Static posture weightbearing joint angle differences in patients with varus ankle osteoarthritis.

BACKGROUND: Advanced varus ankle osteoarthritis is a debilitating disease that can present with limited physical function, severe pain, and diminished quality of life. Weightbearing computed tomography enables submillimeter 3-dimensional visualization, computational analyses, and enhanced diagnoses in reporting complex degenerative changes more accurately. RESEARCH QUESTION: This study set to compare static posture weightbearing joint angle differences in healthy and varus ankle osteoarthritis patients (compensated and non-compensated). METHODS: Our retrospective assessment included 70 individuals, 44 of whom were diagnosed with advanced varus ankle osteoarthritis, and the remaining 26 were healthy participants to serve as controls. An automatic anatomic coordinate system was applied to each patient's 3-dimensional talus and calcaneus bone reconstructions from weightbearing computed tomography scans. Subtalar and midtarsal joint angles were calculated using Euler angles. RESULTS: We report statistical differences between the healthy group and both advanced varus osteoarthritis groups for midtarsal inversion/eversion. Specifically, both osteoarthritis groups' midtarsal joints were more inverted and plantarflexed as compared to healthy participants. Compensated and non-compensated subtalar joints were statistically different with respect to inversion/eversion. Non-compensated ankles exhibited a similar mean to healthy ankles who were both less inverted than compensated ankles. SIGNIFICANCE: Our study helps physicians to better understand underlying mechanisms of peritalar compensation in varus ankle osteoarthritis. Patients featuring hindfoot compensation on average had a greater subtalar joint angle indicating greater inversion than healthy and non-compensated patients.

Sesamoid View Weightbearing Radiography vs Weightbearing Computed Tomography in the Measurement of Metatarsal Pronation Angle.

BACKGROUND: First metatarsal pronation angle (MPA) is increasingly relevant in the management of hallux valgus and is assessed on weightbearing computed tomography (WBCT) and sesamoid-view weightbearing radiography (WBR). The purpose of this study is to compare MPA measured by WBCT against WBR to determine if any systematic discrepancy in MPA measurement exists between the 2 modalities. METHODS: A total of 40 patients with 55 feet were included for study. MPA was measured in all patients by 2 independent readers on both WBCT and WBR with an appropriate washout period between measurement modalities. Mean MPA by WBCT and WBR were analyzed; interobserver reliability was calculated with an intraclass correlation coefficient (ICC) value. RESULTS: Mean MPA as measured by WBCT was 3.7 ± 7.9 degrees (95% CI, 1.6-5.9; range -11.7 to 20.5). Mean MPA measured on WBR was 3.6 ± 8.4 degrees, (95% CI, 1.4-5.8; range -12.6 to 21.4). There was no difference in MPA as measured by WBCT compared to WBR (P = .529). Interobserver reliability was excellent with an ICC of 0.994 for WBCT and 0.986 for WBR. CONCLUSION: Measurement of first MPA by WBCT and WBR was not significantly different. In our cohort of patients with and without forefoot pathology, we found that either sesamoid view weightbearing radiographs or weightbearing CT can be used reliably to measure first MPA and will generate similar values. LEVEL OF EVIDENCE: Level IV, case series.

Scheduled, Simultaneous Dosing of Pregabalin, Celecoxib, and Acetaminophen Markedly Reduces or Eliminates Opioid Use After ACL Reconstruction Using Allograft or Hamstring Tendon Autograft: A Randomized Clinical Trial.

Background: Opioid analgesics continue to be prescribed after ambulatory surgery despite untoward adverse effects, risk of overdose, and association with substance use disorder. Purpose/Hypothesis: The purpose was to investigate the use of a novel system to provide scheduled and simultaneous dosing of acetaminophen, celecoxib, and pregabalin after anterior cruciate ligament reconstruction (ACLR). It was hypothesized that this system would markedly reduce pain and opioid use compared with existing best practice. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: Included were 100 patients scheduled for elective, primary ACLR using allograft or hamstring tendon autograft. Selection criteria included age between 18 and 65 years and weight between 65 and 120 kg. Exclusion criteria were a known allergy to any drug used in the study or the use of opioid analgesics before surgery. Patients in the intervention group received a blister pack with scheduled, simultaneous doses of acetaminophen, celecoxib, and pregabalin; patients were also given oxycodone 5 mg as needed for breakthrough pain. Patients in the control group were prescribed ibuprofen and oxycodone 5 mg/acetaminophen 325 mg as needed for pain. The primary outcome measure was pain. Secondary outcomes were nausea, itching, and daily oxycodone use. Patients were asked to quantify their average pain at rest, nausea, and itching on an 11-point verbal scale (from 0 to 10). These data were recorded for 6 days during daily telephone contacts with patients after hospital discharge. Results: Cumulative results for 6 days showed significantly lower values in the intervention group compared with the control group for pain (median [interquartile range], 28 [14-35] vs 35 [28-41], respectively; P = .009) and oxycodone use (median [interquartile range] number of tablets, 0 [0-2] vs 8 [1.25-16], respectively; P < .001). Based on these data, the upper tolerance limits for the number of oxycodone tablets required by 90% of patients in the intervention and control groups were 8 tablets and 30 tablets, respectively. Cumulative results for nausea and itching were also significantly lower for the intervention group. Most patients in the intervention group used no opioids during recovery. Conclusion: Simultaneous dosing of 3 nonopioid analgesics resulted in reduced postoperative pain and markedly lower opioid use. Registration: NCT04015908 (ClinicalTrials.gov identifier).

Multi-level multi-domain statistical shape model of the subtalar, talonavicular, and calcaneocuboid joints.

Traditionally, two-dimensional conventional radiographs have been the primary tool to measure the complex morphology of the foot and ankle. However, the subtalar, talonavicular, and calcaneocuboid joints are challenging to assess due to their bone morphology and locations within the ankle. Weightbearing computed tomography is a novel high-resolution volumetric imaging mechanism that allows detailed generation of 3D bone reconstructions. This study aimed to develop a multi-domain statistical shape model to assess morphologic and alignment variation of the subtalar, talonavicular, and calcaneocuboid joints across an asymptomatic population and calculate 3D joint measurements in a consistent weightbearing position. Specific joint measurements included joint space distance, congruence, and coverage. Noteworthy anatomical variation predominantly included the talus and calcaneus, specifically an inverse relationship regarding talar dome heightening and calcaneal shortening. While there was minimal navicular and cuboid shape variation, there were alignment variations within these joints; the most notable is the rotational aspect about the anterior-posterior axis. This study also found that multi-domain modeling may be able to predict joint space distance measurements within a population. Additionally, variation across a population of these four bones may be driven far more by morphology than by alignment variation based on all three joint measurements. These data are beneficial in furthering our understanding of joint-level morphology and alignment variants to guide advancements in ankle joint pathological care and operative treatments.

Impact of First Metatarsal Hyperpronation on First Ray Alignment: A Study in Cadavers.

BACKGROUND: There is increased evidence of first metatarsal hyperpronation in patients with hallux valgus, but its impact on the stability of the first metatarsophalangeal and metatarsosesamoid joints is unknown. A previous biomechanical study showed that an increase in hallucal pronation might lead to medial soft tissue failure of the first metatarsophalangeal joint. Conversely, dynamic studies on hallux valgus have shown that the first tarsometatarsal joint moves in supination during weightbearing, and supination was associated with an increase in the intermetatarsal angle (IMA) and hallux valgus angle (HVA). QUESTIONS/PURPOSES: (1) Does an increase in first metatarsal pronation cause an increase in hallucal pronation? (2) Can an intrinsic increase in first metatarsal pronation lead to first ray supination during weightbearing? (3) Can a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increase supination of the first ray during weightbearing? (4) Is first ray supination during weightbearing associated with an increase in the IMA and HVA? METHODS: Twelve transtibial, nonpaired cadaver specimens without deformities were used. Each specimen underwent six weightbearing CT scans under different conditions. The first three CT examinations were performed without any osteotomy of the first metatarsal. The first was a simulated nonweightbearing condition. The second was a simulated weightbearing condition. The third was a simulated weightbearing condition with medial soft tissue release. Subsequentially, a 30° pronation osteotomy of the first metatarsal was performed, and the same sequence of weightbearing CT images was obtained. On each weightbearing CT image, the HVA, IMA, sesamoid rotation angle, metatarsal pronation angle (MPA), metatarsosesamoid rotation angle, and hallucal pronation (HP) were measured. Motions were calculated based on the differential values of these angular measurements produced by the six different conditions (weightbearing, medial soft tissue release, 30° pronation osteotomy, and combinations of these conditions). We compared means using a t-test for normally distributed variables and the Mann-Whitney U test for nonnormally distributed variables. Correlations were assessed with Pearson product-moment correlation coefficients. RESULTS: We found that 30° pronation osteotomy of the first metatarsal increased the MPA and HP by 28° ± 4° and 26° ± 6°, respectively, in the nonweightbearing condition. No differences between the increase in MPA and the increase in HP were noted (mean difference 2° [95% CI -1° to 5°]; p = 0.20). Therefore, an increase in first metatarsal pronation caused an increase in hallucal pronation. When a 30° pronation osteotomy of the first metatarsal was performed, the first ray motion during weightbearing went from pronation to supination (4° ± 2° in pronation without osteotomy versus 4° ± 2° in supination after the osteotomy, mean difference 8° [95% CI 6° to 9°]; p < 0.001). Therefore, an intrinsic increase in pronation of the first metatarsal led to a first ray supination motion during weightbearing. When a first metatarsophalangeal medial soft tissue release was performed in addition to the 30° osteotomy of the first metatarsal, the supination motion of the first ray increased (4° ± 2° without medial soft tissue release versus 11° ± 7° after the release, mean difference 8° [95% CI 3° to 12°]; p = 0.003). Therefore, a combination of intrinsic first metatarsal hyperpronation and first metatarsophalangeal medial soft tissue failure increased supination of the first ray during weightbearing. Regarding static angular measurements, the HVA and IMA were not correlated with the MPA (ρ = 0.20; p = 0.09 and ρ = 0.22; p = 0.07, respectively). Regarding motions, as the HVA and IMA increased from nonweightbearing to weightbearing the pronation decreased, with strong correlations (ρ = -0.82; p < 0.001 and ρ = -0.77; p < 0.001, respectively). Therefore, a first ray supination during weightbearing was associated with an increase in the HVA and IMA. CONCLUSION: The combination of first metatarsal intrinsic hyperpronation and first metatarsophalangeal medial soft tissue failure led to a hallux valgus deformity in this cadaveric study. The static measurement of first metatarsal head pronation relative to the ground (MPA) did not reflect the real intrinsic pronation of the first ray, and foot and ankle specialists should be careful when interpreting these measurements. Hallux valgus is a dynamic condition, and the deformity could be more correlated with motions during weightbearing than with plain static measurements. CLINICAL RELEVANCE: First ray supination compensating for first metatarsal intrinsic hyperpronation might be an important factor in the hallux valgus pathogenesis. Further in vivo studies involving nonweightbearing and weightbearing comparative assessments of hallux valgus and controls should be performed to confirm this pathomechanism.

American Board of Orthopaedic Surgery's Initiatives Toward Competency-Based Education.

The American Board of Orthopaedic Surgery (ABOS) is the national organization charged with defining education standards for graduate medical education in orthopaedic surgery. The purpose of this article is to describe initiatives taken by the ABOS to develop assessments of competency of residents to document their progress toward the independent practice of orthopaedic surgery and provide feedback for improved performance during training. These initiatives are called the ABOS Knowledge, Skills, and Behavior Program. Web-based assessment tools have been developed and validated to measure competence. These assessments guide resident progress through residency education and better define the competency level by the end of training. The background and rationale for these initiatives and how they serve as steps toward competency-based education in orthopaedic residency education in the United States will be reviewed with a vision of a hybrid of time and competency-based orthopaedic residency education that will remain 5 years in length, with residents assessed using standardized tools.

Association of Normal vs Abnormal Meary Angle With Hindfoot Malalignment and First Metatarsal Rotation: A Short Report.

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.

Talar Dome Access Through Posteromedial Surgical Intervals for Fracture Care.

BACKGROUND: Posterior talar body fractures are rare injuries without a consensus surgical approach. This study evaluates the accessible area of the talar dome through 2 posteromedial approach intervals (posteromedial [PM] and modified posteromedial [mPM]) both with and without distraction. METHODS: Ten male cadaveric legs (5 matched pairs) were included. A PM approach, between flexor hallucis longus (FHL) and the tibial neurovascular bundle, and an mPM approach, between FHL and Achilles tendon, was performed on each pair. In total, 4 mm of distraction across the tibiotalar joint was applied with the foot held in neutral position. Accessible dome surface area (DSA) was outlined by drilling with a 1.6-mm Kirschner wire with and without distraction. Specimens were explanted and analyzed by micro-computed tomography with 3-dimensional reconstruction. Primary outcomes were total accessible DSA and sagittal plane access at predetermined intervals. RESULTS: The PM approach allowed access to 19.1% of the talar DSA without distraction and 33.1% of the talar dome with distraction (P < .001). The mPM approach provided access to 20.4% and 35.6% of the talar DSA without and with distraction (P < .001). Both approaches demonstrated similar sagittal plane access at all intervals except the lateral border of the talus, where the mPM approach provided greater access both without distraction (20.5% vs 4.38%, P = .002) and with distraction (34.3% vs 17.8%, P = .02). CONCLUSION: The mPM approach, using an interval between FHL and Achilles tendon, provides similar access to the posterior surface of talar dome and better sagittal plane access to the most lateral portion of the dome. The mPM interval provides the advantage of avoiding direct dissection of the tibial nerve or posterior tibial artery. Using an external fixator for distraction can improve talar dome visualization substantially. LEVEL OF EVIDENCE: Level V, Cadaveric Study.

Interaction of loading and ligament injuries in subtalar joint instability quantified by 3D weightbearing computed tomography.

Despite decades of research since its first description, subtalar joint instability remains a diagnostic enigma within the concept of hindfoot instability. This could be attributed to current imaging techniques, which are impeded by two-dimensional measurements. Therefore, we used weightbearing computed tomography imaging to quantify three-dimensional displacement associated with subtalar joint instability. Three-dimensional models were generated in seven paired cadaver specimens to compute talocalcaneal displacement after different patterns of axial load (85 kg) combined with torque in internal and external rotation (10 Nm). Sequential imaging was repeated in the subtalar joint containing intact ligaments to determine reference displacement. Afterward, the interosseus talocalcaneal ligament (ITCL) or calcaneofibular ligament (CFL) was sectioned, then the ITCL with CFL and after the ITCL, CFL with the deltoid ligament (DL). The highest translation could be detected in the dorsal direction and the highest rotation occurred in the internal direction when external torque was applied to the foot without load. These displacements differed significantly from the condition containing intact ligaments, with a mean difference of 1.6 mm (95% CI, 1.3 to 1.9) for dorsal translation and a mean of 12.4° (95% CI, 10.1 to 14.8) for internal rotation. Clinical relevance: Our study provides a novel and noninvasive analysis to quantify subtalar joint instability based on three-dimensional WBCT imaging. This approach overcomes former studies using trans-osseous fixation to determine three-dimensional subtalar joint displacement and implements an imaging device and software modalities that are readily available. Based on our findings, we recommend applying torque in external rotation to the foot to optimize the detection of subtalar joint instability.

Association Between Hindfoot Alignment and First Metatarsal Rotation.

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.

How Do PROMIS Scores Correspond to Common Physical Abilities?

BACKGROUND: The Patient-Report Outcomes Measurement Information System (PROMIS) is increasingly used as a general-purpose tool for measuring orthopaedic surgery outcomes. This set of questionnaires is efficient, precise, and correlates well with specialty-specific measures, but impactful implementation of patient-specific data, especially at the point of care, remains a challenge. Although clinicians may have substantial experience with established patient-reported outcome measures in their fields, PROMIS is relatively new, and the real-life meaning of PROMIS numerical summary scores may be unknown to many orthopaedic surgeons. QUESTIONS/PURPOSES: We aimed to (1) identify a small subset of important items in the PROMIS Physical Function (PF) item bank that are answered by many patients with orthopaedic conditions and (2) graphically display characteristic responses to these items across the physical function spectrum in order to translate PROMIS numerical scores into physical ability levels using clinically relevant, familiar terms. METHODS: In a cross-sectional study, 97,852 PROMIS PF assessments completed by 37,517 patients with orthopaedic conditions presenting to a tertiary-care academic institution were pooled and descriptively analyzed. Between 2017 and 2020, we evaluated 75,354 patients for outpatient orthopaedic care. Of these, 67% (50,578) were eligible for inclusion because they completed a PROMIS version 2.0 physical function assessment; 17% (12,720) were excluded because they lacked information in the database on individual item responses, and another < 1% (341) were excluded because the assessment standard error was greater than 0.32, leaving 50% of the patients (37,517) for analysis. The PROMIS PF is scored on a 0-point to 100-point scale, with a population mean of 50 and SD of 10. Anchor-based minimum clinically important differences have been found to be 8 to 10 points in a foot and ankle population, 7 to 8 points in a spine population, and approximately 4 points in a hand surgery population. The most efficient and precise means of administering the PROMIS PF is as a computerized adaptive test (CAT), whereby an algorithm intelligently tailors each follow-up question based on responses to previous questions, requiring only a few targeted questions to generate an accurate result. In this study, the mean PROMIS PF score was 41 ± 9. The questions most frequently used by the PROMIS CAT software were identified (defined in this study as any question administered to > 0.1% of the cohort). To understand the ability levels of patients based on their individual scores, patients were grouped into score categories: < 18, 20 ± 2, 25 ± 2, 30 ± 2, 35 ± 2, 40 ± 2, 45 ± 2, 50 ± 2, 55 ± 2, 60 ± 2, and > 62. For each score category, the relative frequency of each possible response (ranging from "cannot do" to "without any difficulty") was determined for each question. The distribution of responses given by each score group for each question was graphically displayed to generate an intuitive map linking PROMIS scores to patient ability levels (with ability levels represented by how patients responded to the PROMIS items). RESULTS: Twenty-eight items from the 165-question item bank were used frequently (that is, administered to more than 0.1% of the cohort) by the PROMIS CAT software. The top four items constituted 63% of all items. These top four items asked about the patient's ability to perform 2 hours of physical labor, yard work, household chores, and walking more than 1 mile. Graphical displays of responses to the top 28 and top four items revealed how PROMIS scores correspond to patient ability levels. Patients with a score of 40 most frequently responded that they experienced "some difficulty" with physical labor, yard work, household chores, and walking more than 1 mile, compared with "little" or "no" difficulty for patients with a score of 50 and "cannot do" for patients with a score of 30. CONCLUSION: We provided a visual key linking PROMIS numerical scores to physical ability levels using clinically relevant, familiar terms. Future studies might investigate whether using similar graphical displays as a patient education tool enhances patient-provider communication and improves the patient experience. CLINICAL RELEVANCE: The visual explanation of PROMIS scores provided by this study may help new users of the PROMIS understand the instrument, feel empowered to incorporate it into their practices, and use it as a tool for counseling patients about their scores.

Complications of Hardware Removal.

BACKGROUND: While hardware removal may improve patient function, the procedure carries risks of unexpected outcomes. Despite being among the most commonly performed orthopaedic procedures, scant attention has been given to its complication profile. METHODS: We queried the American Board of Orthopaedic Surgery (ABOS) de-identified database of Part II surgical case lists from 2013 through 2019 for American Medical Association Current Procedural Terminology (CPT) implant-removal codes (20680, 20670, 22850, 22852, 22855, 26320). Hardware removal procedures that were performed without any other concurrent procedure ("HR-only procedures") were examined for associated complications. RESULTS: In the 7 years analyzed, 13,089 HR-only procedures were performed, representing 2.1% (95% confidence interval [CI], 2.1% to 2.2%) of the total of 609,150 surgical procedures during that period. A complication was reported to have occurred in association with 1,256 procedures (9.6% [95% CI, 9.1% to 10.1%]), with surgical complications reported in association with 1,151 procedures (8.8% [95% CI, 8.3% to 9.3%]) and medical/anesthetic complications reported in association with 196 procedures (1.5% [95% CI, 1.3% to 1.7%]). Wound-healing delay/failure (2.1% [95% CI, 1.8% to 2.3%]) and infection (1.6% [95% CI, 1.4% to 1.8%]) were among the most commonly reported complications after HR-only procedures, but other serious events were reported as well, including unexpected reoperations (2.5% [95% CI, 2.2% to 2.7%]), unexpected readmissions (1.6% [95% CI, 1.4% to 1.8%]), continuing pain (95% CI, 1.2% [1.0% to 1.4%]), nerve injury (0.6% [95% CI, 0.4% to 0.7%]), bone fracture (0.5% [95% CI, 0.4% to 0.6%]), and life-threatening complications (0.4% [95% CI, 0.3% to 0.5%]). CONCLUSIONS: Hardware removal is one of the most commonly performed orthopaedic procedures and was associated with an overall complication rate of 9.6% (95% CI, 9.1% to 10.1%) in a cohort of recently trained orthopaedic surgeons in the United States. Although specific complications such as infection, refractures, and nerve damage were reported to have relatively low rates of occurrence, and associated life-threatening complications occurred rarely, surgeons and patients should be aware that hardware removal carries a definite risk. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Assessment of Hindfoot Alignment Comparing Weightbearing Radiography to Weightbearing Computed Tomography.

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.