Background: Patients with acetabular dysplasia have an abnormal acetabular geometry which results in insufficient coverage of the femoral head. This coverage deficiency reduces contact surfaces within the joint, accelerating the wear of the articular cartilage and predisposing patients to early osteoarthritis. Periacetabular osteotomy is a surgical treatment of acetabular dysplasia that aims to reorient the acetabulum relative to the femoral head, increasing coverage.
Methods: Pelvic kinematics and lower limbs joint kinematics and kinetics during the stance phase of gait were recorded using a 3D motion capture system and force plates, then compared pre- to post- and between limbs with a repeated measures 2-way ANOVA. Radiographic measurements and gait parameters were compared pre- to post-surgery using a t-test for dependant samples. To identify predictors of pelvic symmetry improvements during gait, a multivariate analysis was performed using a forward stepwise linear regression.
Findings: Radiographic measurements improved for all participants while gait parameters remained unchanged. Hip flexion symmetry was improved following surgery. The external rotation moment of the healthy hip was reduced after surgery (-29%) resulting in increased asymmetry. Pelvic tilt was significantly greater on the affected side (+0.5°) during the loading response, and the difference tended to be greater after surgery (+0.8°).
Interpretation: Unilaterally affected dysplastic patients have an asymmetrical gait pattern that is only partially corrected by periacetabular osteotomy even when radiographic and clinical targets are met. Differences between the limbs could be explained in part by a learned antalgic pattern and muscle weaknesses leading to complex compensation mechanisms.
Keywords: Gait analysis; Hip dysplasia; Pelvic kinematics; Periacetabular osteotomy.
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