean. Conclusion In a cohort of normal patients, the mean difference in first metatarsal pronation between sides was approximately 4 to 5 degrees based on MPA and α angle. However, considerable variation in differences was observed. These findings may be considered when assessing first metatarsal pronation using population-based values as it may influence thresholds for identifying pathology in an individual.
... The coronal plane rotational profile of medial column bones in the foot is a recent focus of attention (1)(2)(3)(4)(5)(6) . Previously, understanding of foot pathologies was limited by conventional 2-dimensional radiographs and bone superimpositions (7)(8)(9) . ...
... The reliability of the α angle and the Saltzman angle has already been reported as good in the literature, and our study confirmed these previous findings (3,4,6) . On the other hand, the reliability of navicular, medial cuneiform, first metatarsal base and shaft, and proximal phalanx of the hallux rotations had not been previously assessed. ...
... On the other hand, the reliability of navicular, medial cuneiform, first metatarsal base and shaft, and proximal phalanx of the hallux rotations had not been previously assessed. Najefi et al. (3) and Steadman et al. (4) went further and defined the normative values of the α and Saltzman angles. Considering the excellent reliability ...
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Objective: To assess interobserver reliability of previously described coronal plane rotation measurements of medial column bones and to assess their ability to accurately quantify changes in rotational profile. Methods: Two cadaveric below-knee specimens were implanted with pins in each bone of the medial column. Weight-bearing computed tomography (CT) scans were acquired in a simulated standing position under neutral, supinated, and pronated conditions. For each specimen and condition, 2 observers measured the coronal plane rotation of the navicular, medial cuneiform, first metatarsal base, shaft, and head, and proximal phalanx of the hallux as previously described. The rotation of each pin was measured relative to the ground in the coronal plane for each condition. These measurements were defined as benchmarks for the rotational profile of each bone. The correlation between these benchmarks and direct bone measurements was then assessed. Intraclass correlation coefficient was used to assess interobserver reliability. Pearson's coefficient was used to evaluate correlations. Results: The interobserver reliability of direct bone measurements ranged from 0.98 to 0.99. Correlations between pin rotation and direct measurements ranged from ρ=0.87 to 0.99 across the neutral, supinated, and pronated conditions. Conclusion: Coronal plane rotation measurements of medial column bones described in this study are reliable tools. Level of Evidence III; Case-Control Study.
... & Ankle OrthopaedicsAn et al research-article2022 in hallux valgus is pronated by 9.5 degrees on average compared with normal controls. 5,27,28 The modified Lapidus procedure is a realignment first tarsometatarsal (TMT) or first metatarso-cuneiform arthrodesis that provides 3-dimensional correction for hallux valgus. 14,18 Unlike many osteotomy procedures, the modified Lapidus procedure can reduce pronation deformity associated with hallux valgus. ...
... As understanding of the 3-dimensional deformity of hallux valgus has increased, so has interest in assessment and clinical correlation of first ray rotation. 26,28,32 Conti et al 7 used an alternative computeraided 3-dimensional method of measuring pronation after modified Lapidus, fixed by crossing screws. Their average preoperative (29 degrees) and postoperative (20 degrees) pronation angles were lower than observed in our study, but the magnitude change of -8.8 degrees was similar to our CS cohort. ...
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Background The modified Lapidus procedure (first metatarso-cuneiform fusion) is a powerful technique for correcting triplanar deformity in hallux valgus. Although traditionally fixed with cross-screws (CS), growing awareness of intercuneiform stability and pronation deformity has led to fixation using a plate and first metatarsal–second cuneiform (1MT-2C) screw fixation (PS). We investigated Lapidus patient cohorts using CS vs PS fixation to understand patient-reported outcomes, angular and rotational correction, and complication rates. Methods We retrospectively reviewed cases of modified Lapidus for hallux valgus by a single surgeon. Patients were divided into CS or PS groups according to fixation. All patients had preoperative Patient Reported Outcome Measurement Information System (PROMIS) scores and minimum 12 months of follow-up. PROMIS scores in 6 key domains were compared within and between groups. Radiographic assessment of hallux valgus angle and intermetatarsal angle were performed on pre- and postoperative XR. Pronation of the first ray was measured on pre- and postoperative weightbearing computed tomography. Results We compared 42 patients with PS fixation to 43 with CS fixation. Both groups had significant improvement in hallux valgus angle and intermetatarsal angle ( P < .001), with no difference between groups. PS patients experienced a greater correction of first metatarsal pronation, an average reduction of 11 degrees, compared to 8 degrees in the CS group ( P < .039). Both cohorts experienced improvement in PROMIS physical function, pain interference, pain intensity, and global physical function. There were no differences in PROMIS score improvements between the cohorts. The CS group started weightbearing at 6 weeks vs 3.6 weeks for the PS group. Complication and revision rates were similar. Conclusion A plate and 1MT-2C screw fixation provides safe, robust fixation of Lapidus procedure and prevents instability through the intercuneiform joint. We observed similar improvement in PROMIS compared with patients treated with cross-screws. Complications did not increase despite the PS group weightbearing much earlier. PS patients achieved greater first ray rotational correction. Level of Evidence Level III, retrospective cohort study.
... According to some authors, WBCR provides scant data on the HV deformity in the different planes, with well-known boundaries regarding the overlaying of structures, radiograph source and patient positioning misalignment, and poor evaluation of rotational deformities, among other limitations (34). Recently, WBCT was shown to be a good option for studying complex 3D deformities (34,35). Two comparative studies showed that indirect signs of metatarsal pronation (based on the head round sign) correlate weakly with the a angle measured in WBCT (4). ...
Article
Pronation of the first metatarsal is a risk factor for the formation and progression of the hallux valgus deformity. Recently, Yamaguchi et al. published a study that showed how the round sign increases on digitally reconstructed radiography taken from a CT scan when pronation is applied. In this study, the shape of the lateral edge of the first metatarsal head was evaluated on weight-bearing dorsoplantar radiographs. Yamaguchi's signs were presented to observers after the visual presentation of each foot as an image. The best-fit circle was drawn using the PACS drawing function. Ninety radiographs of adults presenting hallux valgus deformities were classified as mild-to-moderate, based on hallux valgus angle and intermetatarsal angle. The global average observations were 3.72 ± 3.92 (Range 2.3 to 4.6°). The interclass correlation (Fleiss Kappa index κ = 0.225) and the Spearman correlation (0.16 of Kappa) coefficients were poor for inter-observer measurements and statistically significant. Using the linear model, there was no significant variability between the repetitions corresponding to each observer (t-value -1.527, p-value 0.127). Our findings show that the Yamaguchi method can be very subjective and should not be the exclusive technique to assess the rotation of the first metatarsal or head roundness.
... For hallux valgus, the utility and consistent in using weight-bearing CT scan for deformity evaluation were still unclear. Najefi et al. 24 assessed hallux valgus parameters from weight-bearing CT scan and presented that the inter-observer reliability of IMA, HVA and α angle was all very good [ICC: IMA = 0.90, HVA = 0.96, α angle = 0.83]. The intra-observer reliability of HVA was 0.91 and α angle was 0.95, while IMA showed only 0.54 for intra-observer reliability. ...
Article
Background: Radiographic assessment of hallux valgus is an essential process. Residual rotational deformity was shown associated with higher recurrent rate. This study aims to comprehensively assess reliability of measurement of various parameters from plain films and weight-bearing CT scan. Methods: A total of 40 pre-operative plain radiographs, 40 post-operative plain radiographs, and 37 weight-bearing CT scan were evaluated to determine reliability of hallux valgus parameters. Results: TSP and head shape representing coronal plane deformity showed lower inter-observer reliability compared to other parameters using for transverse plane evaluation especially in post-operative period. (post-op TSP amongst 3 assessors: κ = 0.386, 0.520, 0.340; post-op head shape: κ = 0.374, 0.375, 0.295) Using α angle for evaluation 1 st metatarsal rotation in weight-bearing CT scan demonstrated very good reliability for inter-observer (ICC = 0.853 (95% CI = 0.715–0.925)) and intra-observer (ICC = 0.902 (95% CI = 0.844–0.939)). Conclusion: Weight-bearing CT scan can improve reliability in post-operative coronal plane assessment.
... The normal talus-first metatarsal angle ranges from -10° (varus) to +30° (valgus), or 2 SD. The lateral talocalcaneal angle is defined by a line intersecting the longitudinal axis of the talus and a line parallel to the plantar surface of the calcaneus [21]. ...
Article
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Background: Clubfoot is one of the most common foot deformities in children. Surgical treatment is the only choice for patients who have failed conservative treatment. To the best of our knowledge, no studies have been done to compare the McKay surgery with a pin versus without a pin. Our study aimed to compare the outcomes of McKay surgery with and without pins in clubfoot patients. Method: This study is an analytical study. The sample size included patients referred to Imam Reza Hospital from 2016 to 2018. Children who did not respond to plaster therapy were under McKay surgery. In this study, patients were divided into two groups of 50 patients. In the first group, after ligament release and tendon extension, a pin was used to maintain the direction of the talonavicular joint. In the second group, no pin was used. Every six months, radiographs were taken of the patients to monitor their progress. After collecting the study data, they were entered into SPSS software (version 25, IBM Corporation, Armonk, NY) and analyzed. Result: The mean age of patients was 5.36±2.07 months. Of these, 79 were boys and 21 girls, most of the subjects were aged 4-6 months, and 24% had unilateral one-way clubs. The severity of the disease was 7 feet in grade 2 (moderate) and 93 feet in grade 3 (severe). There was a significant relationship between age, outcome and type of complications with surgical type. Conclusion: Finally, it can be concluded that McKay surgery (both with and without a pin) is exceptionally effective at treating clubfoot.
... Two recent articles evaluated the mean α angle in a normal population. 21,35 It appears that the mean value in a control population is around 6 degrees in pronation. Therefore, 6 degrees may be a better correction target. ...
Article
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Category Bunion; Midfoot/Forefoot Introduction/Purpose The Distal Metatarsal Articular Angle (DMAA) has long been described as a valgus increase of the distal articular surface of the first metatarsal in Hallux Valgus (HV) deformity. Since then, several studies have reported a poor reliability of this measurement and some authors currently claim that DMAA is misinterpreted as just the rounded shape of the lateral part of the first metatarsal head reflecting pronation of the first ray and could also be biased by the first metatarsal plantarflexion angle. Our study aimed to compare the DMAA in HV and control populations after correcting, with a dedicated software, pronation and plantarflexion of the first metatarsal. We hypothesized that after correction, DMAA will be higher in the HV population, especially in juvenile cases. Methods We performed a retrospective case-control study including 36 HV and 20 control feet. Patients under 15 or with surgery antecedent were excluded. DMAA1 was measured as initially described on X-rays by the angle between the distal articular surface and the longitudinal axis of the first metatarsal. DMAA2 was measured on Weight Bearing Computed Tomography (WBCT) without any corrections. DMAA3 was measured after correction of the first metatarsal plantarflexion in the sagittal plane. DMAA4 was measured after correction of the pronation of the first ray relative to the ground in the coronal plane using the alpha-angle. And DMAA5 after both corrections. Corrections in the coronal and sagittal planes were performed along the axis of the first metatarsal. Normality was assessed using Shapiro-Wilk tests. Comparisons were made using Student tests for normal variables and Mann-Whitney for non-normals. Correlations between age and angles were assessed by the Pearson correlation coefficient. Results HV and Control groups were comparable on BMI (p=0.69), Age (p=0.58) and Gender (p=0.27). DMAA1 (25.9°+/-7.3 vs 7.6°+/-4.2; p<0.01), DMAA2 (19.1°+/-7.1 vs 3.3°+/-2.4; p<0.01), DMAA3 (16.1°+/-6.2 vs 2.9°+/-2.4; p<0.01), DMAA4 (14.4°+/-5.7 vs 2.6°+/-2.5; p<0.01) and DMAA5 (11.9°+/-4.9 vs 3.3°+/-2.9; p<0.01) were significantly higher in the HV group than in the Control group. Significant decreases in angles were present between DMAA1 and DMAA2 (Δ=-6.9; CI95[-8.6;-5.1]; p<0.01), DMAA2 and DMAA3 (Δ=-3; CI95[-4.1;-1.9]; p<0.01), DMAA2 and DMAA4 (Δ=-4.7; CI95%[-6.3;-3.1]; p<0.01), DMAA2 and DMAA5 (Δ=-7.2 ;CI95%[-8.8;-5.6]; p<0.01) and between DMAA3 and DMAA4 (Δ=-1.7 ;CI95%[-2.9;-0.5]; p<0.01) in the HV group. No significant correlation was found between the 5 different DMAA values and the age in the HV group (respectively ρ=0.1,p=0.55 ; ρ=0.31,p=0.07 ; ρ=0.19,p=0.28 ; ρ=0.1,p=0.56 ; ρ=0.04,p=0.83). Conclusion Although overestimated with the 2-dimensional DMAA assessment, the valgus increase of the distal articular surface of the first metatarsal was present in the HV deformity, even after correction of pronation and plantarflexion of the first ray. DMAA overestimation was close to 14 degrees on X-rays and 7 degrees on WBCT without any correction and pronation of the first metatarsal seemed to play a more important role on this overestimation than plantarflexion. Age did not seem to influence this deformity. Increase of valgus of the distal articular surface of the first metatarsal should be considered in HV correction surgical planning.
... Two recent articles evaluated the mean α angle in a normal population. 21,35 It appears that the mean value in a control population is around 6 degrees in pronation. Therefore, 6 degrees may be a better correction target. ...
Article
Background The Distal Metatarsal Articular Angle (DMAA) was previously described as an increase in valgus deformity of the distal articular surface of the first metatarsal (M1) in hallux valgus (HV). Several studies have reported poor reliability of this measurement. Some authors have even called into question its existence and consider it to be the consequence of M1 pronation resulting in projection of the round-shaped lateral edge of M1 head. Our study aimed to compare the DMAA in HV and control populations, before and after computer correction of M1 pronation and plantarflexion with a dedicated weightbearing CT (WBCT) software. We hypothesized that after computerized correction, DMAA will not be increased in HV compared to controls. Methods We performed a retrospective case-control study including 36 HV and 20 control feet. In both groups, DMAA was measured as initially described on conventional radiographs (XR-DMAA) and WBCT by measuring the angle between the distal articular surface and the longitudinal axis of M1. Then, the DMAA was measured after computerized correction of M1 plantarflexion and coronal plane rotation using the α angle (3d-DMAA). Results The XR-DMAA and the 3d-DMAA showed higher significant mean values in HV group compared to controls (respectively 25.9 ± 7.3 vs 7.6 ± 4.2 degrees, P < .001, and 11.9 ± 4.9 vs 3.3 ± 2.9 degrees, P < .001). Comparing a small subset of precorrected juvenile HV (n=8) and nonjuvenile HV (n=28) demonstrated no significant difference in the measure DMAA values. On the other hand, the α angle was significantly higher in the juvenile HV group (21.6 ± 9.9 and 11.4 ± 3.7 degrees; P = .0046). Conclusion Although the valgus deformity of M1 distal articular surface in HV is overestimated on conventional radiographs, comparing to controls showed that an 8.6 degrees increase remained after confounding factors’ correction. Clinical Relevance After pronation computerized correction, an increase in valgus of M1 distal articular surface was still present in HV compared to controls. Level of Evidence Level III, retrospective case-control study.
... These findings might support the use of Saltzman's method since it does not rely on the visualization of the dorsal aspect of the metatarsal to be obtained [14,32] [4]. Additional interesting secondary findings were observed in our study. ...
Article
PurposeTo verify if indirect radiographic signs of first metatarsal pronation, determined by the head round sign, correspond to weight-bearing computed tomography (WBCT) measurements.Methods In this case–control retrospective study, we analyzed 26 hallux valgus (HV) feet and 20 controls through conventional radiograph (CR) and WBCT images. Two blinded orthopaedic foot and ankle surgeons performed the measurements. Pronation classification (head roundness), head diameter (HD), traditional HV angles, arthritis, sesamoid positioning, and first metatarsal rotation angle (MRA) (alpha angle) were evaluated. Comparisons were performed by Student’s T-test and a multivariate regression was executed. P-values less than 0.05 were considered significant.ResultsMean values were higher in HV patients than controls when evaluating MRA (11.51 [9.42–13.60] to 4.23 [1.84–6.62], 95%CI), HD (22.35 [21.52–23.18] to 21.01 [20.07–21.96]), and sesamoid rotation angle (SRA) (26.72 [24.09–29.34] to 4.56 [1.63–7.50]). The MRA had a low influence in head roundness classification (R2: 0.15). Changes in the pronation classification were explained chiefly by the sesamoid station (SS) (R2: 0.37), where stations 4 to 7 were found to be strong predictors of roundness classifications 2 and 3.Conclusion Indirect signs of metatarsal pronation, determined by the head round sign, correlate weakly with the alpha angle measured in WBCT. The presence of arthritis and sesamoids displacement might modify the perception of first head roundness. The influence of MRA in the classification was low, where SS from 4 to 7 was strong predictors of a higher pronation classification.
Article
Background: The purpose of this study was to determine if a postoperative decrease in first metatarsal pronation on 3-dimensional imaging was associated with changes in patient-reported outcomes as measured by the Patient-Reported Outcomes Measurement Information System (PROMIS) physical function, pain interference, and pain intensity domains or recurrence rates in patients with hallux valgus (HV) who undergo a first tarsometatarsal fusion (modified Lapidus procedure). Methods: Thirty-nine consecutive HV patients who met the inclusion criteria and underwent a modified Lapidus procedure had preoperative and ≥2-year postoperative PROMIS scores and had first metatarsal pronation measured on preoperative and at least 5-month postoperative weightbearing CT scans were included. Multivariable regression analyses were used to investigate differences in the change in PROMIS domains preoperatively and 2 years postoperatively between patients with "no change/increased first metatarsal pronation" and "decreased first metatarsal pronation." A log-binomial regression analysis was performed to identify if a decrease in first metatarsal pronation was associated with recurrence of the HV deformity. Results: The decreased first metatarsal pronation group had a significantly greater improvement in the PROMIS physical function scale by 7.2 points (P = .007) compared with the no change/increased first metatarsal pronation group. Recurrence rates were significantly lower in the decreased first metatarsal pronation group when compared to the no change/increased first metatarsal pronation group (risk ratio 0.25, P = .025). Conclusion: Detailed review of this limited cohort of patients who underwent a modified Lapidus procedure suggests that the rotational component of the HV deformity may play an important role in outcomes and recurrence rates following the modified Lapidus procedure. Level of evidence: Level III, retrospective cohort study.
Article
Background Weightbearing computed tomography (WBCT) can be used to assess alignment and rotation of the first metatarsal. It is unknown whether these measures remain consistent on sequential WBCTs in the same patient when a patient’s standing position may be different. The aim of this study was to establish the repeatability (test-retest) of measurements of first metatarsal alignment and rotation in patients without forefoot pathology on WBCT. Methods We retrospectively identified 42 feet in 26 patients with sequential WBCT studies less than 12 months apart. Patients with surgery between scans, previous forefoot surgery or hallux rigidus were excluded. Hallux valgus angle (HVA) and intermetatarsal angle (IMA) were measured using digitally reconstructed radiographs. Two methods of calculating metatarsal rotation (metatarsal pronation angle [MPA] and alpha angle) were measured on standardized coronal CT slices. Interobserver agreement and test-retest repeatability were assessed using intraclass correlation coefficients (ICCs). Standard error of measurement (SEM) and minimally detectable change (MDC95) were calculated. Results Interobserver agreement was excellent for HVA and IMA (ICC 0.96 and 0.90, respectively) and was good for MPA and alpha angle (ICC 0.81 and 0.80, respectively). There was excellent test-retest repeatability for HVA (ICC=0.90) and good test-retest repeatability for IMA (ICC=0.77). There was excellent test-retest repeatability for MPA (ICC=0.91) and good test-retest repeatability for alpha angle (ICC=0.87). The MDC95 was 4.6 degrees for MPA and 6.1 degrees for alpha angle. Five percent of patients had a difference outside of the MDC95 for the alpha angle, compared with 2% for the MPA. Conclusion Measurements of first metatarsal alignment and rotation are reliable between assessors and repeatable between sequential WBCTs in patients without forefoot pathology. Subtle differences in patient positioning during image acquisition do not significantly affect measurements, supporting the validity of this method of assessment in longitudinal patient care. Level of Evidence Level IV, retrospective case series.
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Hallux valgus deformity is a multiplanar deformity, where the rotational component has been recognized over the past 5 to 10 years and given considerable importance. Years ago, a rounded shape of the lateral edge of the first metatarsal head was identified as an important factor to detect after surgery because a less rounded metatarsal head was associated to less recurrence. More recently, pronation of the metatarsal bone was identified as the cause for the rounded appearance of the metatarsal head, and therefore, supination stress was found to be useful to achieve a better correction of the deformity. Using CT scans, up to 87% of hallux valgus cases have been shown to present with a pronated metatarsal bone, which highlights the multiplanar nature of the deformity. This pronation explained the perceived shape of the metatarsal bone and the malposition of the medial sesamoid bone in radiological studies, which has been associated as one of the most important factors for recurrence after treatment. Treatment options are discussed briefly, including metatarsal osteotomies and tarsometatarsal arthrodesis.
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Background Hallux valgus deformity consists of a lateral deviation of the great toe, metatarsus varus, and pronation of the first metatarsal. Most osteotomies only correct varus, but not the pronation of the metatarsal. Persistent postoperative pronation has been shown to increase deformity recurrence and have worse functional outcomes. The proximal rotational metatarsal osteotomy (PROMO) technique reliably corrects pronation and varus through a stable osteotomy, avoiding fusing any healthy joints. The objective of this research is to show a prospective series of the PROMO technique. Methods Twenty-five patients (30 feet) were operated with the PROMO technique. The sample included 22 women and 3 men, average age 46 years (range 22-59), for a mean prospective follow-up of 1 year (range 9-14 months). Inclusion criteria included symptomatic hallux valgus deformities, absence of severe joint arthritis, or inflammatory arthropathies, with a metatarsal malrotation of 10 degrees or more, with no tarsometatarsal subluxation or arthritis on the anteroposterior or lateral foot radiograph views. The mean preoperative and postoperative Lower Extremity Functional Scale (LEFS) score, metatarsophalangeal angle, intermetatarsal angle, metatarsal malrotation, complications, satisfaction, and recurrence were recorded. Results The mean preoperative and postoperative LEFS scores were 56 and 73. The median pre-/postoperative metatarsophalangeal angle was 32.5/4 degrees and the intermetatarsal angle 15.5/5 degrees. The metatarsal rotation was satisfactorily corrected in 24 of 25 patients. An Akin osteotomy was needed in 27 of 30 feet. All patients were satisfied with the surgery, and no recurrence or complications were found. Conclusions PROMO is a reliable technique, with good short-term results in terms of angular correction, satisfaction, and recurrence. Long-term studies are needed to determine if a lower hallux recurrence rate occurs with the correction of metatarsal rotation in comparison with conventional osteotomies. Level of evidence IV, prospective case series.
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In the last decade, cone-beam computed tomography technology with improved designs allowing flexible gantry movements has allowed both supine and standing weight-bearing imaging of the lower extremity. There is an increasing amount of literature describing the use of weightbearing computed tomography in patients with foot and ankle disorders. To date, there is no review article summarizing this imaging modality in the foot and ankle. Therefore, we performed a systematic literature review of relevant clinical studies targeting the use of weightbearing computed tomography in diagnosis of patients with foot and ankle disorders. Furthermore, this review aims to offer insight to those with interest in considering possible future research opportunities with use of this technology. Level of evidence: Level V, expert opinion.
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Hallux valgus (HV) deformity is closely correlated to the hypermobility of the first metatarsal-cuneiform joint, but adequate understanding of the three-dimentional (3D) mobility of this joint in normal or HV feet is lacking. This study was conducted to investigate the mobility of the first metatarsal-cuneiform joint in multiple planes during body weight-bearing conditions for both normal and HV patients. A total of 10 female volunteers (20 feet) and 10 female HV patients (20 feet) participated in this study. Using a custom-made foot-loading device, computerized tomography (CT) scans of each pair of feet were taken under both unloaded and body weight-bearing conditions. 3D models were reconstructed for the first metatarsal and the medial cuneiform. Rotational and translational motions of the first metatarsal-cuneiform joint in multiple planes from unloaded to loaded conditions were quantitatively evaluated by reverse-engineering software. During body weight-bearing conditions, the first metatarsal-cuneiform joint in HV feet dorsiflexed at an average of 2.91° (standard deviation, SD 1.71) versus 1.18° (SD 0.47) in controls (t = 4.158, P = 0.001); supinated 2.17° (SD 2.28) versus 0.98° (SD 0.81) in controls (t = 2.080, P = 0.045); and internally rotated 2.65° (SD 2.22) versus 0.96° (SD 0.57) in controls (t = 3.114, P = 0.006). Moreover, the joint in HV feet widened significantly compared with the controls (t = 2.256, P = 0.030) and tended to translate more in the dorsal-plantar direction (t = 1.928, P = 0.063); the translation in the medial-lateral direction was not significantly different between the two groups. During weight-loading process, the first metatarsal-cuneiform joint turns dorsiflexed, supinated, and internally rotated. For HV feet, hypermobility of the first metatarsal-cuneiform joint can be observed in multiple planes. This study promotes further understanding of the physiological and pathological mobility of the first metatarsal-cuneiform joint.
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We aimed to find a new radiographic measurement for evaluating first metatarsal pronation and sesamoid position in hallux valgus (HV) deformity. Data from a clinical study of 19 control patients (19 feet) with no HV deformity were compared with preoperative data of 138 patients (166 feet) with HV deformities. Using a weightbearing plain radiograph in anteroposterior (AP) view, the intermetatarsal angles (IMAs) and the hallux valgus angles (HVAs) of the control and study groups were measured. Using a semi-weightbearing coronal computed tomography (CT) axial view, the α angle was measured in the control and study groups. In addition, the tibial sesamoid grades in plain radiograph tangential view and the CT axial view were measured. The tibial sesamoid position in an AP view was checked preoperatively. Based on these measurements, 4 types of HV deformities were defined. The mean values of the α angle in the control and HV deformity groups (control group µ = 13.8 degrees, study group µ = 21.9 degrees) was significantly different. Among 166 HV feet, 145 feet (87.3%) had an α angle of more than 15.8 degrees, which is the upper value of the 95% confidence interval of the control group, indicating the existence of abnormal first metatarsal pronation in HV deformity. Four types of HV deformities were defined based on their α angles and tibial sesamoid grades in CT axial view (CT 4 position). Among 25.9% (43/166) of the study group, abnormal first metatarsal pronation with an absence of sesamoid deviation from its articular facet was observed. The prominent characteristic of this group was that they had high grades in the AP 7 position (≥5); however, in the CT 4 position, their grade was 0. This group was defined as the "pseudo-sesamoid subluxation" group. Patients with HV deformities had a more pronated first metatarsal than the control group, with a greater α angle. Pseudo-subluxation of the sesamoids existed in 25.9% of our study group. From our results, we suggest that the use of the CT axial view in assessments of HV deformity may benefit surgeons when they make operative choices to correct these deformities. With regard to the pseudo-sesamoid subluxation group, the use of the distal soft tissue procedure is not surgically recommended. III, Retrospective Comparative Study. © The Author(s) 2015.
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To prospectively compare computed tomography (CT) of the hindfoot in the supine non-weight-bearing position (NWBCT) with upright weight-bearing position (WBCT). Institutional review board approval and informed consent of all patients were obtained. NWBCT and WBCT scans of the ankle were obtained in 22 patients (mean age, 46.0 ± 17.1 years; range 19-75 years) using a conventional 64-row CT for NWBCT and a novel cone-beam CT for WBCT. Two musculoskeletal radiologists independently performed the following measurements: the hindfoot alignment angle, fibulocalcaneal and tibiocalcaneal distances, lateral talocalcaneal joint space width, talocalcaneal overlap and naviculocalcaneal distance. Significant changes between NWBCT and WBCT were sought using Wilcoxon signed-rank test. P values <0.05 were considered statistically significant. Significant differences were found for all measurements except the hindfoot alignment angle and tibiocalcaneal distance. Significant measurement results were as follows (NWBCT/WBCT reader 1; NWBCT/WBCT reader 2, mean ± standard deviation): fibulocalcaneal distance 3.6 mm ± 5.2/0.3 mm ± 6.0 (P = 0.006); 1.4 mm ± 6.3/-1.1 mm ± 6.3 (P = 0.002), lateral talocalcaneal joint space width 2.9 mm ± 1.7/2.2 mm ± 1.1 (P = 0.005); 3.4 mm ± 1.9/2.4 mm ± 1.3 (P = 0.001), talocalcaneal overlap 4.1 mm ± 3.9/1.4 mm ± 3.9 (P = 0.001); 4.5 mm ± 4.3/1.4 mm ± 3.7 (P < 0.001) and naviculocalcaneal distance 13.5 mm ± 4.0/15.3 mm ± 4.7 (P = 0.037); 14.0 mm ± 4.4/15.7 mm ± 6.2 (P = 0.100). Interreader agreement was good to excellent (ICC 0.48-0.94). Alignment of the hindfoot significantly changes in the upright weight-bearing CT position. Differences can be visualised and measured using WBCT. • Cone-beam computed tomography (CBCT) offers new opportunities for musculoskeletal problems • Visualization and quantification of hindfoot alignment are possible in upright weight-bearing CBCT • Hindfoot alignment changes significantly from non-weight-bearing to weight-bearing CT • The weight-bearing position leads to a decrease in the fibulocalcaneal distance and talocalcaneal overlap • The naviculocalcaneal distance is increased in the weight-bearing position.
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Does metatarsal pronation exist and, if so, what is its impact? Hallux valgus is a deformity associating angulation and a rotational component. The present study sought to investigate the nature and origin of the coronal plane displacement. A prospective single-center radiological and anatomic study was conducted on 100 feet operated on for hallux valgus. Baseline X-ray determined the preoperative position of the 1st metatarsal head in the coronal plane. The range of motion (ROM) of the cuneometatarsal joint in pronation-supination was measured peroperatively. An anatomic study investigated possible diaphyseal torsion. Mean radiologic pronation in hallux valgus was 12.7° (range, 0°-40°). Cuneometatarsal rotational ROM was determined by adding peroperative ROM in pronation (mean, 9.3°; range, 0°-30°) and in supination (mean, 8.7°; range, 0°-20°). Intermetatarsal divergence showed no correlation with radiologic pronation or ROM in pronation. Radiologic pronation showed no correlation with peroperative ROM in pronation. Pronation of the metatarsal head was never observed without associated sesamoid pronation; the latter, however, was in some cases observed without the former. Twenty randomly selected metatarsal cadaver specimens from the anatomy laboratory of the University of Nice (France) showed diaphyseal torsion in 80% of cases, with the metatarsal head in neutral position or in supination with respect to the base. In hallux valgus, 1st ray pronation appears to be systematic, in contrast to the typical supination found in the general population. Metatarsal rotation is always associated with sesamoid rotation, whereas the converse is not the case: displacement of the sesamoids appears to displace the metatarsal head via the metatarsosesamoid ligaments. This "drive-belt" effect, however, varies in its mechanical properties and the transmission is imperfect and likely subject to progressive ligament stretching, so that head rotation does not exactly follow and may even become independent of the sesamoid displacement. Radiologic and clinical rotation thus do not match any longer. The anatomic study showed that, while diaphyseal torsion cannot be ruled out, the metatarsal pronation mainly derives from cuneometatarsal joint rotational instability, the evolution of which does not parallel lateral instability, no correlation being found between degree of varus and rotational instability. The present study found metatarsal pronation to be associated with hallux valgus, making a preoperative AP view useful; the underlying mechanism was generally cuneometatarsal instability. Although difficult to specify exactly without correlation between radiological and clinical data, any such pronation raises the question of whether replacing the metatarsal head on its sesamoid supports is sufficient to achieve stability in all planes, or whether on the contrary derotation should be associated to metatarsal valgization osteotomy to restore horizontal support. Level IV.
Article
Background: Hyperpronation of the first metatarsal in hallux valgus (HV) is poorly understood by conventional weightbearing radiography. We aimed to evaluate this parameter using weightbearing computed tomography (WBCT) and to understand its association with other standard measurements. Methods: Retrospective evaluation of WBCT and weightbearing radiographs (WBXRs) was performed for 20 patients with HV feet and 20 controls with no such deformity. Axial computed tomography images of both groups were compared for the first metatarsal pronation angle (alpha angle) and tibial sesamoid subluxation (TSS) grades. The HV angle (HVA), first-second intermetatarsal angle (IMA), first metatarsal-medial cuneiform angle (MMCA), Meary's angle, and calcaneal pitch (CP) angle of the study and control groups were compared on both WBXR and the corresponding 2-dimensional images of WBCT. All measurements were independently performed by 1 musculoskeletal radiology fellow and 1 foot and ankle surgical fellow. Measurements were averaged and interobserver reliability was calculated. Results: The HV group demonstrated significantly higher values for TSS grade (P < .001) but not for alpha angle (P = .121) compared with controls. Likewise, significantly elevated HVA and IMA were noted in the HV group on both imaging modalities, while no such differences were observed for the CP angle. Higher MMCA and Meary's angle in the HV group were evident only on WBXR (MMCA, P = .039; Meary's, P = .009) but not on WBCT (MMCA, P = .183; Meary's, P = .171).Among all, the receiver operating characteristic (ROC) curves demonstrated the greatest area under the curve (AUC) for HVA, followed by IMA. The alpha angle performed only just outside the range of chance (AUC, 0.65; 95% CI, 0.52-0.69). The Pearson's correlations of the alpha angle, in the HV group, revealed a significant linear relationship with TSS grade and with HVA on WBXR, and only trended toward a weak linear relationship with IMA and with HVA on WBCT. Conclusion: The alpha angle, a measure of abnormal hyperpronation of the first metatarsal, was an independent factor that may coexist with other parameters in HV, but in isolation had limited diagnostic utility. "Abnormal" alpha angles were even observed in individuals without HV. Increases in IMA and MMCA were not necessarily associated with similar increases in alpha angle, despite moderate correlations with TSS grade and HVA on WBXR. Nevertheless, the WBCT was a useful method for assessing hyperpronation and guiding surgical management in individual cases. Level of evidence: Level III, retrospective comparative study.
Article
Background: Hallux abducto valgus (HAV) is a triplane deformity with recent attention given to the significance of correcting the coronal plane component. This study explored the accuracy of the forefoot axial study as a standard radiographic assessment method compared to weight-bearing CT scanning. Methods: Twelve feet with HAV from 12 subjects were included in this study. Three images of the affected foot were taken: 1) forefoot axial radiograph (FFA), 2) weight-bearing CT scan with the foot in a position of a) maximum pronation (Pronated CT) and b) maximum supination (Supinated CT). Five investigators (three faculty members and two podiatric16 medical students) determined the sesamoid rotation angle (SRA) from each of the images. The measurements from a single investigator were used to compare the SRA means from each of the image types, while those from all five investigators were used to determine reliability. Results: The mean SRA for the pronated CT position was 22.1 {plus minus} 7.6 degrees, while that for the supinated CT image was 10.5 {plus minus} 5.0 degrees. In comparison, the mean SRA determined from the FFA image was 12.2 {plus minus} 9.4 degrees. The mean SRA from the Pronated CT was significantly greater than both the Supinated CT (p<0.001) and the FFA SRA (p<0.005). There were no significant differences in mean SRA between the FFA and Supinated CT images (p=1.000). Results indicated a high reliability in measurements between investigators. Conclusions: Using weight-bearing CT, the findings of this study indicate that the sesamoids significantly alter their position in the coronal plane, as determined by the SRA, with changes in weight-bearing subtalar joint position. Moreover, the affected foot positioning required for determining the SRA from the forefoot axial radiograph appears to significantly underestimate the true SRA value. Thus, the use of this image in surgical HAV planning is called into question.
Article
Background: Modified Lapidus arthrodesis (MLA) is a well-established treatment modality for hallux valgus deformities (HVD) associated with instability of the first ray. Although the three-dimensional (3D) nature of HVD has long been recognized, diagnostics still focus on plain radiographs. The objective of this study was to validate 3D Cone Beam CT (CBCT) in the perioperative assessment of HVD with focus on the alignment of the forefoot. Methods: In a prospective clinical study, MLA was performed on 30 patients (25 females, 5 males; mean age: 63.2 years). Pre- and postoperatively standard radiographs and CBCT with full weight-bearing were acquired. For the CBCT based assessment, reproducible criteria have been defined, measured, and correlated with established radiological indicators. Results: Evaluation of standard radiographic parameters (hallux-valgus angle [HVA], intermetatarsal angle 1-2 [IMA 1-2], distal metatarsal articular angle [DMAA], tibial sesamoid position [TSP]) showed significant improvement postoperatively. Comparison of measurements obtained from plain radiographs and CBCT were significantly correlated between both measuring techniques, indicating high reliability. Pronation of the first metatarsal and the sesamoids were significantly reduced by the procedure. Due to this repositioning effect, the second metatarsal head was elevated by 3.1mm, and the lateral sesamoid was lowered by 3.8mm. However, there was no correlation between the amount of pronation and conventional radiographic measures. Conclusions: Compared to plain radiographs, CBCT allows a more detailed view of the forefoot alignment in the coronal plain after MLA. MLA was able to recenter the sesamoids under der first metatarsal head and conversely led to elevation of the second metatarsal head.
Article
Hallux valgus (HV) represents a progressive 3-dimensional deformity that includes bone malalignment, hypermobility of the first ray, and imbalanced soft-tissue structures of the midfoot and forefoot. Conventional radiographs provide sectorized and limited information of the deformity in different planes. The literature evidence supporting the use of cone beam weightbearing computed tomography in the assessment of HV has been growing. It demonstrates important advances that include the ability to reliably perform traditional measurements such as HV angle and intermetatarsal angle in the 3-dimensional setting.
Article
Hallux valgus is a common condition, and it still poses some challenges. The identification of factors associated with the development of the deformity is of paramount importance in obtaining a full correction of the disorder. Hallux pronation is one of the frequently found components, especially in larger deformities, but the cause and exact location of this condition are not fully understood. The aim of the present study was to investigate whether there is a rotational deformity inherent to the first metatarsal bone. A case-control study was conducted on patients with and without hallux valgus who were subjected to computed tomography with multiplanar reconstruction. Statistical analysis was performed by means of a mixed model adjusted for foot and gender to compare metatarsal rotation between cases and controls. Correlations between numerical quantitative measurements were investigated by means of Pearson's correlation coefficient obtained in a linear mixed model. A total of 82 feet (tests) were analyzed in the hallux valgus group and 64 feet (tests) in the control group (N = 146). The hallux valgus group was significantly different from the control group (p< .001). Mean metatarsal bone rotation was 15.36° (range 1.65° to 32.52°) in the hallux valgus group and 3.45° (range -7.40° to 15.56°) in the control group. The difference between the means was 11.9° (confidence interval 9.2° to 14.6°). In conclusion, patients with hallux valgus exhibited increased exclusive bone rotation of the first metatarsal toward pronation compared with the population without this condition.
Article
Background Hallux valgus (HV) is a triplanar deformity of the first ray including pronation of the first metatarsal with subluxation of the sesamoids. The purpose of this study was to investigate if a first tarsometatarsal fusion (modified Lapidus technique), without preoperative knowledge of pronation measured on weightbearing computed tomographic (CT) scans, changed pronation of the first metatarsal and determine if reduction of the sesamoids was correlated with changes in first metatarsal pronation. Methods Thirty-one feet in 31 patients with HV who underwent a modified Lapidus procedure had preoperative and at least 5-month postoperative weightbearing CT scans and radiographs. Differences in preoperative and postoperative pronation of the first metatarsal using a 3-dimensional computer-aided design, HV angle, and intermetatarsal angle (IMA) were calculated using Wilcoxon signed-rank tests. After dividing patients into groups based on sesamoid station, Kruskal-Wallis H tests were used to compare first metatarsal pronation between the groups. Results The mean preoperative and postoperative pronation of the first metatarsal was 29.0 degrees (range 15.8-51.1, SD 8.7) and 20.2 degrees (range 10.4-32.6, SD 5.4), respectively, which was a mean change in pronation of the first ray of −8.8 degrees ( P < .001). There was no difference in pronation of the first ray when stratified by postoperative sesamoid position ( P > .250). The average preoperative and postoperative IMA was 16.7 degrees (SD 3.2) and 8.8 degrees (SD 2.8), which demonstrated a significant change ( P < .001). Conclusions The modified Lapidus procedure was an effective tool to change pronation of the first ray. Reduction of the sesamoids was not associated with postoperative first metatarsal pronation. Level of Evidence Level IV, case series.
Article
Background: The purpose of this study was to clarify 1) the measurement error of the pronation angle using the first metatarsal axial radiograph with the pronation angle along the longitudinal axis of the first metatarsal as the reference standard, 2) the influence of variability in the foot position on the measurement error, and 3) the intra- and interrater reliability of pronation angle measurement using digitally reconstructed radiographs. Methods: Digitally reconstructed radiographs of the first metatarsal were generated from the computed tomography images of 10 feet without hallux valgus (non-HV group) and 10 feet with hallux valgus (HV group). In total, 135 images were created at different degrees of supination, plantarflexion, and adduction from each foot to simulate the first metatarsal axial view. Then, the pronation angle of the first metatarsal was measured. The measurement error was determined using the mean error and 95% limits of agreement. Simple linear regression analysis was used to test the correlations of the measurement error with pronation, plantarflexion and adduction angles. The intra- and interrater reliability of measurement was assessed using the intraclass correlation coefficient and minimum detectable change values. Results: The mean measurement errors were 0.1° for both the non-HV and HV groups. There was no significant correlation of the measurement error with pronation, plantarflexion or adduction angles for both groups. Additionally, the intraclass correlation coefficients for the intra- and interrater reliability were more than 0.9 in both the non-HV and HV groups with the minimum detectable change values ranging from 0.7° to 1.4°. Conclusion: The measurement error of first metatarsal pronation using the axial view was clinically acceptable. The measurements were not influenced by the variability in foot position while obtaining the radiograph. The first metatarsal axial view could be used to quantify the first metatarsal coronal rotation.
Article
Background Modified Bösch osteotomy (distal linear metatarsal osteotomy [DLMO]) is one of the minimally invasive correctional surgeries for hallux valgus. The 3-dimensional correctional angles and distances of the first metatarsal bone in DLMO have not been clarified. The purpose of this study was to analyze the 3-dimensional postoperative morphological changes of the first metatarsal bone in DLMO. Methods Twenty patients (30 feet) who underwent DLMO were enrolled. Preoperative plain radiographs and computed tomography (CT) scans of the feet were examined. Postoperative radiographs and CT scans were also obtained after bone union. The surface data of the pre- and postoperative first metatarsals were reconstructed from the CT data. The positions of the distal ends of the first metatarsals described with respect to the proximal ends were calculated using CT surface-matching technique. Results The distal end of the first metatarsal after DLMO was significantly supinated (10.2 ± 6.0 degrees, P < .001), adducted (6.0 ± 11.8 degrees, P = .004), dorsiflexed (11.1 ± 10.9, P < .001), shortened (7.4 ± 2.5 mm, P < .001), elevated (2.3 ± 3.1 mm, P = .001), and laterally shifted (8.2 ± 3.0 mm, P < .001) compared to the preoperative metatarsal distal end. Supination correction demonstrated a significant correlation with adduction correction ( r = 0.659, P < .001) on correlation analyses between these parameters. Conclusion The 3-dimensional corrections of the first metatarsal bone after DLMO were evaluated. Pronation and abduction were successfully corrected. Furthermore, adduction correction might be an important factor affecting correction of pronation. Level of Evidence Level IV, retrospective case series.
Article
Background: The purpose of this study was to evaluate the associations of the shape of the first metatarsal head with (1) the presence of osteoarthritis in the sesamoid-metatarsal joint and (2) the pronation angle of the first metatarsal head on foot radiographs. Methods: A total of 121 patients, with the mean age of 61 years, underwent weight-bearing dorsoplantar, lateral, and first metatarsal axial radiographs. The shape of the first metatarsal head's lateral edge was classified as either rounded, intermediate, or angular in shape in the dorsoplantar view. The presence of osteoarthritis in the sesamoid-metatarsal joint and the pronation angle of the first metatarsal head were assessed in the first metatarsal axial view. Other variables that could affect the first metatarsal shape, including the lateral first metatarsal inclination angle, were also assessed. Univariate and multivariate analyses were performed to determine the associations. Results: The prevalence of sesamoid-metatarsal osteoarthritis was significantly higher (77%, 27%, and 29% for rounded, intermediate, and angular, respectively, P < .001), and the metatarsal pronation angle was significantly larger (14°, 8°, and 4° for rounded, intermediate, and angular, respectively, P < .001) in feet with a rounded metatarsal head. These associations were also significant in the multiple regression analysis. Conclusion: A rounded metatarsal head was associated with a higher prevalence of osteoarthritis within the sesamoid-metatarsal joint, as well as a larger first metatarsal head pronation angle. A negative round sign can be used as a simple indicator of an effective correction to the first metatarsal pronation angle during hallux valgus surgery. However, in feet with sesamoid-metatarsal osteoarthritis, surgeons will need to be cautious as overcorrection may occur.
Article
Purpose To evaluate the rotational change in the first metatarsal bone (1MT) of the foot during natural standing using an upright computed tomography (CT) scanner with 320‐detector rows. Material and Methods A total of 52 feet of 28 asymptomatic subjects (aged 23‐39 years) were evaluated in the natural standing position with or without weight‐bearing. A foot pressure plate was used to determine the non‐weight‐bearing (NWB) or single leg full‐weight‐bearing (s‐FWB) conditions. CT examinations were performed using a noise index of 15 for a slice thickness of 5 mm, rotation speed of 0.5 s, and slice thickness of 0.5 mm. The rotation of the 1MT was measured on the coronal CT image, which cut the sesamoids’ bellies in the frontal slide of the first metatarsal and sesamoids perpendicular to the longitudinal bisection of the third metatarsal, and compared between the weight‐bearing conditions. Intra‐ and inter‐observer reliabilities of the rotation angle were also evaluated. Results The intra‐ and inter‐observer correlation coefficients were 0.961 and 0.934, respectively. The 1MT pronation angle was significantly greater in the s‐FWB condition than in the NWB condition (15.2°±5.4° vs. 12.5°±5.3°, p<0.01). No sex difference was found in the magnitude of the 1MT pronation angle as a result of weight‐bearing. Conclusions This study firstly demonstrated that pronation of 1MT occurs due to natural full‐weight‐bearing in asymptomatic feet. The 1MT's rotational movement under weight‐bearing conditions may relate to the onset and pathogenesis of the hallux valgus. This article is protected by copyright. All rights reserved.
Article
Background: The current work sought to quantify pronation of the first metatarsal relative to the second metatarsal and of the proximal phalanx of the great toe relative to the first metatarsal. Methods: Three-dimensional models were reconstructed from weightbearing computed tomography (CT) images (10 hallux valgus, 10 normal). The orientations of bones related to hallux valgus (HV) (ie, the phalanx, first and second metatarsals) were determined from coordinate systems established by selecting landmarks. After determining the hallux valgus and intermetatarsal angles, additional calculations geometrically determined the 3-dimensional (3D) angles using the aeronautical system of yaw-pitch-roll. The 3D geometrically determined angles were compared to the conventional plain radiographic angles. Results: HV measurements taken with CT and 3D computer-aided design (3DCAD) geometric methods were the same as measurements taken from plain radiographs (P > .05). The average pronation of the first metatarsal relative to the second metatarsal was 8.2 degrees greater in the hallux valgus group (27.3 degrees) than in the normal group (19.1 degrees) (P = .044). A regression analysis of pronation vs intermetatarsal angle (IMA) was not found to be significant. There was also no correlation between pronation of the great toe and first metatarsal in the HV group. Conclusions: The pronation angle of the first metatarsal relative to the second metatarsal between normal and hallux valgus patients was larger in HV patients but was not well correlated with the IMA. Clinical relevance: The findings of this study indicate that pronation may need to be considered in the operative correction of hallux valgus for restoration of normal anatomy.
Article
Hallux valgus (HV) is not a simple two-dimensional deformity but is instead a three-dimensional deformity that is closely linked to sesamoid position and first metatarsal (MT) pronation. HV may or may not be accompanied by sesamoid subluxation and/or first MT head pronation. Each of these scenarios should be assessed using weighted computed tomography scan preoperatively, and the necessary corrections should be performed accordingly.
Article
Background: The normal hindfoot angle is estimated between 2° and 6° of valgus in the general population. These results are solely based on clinical findings and plain radiographs. The purpose of this study is to assess the hindfoot alignment using weightbear CT. Methods: Forty-eight patients, mean age of 39.6±13.2 years, with clinical and radiological absence of hindfoot pathology were included. A weightbear CT was obtained and allowed to measure the anatomical tibia axis (TAx) and the hindfoot alignment (HA). The HA was firstly determined using the inferior point of the calcaneus (HAIC). A density measurement of this area was subsequently performed to analyze if this point concurred with an increased ossification, indicating a higher load exposure. Secondly the HA was determined by dividing the calcaneus in the long axial view (HALA) and compared to the (HAIC) to point out any possible differences attributed to the measurement method. Reliability was assessed using an intra class correlation coefficient (ICC). Results: The mean HAIC equaled 0.79° of valgus±3.2 (ICCHA IC=0.73) with a mean TAx of 2.7° varus±2.1 (ICCTA=0.76). The HALA equaled 9.1° of valgus±4.8 (ICCHA LA=0.71) and differed significantly by a P<0.001 from the HAIC, which showed a more neutral alignment. Correlation between both was shown to be good by a Spearman's correlation coefficient of 0.74. The mean density of the inferior calcaneal area equaled 271.3±84.1 and was significantly higher than the regional calcaneal area (P<0.001). Conclusions: These results show a more neutral alignment of the hindfoot in this group of non-symptomatic feet as opposed to the generally accepted constitutional valgus. This could have repercussion on hindfoot position during fusion or in quantifying the correction of a malalignment. The inferior calcaneus point in this can be used during pre-operative planning of a hindfoot correction as an anatomical landmark due to its shown influence on load transfer.
Article
Background: Some physicians report that patients with hallux valgus have hypermobility at the tarsometatarsal (TMT) joint of the first ray and 3-dimensional (3-D) deformity. With use of non-weight-bearing and weight-bearing computed tomography (CT), we evaluated the 3-D mobility of each joint of the first ray in feet with hallux valgus compared with normal feet. Methods: Ten feet of 10 patients with hallux valgus and 10 feet of 10 healthy volunteers with no foot disorders were examined. All participants were women. Weight-bearing (a load equivalent to body weight) and non-weight-bearing CT scans were made with use of a device that we developed. Orthogonal coordinate axes were set and a 3-D model was reconstructed. Each joint of the first ray was aligned with the respective proximal bone, and 3-D displacement of the distal bone relative to the proximal bone under loading was quantified. Results: At the talonavicular joint, significantly greater dorsiflexion of the navicular relative to the talus was observed in the hallux valgus group compared with the control group. At the medial cuneonavicular joint, the hallux valgus group showed significantly greater eversion and abduction of the medial cuneiform relative to the navicular. At the first TMT joint, the hallux valgus group showed significantly greater dorsiflexion, inversion, and adduction of the first metatarsal relative to the medial cuneiform. At the first metatarsophalangeal joint, the hallux valgus group showed significantly greater eversion and abduction of the first proximal phalanx relative to the first metatarsal (all p < 0.05). Conclusions: The results of this study suggest that loading of the foot causes significant 3-D displacement not only at the TMT joint but also at the other joints of the first ray. There is increased mobility in the first ray in patients who have hallux valgus.
Article
The limb deformity-based principles originate from a standard set of lower extremity radiographic angles and reference points. Objective radiographic measures are the building blocks for surgical planning. Critical preoperative planning and intraoperative and postoperative evaluation of radiographs are essential for proper deformity planning and correction of all foot and ankle cases. A total of 33 angles and reference points were measured on 24 healthy feet. The radiographic measurements were performed on standard weightbearing anteroposterior, lateral, and axial views of the right foot. A total of 4 measurements were made from the axial view, 12 from the lateral view, and 17 from the anteroposterior view. All angles were measured by both senior authors twice, independent of each other. The radiographic angles and measurements presented in the present study demonstrate a comprehensive and useful set of standard angles, measures, and reference points that can be used in clinical and perioperative evaluation of the foot and ankle. The standard radiographic measures presented in the present study provide the foundation for understanding the osseous foot and ankle position in a normal population.
Article
Background: A precise pre-operative measurement of hindfoot malalignment is paramount to plan and obtain an accurate surgical correction. Hindfoot alignment is currently determined on standard weightbearing radiographs. However this is hampered by the superposition of the skeletal structures. Recent technology developed weightbearing cone beam CT to overcome this problem. The objective is to introduce a clinically relevant and reproducible method to measure hindfoot alignment on weightbearing CT. Methods: Sixty malalignments of the hindfoot were divided in to two groups; group one containing a valgus alignment (n=30) and group two a varus alignment (n=30) of the hindfoot. Imaging techniques used were standard radiographs and a weightbearing CT (pedCAT(®)). Following angles were measured by two different authors: standard long axial hindfoot angle both on standard radiographs and on CT, clinical hindfoot, novel hindfoot angle, talar shift (distance from a neutral alignment), tibial inclination angle, talar tilt and subtalar vertical angle on CT. Results: Hindfoot alignment angles showed to significantly differ from each other (P<0.001). The novel hindfoot alignment angle showed the highest correlation with the clinical measurement method. Correlation of this novel angle with the talar shift showed a Spearman's correlation coefficient=0.87. Interclass correlation coefficient of the novel hindfoot alignment angle=0.72 and was the highest among the hindfoot alignment angles. Conclusion: Weightbearing CT is allows to objectively assess hindfoot alignment. The proposed novel hindfoot alignment angle showed to be both clinically relevant and reproducible as compared to previous methods. The lateral tibiocalcaneal shift, on which the angle is highly correlated to, can help the surgeon in determining how much translation is necessary to obtain a neutral alignment during a calcaneal osteotomy. Level of evidence: Level III: retrospective cohort study.
Article
Risk factors for hallux valgus recurrence include postoperative round-shaped lateral edge of the first metatarsal head and postoperative incomplete reduction of the sesamoids. To prevent the occurrence of such conditions, we developed a proximal supination osteotomy of the first metatarsal. Our aim was to describe this novel technique and report the outcomes in this report. Sixty-six patients (83 feet) underwent a distal soft tissue procedure combined with a proximal supination osteotomy. After the proximal crescentic osteotomy, the proximal fragment was pushed medially, and the distal fragment was abducted, and then the distal fragment of the first metatarsal was manually supinated. Outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) score and radiographic examinations. The average follow-up duration was 34 (range, 25 to 52) months. The mean AOFAS score improved significantly from 58.0 points preoperatively to 93.8 points postoperatively (P < .0001). The mean hallux valgus and intermetatarsal angle decreased significantly from 38.6 and 18.0 degrees preoperatively to 11.0 and 7.9 degrees postoperatively, respectively (both, P < .0001). Sixty-nine feet (69/83, 83%) had a positive round sign preoperatively, and 66 feet (66/83, 80%) had a negative round sign postoperatively. According to the Hardy's classification of position of the sesamoids, all feet were classified as grade V or greater preoperatively, and 49 feet (49/83, 59%) were classified as grade IV or less postoperatively. Three feet (3/83, 4%) had recurrence of hallux valgus, defined as a hallux valgus angle ≥ 25 degrees. The rates of occurrence of a positive round sign and incomplete reduction of the sesamoids significantly decreased postoperatively, which may have contributed to the low hallux valgus recurrence rates. We conclude that a proximal supination osteotomy was an effective procedure for correction of hallux valgus and can achieve a low rate of hallux valgus recurrence. Level IV, retrospective case series. © The Author(s) 2015.
Article
Hallux valgus is a common but aetiologically not perfectly understood condition. Imaging in hallux valgus is based on weight bearing plain radiographs or in exceptional cases on non-weight bearing computerized tomography (CT)-studies. A portable extremity CT was used to study the forefoot with focus on first metatarsal bone in ten hallux valgus patients and five asymptomatic controls at rest and at weight bearing. Two-dimensional (2D) or three-dimensional (3D) hallux valgus angles, intermetatarsal angles and various other parameters were measured on CT data and the measurements between study groups were compared. The measured angles were also compared to angles measured on plain radiographs. 2D or 3D angles from CT data sets can be used to evaluate hallux valgus. In hallux valgus, when compared with normal asymptomatic foot, the first metatarsal bone is medially deviated (intermetatarsal angle is wider), the width of the forefoot is increased and the proximal phalanx pronates. Between the study groups there was a statistically significant difference of the measured 3D hallux valgus angles at weight bearing but not at rest suggesting the importance of weight bearing CT studies when evaluating hallux valgus. To our knowledge, this is the first time weight bearing CT data is presented when evaluating hallux valgus, offering a true alternative to plain radiographs. The relationships of bones of the forefoot, including rotational changes, can be reliably measured using this imaging method.
Article
Objective: The purpose of this article is to describe weight-bearing CT of the lower extremity joints using a novel portable imager utilizing cone-beam CT technology. Conclusion: Cone-beam CT technology with new design and flexible gantry movements allows both supine and weight-bearing imaging of the lower extremities, with a reasonable radiation dose and excellent image quality. Weight-bearing CT of joints can provide important new clinical information in musculoskeletal radiology.
Article
We have devised a new intraoperative technique (supination stress of the great toe) in which correction of hallux valgus and metatarsus primus varus, and reduction of the sesamoids could be simultaneously obtained at hallux valgus surgery. The purpose of this study was to prospectively investigate the efficacy of supination stress for assessing intraoperative correction of hallux valgus. Thirty patients (31 feet) with an average age of 59.8 years who had hallux valgus were treated with a proximal metatarsal osteotomy. Supination stress under traction was manually applied to the great toe after release of the distal soft tissues and a proximal metatarsal osteotomy. C-arm fluoroscopy was used to verify correction of hallux valgus and to obtain dorsoplantar non-weightbearing images under supination stress. The dorsoplantar non-weightbearing fluoroscopic images were assessed preoperatively and at the time of intraoperative supination stress. The hallux valgus and intermetatarsal angles were measured. The position of the medial sesamoids was classified with a grading system ranging from I to VII as described by Hardy and Clapham. We defined a grade of IV or less as the normal position of the sesamoids and grade V or greater as lateral displacement of the sesamoids. The average hallux valgus angle was 34.3° preoperatively and 11.9° at the time of intraoperative supination stress. The average intermetatarsal angle was 16.4° preoperatively and 5.5° at the time of intraoperative supination stress (p < 0.0001, p < 0.0001, respectively). At the time of intraoperative supination stress, the hallux valgus angle was 20° or less in all feet, and the intermetatarsal angle was 10° or less in all feet. Preoperatively, all feet were classified as having lateral displacement of the sesamoids. At the time of intraoperative supination stress, all feet were classified as having normal positioning of the sesamoids. Supination stress of the great toe was an effective maneuver for assessing intraoperative correction of hallux valgus and metatarsus primus varus, and reduction of the sesamoids.
Article
Various radiographic measurements of the normal adult foot have been reported in both early and recent literature; however, a complete description of radiographic quantitative data has yet to be reported. The purpose of this study is to describe the range of the normal foot using standard radiographic techniques that can be applied to the clinical setting. This should provide the data necessary for the accurate interpretation of foot radiographs. This study demonstrates the wide variation in bony relationships of the normal adult foot. When certain recognized criteria of radiographic measurements were evaluated, some were found to be defined as too narrow or inaccurate. Most importantly, because of this wide range, surgical procedures to produce radiographic homogeneity are not indicated. Treatment should be directed specifically toward areas of pain and not radiographic appearance.
Article
Dissection and roentgenographic findings in 35 nonoperative cadaveric and freshly amputated feet were correlated with disorders of the first day--specifically the sesamoids. There are four noteworthy factors associated with first ray pathology. The most significant are axial rotation of the first metatarsal bone and degenerative changes at the first metatarsophalangeal joint. Significant anatomic variations can be correlated with failed bunion surgery.
Article
This study describes a method of detecting first metatarsal pronation on the basis of the movement of the inferior tuberosity of the base of 20 cadaveric first metatarsals at 0 degrees, 10 degrees, 20 degrees and 30 degrees pronation. On pronation, the inferior tuberosity of the base of the first metatarsal moved lateral to the mid-line axis. At 10 degrees, the tuberosity pointed to the junction of the inner third and outer two-thirds of a line between the midpoint and lateral tubercle of the base. At 20 degrees, it pointed to the junction of the inner two-thirds and outer third of that line. At 30 degrees, it pointed to the outer margin of the lateral third. Using these features, the amount of first metatarsal pronation in 100 consecutive weight-bearing views of feet was recorded and plotted against the corresponding intermetatarsal angles in those feet. Four of 43 patients with an intermetatarsal angle of less than 9 degrees had pronation greater than 10 degrees, 48 of 57 patients with an intermetatarsal angle greater than 9 degrees had pronation greater than 10 degrees (P < 0.001). As intermetatarsal angles increase, the amount of first metatarsal pronation increases (r = 0.69). Pronation and varus deviation of the first metatarsal are linked; both alter the tendon balance maintaining proximal phalanx alignment and lead to the development of hallux valgus.
Article
A method for measuring first metatarsal rotation on weightbearing tangential radiographs is described. Under controlled conditions using cadaver specimens, 5 degree changes in first metatarsal rotation were associated with a mean change in radiographically measured rotation of 5.4 degrees (SD = 1.7 degrees). A clinical study of 30 hallux valgus and 30 control patients was undertaken to assess the reliability of the method of measurement. The overall reliability was high for both hallux valgus and control patients (r = 0.93 and 0.95, respectively). In these two groups, no significant difference was found between the mean values for first metatarsal rotation. Likewise, we found no correlation between first metatarsal rotation measured on tangential standing ("sesamoid" view) radiographs and the first metatarsophalangeal angle or the intermetatarsal 1-2 angle measured on anteroposterior standing radiographs.
Article
The position of the hallucal sesamoids needs to be included in evaluation of hallux valgus. In order to quantify the rotational position of the hallucal sesamoids, a new weightbearing tangential radiograph was established by means of a specially designed tangential positioning device. This device has a depression, and a tangential radiograph is taken with the metatarsophalangeal joint at 45° dorsiflexion. A lead marker plate is placed on the depression to show the horizontal plane, and the sesamoid rotation angle (SRA) is measured. The SRA is the angle between the tangential line of the most inferior aspect of the medial-lateral sesamoids and the lead marker line. The SRA was compared with values of the four-grade scale and seven-position scale which were measured from the antero-posterior view, with respect to the hallux valgus angle (HVA), by means of conventional methods. Measurements were made of 58 feet in 29 patients with hallux valgus and 64 feet in 32 normal subjects. The SRA showed the highest correlation among the three parameters (r = 0.817). Some cases had a disparity regarding the position of the sesamoids between the tangential view and the AP view due to misclassification on the AP view. We conclude that the scale of position of the sesamoid on the AP view is not valid in some cases, whereas the SRA is useful for assessing quantitatively the rotational position of the hallucal sesamoids in cases of hallux valgus.
Article
Knee alignment is an essential problem in reconstructive surgeries of the knee. Quite a number of reference parameters have been suggested to help the surgeons to get proper alignment during operations. In this article, most commonly used reference axes, both for the axial and the rotational, are reviewed, in an attempt to highlight their reliabilities and clinical relevance.
Article
Lateral displacement of the sesamoids of the first toe relative to the metatarsal head is a common finding in hallux valgus deformity. Several methods have been described for quantifying the amount of subluxation from anteroposterior radiographs but a tangential sesamoid radiograph has been determined to be the best view to evaluate sesamoid displacement. We evaluated the sesamoid position at different angles of the first metatarsophalangeal (MTP) joint to determine the effect of first MTP joint dorsiflexion on sesamoid position when tangential sesamoid view radiographs are made. Sesamoid positions of 22 feet with hallux valgus were graded from the short axis computed tomography (CT) images obtained with the MTP joint in 0, 35, and 70 degrees of dorsiflexion. Approximation of the sesamoids to reduction was apparent as dorsiflexion of the first MTP joint increased. Different dorsiflexion degrees of the first MTP joint when tangential sesamoid radiographs are made modulate the position of the sesamoids and may lead to misclassification on grading.
Article
Radiographic angular measurements are commonly used in decision making in adult foot and ankle surgery. Unfortunately, there are few controlled studies available to substantiate comprehensive radiographic values in the adult foot. The purpose of this study was to determine the values of a variety of radiographic measurements of the adult foot in a standardized population. A total of 100 participants, 50 men and 50 women (200 feet), were evaluated. Individuals with a history of foot/ankle pain, previous foot/ankle operation or fracture, or a history of systemic disease were excluded from the study. Bilateral weight-bearing digital anterior-posterior and lateral radiographs were taken using a standardized method. In all, 21 measurements were made in the anterior-posterior view and 9 in the lateral view for a total of 6000 measurements. Some traditional measurement techniques of selected angles were found to be not consistently reproducible and alternative consistently reproducible techniques are described. Results are given in table form for maximum, minimum, average, median, and SD. Left and right foot maximum, minimum, and average differences were determined. Differences were also briefly explored for age and sex.