BACKGROUND: Controversy exists regarding mandatory hindfoot varus in Müller-Weiss disease (MWD).
METHODS: This retrospective cohort study examined weightbearing computed tomography (WBCT) in 22 feet with MWD. Measurements included hindfoot moment arm (HMA), middle facet subluxation in coronal (MFSC) and sagittal (MFSS) planes, posterior facet uncoverage, and angles between inferior and superior talar surfaces (inftal-suptal) at 33%, 50%, and 67% of the way moving from anterior to posterior along the posterior facet.
RESULTS: From the cohort consisting of 14 patients (22 feet, mean age 51.14 ± 13.90 years), based on a neutral zero HMA, 10 feet were designated as varus-offset and 12 as valgus-offset. Mean MFSC in valgus-offset (49.3 ± 6.3%) is significantly greater than in varus-offset feet (28.2 ± 6.1%) (P = .022). Greater MFSS and posterior facet uncoverage in valgus-offset feet are not statistically significant. Based on inftal-suptal angles, 2 groups of talar configurations are identified, each with increased predisposition towards either varus or valgus offset. In talus configurations with inftal-suptal angles open laterally at all 3 levels, the predominant heel offset is varus (89%), whereas in talus configurations featuring an inftal-suptal angle open medially, the predominant heel offset is valgus (85%) (P = .002). As HMA changes from varus to valgus, inftal-suptal angles change from open laterally to open medially at all 3 levels, reaching greatest significance at the 67% mark (P < .001).
CONCLUSION: To our knowledge, this is the largest WBCT study of MWD to date. In these patients, we identified significantly greater MFSC in valgus-offset feet and different talus configurations, which may explain the more frequent 55% incidence of valgus offset. Because universal heel varus is not always the rule, caution is advised in advocating lateral displacement calcaneal osteotomy for all MWD feet.
LEVEL OF EVIDENCE: Level IV, retrospective cohort study.
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