Patient-Specific Preoperative Plans Can Optimize Femoral Head Coverage and Range of Motion After Periacetabular Osteotomies

Abstract

Background: The goal of a periacetabular osteotomy is to increase the coverage of the femoral head, primarily in the antero-lateral region, through rotation of the acetabulum in three anatomical planes. The present study was undertaken to determine whether specific combinations of lateral rotation, anterior rotation, and anteversion of the acetabular fragment can be targeted to provide the best balance between femoral head coverage and joint motion.

Methods: Three-dimensional patient-specific hip models were reconstructed from preoperative computerized tomography scans of 15 patients diagnosed with hip dysplasia. Each model was placed in a standard coordinate system with neutral pelvic tilt and femoral rotation. Osteotomies of a standard Bernese periacetabular osteotomy were performed, and 12 surgical plans (lateral center-edge angle: 25, 30, and 35°; acetabular anteversion: 0 and 10°; and anterior rotation: 0 and 10°) were simulated for each patient to analyze the changes in femoral head coverage and maximum hip internal rotation at 90° flexion. The percentage of patients achieving acceptable coverage and hip motion was compared between the surgical plans.

Results: No single plan led to acceptable values of coverage and internal rotation in all patients. The "30° lateral center-edge angle-10° anterior rotation-10° anteversion" plan achieved the highest percentage (86.7%) of patients who have acceptable outcomes, while the "35-10-0°" plan resulted in the worst outcome (13.3%). Additionally, the standard "30-0-0°" plan was able to achieve acceptable outcomes in 73.3% of patients.

Conclusions: Different combinations of acetabular rotations can result in large variations in femoral head coverage and hip motion, and no single combination is applicable to all cases. Therefore, preoperative planning based on patient-specific morphological characteristics is recommended to determine the best procedure for each case.

Keywords: Hip dysplasia; acetabular coverage; periacetabular osteotomy; range of motion; surgical planning.