Analysis of posterior hip joint impingement about developmental dysplasia of the hip after total hip arthroplasty.

Background: Total hip arthroplasty is the preferred treatment for advanced hip osteoarthritis, yet complications like hip dislocation (0.2 %-10 %) persist due to factors such as implant design, positioning, surgical technique, and patient-specific conditions. Impingement between prosthetic components or the acetabulum and proximal femur is a primary cause of instability.

Methods: A retrospective analysis of 120 patients (130 hips) undergoing total hip arthroplasty at XX Hospital (2011-2023) categorized patients by lateral center-edge angle: developmental dysplasia of the hip, borderline developmental dysplasia of the hip, and normal hip. ct imaging facilitated virtual 3D bone models for motion analysis, excluding cases with prior hip surgery or spinal fusion. Statistical analyses utilized the Mann-Whitney U test and one-way ANOVA.

Findings: The developmental dysplasia of the hip group showed the highest posterior impingement frequency, significantly affecting range of motion in flexion, adduction, and external rotation compared to borderline developmental dysplasia of the hip and normal hip groups. Variations in femoral neck anteversion, lesser trochanter version, and ischiofemoral space were notable. Posterior impingement commonly occurred between the lesser trochanter and ischial tuberosity.

Interpretation: Posterior bony impingement emerged as a predominant factor reducing range of motion and increasing dislocation risk, particularly in developmental dysplasia of the hip patients, challenging the conventional "safe zone" for implant positioning. Personalized surgical strategies tailored to individual bone morphology are crucial for enhancing total hip arthroplasty outcomes and minimizing complications, although limitations include the exclusion of soft tissue influences and focusing solely on range of motion until impingement occurs.