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Background: Three-dimensional weightbearing CT (WBCT) has been widely used to assess foot and ankle alignment. However, most current measurement methods are based on 2-dimensional concepts—distance, long axis, angulation, etc—and are sensitive to changes in orientation of the WBCT images. This study demonstrated how changes in positioning of the image can significantly influence the evaluation of hindfoot alignment. Methods: WBCT scans of 10 feet without deformities were used. In the horizontal view, the long axis of the foot image was aligned to a neutral position and then rotated 5, 10, 15, and 20 degrees both internally and externally to simulate malposition. The Calcaneal Moment Arm (CMA) was measured by 2 investigators independently in the above positions. An intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliabilities. The correlation between the CMA and the rotation angle of the foot images was analyzed using linear regression. Results: The CMA measurements demonstrated that internal rotation of the image changed the neutral hindfoot into valgus, whereas external rotation led to varus. A 1-degree internal or external rotation of the image correlated with 0.48 (±0.03) mm increase or decrease in the modified WBCT-CMA value (P <.0001, R 2 = 0.6406). Conclusion: This study demonstrated that although 3D WBCT provides the ability to observe the foot from different perspectives, current alignment evaluation tools are limited to 2 dimensions. Therefore, positioning the WBCT images in a consistent orientation is important to generate correct data. [ABSTRACT FROM AUTHOR]

Background/Objectives: To assess magnetic resonance image (MRI) findings in children and adolescents with atraumatic non-overload ankle pain and to identify potential anatomic risk factors. Methods: In total, 310 MRIs of 6- to 20-year-old patients were evaluated regarding detectable ankle pathologies. A total of 147 patients (68 males; 79 females) suffered from atraumatic non-overload ankle pain. The findings were compared to a control group (163 patients: 89 males; 74 females), including patients with ankle trauma in the 4 weeks prior to MRI examination. A t-test for unpaired samples and a binary logistic regression model were used to identify significant differences between both groups and determine potential anatomic risk factors. Results: In the group with atraumatic ankle pain, 95 patients (64.6%) showed at least one pathology. Anterolateral impingement of the upper ankle joint was found in 29 patients (19.7%). Its occurrence was significantly higher in atraumatic non-overload patients than in the control group (p = 0.043). Moreover, a significant correlation between anterolateral impingement of the upper ankle and the presence of hindfoot valgus malposition (n = 25; 17.0%) could be proven in atraumatic non-overload patients (p = 0.035). Conclusions: Anterolateral impingement of the upper ankle joint is frequently observed in children and adolescents suffering from atraumatic non-overload ankle pain, whereby a hindfoot valgus malposition seems to present an anatomic risk factor. [ABSTRACT FROM AUTHOR]

Hindfoot malalignment can cause various foot and ankle problems. For better surgical performance and correction of hindfoot malalignments, reliable intraoperative determination of hindfoot alignment is essential. However, there is no standard method for the intraoperative assessment of hindfoot alignment. We devised an intraoperative modified Méary posteroanterior (IOPPA) view to assess intraoperative hindfoot alignment. This study aimed to compare this intraoperative method with other radiographic hindfoot alignment measurements. Thirty-seven patients (47 feet) with various foot and ankle conditions scheduled to undergo surgery were prospectively recruited. Before surgery, the Saltzman, long axial, and modified Méary views were taken in a controlled and standardized fashion. IOPPA views were obtained under simulated weight bearing conditions using C-arm fluoroscopy in the operating room before surgery. The relationship between the IOPPA view and the three radiographic hindfoot alignments was evaluated using Pearson's correlation. The mean hindfoot alignment angle was varus 3.50° (CI, varus 1.91 to 5.08) on the Saltzman view, varus 2.00° (CI, varus 0.60 to 3.39) on the long axial view, varus 0.13° (CI, valgus 1.41 to varus 1.67) on the modified Méary view, and varus 1.32° (CI, valgus 0.02 to varus 2.65) on IOPPA view. The IOPPA view and the three other hindfoot alignment views were found to be significantly correlated (r = 0.60 for the Saltzman view, r = 0.50 for the long axial view, r = 0.71 for the modified Méary view, P <.05). The intraobserver ICC (Intraclass Correlation Coefficient) value was 0.974 and interobserver ICC (Intraclass Correlation Coefficient) value was 0.988 for the IOPPA view (P <.001). There was a statistically significant correlation between the IOPPA view and the other three hindfoot alignment views. We also found that interobserver and intraobserver ICC values were excellent. This study proposes that the IOPPA view can be used as a reliable intraoperative assessment tool for hindfoot alignment. Prospective study. [ABSTRACT FROM AUTHOR]

Ankle arthrodesis was performed on a 55-year-old male patient with an active lifestyle who developed severe arthritis in the left ankle. Over the follow-up period, high tibial valgization osteotomy was conducted for painful medial knee joint arthritis with genu varum deformity to correct overall lower limb alignment from varus to valgus with respect to the fused ankle. This study was conducted to investigate how hindfoot alignment would change when the overall alignment of the lower limb shifted from varus to valgus with the ipsilateral ankle in a fused state. Conclusively, while no intrinsic changes in the hindfoot alignment were observed following the alteration of lower limb alignment, the hindfoot naturally adjusted to valgus deviation in response to limb valgus realignment. Moreover, symptoms changed in line with this adjustment. Given the absence of similar case studies or reports, a review of relevant literature is included to contribute to knowledge of this subject. [ABSTRACT FROM AUTHOR]

Abstract Background The biomechanics of the hindfoot in ankle osteoarthritis (OA) are not yet fully understood. Here, we aimed to identify hindfoot motion in a gait analysis using a multi-segment foot model (MFM) according to ankle OA stage and the presence of subtalar compensation defined by hindfoot alignment. Methods We retrospectively reviewed the medical records, plain radiographs, and gait MFM data of 54 ankles admitted to our hospital for the treatment of advanced ankle OA. Spatiotemporal gait parameters and three-dimensional motions of the hindfoot segment were analyzed according to sex, age, body mass index, Takakura classification, and the presence of subtalar compensation. Twenty ankles were categorized as compensated group, and 34 ankles as decompensated group. Results No spatiotemporal gait parameters differed significantly according to the presence of subtalar compensation or ankle OA stage. Only normalized step width differed significantly (P = 0.028). Average hindfoot motion (decompensation vs. compensation) did not differ significantly between the sagittal and transverse planes. Graphing of the coronal movement of the hindfoot revealed collapsed curves in both groups that differed significantly. Compared with Takakura stages 3a, 3b, and 4, cases of more advanced stage 3b had a smaller sagittal range of motion than those of stage 3a (P = 0.028). Coronal movement of the hindfoot in cases of Takakura stage 3a/3b/4 showed a relatively flat pattern. Conclusions The spatiotemporal parameters were not affected by the hindfoot alignment resulting from subtalar compensation. The sagittal range of hindfoot motion decreased in patients with advanced ankle OA. Once disrupted, the coronal movement of the subtalar joint in ankle OA did not change regardless of ankle OA stage or hindfoot compensation state.

Background: The biomechanics of the hindfoot in ankle osteoarthritis (OA) are not yet fully understood. Here, we aimed to identify hindfoot motion in a gait analysis using a multi-segment foot model (MFM) according to ankle OA stage and the presence of subtalar compensation defined by hindfoot alignment. Methods: We retrospectively reviewed the medical records, plain radiographs, and gait MFM data of 54 ankles admitted to our hospital for the treatment of advanced ankle OA. Spatiotemporal gait parameters and three-dimensional motions of the hindfoot segment were analyzed according to sex, age, body mass index, Takakura classification, and the presence of subtalar compensation. Twenty ankles were categorized as compensated group, and 34 ankles as decompensated group. Results: No spatiotemporal gait parameters differed significantly according to the presence of subtalar compensation or ankle OA stage. Only normalized step width differed significantly (P = 0.028). Average hindfoot motion (decompensation vs. compensation) did not differ significantly between the sagittal and transverse planes. Graphing of the coronal movement of the hindfoot revealed collapsed curves in both groups that differed significantly. Compared with Takakura stages 3a, 3b, and 4, cases of more advanced stage 3b had a smaller sagittal range of motion than those of stage 3a (P = 0.028). Coronal movement of the hindfoot in cases of Takakura stage 3a/3b/4 showed a relatively flat pattern. Conclusions: The spatiotemporal parameters were not affected by the hindfoot alignment resulting from subtalar compensation. The sagittal range of hindfoot motion decreased in patients with advanced ankle OA. Once disrupted, the coronal movement of the subtalar joint in ankle OA did not change regardless of ankle OA stage or hindfoot compensation state. [ABSTRACT FROM AUTHOR]

Purpose: Emerging reports suggest an important involvement of the ankle/hindfoot alignment in the outcome of knee osteotomy; however, a comprehensive overview is currently not available. Therefore, we systematically reviewed all studies investigating biomechanical and clinical outcomes related to the ankle/hindfoot following knee osteotomies. Methods: A systematic literature search was conducted on PubMed, Web of Science, EMBASE and Cochrane Library according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered on international prospective register of systematic reviews (PROSPERO) (CRD42021277189). Combining knee osteotomy and ankle/hindfoot alignment, all biomechanical and clinical studies were included. Studies investigating knee osteotomy in conjunction with total knee arthroplasty and case reports were excluded. The QUality Appraisal for Cadaveric Studies (QUACS) scale and Methodological Index for Non-Randomized Studies (MINORS) scores were used for quality assessment. Results: Out of 3554 hits, 18 studies were confirmed eligible, including 770 subjects. The minority of studies (n = 3) assessed both high tibial- and distal femoral osteotomy. Following knee osteotomy, the mean tibiotalar contact pressure decreased (n = 4) except in the presence of a rigid subtalar joint (n = 1) or a talar tilt deformity (n = 1). Patient symptoms and/or radiographic alignment at the level of the ankle/hindfoot improved after knee osteotomy (n = 13). However, factors interfering with an optimal outcome were a small preoperative lateral distal tibia angle, a small hip–knee–ankle axis (HKA) angle, a large HKA correction (>14.5°) and a preexistent hindfoot deformity (>15.9°). Conclusions: Osteotomies to correct knee deformity alter biomechanical and clinical outcomes at the level of the ankle/hindfoot. In general, these changes were beneficial, but several parameters were identified in association with deterioration of ankle/hindfoot symptoms following knee osteotomy.

Abstract Background Alignment is indispensable for the foot and ankle function, especially in the hindfoot alignment. In the preoperative planning of patients with varus or valgus deformity, the precise measurement of the hindfoot alignment is important. A new method of photographing and measuring hindfoot alignment based on X-ray was proposed in this study, and it was applied in the assessment of flatfoot. Methods This study included 28 patients (40 feet) with flatfeet and 20 volunteers (40 feet) from January to December 2018. The hindfoot alignment shooting stand independently designed by our department was used to take hindfoot alignment X-rays at 10 degree, 15 degree, 20 degree, 25 degree, and 30 degree. We measured the modified tibio-hindfoot angle (THA) at the standard hindfoot aligment position (shooting at 20 degree) and evaluated consistency with the van Dijk method and the modified van Dijk method. In addition, we observed the visibility of the tibiotalar joint space from all imaging data at five projection angles and evaluated the consistency of the modified THA method at different projection angles. The angle of hindfoot valgus of flatfoot patients was measured using the modified THA method. Results The mean THA in the standard hindfoot aligment view in normal people was significantly different among the three evaluation methods (P

Purpose: Development of valgus tibiotalar tilt is a significant complication after subtalar fusion for progressive collapsing foot deformity (PCFD) correction. However, its incidence and etiologic factors have not been extensively studied. The purpose of this study was to define the incidence of valgus tibiotalar tilt after subtalar fusion for PCFD reconstruction, and to determine predictors of this complication. Methods: This study included 59 patients who underwent PCFD reconstruction with subtalar fusion. Patients with tibiotalar tilt prior to surgery were excluded. On standard weightbearing radiographs, the talonavicular coverage angle, talo-1st metatarsal angle, calcaneal pitch, hindfoot moment arm (HMA), and medial distal tibial angle were measured. Weightbearing computed tomography (WBCT) was used to determine the presence of lateral bony impingement. A radiologist evaluated the superficial and deep deltoid ligaments using magnetic resonance imaging (MRI). Univariate regression analysis was used to identify the factors associated with development of postoperative valgus tibiotalar tilt, defined as tilt > 2 degrees. Results: Seventeen patients (28.8%) developed postoperative valgus tibiotalar tilt at a mean of 7.7 (range 2–31) months. Eight (47.1%) of these patients developed valgus tibiotalar tilt within 3 months. Univariate logistic regression demonstrated association between preoperative HMA and postoperative valgus tibiotalar tilt (odds ratio 1.06, P = 0.026), with a 6% increase in risk per millimeter of increased HMA. Deltoid ligament status and concomitant procedures on other joints did not correlate with postoperative valgus tilt. Conclusion: Our findings indicate that surgeons should be cognizant of patients with a greater degree of preoperative hindfoot valgus and their propensity to develop a valgus ankle deformity. Additionally, our relatively high incidence of valgus tibiotalar tilt suggests that weightbearing ankle radiographs should be included in the initial and subsequent follow-up of PCFD patients with hindfoot valgus treated with subtalar fusion. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: In clinical practice and research, there are several scenarios when a hindfoot alignment view weightbearing XR is not obtained whether as a result of a lack of resources, technology, in retrospective studies when a hindfoot view was not obtained, as well as in many practices where a hindfoot view XR is not considered a routine examination for foot and ankle disorders. A lateral weightbearing radiograph however is almost routinely obtained, and the goal of this study was to correlate the hindfoot alignment angle with measurements on lateral weightbearing images. Methods: Four volunteers (8 feet) with flexible feet and ankles and no symptoms, nor significant trauma & surgical history in their lower limbs were recruited for this study. A portable fluoroscopy machine (Smart C, Turner Imaging, Salt Lake City, USA) was used for imaging. The participant was asked to stand on different custom wooden wedges with the angle changed every 5 degrees from 30 degrees of varus to 30 degrees of valgus and a weightbearing lateral image was taken for each position. The hindfoot alignment was measured using a skin marker which had been drawn prior to initiation of the imaging, and the angular changes of the hindfoot was measured with the placement of each wedge placed. All standardized measurements of the midfoot and hindfoot were obtained on the lateral images. Results: With the hindfoot positional changes between 30o of varus to 30o of valgus, there was a gradual measurable change in the subtalar joint, with corresponding changes in the midfoot and hindfoot. There was a significant linear correlation between the hindfoot alignment angle and all radiographic parameters on lateral images. When the hindfoot alignment angle increased by 1 degree in the valgus direction, there was 0.49o decrease in the pitch angle, 0.58o of decrease in the middle vs posterior facet angle, 0.06o of decrease in the proximal cuneiform/cuboid height, 0.40o of decrease in the proximal cuneiform/5th Metatarsal height, 0.40o of increase in the fifth metatarsal/cuboid height, 0.009o of increase in the sinus tarsi/lateral process height, and 0.015o increase in Cuboid/Anterior Process Height. (Figure 1) Conclusion: The lateral weightbearing XR can be used to predict the status of the hindfoot alignment, and this study has proven that this can be none not only qualitatively but also quantitatively. This novel research can provide our colleagues with linear regression equations to correlate the lateral imaging metrics with the hindfoot alignment angle. Further study with a larger sample size and participants with different types of hindfoot deformities is needed to help develop an algorithm that would help both clinical practice and research. [ABSTRACT FROM AUTHOR]

Background: Recovering normal hindfoot alignment and correcting deformity of the ankle joint following total ankle arthroplasty (TAA) in osteoarthritis (OA) is essential for improving clinical outcomes and increasing long-term survival. We aim to evaluate hindfoot alignment following standard TAA compared to TAA with a total talar prosthesis ("combined TAA") in varus-type OA patients. Methods: This retrospective study was conducted between 2010 and 2022. We included 27 patients (30 feet) who underwent standard TAA and 19 patients (22 feet) who underwent combined TAA. Hindfoot alignment at the subtalar joint was measured by weightbearing subtalar radiographic view before and after surgery. Results: In the standard TAA, the angle between the tibial shaft axis and the articular surface of the talar dome joint (TTS) changed from 75 to 87 degrees (P <.01), the angle between the tibial axis and the surface on the middle facet (TMC) from 89 to 94 degrees (P <.01), and the angle between the tibial axis and the surface on the posterior facet (TPC) from 80 to 84 degrees (P <.01). The angle between the articular surface of the talar dome and the posterior facet of the calcaneus (SIA) decreased from 4.7 to −2.5 degrees (P <.01). In the combined TAA, TTS angle changed from 77 to 88 degrees (P <.01), TMC angle from 93 to 101 degrees (P <.01), TPC angle from 84 to 90 degrees (P <.05), and SIA from 6.6 to 2.1 degrees (P <.01). Varus deviation to the subtalar joint (TMC, TPC) significantly improved postoperatively in both groups. However, TPC was smaller than TTS and SIA was negative in standard TAA, and TPC was larger than TTS and SIA was positive in combined TAA. Conclusion: The amount of correction of the subtalar joint differed depending on the ligament dissection of the subtalar joint and shape of the talar component Level of Evidence: Level III, retrospective cohort study. [ABSTRACT FROM AUTHOR]

Background: Hindfoot varus deformity is a known risk factor for chronic lateral ankle instability (CLAI). The impact of this deformity on clinical results following arthroscopic lateral ankle ligament repair (ALLR) for CLAI has not been studied. Methods: Sixty-three ankles from 62 patients who received ALLR for CLAI were retrospectively examined. Preoperative plain radiographs were used to measure tibial articular surface (TAS) angles, and long axial hindfoot alignment radiographs were used to measure tibiocalcaneal angles (TCAs) pre- and postoperatively. Results included ratings on the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) and recurrent ankle instability (respraining of the operated ankle following surgery). Results: Recurrent ankle instability, defined as incidence of any new ankle sprain after surgery reported in the follow-up period, occurred in 13 ankles. The TAS angles of these patients were significantly low, and their preoperative TCA was significantly high. Multivariate analysis showed that preoperative TCA was an independent risk factor for recurrent ankle instability. The threshold values for preoperative TCA for recurrent instability were determined via the receiver operating characteristic curve analysis to be 3.4 degrees. Patients were assigned to a low- or high-TCA group based on the reported average TCA (2.7 degrees) of healthy patients. In the high-TCA group, recurrent instability was significantly more frequent, and the scores on the pain subscale of the postoperative SAFE-Q were significantly lower. Conclusion: Hindfoot varus alignment was associated with pooreroutcomes after ALLR. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

Background: Alignment is indispensable for the foot and ankle function, especially in the hindfoot alignment. In the preoperative planning of patients with varus or valgus deformity, the precise measurement of the hindfoot alignment is important. A new method of photographing and measuring hindfoot alignment based on X-ray was proposed in this study, and it was applied in the assessment of flatfoot. Methods: This study included 28 patients (40 feet) with flatfeet and 20 volunteers (40 feet) from January to December 2018. The hindfoot alignment shooting stand independently designed by our department was used to take hindfoot alignment X-rays at 10 degree, 15 degree, 20 degree, 25 degree, and 30 degree. We measured the modified tibio-hindfoot angle (THA) at the standard hindfoot aligment position (shooting at 20 degree) and evaluated consistency with the van Dijk method and the modified van Dijk method. In addition, we observed the visibility of the tibiotalar joint space from all imaging data at five projection angles and evaluated the consistency of the modified THA method at different projection angles. The angle of hindfoot valgus of flatfoot patients was measured using the modified THA method. Results: The mean THA in the standard hindfoot aligment view in normal people was significantly different among the three evaluation methods (P <.001). The results from the modified THA method were significantly larger than those from the Van Dijk method (P <.001) and modified Van Dijk method (P <.001). There was no significant difference between the results of the modified THA method and the weightbearing CT (P =.605), and the intra- and intergroup consistency were the highest in the modified THA group. The tibiotalar space in the normal group was visible in all cases at 10 degree, 15 degree, and 20 degree; visible in some cases at 25 degree; and not visible in all cases at 30 degree. In the flatfoot group, the tibiotalar space was visible in all cases at 10 degree, visible in some cases at 15 degree and 20 degree, and not visible in all cases at 25 degree and 30 degree. In the normal group, the modified THA was 4.84 ± 1.81 degree at 10 degree, 4.96 ± 1.77 degree at 15 degree, and 4.94 ± 2.04 degree at 20 degree. No significant differences were found among the three groups (P =.616). In the flatfoot group, the modified THA of 18 feet, which was visible at 10 degree, 15 degree and 20 degree, was 13.58 ± 3.57 degree at 10 degree, 13.62 ± 3.83 degree at 15 degree and 13.38 ± 4.06 degree at 20 degree. There were no significant differences among the three groups (P =.425). Conclusions: The modified THA evaluation method is simple to use and has high inter- and intragroup consistency. It can be used to evaluate hindfoot alignment. For patients with flatfeet, the 10 degree position view and modified THA measurement can be used to evaluate hindfoot valgus. [ABSTRACT FROM AUTHOR]

Introduction: Foot–ankle offset (FAO) is a three-dimensional (3D) biometric measurement of hindfoot alignment (HA) measured on images from weight-bearing computed tomography (WBCT). Our aim was to investigate its distribution in a large cohort of patients, hypothesizing that threshold FAO values in valgus or varus could be identified as markers for increased risk of associated pathologies. Materials and methods: Prospective, monocentric, level II study including 125 subjects (250 feet) undergoing bilateral WBCT [58.4% female; mean age, 54 years (18–84)]. Patients were clinically assessed and pathologies were classified according to anatomic location (valgus- or varus associated). HA was measured using FAO on 3D datasets and tibio-calcaneal angles (TCA) on two-dimensional Saltzman-El-Khoury views. Threshold FAO values and area under the receiver operating characteristics curve (AUC) were calculated for predicting increased risk of medial or lateral pathologies. Results: Mean FAO was 1.65% ± 4.72 and mean TCA was 4.15° ± 7.67. Clinically, 167 feet were normal, 33 varus and 50 valgus with FAO values of 1.71% ± 3.16, − 4.96% ± 5.30 and 5.79% ± 3.77, respectively. Mean FAO was 0.99% ± 3.26 for non-pathological feet, − 2.53% ± 5.05 for lateral and 6.81% ± 2.70 for medial pathologies. Threshold FAO values of − 1.64% (51.4% sensitivity, 85.1% specificity, AUC = 0.72) and 2.71% (95% sensitivity, 82.8% specificity, AUC = 0.93) best predicted the risk of lateral and medial pathology, respectively. Conclusion: Patients with FAO between − 1.64% and 2.71% had the least risk of degenerative foot and ankle pathology. This interval could be considered a target for patients undergoing realignment procedures. Clinical relevance: A "safe zone" for Foot Ankle Offset was described between − 1.64% and 2.71%, for which the risk of foot and ankle pathologies is lower. Level of evidence: II—Diagnostic study. [ABSTRACT FROM AUTHOR]

Background: Intraoperative evaluation of hindfoot alignment is one of the factors that may affect outcomes for foot and ankle reconstructive surgery. The present study was performed to evaluate the effect of simulated weightbearing fluoroscopy on the intraoperative assessment of hindfoot alignment reconstruction. Methods: The medical records of patients diagnosed with disorders of the foot and ankle with abnormal hindfoot alignment were retrospectively reviewed from November 2014 to November 2021. Hindfoot alignment view (HAV) fluoroscopy in the simulated weightbearing position and HAV radiographs were routinely recorded during and after surgery, respectively. The hindfoot alignment angle (HAA) and hindfoot alignment ratio (HAR) were measured on intraoperative and postoperative images, respectively. Results: Seventy-two women and 82 men (155 ankles) with a mean age of 45.48 years were included in the present study. The intraobserver and interobserver reliabilities of the HAA and HAR measurements were satisfactory. The intraoperative and postoperative HAA was −0.7 ± 4.8 degrees and −0.2 ± 5.0 degrees, respectively. The mean HAR on intraoperative fluoroscopy and postoperative radiographs was 37.4% ± 19.7% and 40.4% ± 18.2%, respectively. Simple regression analysis revealed a correlation between the intraoperative and postoperative HAA (R 2 = 0.631, P <.001) and HAR (R 2 = 0.262, P <.001). Univariate analysis suggested that the difference between the intraoperative and postoperative HAA was positively affected by the body mass index (P <.001). Conclusion: The present study showed that intraoperative HAV fluoroscopy in the simulated weightbearing position is a potentially useful method to predict postoperative hindfoot alignment in the weightbearing position. Patients with a lower body mass index had smaller HAA deviations between intraoperative and postoperative measurements of hindfoot alignment. Level of Evidence: Level IV, retrospective case series. [ABSTRACT FROM AUTHOR]

Background: To date, only a few studies have reported postoperative changes in coronal ankle alignment after valgus knee correction through medial closing wedge distal femoral varization osteotomy (MCWDFO). This study aimed to measure the changes of MCWDFO on coronal ankle and hindfoot alignment. Methods: We retrospectively reviewed the radiographic findings of 27 consecutive patients (34 cases) with knee valgus malalignment who underwent MCWDFO for either lateral knee joint osteoarthritis (OA) or recurrent patellar subluxation/dislocation (RPD). Several radiographic parameters were measured and compared based on the reason for operation, followed by the status of preoperative hindfoot alignment (hindfoot alignment angle [HAA] > 4 degrees, varus; −4 degrees ≤HAA ≤ 4 degrees, neutral; HAA < −4 degrees, valgus) in each group. Results: Overall, pre- and postoperative hindfoot alignments were within the neutral alignment range and were not significantly changed after the operation (P >.05). Nineteen cases were for lateral knee OA and 15 were for RPD, respectively. In both groups, preoperative neutral hindfoot alignments accounted for the largest portion (52.6% in the lateral OA group; 80.0% in the RPD group). Postoperatively, regardless of the reason for operation, hindfoot alignments changed toward the neutral range in all subgroups (ie, no changes in the preoperative neutral group; increased in the valgus group; decreased in the varus group). Conclusion: We recommend that surgeons leave the hindfoot untouched when they plan the MCWDFO to correct knee joint valgus malalignment concomitant with hindfoot valgus or varus deviation as the hindfoot malalignment appears to change toward the neutral range postoperatively. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

Background: Correct alignment of the knee is considered to be one of the most influential factors in determining the long-term outcomes after Total Knee Arthroplasty (TKA), and is believed to decrease both the mechanical and shear stresses placed on the bearing surfaces, as well as the bone/prosthesis interfaces. Compensatory malalignment of ankle and hindfoot is a recognized cause for ankle disability and deformity in long-standing osteoarthritic patients with varus deformity. This study aims to assess changes in ipsilateral ankle and hindfoot if any, pre- and post-operative TKA. Methods: 65 knees of 54 patients of osteoarthritis knee were evaluated for alignment in knee, ankle and hindfoot pre- and post-TKA. Pre- and post-operative scanogram were evaluated for knee and ankle alignment. Hindfoot alignment view was used to calculate hindfoot alignment angle. All parameters were compared before TKA and after 10 weeks TKA and Wilcoxon signed rank test was used to test the significance of the values. Results: Mean age of the patients was 62.9 years (49–80 years). Mean varus before surgery was 14.49 which changed to 4.01 and mean hindfoot angle valgus reduced from 9.23 to 6.62, both of which was found significant. Significant changes were also observed between pre- and post-op measurements of knee society scores, AOFAS, with improved functional outcomes both in knee and ankle. Conclusion: This study reveals the radiological and functional changes occurring in the ankle and hindfoot after acute correction of long-standing varus deformity of the knee using total knee arthroplasty. Hindfoot valgus alignment in varus knees decreased significantly post-TKA without any intervention at ankle level. In cases undergoing knee arthroplasty, effect of the acute change in the alignment of the knee on the ankle and hindfoot should be taken into consideration and the amount of correction of knee alignment can be a predictor of correction of ankle and hindfoot malalignment too. The lateral benefit of improvement in ankle pain after TKA is a significant gain in this study. [ABSTRACT FROM AUTHOR]

Introduction: Joint preserving surgery for flatfoot reconstruction utilizes correction of bony malalignment and medial soft tissue reconstruction. A medial displacement calcaneal osteotomy (MDCO) can be an essential adjunct to deformity correction and good patient outcomes. Our cadaveric study compares three different surgical techniques utilizing two cannulated screws to best maintain medial translation of the calcaneal osteotomies. Materials and methods: Fifteen above knee fresh-frozen, matched pair cadaveric specimens (30 limbs) were randomized equally to three groups. MDCO were performed on all specimens, followed by manual 10 mm translation. The groups consisted of a “simultaneous drilling,” “staggered drilling,” and a control group, which involved simultaneous drilling of only the near cortex. Following screw fixation, the calcaneal tuberosity was manually translated in a lateral direction. The loss of correction was measured in millimeters. Results: The “simultaneous” drilling group experienced the greatest mean loss of correction at 2.6 mm (range 1.37–3.48 mm). The “staggered” group showed an average loss of 1.16 mm (range 0.36–2.67 mm). The control group demonstrated the greatest maintenance of correction with a mean loss of 0.036 mm (range 0.01–0.06 mm). Conclusions: MDCO realigns the hindfoot adding support to the medial soft tissue reconstruction during flatfoot correction. Loss of initial correction may result in residual deformity and poor long-term outcomes. Our study demonstrates that simultaneous drilling of only the tuberosity near cortex prior to screw fixation was the best at maintaining osteotomy correction. Level of evidence: : Level V, Cadaveric study

Introduction: Currently there is no consensus how hindfoot alignment (HA) should be assessed in CBCT scans. The aim of this study is to investigate how the reliability is affected by the anatomical structures chosen for the measurement. Materials and methods: Datasets consisting of a Saltzman View (SV) and a CBCT of the same foot were acquired prospectively and independently assessed by five raters regarding HA. In SVs the HA was estimated as follows: transversal shift between tibial shaft axis and heel contact point (1); angle between tibial shaft axis and a tangent at the medial (2) or lateral (3) calcaneal wall. In CBCT the HA was estimated as follows: transversal shift between the centre of the talus and the heel contact point (4); angle between a perpendicular line and a tangent at the medial (5) or lateral (6) calcaneal wall; angle between the distal tibial surface and a tangent at the medial calcaneal wall (7). Intraclass correlation coefficients (ICC) were calculated to assess inter-rater reliability. A linear regression was performed to compare the different measurement regarding their correlation. Results: 32 patients were included in the study. The ICCs for the measurements 1–7 were as follows: (1) 0.924 [95% CI 0.876–0.959] (2) 0.533 [95% CI 0.377–0.692], (3) 0.553 [95% CI 0.399–0.708], (4) 0.930 [95% CI 0.866–0.962], (5) 0.00 [95% CI − 0.111 to 0.096], (6) 0.00 [95% CI − 0.103 to 0.111], (7) 0.152 [95% CI 0.027–0.330]. A linear regression between measurement 1 and 4 showed a correlation of 0.272 (p = 0.036). Conclusions: It could be shown that reliability of measuring HA depends on the investigated anatomical structure. Placing a tangent along the calcaneus (2, 3, 5, 6, 7) was shown to be unreliable, whereas determining the weight-bearing heel point (1, 4) appeared to be a reliable approach. The correlation of the measurement workflows is significant (p = 0.036), but too weak (0.272) to be used clinically. [ABSTRACT FROM AUTHOR]

Background: Although correction of ankle and hindfoot deformity after supramalleolar osteotomy has been investigated extensively, the specific effect on the subtalar joint alignment remains elusive. This can be attributed to the limitations of 2-dimensional measurements, which impede an exact quantification of the 3-dimensional subtalar joint alignment. Therefore, we determined both the ankle, hindfoot, and subtalar joint alignment before and after supramalleolar osteotomy using autogenerated 3-dimensional measurements based on weightbearing CT imaging. Methods: Twenty-nine patients with a mean age of 50.4±10.6 years were retrospectively analyzed in a pre-post study design using weightbearing CT. Inclusion criteria were correction of ankle varus deformity by an opening wedge (n = 22) or dome osteotomy (n = 7). Exclusion criteria consisted of an additional inframalleolar arthrodesis or osteotomy. Corresponding 3-dimensional bone models were reconstructed to compute following autogenerated measurements of the ankle- and hindfoot alignment: tibial anterior surface (TAS), tibiotalar surface (TTS), talar tilt (TT) angle, hindfoot angle (HA). In addition, the talocalcaneal angle (TCA) in the axial (TCAax), sagittal (TCAsag), and coronal (TCAcor) plane were measured to assess the subtalar joint alignment. Results: The preoperative radiographic parameters of the ankle joint alignment (TAS=88±4 degrees, TTS=82±7 degrees, TT=5.8±4.9 degrees) improved significantly relative to their postoperative equivalents (TAS = 93±5 degrees, TTS = 88±7 degrees, TT=4.2±4.5 degrees; P <.05). The following radiographic parameters of the hindfoot and subtalar joint alignment improved significantly from preoperatively (8.7±8.9 degrees, TCAax = 41±10 degrees, TCAsag = 48±10 degrees) to postoperatively (HA=4.5±8.6 degrees, TCAax = 38±9 degrees, TCAsag = 44±11 degrees; P <.05). No significant differences could be detected in the coronal plane alignment of the subtalar joint (TCAcor) pre- compared to postoperatively (P >.05). Conclusion: This study quantified the 3-dimensional ankle, hindfoot, and subtalar joint alignment after a solitary supramalleolar osteotomy. We found alterations in the subtalar joint alignment, which occurred by 2 to 3 degrees in each anatomic plane. However, before recommendations can be given related to inframalleolar procedures in conjunction to supramalleolar osteotomies, further studies on the variation of subtalar joint alignment change are needed. [ABSTRACT FROM AUTHOR]

Abstract Background The change in hip-knee-ankle (HKA) angle after total knee arthroplasty (TKA) may cause an adjustment in hindfoot alignment (HFA). However, the relationship between the changes in HKA angle and HFA is still not well studied. This study aimed to investigate the association between HKA angle and hindfoot alignment changes after TKA for varus knee osteoarthritis. Methods A prospective study was carried out in which 108 patients with varus knee deformities were radiographically and clinically evaluated before and 3 months after TKA. The relationship of change in HFA with correction in HKA angle was investigated. Results The results showed that the HFA was adjusted significantly by 3 months after TKA (p

The aim of the current study was to understand the importance of the joint alignment following triple arthrodesis by analysing the contact characteristics in a normal and arthritic ankle joint using a patient-specific numerical model developed using open source software. The alignment of the hindfoot with respect to tibia is calculated from CT scans and the ankle joint model was numerically analysed for neutral, valgus and varus positions in both normal and arthritic conditions. The contact area, the magnitude and distribution of the contact pressure on the articular surface of the talar dome was evaluated using a cell-centred Finite Volume Method implemented in open-source software OpenFOAM. It was found that all positions of the hindfoot predict higher lateral pressures during heel strike. The varus position predicts the maximum increase in lateral pressures. Comparing the valgus and neutral positions, although the neutral position predicts 9.1 % higher increase in lateral pressures during heel strike than valgus, it predicts 33.6 % decrease in pressures during heel-rise and the distribution is more medial during toe-off. In the case of arthritic ankle, it could be observed that the neutral and varus hindfoot fusion positions result in a concentrated increase of lateral pressures in heel strike and flat-foot. In the case of toe-off, the neutral alignment results in an increase of 62.3 % in the contact pressures compared to the arthritic pressure of the unfused foot and is 20.8 % higher than the valgus alignment. The study helps to conclude that the fusion is more beneficial at the neutral position of the hindfoot for the patient specific ankle. However, the 5° valgus position of hindfoot alignment could be more beneficial in the arthritic ankle. Patient-specific approach to the placement of the hindfoot with the help of numerical analysis could help address the issue of ankle degradation following arthrodesis. • 5° valgus position of the calcaneus increased the predicted contact pressures with the lateral talar dome stressed during the entire stance phase. • Neutral position predict movement in the contact pressures from lateral to medial when ankle moves from heel strike to toe-off. • The valgus position predicts lesser contact pressure than the neutral position for arthritic ankle. • Patient-specific approach to the placement of hindfoot could help address the issue of ankle degradation following arthrodesis. [ABSTRACT FROM AUTHOR]

Introduction: Pes planus is a common three-dimensional (3D) deformity characterised by forefoot abduction, the collapse of the medial longitudinal arch, and hindfoot valgus. Several radiological measurements such as anteroposterior talocalcaneal angle (Kite's) and 'Calcaneal pitch angle' (CPA) exist to calculate the degree of hindfoot alignment in these patients with variable intra- and interobserver reliability. Objective: To describe a new radiological ancillary method of measuring hindfoot alignment, the calcaneal offset index (COI). Material and Methods: Anteroposterior (mortise) and lateral view weight-bearing (WB) ankle radiographs of 200 consecutive patients referred for foot and ankle pain were reviewed. Demographic details, clinical indication, and COI calculation were undertaken on the mortise view along with the measurement of CPA for each patient. A one-way analysis of variance (ANOVA) was performed. Intraclass correlation coefficient (ICC) analysis was evaluated to assess the intraclass reliability between observers. Results: There was a female preponderance of 2:1 in the study population with a mean age of 51.21 years (13–86 years). The calcaneal offset was increased in pes planus (hindfoot valgus). The p-value was 0.00023 on ANOVA. The COI gave an excellent interobserver correlation with ICC of 0.9 and moderate intraobserver reliability on the ICC analysis of 0.55. Conclusion: The COI can be an additional index of measuring hindfoot alignment in patients with pes planus. Contrary to the traditional angular measurements, this linear transverse plane measure is easier to calculate and reproducible. COI measurement has shown moderate intraobserver reliability but excellent interobserver reliability. [ABSTRACT FROM AUTHOR]

Background: Recent work has reported a significant association between first metatarsal (M1) rotation and hindfoot alignment, with the finding of a moderate association between the calcaneal moment arm (CMA) and 2 M1 pronation angular measures: Saltzman (r = 0.641, P <.01) and Kim (r = 0.615, P <.01). The aim of the current post hoc investigation was to determine if this association is related with Meary angle. Methods: We reanalyzed previously published data set separating patients into 2 groups: (1) those with normal Meary angle (n = 128) and (2) those with abnormal Meary angle (n = 147). Hindfoot alignment and M1 rotation were measured on weightbearing computed tomography. Statistical analyses were performed to evaluate for association between these variables among the groups. Results: The correlation between CMA and M1 rotation of the entire cohort was r = 0.577 (Saltzman ankle) and r = 0.540 (Kim angle). For the subset with a normal Meary angle, this association was negligible (Saltzman and Kim angles, r = 0.194 and 0.240, respectively). Conversely, for the abnormal Meary angle subset, the association was substantial (Saltzman and Kim angles, r = 0.733 and 0.675, respectively). Conclusion: Patients presenting with an abnormal Meary angle and hindfoot deformity have a high likelihood of manifesting a proportionate degree of M1 rotation. Level of Evidence: Level III, Retrospective Cohort Study. [ABSTRACT FROM AUTHOR]

Background: Traditional imaging techniques for total ankle arthroplasty (TAA) evaluation are limited by rotational bias and bone superimposition, highlighting the necessity for more precise assessment methods. The advent of weight-bearing computed tomography (WBCT) generated 3D enhance the visualization of foot and ankle alignment, offering unmatched detail. This study aims to assess the accuracy of preoperative and postoperative measurements in TAA across all three planes using WBCT-generated 3D models. We hypothesize that these models can be reliably used to compare preoperative and postoperative alignment., Methods: For 81 patients undergoing TAA, preoperative and postoperative WBCT models were created. Measurements included five coronal angles: Alpha, Tibiotalar Surface Angle (TSA), Talar Tilt Angle (TT), Salzmann's 20 degrees Angle (SA), and Talocalcaneal Angle (TCA); three sagittal angles: Beta, Gamma, and Tibiotalar Ratio (TTR); and one axial angle: The Posterior Talar Rotational Angle (PTARA). Two raters evaluated these before and after surgery in two separate sessions. The study then compared preoperative to postoperative measurements, calculating inter-rater and intra-rater reliability., Results: Significant changes were observed in three coronal angles (TSA, TT, and SA) and two sagittal angles (Beta and Gamma), with P-values of 0.2, 0.007, 0.019, <0.001, and <0.001, respectively. No significant changes were noted in Alpha, TCA, TTR, and PTARA, with P-values of 0.2, 0.9, 0.2, and 0.6, respectively. Intra-rater and inter-rater reliability scores ranged from 0.885 to 0.97, indicating good to excellent interclass correlation across all planes, both pre-and postoperatively., Conclusion: WBCT-generated 3D modeling and image analysis software have enabled a detailed comparison between preoperative alignment and postoperative TAA positioning across coronal, sagittal, and axial planes, revealing significant adjustments in coronal and sagittal alignments. The high reliability and reproducibility of these measurements affirm their value in preoperative planning in improving the accuracy of surgical interventions., Level of Evidence: Level III of evidence., Competing Interests: Declaration of Competing Interest The authors declared the following potential conflicts of interest with respet to the research autrhorship and/or publicaction of this article: F.U. is consultant for Zimmer Biomet, Arthrex Inc., Episurf, Planmed Oy, Geistlich Pharma AG, BRM Trust, Paragon 28 Inc., (Copyright © 2024 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

Background: The association between forefoot and hindfoot position for planus and cavus feet is fundamental to the treatment of these deformities. However, no studies have evaluated the association between hindfoot alignment and first metatarsal (M1) axial rotation. Understanding this possible relationship may help to understand the deformity and improve patient care. The purpose of this study is to determine a correlation between hindfoot alignment and metatarsal rotation as assessed by weightbearing computed tomography (WBCT). Methods: Patients who underwent weightbearing plain radiography (WBPR) and WBCT between 2015 and 2018 were evaluated. Hindfoot alignment was measured with the calcaneal moment arm (CMA). M1 rotation was measured using the Kim and Saltzman angles. Patient subgroups were created according to the severity of valgus/varus hindfoot alignment. Statistical analyses were performed to evaluate for association between variables. Results: Among the 196 patient feet included in the study, the average CMA was 6.0 ± 16.2 mm. The average Kim and Saltzman angles were 7.7 ± 12.9 degrees and 2.8 ± 13.1 degrees, respectively. The average Meary angle was 182.0 ± 11.9 degrees. A moderately strong association was found between the CMA and the Saltzman (r = 0.641, P <.01) and Kim angles (r = 0.615, P <.01). Hindfoot valgus was associated with M1 pronation and hindfoot varus with M1 supination. Additionally, inverse relationships between the Meary angle and the Saltzman (r = −0.600, P <.01) and Kim angles (r = −0.529, P <.01) were identified. Conclusion: In this well-defined cohort, we found substantial correlation between hindfoot alignment and M1 rotation. Hindfoot valgus was associated with M1 pronation, and hindfoot varus was associated with M1 supination. Surgeons correcting cavovarus/planovalgus deformities should be aware of this association and evaluate the need for first-ray derotation. Level of Evidence: Level III, retrospective cohort study. [ABSTRACT FROM AUTHOR]

Background: Hindfoot alignment view (HAV) radiographs are widely utilized for 2-dimensional (2D) radiographic assessment of hindfoot alignment; however, the development of weightbearing computed tomography (WBCT) may provide more accurate methods of quantifying 3-dimensional (3D) hindfoot alignment. The aim of this study was to compare the 2D calcaneal moment arm measurements on HAV radiographs with WBCT. Methods: This retrospective cohort study included 375 consecutive patients with both HAV radiographs and WBCT imaging. Measurement of the 2D hindfoot alignment moment arm was compared between both imaging modalities. The potential confounding influence of valgus/varus/neutral alignment, presence of hardware, and motion artifact were further analyzed. Results: The intraclass correlation coefficients (ICCs) of interobserver and intraobserver reliability for measurements with both imaging modalities were excellent. Both modalities were highly correlated (Spearman coefficient, 0.930; P <.001). HAV radiographs exhibited a mean calcaneal moment arm difference of 3.9 mm in the varus direction compared with WBCT (95% CI, –4.9 to 12.8). The difference of hindfoot alignment between both modalities was comparable in subgroups with neutral/valgus/varus alignment, presence of hardware, and motion artifact. Conclusion: Both HAV radiographs and WBCT are highly reliable and highly correlated imaging methods for assessing hindfoot alignment. Measurements were not influenced by severe malalignment, the presence of hardware, or motion artifact on WBCT. On average, HAV radiographs overestimated 3.9 mm of varus alignment as compared with WBCT. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

Background: The change in hip-knee-ankle (HKA) angle after total knee arthroplasty (TKA) may cause an adjustment in hindfoot alignment (HFA). However, the relationship between the changes in HKA angle and HFA is still not well studied. This study aimed to investigate the association between HKA angle and hindfoot alignment changes after TKA for varus knee osteoarthritis.Methods: A prospective study was carried out in which 108 patients with varus knee deformities were radiographically and clinically evaluated before and 3 months after TKA. The relationship of change in HFA with correction in HKA angle was investigated.Results: The results showed that the HFA was adjusted significantly by 3 months after TKA (p < 0.001), along with improved American Orthopaedic Foot and Ankle Society (AOFAS) ankle hindfoot score (p < 0.001). Next, a univariate correlation and linear regression analysis showed that the change in HFA was weakly correlated with the change in HKA angle (r=-0.262, β=-0.14, 95 % CI: -0.23 to -0.04, P = 0.006). Further stratified analysis and interaction tests revealed that age has a distinct effect on the correlation between the changes in HFA and HKA angle. The correlation was dramatically greater in the group under 65 years (r=-0.474, β=-0.26, 95 % CI: -0.41 to -0.12, P = 0.001), whilst, no correlation was observed in those above 65 years old (r=-0.036, β=-0.02, 95 % CI: -0.14 to 0.11, P = 0.779).Conclusions: Our findings indicated that correction of HKA after TKA tend to promote adjustment in the hindfoot alignment toward re-balance of the whole lower limb weight-bearing axis. However, this mechanism obviously weakens in elderly patients. Therefore, if apparent hindfoot deformity exists in these patients before TKA, more perioperative intervention is required for hindfoot adjustment, and even HKA undercorrection may be considered. [ABSTRACT FROM AUTHOR]

Background: The primary aim of this study was to determine the mean values for three of the most common parameters measured to assess hindfoot alignment in asymptomatic subjects: hindfoot alignment angle (HAA), hindfoot alignment ratio (HAR), and hindfoot moment arm (HMA). The secondary aim was to evaluate the mean value of each parameter according to age and sex.Methods: We assessed 1128 asymptomatic subjects from January 2014 to June 2019. HAA, HAR and HMA were measured to evaluate the degree of hindfoot varus or valgus deviation on the hindfoot alignment view, described by Saltzman and el-Khoury. All subjects were divided into subgroups according to sex and age (<45 years versus ≥45 years).Results: The overall mean HAA, HAR, and HMA were -4.07 ± 3.48°, 0.21 ± 0.15, and -6.12 ± 5.22 mm, respectively. Female subjects ≥45 years old had the largest valgus deviation (HAA, -7.08 ± 6.34°; HAR 0.09 ± 0.25; HMA, -10.58 ± 11.46 mm).Conclusions: HAA, HAR, and HMA evaluation revealed that asymptomatic subjects had a hindfoot alignment with valgus deviation. Furthermore, the degree of valgus deviation was the largest in female subjects aged ≥45 years. We hope that the results of our study will be helpful to inform other researchers about the usefulness of these parameters as references. [ABSTRACT FROM AUTHOR]

Background: In patients with end-stage varus ankle osteoarthritis (OA), hindfoot varus malalignment resulting from the varus deformity of the ankle joint is common. Although total ankle arthroplasty (TAA) performed to correct varus deformity of the ankle joint has the effect of correcting hindfoot alignment, no reports to date have described how much hindfoot alignment correction can be achieved. The purpose of this study was to identify correlation between ankle deformity correction and hindfoot alignment change after performing TAA in patients with end-stage varus ankle OA. Methods: A total of 61 cases that underwent TAA for end-stage varus ankle OA and followed up for at least 1 year were enrolled for this study. Correlation between changes of tibial-ankle surface angle (TAS), talar tilt (TT), and tibiotalar surface angle (TTS) and changes of hindfoot alignment angle (HA), hindfoot alignment ratio (HR), and hindfoot alignment distance (HD) measured preoperatively and at postoperative year 1 was analyzed. Results: TAS, TT, and TTS changed from 83.9 ± 4.1 degrees, 5.8 ± 5.0 degrees, and 78.1 ± 5.9 degrees, respectively, before operation to 89.2 ± 2.1 degrees, 0.4 ± 0.5 degrees, and 88.7 ± 2.3 degrees, respectively, after operation. HA, HR, and HD also changed from −9.2 ± 4.6 degrees, 0.66 ± 0.18, and −11.2 ± 6.9 mm to −3.7 ± 4.1 degrees, 0.48 ± 0.14, and −5.0 ± 5.3 mm. All the changes were statistically significant (P <.001, respectively). The regression slope of correlation was 0.390 (R 2 = 0.654) between TTS and HA; 0.017 (R 2 = 0.617) between TTS and HR; and 0.560 (R 2 = 0.703) between TTS and HD. Conclusion: In patients with end-stage varus ankle OA, changes of hindfoot alignment could be predicted based on degree of ankle deformity corrected with TAA. Level of Evidence: Level IV, case series. [ABSTRACT FROM AUTHOR]

Aim: To investigate the incidence of concomitant osteochondral lesions of the talus (OLT) and their effect on clinical outcome in anterolateral impingement syndrome (ALIS). Materials and Methods: Patients who underwent ankle arthroscopy due to ALIS of the ankle between 2012 and 2018 were retrospectively screened. The patients were divided into two groups according to the presence of OLT. Preoperatively hindfoot alignment (HA) was measured on long axial view radiographs. All measurements were performed by the experienced musculoskeletal radiologist. The association between osteochondral lesions of the talus and hindfoot alignment disorder was statistically assessed. The patients before and after surgery were evaluated with American Orthopedic Foot and Ankle Society (AOFAS) Hindfoot score for clinical performance. Results: OLT accompanied impingement syndrome in 38 (34.8%) of 109 patients examined. The preoperative and postoperative AOFAS Pain and AOFAS Function results were found no significantly different between the two groups according to the presence of OLT (n.s.). However, AOFAS Alignment results of OLT (-) Group were significantly higher than OLT (+) Group. Mean Hindfoot Angle (HA) was −3.7 ± 12.8 (varus) and 4.6 ± 11.2 (valgus) in feet with and without OLT, respectively (Table 1). In this study, there was a significant association between positive OLT and clinical varus hindfoot (p < .001) Conclusion: In the current study the hindfoot alignment showed association with the location of OLT in Anterolateral Impingement Syndrome. However, it was also determined that the presence of chondral damage had no negative effect on the treatment of anterolateral impingement syndrome. It should be kept in mind that this syndrome can be accompanied by osteochondral lesions of the talus at a significant rate. [ABSTRACT FROM AUTHOR]

Background: Auto-generated 3-dimensional (3D) measurements based on weightbearing cone-beam computed tomography (CT) scan technology may allow for a more accurate hind- and midfoot assessment. The current study evaluated the reliability and clinical relevance of such measurements in patients with posttraumatic end-stage ankle osteoarthritis. Methods: Seventy-two patients treated at our institution for posttraumatic end-stage ankle osteoarthritis, with available weightbearing conventional radiographs and a cone-beam CT scan, were analyzed. Twenty healthy individuals aged between 40 and 70 years served as controls. Seven variables were measured on weightbearing conventional radiographs (2D) and compared to 3D measurements that were based on reconstructions from weightbearing cone-beam CT scans. The reliability of each measurement was calculated and subgroups formed according to commonly observed deformities. Results: Inter- and intraobserver reliability was superior for 3D compared to 2D measurements. The accuracy of 3D measurements performed on osteoarthritic ankles was similar to 3D measurements performed on healthy individuals. Thirty-three of the 72 included patients (46%) evidenced an inframalleolar compensation of a supramalleolar/intra-articular ankle deformity (78% = varus compensation; 22% = valgus compensation), whereas 24 of those 72 patients (33%) showed no compensation or a further increase of a supramalleolar/intra-articular ankle deformity (67% = varus deformity; 33% = valgus deformity). Conclusion: Auto-generated 3D measurements of the hind- and midfoot were found to be reliable in both healthy individuals and patients with posttraumatic end-stage ankle osteoarthritis. Such measurements may be crucial for a detailed understanding of the location and extent of hindfoot deformities, possibly impacting decision making in the treatment of end-stage ankle osteoarthritis. Level of Evidence: Level III, comparative study. [ABSTRACT FROM AUTHOR]

Background: Low tibial valgization osteotomy with medial opening wedge (LTO) is generally indicated for ankle arthritis with a small talar tilt (TT). We addressed the following research questions: the efficacy of LTO for more significant varus ankle arthritis, the effect of additional inframalleolar correction followed by LTO, and the preoperative or operation-related factors influencing postoperative TT decrease. Methods: We retrospectively reviewed the radiographic and clinical findings of 31 patients with more significant varus ankle arthritis (≥8 degrees) who underwent LTO or LTO plus inframalleolar correction. We grouped the included patients according to combination with inframalleolar correction and postoperative decreased TT. Furthermore, a binary logistic regression analysis was performed to determine the factors influencing postoperative TT decrease. Results: Even though the mean TT was unchanged postoperatively (from 12.1 to 9.9 degrees, P =.052), clinical parameters were significantly increased. In the group with concomitant inframalleolar correction, we found that TT was more corrected (3.9 vs 1.8 degrees, P =.023) with a greater lateralization of the talar center and a greater correction of the hindfoot alignment to valgus. The results of the binary logistic regression analysis showed a significant relationship between postoperative decreased TT and preoperative talar center migration (P =.016), hindfoot alignment angle (P =.033), hindfoot moment arm (P =.041), and hindfoot alignment ratio (P =.016). Conclusion: LTO in more significant varus ankle arthritis could result in clinical improvement, although TT was not significantly changed. We recommend adding inframalleolar correction after LTO for the patients with more significant varus ankle arthritis. Level of Evidence: Level III, comparative series. [ABSTRACT FROM AUTHOR]

Background: Semiautomatic 3-dimensional (3D) biometric weightbearing computed tomography (WBCT) tools have been shown to adequately demonstrate the relationship between the center of the ankle joint and the tripod of the foot. The measurement of the foot and ankle offset (FAO) represents an optimized biomechanical assessment of foot alignment. The objective of this study was to evaluate the correlation between FAO and traditional adult acquired flatfoot deformity (AAFD) markers, measured in different planes. We hypothesized that the FAO would significantly correlate with other radiographic markers of pronounced AAFD. Methods: In this retrospective comparative study, we included 113 patients with stage II AAFD, 43 men and 70 women, mean age of 53.5 (range, 20-86) years. 3D coordinates (x, y, and z planes) of the foot tripod (most plantar voxel of the first and fifth metatarsal heads, and calcaneal tuberosity) and the center of the ankle joint (most proximal and central voxel of the talar dome) were assessed by 2 blinded and independent fellowship-trained orthopedic foot and ankle surgeons. The FAO was automatically calculated using the 3D coordinates by dedicated software. Multiple WBCT parameters related to the severity of the deformity in the coronal, sagittal, and transverse planes were manually measured. Results: We found overall good to excellent intra- (range, 0.75-0.99) and interobserver (range, 0.73-0.99) reliability for manual AAFD measurements. FAO semiautomatic measurements demonstrated excellent intra- (0.99) and interobserver (0.99) reliabilities. Hindfoot moment arm (HMA) (P <.00001), subtalar horizontal angle (P <.00001), talonavicular coverage angle (P =.00004), and forefoot arch angle (P =.0001) were the only variables found to significantly influence and correlate with FAO measurements, with an R 2 value of 0.79. An HMA value of 19.8 mm was found to be a strong threshold predictor of increased values of FAO, with mean values of FAO of 6.5 when the HMA was lower than 19.8 mm and 14.6 when the HMA was equal to or higher than 19.8 mm. Conclusion: We found that 3D WBCT semiautomatic measurements of FAO significantly correlated with some traditional markers of pronounced AAFD. Measurements of FAO were also found to be slightly more reliable than the manual measurements. The FAO offers a simple and more complete biomechanical and multiplanar assessment of the AAFD, representing in a single measurement the 3D components of the deformity. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

Background: Cavovarus foot constitutes a complex 3-dimensional deformity. The Coleman block test has traditionally been used to distinguish between forefoot- and hindfoot-driven deformity. However, there has been no objective evaluation of the Coleman block test using radiographs or weightbearing computed tomography (WBCT). The purpose of this study was to compare hindfoot alignment in adult cavovarus feet with and without the Coleman block using clinical examination, radiography, and WBCT. Methods: Six feet in 6 patients with a clinical diagnosis of cavovarus foot deformity were prospectively enrolled. All feet underwent clinical photography with the camera positioned at 0 degrees to the heel, hindfoot alignment view radiography with the beam positioned 20 degrees off the ground, and WBCT, both with and without the Coleman block in place. Clinical photos were characterized using the standing talocalcaneal angle (STCA), radiographs were characterized using the hindfoot alignment angle (HAA), and WBCTs were characterized using manual and automated hindfoot alignment angle (HAA) and foot and ankle offset (FAO). Using paired analyses, measurements taken with the Coleman block in place were compared to those taken without the Coleman block. Finally, the different methods of measuring hindfoot alignment were tested for correlation with each other. Mean age was 56 years (range 38-69). Results: On clinical photography, the STCA decreased by 3.8 degrees with addition of the block (from 10.0+6.6 degrees varus without block to 6.2+7.1 degrees varus with block; P = .001). On radiograph, HAA decreased by 9.0 degrees with addition of the block (from 16.8+8.4 degrees varus without block to 7.5+6.3 degrees varus with block; P = .07). On WBCT, hindfoot alignment angle changed an average of 3.2 degrees (33.4 degrees varus without block, 30.2 degrees varus with block; P = .008). On WBCT, FAO decreased by 1.4% (from 11.3% varus without block to 10.1% varus with block; P = .003). Clinical examination and automated WBCT measurements were strongly correlated with each other. Conclusion: Clinical examination, radiograph, and WBCT demonstrated improvements in hindfoot varus using the Coleman block test in adults, but no patient demonstrated complete resolution of deformity regardless of the measurement modality. Clinical examination correlated strongly with automated WBCT measurements. [ABSTRACT FROM AUTHOR]

Purpose: Osteoarthritis of knees with varus deformity is associated with a compensatory valgus deformity of the hindfoot and a lateral loading foot pressure pattern. However, whether this abnormal loading pattern is corrected in total knee arthroplasty (TKA) is unclear.Methods: The alignment and loading pattern of 91 consecutive patients (121 knees) undergoing TKA with pre-operative varus more than 10° were evaluated prospectively with functional outcome scores, static conventional radiography and dynamic pedobarogaphy pre-operatively and 1-year post-operatively. Outcomes assessed were Oxford Knee Scores, American Orthopaedic Foot and Ankle Scores, femorotibial mechanical angle, tibia-hindfoot angle, hindfoot valgus/varus index (VVI), foot line of pressure (LOP) laterality and peak pressure (PP) at both time points.Results: Of 121 knees, 98 (81%) regained normal alignment of the knee and 114 (92%) of the hindfoot. Similarly, PP (p < 0.001), VVI (pre-operative: - 0.29 ± 0.22, post-operative: - 0.04 ± 0.23, p < 0.001) and LOP laterality (pre-operative: 7% medial, post-operative: 96% medial, p < 0.001) all medialised post-operatively. All patients had improved functional outcomes at the knee (pre-operative: 20 ± 2, post-operative: 40 ± 2, p < 0.001) and ankle (pre-operative: 59 ± 10, post-operative: 89 ± 6, p < 0.001).Conclusion: The present study shows, following the correction of knee varus with TKA, hindfoot alignment and foot loading pattern are both restored in the majority of patients. TKA offers both static and dynamic correction as seen in the hindfoot and loading pattern, respectively.Level Of Evidence: Level III: prospective case-control study. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: When weight bearing radiographs are taken, the patient is frequently asked to stand on the foot being examined with the other foot lifted off the floor. We have found however that alignments of the hind and midfoot change when bearing weight switches from bilateral to unilateral standing. This study investigated the possible differences in hindfoot alignments between unilateral and bilateral weight bearing using radiographical evaluation. Methods: Eight flexible feet without symptoms symptoms, nor significant trauma & surgical history in their lower limbs were recruited for this study. A portable fluoroscopy machine (Smart C, Turner Imaging, Salt Lake City, USA) was used to take weightbearing lateral views. The patient first stood on both feet with the non-examined foot standing outside of the collimator but bearing weight evenly (Figure 1), and then lifted the non-examined foot off the floor when the lateral XR image was taken for the examined foot. Hindfoot alignment in both positions was reflected by measuring the angle between the long axes of the proximal and distal portions of the Achilles tendon on the skin using the subtalar joint line as the intersection. On lateral XRs, various parameters were measured to reflect the subtalar joint alignment, the position of the calcaneus with inversion and eversion of the hindfoot, and the lateral and medial arch heights. Results: From bearing weight on two feet (bilaterally) to one foot (unilaterally), the Hindfoot Alignment Angle (Achilles) increased (6.23 to 11.21 degrees), the Calcaneal Pitch Angle decreased (22.06 to 19.22 degrees), the Middle vs Posterior Facets Angle decreased (166.46 to 160.74 degrees), and the 5th metatarsal/cuboid height decreased (0.73 to 0.67) all significant changes (p < 0.05). All of these represented a pronation movement in the mid and hindfoot, ie, valgus tilt/eversion of the calcaneus, decreased sinus tarsi opening, and reduced lateral arch height. In this small cohort, these differences were more obvious in the feet that were either slightly flat or cavus shaped (Figure 1, Table 1, and 2) than in feet with a more neutral alignment. Conclusion: The hindfoot and midfoot are more pronated in unilateral weightbearing than in bilateral weightbearing which may mask the severity of the deformity in a flexible cavovarus foot, but increase that in a flexible flatfoot. Modification of the traditionally used unilateral weightbearing position in obtaining clinical radiographs should be considered. Bilateral WBCT scans may be a better alternative, taking advantage of allowing both feet to stand in the most natural position without one foot blocking the other during the radiographic imaging. [ABSTRACT FROM AUTHOR]

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: When AP, lateral, and hindfoot views weight bearing XR's were taken, patients were frequently asked to stand on the foot being examined with the other foot lifted off the floor. However, we have found that alignments of the hind and midfoot during unilateral standing are different from those when bearing weight on both feet. This study compared the kinematics and plantar pressures between unilateral and bilateral standing positions in a group of asymptomatic volunteers. Methods: Ten participants (20 feet) without symptoms, previous trauma and surgical history in both lower limbs were included. Each participant first stood comfortably on both feet, then lifted the non-examined foot off the floor. Each person switched between the above two positions three times. Kinematic data was collected using an eight-camera Optitrack 3D motion capture system to reflect changes in alignments of the ankle, subtalar, and midtarsal joints. Plantar pressure distribution was assessed using a pressure platform. Paired t-tests were used to compare the metrics between the two standing positions, with statistical significance level set at P < 0.05. Results: From bilateral to unilateral weightbearing, 14 out of 21 kinematic angular parameters showed medium to high level of statistical significance (p=0.001-0.046) reflecting differences in the relative positions of the ankle, subtalar, and midtarsal joints in the two weightbearing positions resulting from pronation of the hindfoot and midfoot; the average plantar pressure change underneath the hallux (0.1616N), toes 2-5 (0.0907N), metatarsals 2-4 (0.2481N, 0.3204N, 0.2649N), midfoot (0.1794N), medial and lateral heel (0.259N, 0.246N) all showed statistically significant increase. There was a significantly higher plantar pressure increase on the medial than the lateral side of the feet. This corresponded to both the kinematic changes, and our findings in another study investigating the alignment change between the positions radiographically. Conclusion: The hindfoot and midfoot are more pronated in unilateral weightbearing than in bilateral weightbearing which may mask the severity of the deformity in a flexible cavovarus foot but increase that in a flexible flatfoot. Modification of the traditionally used unilateral weightbearing position in obtaining clinical radiographs should be considered. Bilateral WBCT scans may be a better alternative, taking advantage of allowing both feet to bearing weight naturally without concerning about one foot blocking the other during the radiographic imaging. [ABSTRACT FROM AUTHOR]

Background: A medializing calcaneal osteotomy is frequently performed to correct adult-acquired flatfoot deformities, but there is lack of data on the associated three-dimensional variables defining the final correction. The aim of this study was to assess the correlation between the pre-operative hindfoot valgus deformity and calcaneal osteotomy angles and the post-operative calcaneal displacement.Methods: Weight-bearing CT scans obtained pre- and post-operatively were retrospectively analyzed for sixteen patients. Corresponding three-dimensional bone models were used to measure valgus deformity pre- and post-operatively, inclination of the osteotomy and displacement of the calcaneus. Linear regression was conducted to assess the relationship between these measurements.Results: On average, the hindfoot valgus changed from 13.1° (±4.6) pre-operatively to 5.7° (±4.3) post-operatively. A mean inferior displacement of 3.2mm (±1.3) was observed along the osteotomy with a mean inclination of 54.6° (±5.6), 80.5° (±10.7), -13.7° (±15.7) in the axial, sagittal and coronal planes, respectively. A statistically significant positive relationship (p<.05, R2=0.6) was found between the pre-operative valgus, the axial osteotomy inclination, and the inferior displacement.Conclusions: This study shows that the degree of pre-operative hindfoot valgus and the axial osteotomy angle are predictive factors for the amount of post-operative inferior displacement of the calcaneus. These findings demonstrate the added value of a computer-based pre-operative planning in clinical practice. Level of evidence II Prospective comparative study. [ABSTRACT FROM AUTHOR]

Background: Clinical assessment of hindfoot alignment (HA) in adult acquired flatfoot deformity (AAFD) can be challenging and weightbearing (WB) cone beam CT (CBCT) may potentially better demonstrate this three-dimensional (3D) deformity. Therefore, we compared clinical and WB CBCT assessment of HA in patients with AAFD.Methods: In this prospective study, we included 12 men and 8 women (mean age: 52.2, range: 20-88) with flexible AAFD. All subjects also underwent WB CBCT and clinical assessment of hindfoot alignment. Three fellowship-trained foot and ankle surgeons performed six hindfoot alignment measurements on the CT images. Intra- and Inter-observer reliabilities were calculated using intra-class correlation (ICC). Measurements were compared by paired T-tests, and p-values of less than 0.05 were considered significant.Results: The mean of clinically measured hindfoot valgus was 15.2 (95% confidence interval [CI]: 11.5-18.8) degrees. It was significantly different from the mean values of all WB CBCT measurements: Clinical Hindfoot Alignment Angle, 9.9 (CI: 8.9-11.1) degrees; Achilles tendon/Calcaneal Tuberosity Angle, 3.2 (CI: 1.3-5.0) degrees; Tibial axis/Calcaneal Tuberosity Angle, 6.1 (CI: 4.3-7.8) degrees; Tibial axis/Subtalar Joint Angle 7.0 (CI: 5.3-8.8) degrees, and Hindfoot Alignment Angle 22.8 (CI: 20.4-25.3) degrees. We found overall substantial to almost perfect intra- (ICC range: 0.87-0.97) and inter-observer agreements (ICC range: 0.51-0.88) for all WB CBCT measurements.Conclusions: Using 3D WB CBCT can help characterize the valgus hindfoot alignment in patients with AAFD. We found the different CT measurements to be reliable and repeatable, and to significantly differ from the clinical evaluation of hindfoot valgus alignment.Level Of Evidence: Level II-prospective comparative study. [ABSTRACT FROM AUTHOR]

Background: Varus hindfoot deformity may increase the risk of chronic lateral ankle instability (CLAI). Our aim was to analyze hindfoot alignment (HFA) in patients with CLAI using weight-bearing cone beam computed tomography (WBCT) to assess this risk. Methods: This retrospective, comparative analysis was carried out using an existing WBCT database (Talas, CurveBeam LLC), including data sets for 370 consecutive feet (189 patients) obtained between July 2016 and October 2018 at a single institution. The software provided semiautomated measurement of HFA, given as foot ankle offset (FAO). Univariate analysis was conducted to compare feet with and without CLAI against sex, age, body mass index, and FAO. Significant variables were included in a multivariable logistic model with random effects to take into account correlation between feet of the same patient. Results: Forty-three feet had CLAI (34 patients). FAO (P =.0009) was significant for CLAI by univariate analysis. Mean FAO was −2.2% ± 5.5% (varus) and + 2.6% ± 4.7% (valgus) with and without CLAI history, respectively. Multivariable logistic regression adjusted for sex and age demonstrated a 35% increased odds ratio (OR) of CLAI per 1% reduction in FAO value (varus) (adjusted OR=0.64, 95% confidence interval [CI]: 0.49-0.84; P =.001) and no significant effect of sex (adjusted OR=0.52; P =.617) or age (adjusted OR=0.94; P =.165) after adjustment for FAO. Conclusion: A positive relationship was found between varus HFA and the risk to have CLAI. Systematic recording of FAO measurements from WBCT images along with clinical data regarding CLAI history proved successful at quantifying the risk of CLAI. Level of Evidence: Level III, retrospective cohort study. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]