Gait Recovery After Total Hip Arthroplasty with Subtrochanteric Osteotomy in Highly Dislocated Hips: A Retrospective Single-Center Cohort Study

<b>Background</b>: We aimed to analyze various gait parameters before and after THA for patients with a highly dislocated hip to examine gait recovery and whether it is continued. <b>Methods</b>: This was a retrospective, single-center study. We enrolled 10 patients with a highly dislocated hip (10 hips) due to developmental dysplasia of the hip (DDH) or sequelae of septic arthritis of the hip (SSH). A spatio-temporal gait analysis was performed before THA with subtrochanteric osteotomy and one year after surgery for all patients, and 5 of them had a complete follow-up gait analysis at five years postoperatively. Demographics, clinical outcome, and radiological data were collected. <b>Results</b>: At one year postoperatively, the terminal double support (TDS) increased from 8.6% (4.3-12.6) to 11.3% (5.8-14.0) of the gait cycle (<i>p</i> = 0.02). The vertical ground reaction force (vGRF) increased from 0.96 N/BW (0.69-1.30) to 1.11 N/BW (0.95-1.31) for the first peak (<i>p</i> = 0.045) and from 0.87 N/BW (0.59-1.12) to 1.10 N/BW (1.00-1.30) for the second peak (<i>p</i> = 0.001). However, there was no improvement in any gait parameters at five years postoperatively compared to one year postoperatively. The mean HHS was 57.2 (43-67) before surgery and 79.6 (61-88) at the last follow-up (<i>p</i> = 0.001). The preoperative leg length discrepancy (LLD), which was 43.6 mm (18.2-71.6), and improved to 9.8 mm (2.1-22.1) after surgery. <b>Conclusions</b>: Improvements in stance-phase stability (TDS) and vertical ground reaction forces (vGRF) enhanced gait after THA in patients with highly dislocated hips; however, these gains were only observed until 1 year postoperatively, with no further improvement thereafter. Notably, the magnitude of improvement in TDS and vGRF may exceed that typically reported after THA for primary osteoarthritis.