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Repeatability of Weightbearing Computed Tomography Measurement of First Metatarsal Alignment and Rotation
Abstract
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.
... b JSW test-retest repeatability limits of agreement (mm) displayed across the template. Inner surface aspects with respect to the talus are shaded grey Although reproducibility is often cited in published studies, test-retest repeatability is rarely reported [14,19], yet it is critical for understanding repeat performance. To the best of our knowledge, this has not been previously reported for 3-D JSW measurements at the ankle. ...
Objectives:
We present a 3-D approach to joint space width (JSW) measurement across the ankle from weight-bearing CT (WBCT) to demonstrate inter-operator reproducibility, test-retest repeatability, and how differences in angulation affect ankle JSW distribution.
Methods:
One side from repeat WBCT imaging of both feet and ankles was analysed from 23 individuals as part of their routine clinical care pathway. Joint space mapping was performed at four facets across the talus: talonavicular, talar dome and medial gutter (dome-medial), lateral gutter, and posterior subtalar. Inter-operator reproducibility was calculated for two users, while test-retest repeatability was calculated by comparing the two visits, both presented as Bland-Altman statistics. Statistical parametric mapping determined any significant relationships between talocrural joint space angulation and 3-D JSW distribution.
Results:
The average ± standard deviation interval between imaging was 74.0 ± 29.6 days. Surface averaged bias ± limits of agreement were similar for reproducibility and repeatability, the latter being: talonavicular 0.01 ± 0.26 mm, dome-medial 0.00 ± 0.28 mm, lateral gutter - 0.02 ± 0.40 mm, and posterior subtalar 0.02 ± 0.34 mm. Results are presented as 3-D distribution maps, with optimum test-retest repeatability reaching a smallest detectable difference of ± 0.15 mm.
Conclusions:
Joint space mapping is a robust approach to 3-D quantification of JSW measurement, inter-operator reproducibility, and test-retest repeatability at the ankle, with sensitivity reaching a best value of ± 0.15 mm. Standardised imaging protocols and optimised metal artefact reduction will be needed to further understand the clinical value of these 3-D measures derived from WBCT.
Clinical relevance statement:
Weight-bearing computed tomography is an increasingly important tool in the clinical assessment of orthopaedic ankle disorders. This paper establishes the performance of measuring 3-D joint space width using this technology, which is an important surrogate marker for severity of osteoarthritis.
Key points:
• Joint space width values and error metrics from across the ankle measured from weight-bearing CT can be presented as 3-D maps that show topographic variation. • The best sensitivity for detecting meaningful change in 3-D joint space width at the ankle was ± 0.15 mm, a value less than the isotropic imaging voxel dimensions. • Standardised imaging protocols and optimised metal artefact reduction will be needed to understand the clinical value of 3-D measures from weight-bearing CT.
... & 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. ...
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.
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.
The 3D anatomical complexity of the foot and ankle and the importance of weight-bearing in diagnosis have required the combination of conventional radiographs and medical CT.
Conventional plain radiographs (XR) have demonstrated substantial limitations such as perspective, rotational and fan distortion, as well as poor reproducibility of radiographic installations. Conventional CT produces high levels of radiation exposure and does not offer weight-bearing capabilities.
The literature investigating biometrics based on 2D XR has inherent limitations due to the technology itself and thereby can focus only on whether measurements are reproducible, when the real question is whether the radiographs are.
Low dose weight-bearing cone beam CT (WBCT) combines 3D and weight-bearing as well as ‘built in’ reliability validated through industry-standardized processes during production and clinical use (quality assurance testing).
Research is accumulating to validate measurements based on traditional 2D techniques, and new 3D biometrics are being described and tested.
Time- and cost-efficient use in medical imaging will require the use of automatic measurements. Merging WBCT and clinical data will offer new perspectives in terms of research with the help of modern data analysis techniques.
Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170066
Objective
To determine the test–retest reliability of knee joint space width (JSW) measurements made using standing CT (SCT) imaging. Subjects and methodsThis prospective two-visit study included 50 knees from 30 subjects (66% female; mean ± SD age 58.2 ± 11.3 years; BMI 29.1 ± 5.6 kg/m2; 38% KL grade 0–1). Tibiofemoral geometry was obtained from bilateral, approximately 20° fixed-flexed SCT images acquired at visits 2 weeks apart. For each compartment, the total joint area was defined as the area with a JSW <10 mm. The summary measurements of interest were the percentage of the total joint area with a JSW less than 0.5-mm thresholds between 2.0 and 5.0 mm in each tibiofemoral compartment. Test–retest reliability of the summary JSW measurements was assessed by intraclass correlation coefficients (ICC 2,1) for the percentage area engaged at each threshold of JSW and root-mean-square errors (RMSE) were calculated to assess reproducibility. ResultsThe ICCs were excellent for each threshold assessed, ranging from 0.95 to 0.97 for the lateral and 0.90 to 0.97 for the medial compartment. RMSE ranged from 1.1 to 7.2% for the lateral and from 3.1 to 9.1% for the medial compartment, with better reproducibility at smaller JSW thresholds. Conclusion
The knee joint positioning protocol used demonstrated high day-to-day reliability for SCT 3D tibiofemoral JSW summary measurements repeated 2 weeks apart. Low-dose SCT provides a great deal of information about the joint while maintaining high reliability, making it a suitable alternative to plain radiographs for evaluating JSW in people with knee OA.
http://rdcu.be/ncdQ
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.
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.
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.
Hallux valgus is a common orthopaedic condition affecting elderly people. Grading the severity of the condition commonly involves obtaining measurements from radiographs, which may not be feasible or necessary in some clinical or research settings. Recently, a non-invasive clinical assessment tool (the Manchester scale), consisting of four standardized photographs, has been developed; however, its validity has not yet been determined. Therefore, the objective of this study was to determine the validity of this tool by correlating Manchester scale scores with hallux valgus measurements obtained from radiographs.
Weight-bearing dorsoplantar foot radiographs were obtained from 95 subjects (31 men and 64 women) aged 62-94 yr (mean 78.6, s.d. 6.5), and measurements of the hallux abductus angle, intermetatarsal angle and hallux interphalangeal adbuctus angle were performed. These measurements were then correlated with the Manchester scale scores (none, mild, moderate or severe).
The Manchester scale score was highly correlated with hallux abductus angle (Spearman's rho = 0.73, P<0.01) and moderately associated with intermetatarsal angle (rho = 0.49, P<0.01) measurements obtained from radiographs. Analysis of variance revealed significant differences in mean hallux abductus angles [F3 = 119.99, P<0.001] and intermetatarsal angles [F3 =29.56, P<0.001] between the four Manchester scale categories.
These findings indicate that the Manchester scale provides a valid representation of the degree of hallux valgus deformity determined from radiographic measurement of hallux abductus angle and intermetatarsal angle. We therefore recommend the use of this instrument as a simple, non-invasive screening tool for clinical and research purposes.
Changes in scores on health status questionnaires are difficult to interpret. Several methods to determine minimally important changes (MICs) have been proposed which can broadly be divided in distribution-based and anchor-based methods. Comparisons of these methods have led to insight into essential differences between these approaches. Some authors have tried to come to a uniform measure for the MIC, such as 0.5 standard deviation and the value of one standard error of measurement (SEM). Others have emphasized the diversity of MIC values, depending on the type of anchor, the definition of minimal importance on the anchor, and characteristics of the disease under study. A closer look makes clear that some distribution-based methods have been merely focused on minimally detectable changes. For assessing minimally important changes, anchor-based methods are preferred, as they include a definition of what is minimally important. Acknowledging the distinction between minimally detectable and minimally important changes is useful, not only to avoid confusion among MIC methods, but also to gain information on two important benchmarks on the scale of a health status measurement instrument. Appreciating the distinction, it becomes possible to judge whether the minimally detectable change of a measurement instrument is sufficiently small to detect minimally important changes.
Reproducibility concerns the degree to which repeated measurements provide similar results. Agreement parameters assess how close the results of the repeated measurements are, by estimating the measurement error in repeated measurements. Reliability parameters assess whether study objects, often persons, can be distinguished from each other, despite measurement errors. In that case, the measurement error is related to the variability between persons. Consequently, reliability parameters are highly dependent on the heterogeneity of the study sample, while the agreement parameters, based on measurement error, are more a pure characteristic of the measurement instrument.
Using an example of an interrater study, in which different physical therapists measure the range of motion of the arm in patients with shoulder complaints, the differences and relationships between reliability and agreement parameters for continuous variables are illustrated.
If the research question concerns the distinction of persons, reliability parameters are the most appropriate. But if the aim is to measure change in health status, which is often the case in clinical practice, parameters of agreement are preferred.
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.
Background:
First metatarsal (M1) axial rotation is recognized as a clinically relevant component of hallux valgus deformity. Methods to realign the M1 in 3 dimensions have been developed. One goal of these operations is to restore normal rotation of the first ray. The aim of this study is to provide estimates for the normal distribution of M1 rotation in patients without relevant anatomic pathology.
Methods:
Using stringent clinical and radiographic criteria, we evaluated a set of plain radiograph and weightbearing computed tomography (WBCT) images of 62 feet from a consecutive patient database. Subjects included had normal foot alignment without bunion symptoms. M1 rotation of each foot was measured using 2 unique methods (Saltzman et al and Kim et al methods). Measurement of rotation was performed by 2 observers from coronal WBCT images. Mean values and confidence intervals (CIs) of M1 rotation were calculated for each method. Inter- and intraobserver reliability values were also reported.
Results:
Mean M1 rotation values of 2.1 degrees (95% CI: 0.9-3.4) and 6.1 degrees (95% CI: 4.4-7.8) were identified using the Saltzman et al and Kim et al methods, respectively. Inter- and intraobserver reliability values were interpreted as excellent for both methods.
Conclusion:
In this study, we describe the natural distribution of the M1 axial rotation in subjects without bunion or other identifiable bony foot deformities. This information should provide a normative reference for surgeons correcting rotational issues of the first metatarsal.
Level of evidence:
Level III.
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.
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.
With the development of recent technology, radiographs can be saved digitally, and angular measurements can be processed using various software packages. We developed an innovative computer-aided design method with Materialize Interactive Medical Image Control System software to measure hallux valgus angle (HVA), the intermetatarsal angle (IMA), and the distal metatarsal articular angle (DMAA) and assessed its concordance with traditional X-ray imaging methods. All measurements were carried out on 42 feet from 26 adult patients diagnosed with hallux valgus who were prospectively selected from July 2016 to April 2018. Standing X-ray radiograph and weightbearing computed tomography scans were conducted on all patients, and HVA, IMA, and DMAA were generated using both a traditional X-ray method and our innovative method. Two different observers assessed measurements for each patient. Finally, statistical analyses were conducted to assess the reliability of the measurements. Both X-ray imaging and our innovative method had strong interobserver and test-retest reliability. The ICC of X-ray imaging was 0.945, p < .001, and the ICC of the innovative method was 0.915, p < .001. There was no statistical difference between the 2 methods for HVA and IMA measurements (p > .05); however, a difference was detected for DMAA (p < .05). Bland-Altman analyses demonstrated a high degree of agreement between the 2 methods for HVA and IMA, but a significant difference for DMAA. From the results, we concluded that our innovative computer-aided design method is a feasible, reliable way to quantitatively assess HVA, IMA, and DMAA, and it is likely more accurate for measuring DMAA.
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.
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.
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.
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.
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.
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.
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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.
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.
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.
Objective:
Intraclass correlation coefficient (ICC) is a widely used reliability index in test-retest, intrarater, and interrater reliability analyses. This article introduces the basic concept of ICC in the content of reliability analysis.
Discussion for researchers:
There are 10 forms of ICCs. Because each form involves distinct assumptions in their calculation and will lead to different interpretations, researchers should explicitly specify the ICC form they used in their calculation. A thorough review of the research design is needed in selecting the appropriate form of ICC to evaluate reliability. The best practice of reporting ICC should include software information, "model," "type," and "definition" selections.
Discussion for readers:
When coming across an article that includes ICC, readers should first check whether information about the ICC form has been reported and if an appropriate ICC form was used. Based on the 95% confident interval of the ICC estimate, values less than 0.5, between 0.5 and 0.75, between 0.75 and 0.9, and greater than 0.90 are indicative of poor, moderate, good, and excellent reliability, respectively.
Conclusion:
This article provides a practical guideline for clinical researchers to choose the correct form of ICC and suggests the best practice of reporting ICC parameters in scientific publications. This article also gives readers an appreciation for what to look for when coming across ICC while reading an article.
A survey of this type cannot be used to point to any definite factor or factors predisposing to the development of hallux valgus. Nevertheless, a comparison of measurements in the morbid and control groups shows several outstanding differences:
1) There was a high degree of correlation between valgus and intermetatarsal angle in the two groups combined (coefficient, 0·7) but the correlation was higher in those cases with a degree of valgus greater than 25 degrees than in the remainder (coefficients, 0·36 and 0·53).
2) In the control group the first metatarsal was longer than tile second by a mean measure of 2 millimetres; in the morbid group by a mean measure of 4 millimetres. For a high degree of valgus and a low intermetatarsal angle the first metatarsal tends to be longer than the second by a significantly greater amount than when the high valgus is associated with iligh intermetatarsal angle.
3) In 90 per cent of the control cases there was a lateral displacement of the medial sesamoid of the first metatarsal of 3 degrees or less, whereas 88 per cent of the morbid group showed a displacement of 4 degrees or more. There was very little overlap in the distributions of this observation in the two groups. There was a high correlation between the degree of this displacement and the severity of hallux valgus.
4) Rotation of the hallux was not observed among the controls; in the morbid group those cases showing rotation had an average degree of valgus of 36 degrees while the rest had an average of 19 degrees. The mean degree of valgus in the morbid group was 32·0 degrees and that of the controls 15·5 degrees. The mean angle between the axes of the first and second metatarsals was 13·0 degrees in the morbid group and 8·5 degrees in the controls.
Since tile morbid group consisted largely of women (98 per cent) it is important to know that in the control group the only measure showing a statistically significant sex difference is that of intermetatarsal angle, but that, even so, the mean difference is only 1·3 degrees. Thus tile sex difference between the two groups is probably only of minor importance. The role of age in influencing the observations cannot be clearly elucidated from the data at present available. It can only be stated that there is no positive indication that age is a controlling factor in the departure observed in the morbid group from the control observations.
Evolution of the terminology applied to the bunion deformity has progressed in parallel with our changing understanding of the deformity itself. Along this path of progression have been multiple terms, sometimes with multiple meanings. Hallux valgus and metatarsus primus varus are 2 of the most common terms for the deformity. Although commonly used, these descriptors can have multiple meanings, and inconsistencies in interpretation can lead to confusion. We propose a more detailed terminology to provide a more accurate description of the entire bunion deformity in 3 planes and for both the hallux and the metatarsal component of the deformity. The term we propose is hallux abducto valgus with metatarsus primus adducto valgus. An accurate understanding of the multiplanar position of the deformed foot is important for planning deformity correction. The descriptors in the terminology proposed will keep in the forefront the aspects of correction required for the first ray and hallux to be returned to an anatomically correct position.
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.
Background:
Radiographic angles are commonly used in patients with hallux valgus deformity to assess the severity, plan surgery, assess outcome and compare results. Many different manual methods have been used, but are prone to error. More recently computer-assisted methods using software have become available.
Objective:
To review the different methods that have been used to measure radiographic angles in hallux valgus.
Method:
A general literature search using relevant key words was undertaken using databases such as Medline, Embase, Cinahl and Cochrane Library. REVIEW FINDINGS AND DISCUSSION: The manual methods used are prone to errors. The reliability can be improved by using standardised radiographic technique and measurement technique using specific reference points. Computer-assisted methods using software, might improve reliability of measurements. Further studies are needed to assess if these methods are easy to use, and to compare different software's that are available. Specifically designed software for the foot might further improve the reliability of radiographic measurements in hallux valgus.
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.
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.
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.