Evaluation the hip joint contact force in subjects with Perthes based on OpenSIM

Background: The head of femoral bone is deformed in subjects with Leg Calve Perthes disease (LCPD). It may be due to the excessive loads applied on it. There are no studies that report the hip joint contact force in subjects with LCPD. Therefore, the aim of this study was to evaluate the hip joint contact force in subjects with Perthes disease. Method: Ten typically-developing (TD) children and 10 children with LCPD were recruited in this study. The kinematics and kinetics of the subjects were evaluated in 3D motion analysis. The hip joint contact force was estimated with OpenSIM software. Differences were determined with independent t-test. Findings: There was a significant difference between walking speed of TD and Perthes subjects 63.8(8.1) and 57.4(7.0) m/min, respectively). The first peak of hip joint contact force was 4.8(1.7) N/BW in Perthes subjects, compared to 7.6(2.5) N/BW in TD subjects (p=0.004). The peak of hip joint contact force in mediolateral and anteroposterior directions was significantly lower in Perthes subjects (p 0.05). The hip joint excursion was 40.0(5.6) and 46.4(8.5) degrees in Perthes and normal subjects, respectively (p=0.03). Interpretation: The hip joint contact forces were lower in subjects with Perthes disease. Therefore, it can be concluded that the strategies used by LCPD subjects were successful to decrease hip joint contact force.