Background: Residual deformities after Perthes disease, such as high-rising greater trochanter (HGT) and reduced femoral offset (FO), may compromise abductor function and influence long-term hip function.
Purpose: To determine the prevalence of HGT and abnormal FO in young adults with healed unilateral Perthes disease and evaluate their associations with the Stulberg classification and hip function.
Methods: In this cross-sectional follow-up study, 180 individuals (mean age 28.2 years, 72% male) previously diagnosed with unilateral Perthes disease were examined with radiographs and clinical tests. Articulo-trochanteric distance (ATD) and FO were measured on calibrated pelvic radiographs. Femoral head shape was classified using a modified 3-group Stulberg classification. Hip function was evaluated using the Trendelenburg test, passive hip abduction range of motion, and the Copenhagen Hip and Groin Outcome Score (HAGOS).
Results: ATD was significantly lower in Perthes hips compared to contralateral hips (7.7 mm [SD 9.6] vs. 20.7 mm [SD 6.2], p < 0.001). HGT was present in 70 individuals (39%), and a positive Trendelenburg test was observed in 12 Perthes hips (7%). Risk factors for a positive test included hip pain, aspherical femoral head, and surgical treatment. Mean FO was lower in Perthes hips (34.2 mm vs. 39.7 mm, p < 0.001), as was hip abduction (25.5° vs. 29.7°). ATD and FO were significantly associated with the modified Stulberg classification, particularly between Stulberg 1 and Stulberg 3 hips (p < 0.001). No significant associations were found between ATD, FO, and hip function parameters, nor between HGT and HAGOS scores in spherical hips.
Conclusions: Reduced ATD and FO were prevalent in young adults with previous PD and were associated with the modified Stulberg classification but not with hip function.
Clinical trials registration: ClinicalTrials.gov (NCT03995960).
Keywords: Articulo-trochanteric distance; Perthes disease; Trendelenburg sign; femoral offset; hip function.