Global Offset Restoration: A Critical Factor Influencing Limb-Length Correction After Total Hip Arthroplasty in Legg-Calvé-Perthes Disease.

Abstract

Limb-length discrepancy (LLD) correction in total hip arthroplasty (THA) for patients who have Legg-Calvé-Perthes disease (LCPD) remains challenging due to anatomical deformities. Identifying biomechanical factors associated with residual LLD may improve clinical outcomes. This retrospective matched cohort study included 72 patients undergoing THA for LCPD and 114 matched patients who had primary osteoarthritis (OA). Matching criteria included sex, surgical side, Charlson Comorbidity Index (CCI), surgery year, age, and body mass index (BMI). Pre- and postoperative radiographs were analyzed for LLD, global offset restoration, and implant positioning parameters. Clinical outcomes and complication rates were also evaluated. Spearman's correlation was utilized to examine associations between postoperative global offset restoration and residual LLD. Preoperative LLD was significantly greater in LCPD patients compared to primary OA (1.70 ± 1.23 versus 0.93 ± 0.71 mm; P < 0.001), yet postoperative LLD was comparable (0.85 ± 0.88 versus 0.82 ± 0.74 mm; P = 0.52). A subgroup of LCPD patients (29%) had persistent postoperative LLD ≥ 10 mm, significantly associated with inadequate global offset restoration and lower Harris Hip Scores (HHS) at 1-year follow-up compared to those who had an LLD < 10 mm (88.5 ± 9 versus 93.5 ± 4; P < 0.001). A significant negative correlation (rho = -0.44, P = 0.0001) was identified between global offset restoration and residual LLD in the LCPD group, a correlation not observed in primary OA. Surgical details and postoperative complications were similar between groups. A THA successfully corrects LLD in most LCPD patients, but a subgroup remains at risk for residual shortening. Insufficient global offset restoration significantly correlates with greater residual LLD, highlighting the importance of offset reconstruction to achieve optimal limb length equalization. Surgeons should prioritize restoring global offset alongside leg-length correction in patients undergoing THA for LCPD.