Muscle Strength And Patient-reported Outcome Improvements 6-months After Periacetabular Osteotomy In Individuals With Acetabular Dysplasia

PURPOSE: Acetabular dysplasia (AD) is a hip condition characterized by insufficient development of the acetabulum that often leads to joint instability, pain, and decreased muscle strength. Periacetabular osteotomy (PAO) is the current surgical treatment for individuals with AD that aims to decrease pain and improve function by increasing hip joint bony congruency. Little is known regarding longitudinal recovery of muscle strength and patient-reported outcomes (PROs) following PAO. We examined changes in muscle strength and PROs from before to 6 months after PAO. METHODS: We enrolled 22 individuals with AD that were scheduled for PAO (21 females). Before and 6 months after PAO, we evaluated isometric strength of the knee flexors and extensors and the hip flexors, extensors, and abductors, using an electromechanical dynamometer, and assessed PROs using the Hip disability and Osteoarthritis Outcome Score (HOOS). The HOOS assesses distinct clinical domains with subscales including symptoms, pain, activities of daily living, sport function, and quality-of-life. For muscle strength measure, we calculated peak torque values (normalized; Nm/kg) for the involved limb as well as limb symmetry indices (LSI; involved/uninvolved limb values*100%). We used paired sample t-tests to examine improvements in muscle strength and PROs 6 months after PAO compared to before PAO. RESULTS: Compared to before PAO, involved knee flexor peak torque (Before = 1.0 ± 0.2 Nm/kg, 6 Months = 0.4 ± 0.5 Nm/kg; p < 0.001), involved hip abductor peak torque (Before = 0.9 ± 0.5 Nm/kg, 6 Months = 0.5 ± 0.3 Nm/kg; p < 0.001), and knee flexor LSI (Before = 90 ± 10%, 6 Months = 40 ± 30%; p < 0.001) significantly decreased at 6 months after PAO. In contrast, only knee extension LSI significantly-improved from before to 6 months after PAO (Before = 80 ± 20%, 6 Months = 120 ± 40%; p = 0.002). All HOOS-subscale scores were significantly improved from before to 6 months after PAO (all p < 0.05). CONCLUSIONS: Individuals with AD exhibited significant reductions in muscle strength for involved knee flexors and hip abductors 6 months after PAO and that all PROs examined were improved 6 months after PAO. Further studies are needed to examine factors associate with greater muscle strength following PAO to inform designing rehabilitation interventions for this patient population. Supported by: This study was supported by the NIH National Rehabilitation Research Resource to Enhance Clinical Trials (REACT) Scholar Award. Dr. Alrashdi’s PhD studies are supported by the Saudi Arabian Cultural Mission.