Article

3D imaging for hindfoot alignment assessment: a comparative study between non-weight-bearing MRI and weight-bearing CT

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Abstract

Purpose: The authors compared measurements of hindfoot alignment on MR imaging with weight-bearing CT (WB-CT) to establish the degree of correlation. Forty-seven feet in 44 patients had weight-bearing CT and MRI studies performed on the same day. Materials and methods: Hindfoot alignment on MRI was assessed by two radiologists who calculated tibiocalcaneal angle (TCA) and calcaneofibular ligament angle (CFLA). On WB-CT, foot ankle offset (FAO), calcaneal offset (CO) and hindfoot angle (HA) were assessed by a senior Foot and Ankle Surgeon using dedicated software. Pearson correlation coefficient was used to evaluate the correlation between these measurements. Results: The study group comprised 27 males and 17 females with a mean age of 45 years (range 13-79 years). A statistically significant positive correlation was identified between TCA on MRI and all measurements of hindfoot alignment on WB-CT (p = 0.001-0.005). The CFLA on MRI only had significant correlation with CO on WB-CT (p = 0.03). A significant negative correlation was observed between both MRI parameters (p < 0.001). Conclusion: A highly significant correlation between tibiocalcaneal angle on non-weight-bearing ankle MR imaging and hindfoot alignment measurements on weight-bearing CT was identified.

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... These modern CBCT devices can provide 3D scans in weight-bearing, which is particularly valuable for foot and ankle studies 20-24 . This new feature adds to the demonstrated relatively low radiation, high spatial resolution, and convenient ergonomy and post-processing 13,25-29 , making this technology fundamental nowadays in many clinical studies 6,7,10,[12][13][14][15][16][20][21][22][23][26][27][28]30 . The load can be modulated from case to case, ranging from standard single-or doubleleg up-right postures to other postural conditions with the leg under determined and controlled positions 13 . ...
... All these advancements may also be supported by modern visualisation modalities, for example from virtualreality or 3D printing. The present techniques and measures shall be combined with other medical imaging 23 and biomechanical 13,47,56,64 analyses, for a thorough 3D radiological and functional assessments of the severity of the pathology and of the effects of treatments. Finally, distance map analyses can detect very carefully how the disruption of the skeletal structure affects the joint surface interactions under load 65 . ...
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... These modern devices provide valuable 3D scans of the foot and ankle with subjects in one-or two-leg stance 15-19 , with low radiation doses, high spatial resolution, convenient ergonomy and suitable post-processing 7,20-24 . CBCT scans are proving to be very valuable in many different clinical contexts 1,5,7,12,[14][15][16][17][18][21][22][23]25,26 , but the assessment of hindfoot alignment angle (HAA) in severely deformed feet can be among the areas of most considerable benefit. ...
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The first goal of this study was to develop reliable three‐dimensional definitions of alignment for the ankle, subtalar, and hindfoot joints. These alignments are based on three‐dimensional morphological features derived from renderings of the bones obtained from weightbearing computer tomography. The second goal was to establish a database quantifying the alignment of the ankle, subtalar, and hindfoot joints in a healthy population during weightbearing bilateral standing. This level 1 study was performed on 95 normal subjects in which random subjects were recruited into a control group. Weightbearing computed tomography scans of the leg were collected in neutral, bilateral, standing posture. In 30 of the subjects, both the left and right leg was scanned. Six alignment parameters for each joint were calculated from morphological measurements conducted on three‐dimensional renderings of the bones. Intra‐ and intertester reliability was assessed from repeated measurements by several testers. Analysis of variance statistics of the alignment parameters showed no statistical differences due to age, gender, or foot side. Intraclass correlation coefficient analysis showed excellent inter‐ and intratester reliability. It was concluded that the alignment process is comprehensive and reliable. Therefore, without classification by gender or age, it may be used as a foundation for quantifying abnormal alignment associated with various ankle deformities. Clinical significance: The alignment methodology and control database may be used to diagnose ankle, subtalar, and hindfoot misalignment. It can also serve as basis for surgical planning designed to restore normal alignment in various hindfoot pathologies, such as ankle realignment in total ankle replacement.
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The term progressive collapsing foot deformity (PCFD) is currently recommended as the replacement to adult-acquired flatfoot deformity and posterior tibial tendon dysfunction to better reflect its pathology, which consists of a complex three-dimensional deformity involving the foot and ankle. The new consensus has also provided a new classification that requires clinical and radiographic findings for patient stratification into each class. However, conventional radiographs are susceptible to errors resulting from the inadequate positioning of patients, incorrect angulation of the X-ray tube, and overlapping of bone structures. Weightbearing cone beam computed tomography (WBCBCT), which has greater diagnostic accuracy than conventional radiograph, is useful for evaluating progressive collapsing foot deformity to determine medial arch collapse, hindfoot alignment, peritalar subluxation, posterior subtalar joint valgus, intrinsic talus valgus, and lateral extra-articular bone impingement. The present review aimed to discuss the new recommendations for nomenclature, classification, and imaging evaluation of PCFD, with an illustrative and quantitative focus on the measurements used in conventional radiography and WBCBCT. The measurements presented here are important criteria for decision-making.
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Undiagnosed medial ankle instability can be a prerequisite for pathogenic progression in the foot, particularly for adult acquired flatfoot deformity. With the complex anatomy in this region, and the limitations of each individual investigational method, accurately identifying peritalar instability remains a serious challenge to clinicians. Performing a thorough clinical examination aided by evaluation with advanced imaging can improve the threshold of detection for this condition and allow early proper treatment to prevent further manifestations of the instability.
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Background A simple, non-quantitative, and cost-effective diagnostic tool would enable the diagnosis of flatfoot without need for specialized training. A simple footprint assessment board that investigates which toe the cord passes through from the centre point of the heel to the most lateral point of the medial contour of the footprint has been developed to assess flatfoot. The purpose of this study was to verify the validity of a simple footprint assessment board for flatfoot. Methods Thirty-five consecutive patients with foot pain, foot injury, or any associated symptoms who underwent computed tomography (CT) were analysed prospectively. At the time of the CT scan, a footprint analysis using a simple footprint assessment board was performed. The navicular index, tibiocalcaneal angle, and calcaneal inclination angle were evaluated by CT to assess flat feet. These three criteria were compared to those evaluated with the simple footprint assessment board by regression analysis. In addition, the same analysis was conducted separately for young, middle-aged, and older patients in order to investigate each age group. Results The navicular index and tibiocalcaneal angle generally decreased as the score of the simple footprint assessment board increased. Calcaneal inclination angle generally increased as the score of the simple footprint assessment board increased. As the scores of the simple footprint assessment board decreased by approaching the great toe, the navicular index and tibiocalcaneal angle were higher and calcaneal inclination angle was lower, which is indicative of a higher likelihood of flatfoot. The scores derived from the simple footprint assessment board was correlated with these three criteria measured by CT, not only when the result of simple footprint assessment board was set as a non-continuous variable but also when the result was set as a continuous variable. The results of the age-stratified survey were similar for all groups. Conclusions The findings of this study suggest that a simple footprint assessment board can be potentially useful to detect flatfoot. Trial registration Retrospectively registered.
Article
Objective Hindfoot malalignment is a relatively common clinical finding and several studies have suggested that hindfoot valgus can be identified on non-weight-bearing ankle MRI. The aim of this study was to determine the awareness of hindfoot malalignment on ankle MRI amongst consultant musculoskeletal radiologists.Materials and methodsAll MRI studies referred by Foot and Ankle Unit Consultants reported by one of 14 consultant musculoskeletal radiologists between March 2016 and August 2019 were retrieved from the Hospital Radiology Information System. These were reviewed independently by a radiology fellow and a consultant radiologist. Tibiocalcaneal angle (TCA) was measured, and extra-articular talocalcaneal (EA-TCI) and calcaneofibular impingement (EA-CFI) were recorded. Radiology reports were then analysed for mention of hindfoot malalignment and the presence of EA-TCI and EA-CFI.ResultsThe study group comprised 129 patients, 46 males and 83 females with a mean age of 46.8 years (range 8–84 years). Based on review, hindfoot valgus was present in 78–80 cases (60.5–62%), EA-TCI in 30–36 cases (23.2–27.9%) and EA-CFI in 18–21 cases (14–16.3%). By comparison, MRI reports mentioned hindfoot valgus in 18 cases (2 incorrectly), EA-TCI in 8 cases (1 incorrectly) and EA-CFI in 10 cases (1 incorrectly).Conclusion Hindfoot valgus, EA-TCI and EA-CFI were present relatively commonly on review of ankle MRI studies in patients referred from a specialist Foot and Ankle Unit but were commonly under-reported highlighting a relative lack of awareness of hindfoot malalignment on ankle MRI amongst musculoskeletal radiologists, which could impact negatively on patient management.
Article
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Adult acquired flatfoot deformity (AAFD) is a common disorder that typically affects middle-aged and elderly women, resulting in foot pain, malalignment, and loss of function. The disorder is initiated most commonly by degeneration of the posterior tibialis tendon (PTT), which normally functions to maintain the talonavicular joint at the apex of the three arches of the foot. PTT degeneration encompasses tenosynovitis, tendinosis, tendon elongation, and tendon tearing. The malaligned foot is initially flexible but becomes rigid and constant as the disorder progresses. Tendon dysfunction commonly leads to secondary damage of the spring ligament and talocalcaneal ligaments and may be associated with injury to the deltoid ligament, plantar fascia, and other soft-tissue structures. Failure of multiple stabilizers appears to be necessary for development of the characteristic planovalgus deformity of AAFD, with a depressed plantar-flexed talus bone, hindfoot and/or midfoot valgus, and an everted flattened forefoot. AAFD also leads to gait dysfunction as the foot is unable to change shape and function adequately to accommodate the various phases of gait, which require multiple rapid transitions in foot position and tone for effective ambulation. The four-tier staging system for AAFD emphasizes physical examination findings and metrics of foot malalignment. Mild disease is managed conservatively, but surgical procedures directed at the soft tissues and/or bones become necessary and progressively more invasive as the disease progresses. Although much has been written about the imaging findings of AAFD, this article emphasizes the anatomy and function of the foot's stabilizing structures to help the radiologist better understand this disabling disorder. Online supplemental material is available for this article.©RSNA, 2019.
Article
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Adult-acquired flatfoot deformity (AAFD) comprises a wide spectrum of ligament and tendon failure that may result in significant deformity and disability. It is often associated with posterior tibial tendon deficiency (PTTD), which has been linked to multiple demographic factors, medical comorbidities, and genetic processes. AAFD is classified using stages I through IV. Nonoperative treatment modalities should always be attempted first and often provide resolution in stages I and II. Stage II, consisting of a wide range of flexible deformities, is typically treated operatively with a combination of soft tissue procedures and osteotomies. Stage III, which is characterized by a rigid flatfoot, typically warrants triple arthrodesis. Stage IV, where the flatfoot deformity involves the ankle joint, is treated with ankle arthrodesis or ankle arthroplasty with or without deltoid ligament reconstruction along with procedures to restore alignment of the foot. There is limited evidence as to the optimal procedure; thus, the surgical indications and techniques continue to be researched.
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Background: Hindfoot alignment on 2D radiographs can present anatomical and operator-related bias. In this study, software designed for weightbearing computed tomography (WBCT) was used to calculate a new 3D biometric tool: the Foot and Ankle Offset (FAO). We described the distribution of FAO in a series of data sets from clinically normal, varus, and valgus cases, hypothesizing that FAO values would be significantly different in the 3 groups. Methods: In this retrospective cohort study, 135 data sets (57 normal, 38 varus, 40 valgus) from WBCT (PedCAT; CurveBeam LLC, Warrington, PA) were obtained from a specialized foot and ankle unit. 3D coordinates of specific anatomical landmarks (weightbearing points of the calcaneus, of the first and fifth metatarsal heads and the highest and centermost point on the talar dome) were collected. These data were processed with the TALAS system (CurveBeam), which resulted in an FAO value for each case. Intraobserver and interobserver reliability were also assessed. Results: In normal cases, the mean value for FAO was 2.3% ± 2.9%, whereas in varus and valgus cases, the mean was -11.6% ± 6.9% and 11.4% ± 5.7%, respectively, with a statistically significant difference among groups ( P < .001). The distribution of the normal population was Gaussian. The inter- and intraobserver reliability were 0.99 +/- 0.00 and 0.97 +/-0.02 Conclusions: This pilot study suggests that the FAO is an efficient tool for measuring hindfoot alignment using WBCT. Previously published research in this field has looked at WBCT by adapting 2D biometrics. The present study introduces the concept of 3D biometrics and describes an efficient, semiautomatic tool for measuring hindfoot alignment. Level of evidence: Level III, retrospective comparative study.
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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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Objective: To investigate the ability of coronal non-weight-bearing MR images to discriminate between normal and abnormal hindfoot alignment. Methods: Three different measurement techniques (calcaneal axis, medial/lateral calcaneal contour) based on weight-bearing hindfoot alignment radiographs were applied in 49 patients (mean, 48 years; range 21-76 years). Three groups of subjects were enrolled: (1) normal hindfoot alignment (0°-10° valgus); (2) abnormal valgus (>10°); (3) any degree of varus hindfoot alignment. Hindfoot alignment was then measured on coronal MR images using four different measurement techniques (calcaneal axis, medial/lateral calcaneal contour, sustentaculum tangent). ROC analysis was performed to find the MR measurement with the greatest sensitivity and specificity for discrimination between normal and abnormal hindfoot alignment. Results: The most accurate measurement on MR images to detect abnormal hindfoot valgus was the one using the medial calcaneal contour, reaching a sensitivity/specificity of 86 %/75 % using a cutoff value of >11° valgus. The most accurate measurement on MR images to detect abnormal hindfoot varus was the sustentaculum tangent, reaching a sensitivity/specificity of 91 %/71 % using a cutoff value of <12° valgus. Conclusion: It is possible to suspect abnormal hindfoot alignment on coronal non-weight-bearing MR images. Key points: • Abnormal hindfoot alignment can be identified on coronal non-weight-bearing MR images. • The sustentaculum tangent was the best predictor of an abnormally varus hindfoot. • The medial calcaneal contour was the best predictor of a valgus hindfoot.
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Hindfoot malalignment is a recognized cause of foot and ankle disability. For preoperative planning and clinical follow-up, reliable radiographic assessment of hindfoot alignment is important. The long axial radiographic view and the hindfoot alignment view are commonly used for this purpose. However, their comparative reliabilities are unknown. As hindfoot varus or valgus malalignment is most pronounced during mid-stance of gait, a unilateral weight-bearing stance, in comparison with a bilateral stance, could increase measurement reliability. The purpose of this study was to compare the intra- and interobserver reliability of hindfoot alignment measurements of both radiographic views in bilateral and unilateral stance. A hindfoot alignment view and a long axial view were acquired from 18 healthy volunteers in bilateral and unilateral weight-bearing stances. Hindfoot alignment was defined as the angular deviation between the tibial anatomical axis and the calcaneus longitudinal axis from the radiographs. Repeat measurements of hindfoot alignment were performed by nine orthopaedic examiners. Measurements from the hindfoot alignment view gave intra- and interclass correlation coefficients (CCs) of 0.72 and 0.58, respectively, for bilateral stance and 0.91 and 0.49, respectively, for unilateral stance. The long axial view showed, respectively, intra- and interclass CCs of 0.93 and 0.79 for bilateral stance and 0.91 and 0.58 for unilateral stance. The long axial view is more reliable than the hindfoot alignment view or the angular measurement of hindfoot alignment. Although intra-observer reliability is good/excellent for both methods, only the long axial view leads to good interobserver reliability. A unilateral weight-bearing stance does not lead to greater reliability of measurement.
Article
Background: The goals of lower limb reconstruction are to restore alignment, to improve function, and to reduce pain. However, it remains unclear whether alignment of the lower limb and hindfoot are associated because an accurate assessment of hindfoot deformities has been limited by superposition on plain radiography. Consequently, surgeons often overlook hindfoot deformity when planning orthopaedic procedures of the lower limb. Therefore, we used weight-bearing CT to quantify hindfoot deformity related to lower limb alignment in the coronal plane. Questions/purposes: (1) Is lower-limb alignment different in varus than in valgus hindfoot deformities for patients with and without tibiotalar joint osteoarthritis? (2) Does a hindfoot deformity correlate with lower-limb alignment in patients with and without tibiotalar joint osteoarthritis? (3) Is joint line orientation different in varus than in valgus hindfoot deformities for patients with tibiotalar joint osteoarthritis? (4) Does a hindfoot deformity correlate with joint line orientation in patients with tibiotalar joint osteoarthritis? Methods: Between January 2015 and December 2017, one foot and ankle surgeon obtained weightbearing CT scans as second-line imaging for 184 patients with ankle and hindfoot disorders. In 69% (127 of 184 patients) of this cohort, a combined weightbearing CT and full-leg radiograph was performed when symptomatic hindfoot deformities were present. Of those, 85% (109 of 127 patients) with a median (range) age of 53 years (23 to 75) were confirmed eligible based on the inclusion and exclusion criteria of this retrospective comparative study. The Takakura classification was used to divide the cohort into patients with (n = 74) and without (n = 35) osteoarthritis of the tibiotalar joint. Lower-limb measurements, obtained from the full-leg radiographs, consisted of the mechanical tibiofemoral angle, mechanical tibia angle, and proximal tibial joint line angle. Weightbearing CT images were used to determine the hindfoot's alignment (mechanical hindfoot angle), the tibiotalar joint alignment (distal tibial joint line angle and talar tilt angle) and the subtalar joint alignment (subtalar vertical angle). These values were statistically assessed with an ANOVA and a pairwise comparison was subsequently performed with Tukey's adjustment. A linear regression analysis was performed using the Pearson correlation coefficient (r). A reliability analysis was performed using the intraclass correlation coefficient. Results: Lower limb alignment differed among patients with hindfoot deformity and among patients with or without tibiotalar joint osteoarthritis. In patients with tibiotalar joint osteoarthritis, we found knee valgus in presence of hindfoot varus deformity and knee varus in presence of hindfoot valgus deformity (mechanical tibiofemoral angle 0.3 ± 2.6° versus -1.8 ± 2.1°; p < 0.001; mechanical tibia angle -1.4 ± 2.2° versus -4.3 ± 1.9°; p < 0.001). Patients without tibiotalar joint osteoarthritis demonstrated knee varus in the presence of hindfoot varus deformity compared with knee valgus in presence of hindfoot valgus deformity (mechanical tibiofemoral angle -2.2 ± 2.2° versus 0.9 ± 2.4°; p < 0.001; mechanical tibia angle -1.8 ± 2.1° versus -4.3 ± 1.9°; p < 0.001). Patients with more valgus deformity in the hindfoot tended to have more tibiofemoral varus (r = -0.38) and tibial varus (r = -0.53), when tibiotalar joint osteoarthritis was present (p < 0.001). Conversely, patients with more valgus deformity in the hindfoot tended to have more tibiofemoral valgus (r = 0.4) and tibial valgus (r = 0.46), when tibiotalar joint osteoarthritis was absent (p < 0.001). The proximal joint line of the tibia had greater varus orientation in patients with a hindfoot valgus deformity compared with greater valgus orientation in patients with a hindfoot varus deformity (proximal tibial joint line angle 88.5 ± 2.0° versus 90.6 ± 2.2°; p < 0.05). Patients with more valgus deformity in the hindfoot tended to have more varus angulation of the proximal tibial joint line angle (r = 0.31; p < 0.05). Conclusions: In patients with osteoarthritis of the tibiotalar joint, varus angulation of the knee was associated with hindfoot valgus deformity and valgus angulation of the knee was associated with hindfoot varus deformity. Patients without tibiotalar joint osteoarthritis exhibited the same deviation at the level of the knee and hindfoot. These distinct radiographic findings were most pronounced in the alignment of the tibia relative to the hindfoot deformity. This suggests a detailed examination of hindfoot alignment before knee deformity correction at the level of the proximal tibia, to avoid postoperative increase of pre-existing hindfoot deformity. Other differences detected between the radiographic parameters were less pronounced and varied within the subgroups. Future research could identify prospectively which of these parameters contain clinical relevance by progressing osteoarthritis or deformity and how they can be altered by corrective treatment. Level of evidence: Level III, prognostic study.
Article
Objective Hindfoot valgus malalignment has been assessed on coronal MRI by the measurement of the tibio-calcaneal (TC) angle and apparent moment arm (AMA). This study aimed to determine if the calcaneofibular ligament (CFL) angle could be used as a further marker of hindfoot valgus malalignment on routine non-weight-bearing ankle MRI. Material and methods One hundred ninety-five consecutive 3-T ankle MRI studies were identified from the hospital PACS system. The TC and CFL angles could be measured in 155 cases (78%), and the AMA on 153 cases. Results The study group comprised 56 males and 72 females with a mean age of 46 years (range 4–89 years). In 27 patients, both ankles had been imaged. The Pearson correlation between the TC and CFL angles was −0.43, with a corresponding p value of 0.001 indicating a strong negative correlation between the TC and CFL angles. The CFL angle was significantly lower in those with hindfoot valgus (113 ± 14) compared with those without (123° ± 15°) (p = 0.001). The optimal cut-off point of the CFL angle for hindfoot valgus was ≤119°, with a sensitivity and specificity of 66% and 63% respectively. The Pearson correlation between the CFL angle and AMA was −0.10, with a corresponding p value of 0.21 indicating a weak negative correlation that did not reach statistical significance. Conclusion Hindfoot valgus as estimated by the increased TC angle on coronal non-weight-bearing ankle MRI is associated with a reduced CFL angle on sagittal MR images, but is not associated with AMA. Therefore, a horizontal orientation of the CFL on sagittal MR images may be a further useful sign of hindfoot valgus.
Article
Background: Weightbearing computed tomography (WBCT) is a useful tool for the assessment of hindfoot alignment (HA). Foot ankle offset (FAO) is a recently introduced parameter, determined from WBCT images using semiautomatic software. The aim of this study was to determine the clinical relevance and reproducibility of FAO for the evaluation of HA. Methods: A prospective comparative study was performed on consecutive patients requiring bilateral WBCT between September 2017 and April 2018. Based on the clinical assessment of HA, patients were divided into 3 groups: (1) normal alignment group (G1), (2) valgus (G2), and (3) varus (G3). FAO and long axial view (HACT) were measured on WBCT images, and the groups were compared. The reproducibility of FAO and HACT was determined through intraclass correlation coefficients (ICCs). Regression analysis was performed to investigate the correlation between the 2 methods. Overall, 249 feet (126 patients) were included (G1 = 115, G2 = 78, and G3 = 56 feet). Results: The mean values for FAO and HACT were 1.2% ± 2.8% and 3.9 ± 3.1, respectively, in G1; 8.1% ± 3.7% and 9.7 ± 4.9 in G2; and -6.6% ± 4.8% and -8.2 ± 6.6 in G3. Intra- and interobserver reliability was 0.987 and 0.988 for FAO and 0.949 and 0.949 for HACT, respectively. There was a good linear correlation between HACT and FAO ( R2 = 0.744), with a regression slope of 1.064. Conclusions: WBCT was a useful method for the characterization of HA. FAO was reproducible and correlated well with physical examination. Level of evidence: Level II, prospective comparative study.
Article
Standard knee imaging with MRI is usually performed with patient in recumbent position under non-weight-bearing conditions. Recently, magnetic resonance imaging systems to scan the knee joint under weight bearing conditions has been proposed as an approach to improve the clinical utility of musculoskeletal MRI. Imaging under loading can be useful to understand the natural motion behavior of the knee joint and to identify conditions that are challenging to diagnose by using standard position. We reviewed the literature on weight-bearing MR imaging of the knee to describe the current state of use of such MRI technologies, evaluating the advantages and the potential limitations of these technologies.
Article
" Adult-acquired flatfoot deformity is a complex process attributed mainly to posterior tibial tendon insufficiency. " Thorough physical examination and radiographs of the foot and ankle are usually adequate to achieve diagnosis. " Nonoperative management is the first line of treatment and has a reported success rate ranging from 67% to 90%. " A multitude of surgical options are available, particularly for stage II, with no consensus on the best options. " Fusions are associated with poor outcomes; hence, there is a trend toward earlier reconstruction before arthritis ensues. . © 2017 by the journal of bone and joint surgery, incorporated..
Article
Objective: To compare the hindfoot alignment measured on standing HAV radiographs (Saltzman view) and on non-weight-bearing coronal MR images. Materials and methods: The apparent moment arm was measured on weight-bearing conventional radiographs (Saltzman views) and on MRIs of the ankle in 50 consecutive patients (mean age, 54 years; age range, 18-77 years). The evaluation was performed independently by three readers using analogous reference points for both methods. Positive values were assigned when the deepest point of the calcaneus was lateral to the tibial axis as valgus, negative values as varus. The intertechnique agreement and correlation for the measurements performed with HAV radiographs and MRI were assessed for each reader using the Bland-Altman method and the Pearson correlation coefficient, respectively. The interobserver agreement was assessed using the intraclass correlation coefficient. Results: The means of apparent moment arms, with the standard deviation (SD) in parentheses, of three readers were +2.0 (±8.4) mm, +1.5 (±6.6) mm and -1.4 (±8.2) mm on HAV radiographs and +4.6 (±7.4) mm, +6.3 (±5.3) mm and +5.4 (±6.4) mm on MRI. The Bland-Altman analysis found a systematic bias for all three readers, corresponding to an overestimation of measurements with MRI (systematic bias ranging from 2.6 to 4.8 mm). The intertechnique correlation was found moderate to high. The Pearson coefficients for the three readers were 0.75, 0.64 and 0.65. The interobserver agreement among the three readers was 0.72, 0.77 and 0.68 for HAV, MRI and both modalities together, respectively. Conclusion: Hindfoot alignment can be estimated on MRI but the correlation between the values on HAV radiographs and MR images is only moderate with a tendency to increased positive values (valgization) on MR images.
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
EDUCATIONAL OBJECTIVES As a result of reading this article, physicians should be able to: 1. Recognize posterior tibialis tendon dysfunction and begin to include it in differential diagnoses. 2. Recall the basic anatomy and pathology of the posterior tibialis tendon. 3. Assess a patient for posterior tibialis tendon dysfunction with the appropriate investigations and stratify the severity of the condition. 4. Develop and formulate a treatment plan for a patient with posterior tibialis tendon dysfunction. The posterior tibialis is a muscle in the deep posterior compartment of the calf that plays several key roles in the ankle and foot. Posterior tibialis tendon dysfunction is a complex but common and debilitating condition. Degenerative, inflammatory, functional, and traumatic etiologies have all been proposed. Despite being the leading cause of acquired flatfoot, it is often not recognized early enough. Knowledge of the anatomical considerations and etiology of posterior tibialis tendon dysfunction, as well as key concepts in its evaluation and management, will allow health care professionals to develop appropriate intervention strategies to prevent further development of flatfoot deformities. [Orthopedics. 2015; 38(6):385-391.]. Copyright 2015, SLACK Incorporated.
Article
Background PedCAT (Curvebeam, Warrington, USA) is a new technology that allows 3D imaging with full weight bearing which is be not influenced by projection and/or foot orientation (as radiographs). The aim of this study was to compare time spent of the image acquisition, and comparison of specific bone position (angle) measurements between three imaging methods (radiographs, CT, pedCAT), and to analyse and compare measurement differences and inter- and intraobserver reliability. Methods In a prospective consecutive controlled study, 30 patients in which standard digital radiographs with full weight bearing in standing position (feet bilateral dorsoplantar and lateral views and Saltzman hindfoot view), CT without weight bearing, and pedCAT scan with full weight bearing in standing position were included, starting July 1, 2013. The following angles were measured for the right foot by three different investigators three times: 1st - 2nd intermetatarsal angle, talo-metatarsal 1-angle (TMT) both dorsoplantar and lateral projection, hindfoot angle, calcaneal pitch. The angles were digitally measured and compared (ANOVA with Post Hoc Scheffe test). Results The angles differed between radiographs, CT and pedCAT (ANOVA, all p≤.01). The angles differed between pedCAT and both radiographs and CT (Post Hoc Scheffe test, each p≤.05 except for TMT dorsoplantar and calcaneal pitch angels versus radiographs). Conclusions The angles differed between radiographs, CT and pedCAT, indicating that only pedCAT is able to detect the correct angles. PedCAT includes weight bearing in contrast to CT. PedCAT prevents inaccuracies of projection and foot orientation in contrast to radiographs due to the 3D dataset which is principally independent from projection and foot orientation.
Article
The tibio-calcaneal angle (TCA) does not measure individual forefoot contributions to the overall foot balance. Using standard radiographs we calculated the ideal hindfoot alignment based on ground reaction force (GRF), independently from the tibial axis. Thirty-six patients (40ft.) were included. Mean age was 56. Weight bearing radiographs were taken. Calcaneal offsets were measured using tibio-calcaneal angles and GRF algorithms. Measurements were compared using the Bland-Altman method. Both methods agreed (p>0.05) but individual discrepancies were found. Mean measured offsets were -11.5mm (SD: 10.2) using TCA and -8mm (SD: 9.3) using GRF. Mean bias between the methods was -0.88mm. The GRF algorithm successfully measured hindfoot alignment. The absence of a previous gold standard and radiographic variability are a limit. The TCA underestimated calcaneal offset. Discrepancies showed that forefoot position data provided increased accuracy. This could be of particular relevance for surgical planning.
Article
The posterior tibial tendon (PTT) is the most important dynamic stabilizer of the medial ankle and longitudinal arch of the foot. PTT dysfunction is a degenerative disorder of the tendon, which secondarily involves multiple ligaments, joint capsules, fascia, articulations, and bony structures of the ankle, hindfoot, midfoot, and forefoot. When the tendon progressively attenuates, the patient develops a painful, progressive collapsed flatfoot or pes planovalgus deformity. This comprehensive review illustrates the 3-Tesla magnetic resonance imaging (3T MRI) features of PTT dysfunction. In addition, the reader will gain knowledge of the expected pathologic findings on MRI, as they are related to clinical staging of PTT dysfunction.
Article
A modification of Cobey's method for radiographically imaging the coronal plane alignment of the hindfoot is described. Using this view, we estimated the moment arm between the weightbearing axis of the leg and the contact point of the heel. Normative data on 57 asymptomatic adult subjects are presented. The weightbearing line of the tibia falls within 8 mm of the lowest calcaneal point in 80% of subjects and within 15 mm of the lowest calcaneal point in 95% of subjects. The technique for measuring coronal plane hindfoot alignment is reliable, with an interobserver correlation coefficient of 0.97. This radiographic technique should help in the evaluation of complex hindfoot malalignments.
Flexible adult acquired flatfoot deformity
  • N C De Cesar
  • L C Schon
  • G K Thawait
  • L F Da Fonseca
  • A Chinanuvathana
  • W B Zbijewski