Influence of Hip Prosthesis Position on Postoperative Gait After Primary THA in Patients With Unilateral Femoral Head Necrosis

To investigate the effect of hip component position on gait after primary THA in patients with unilateral femoral head necrosis. A total of 40 patients underwent primary THA due to unilateral femoral head osteonecrosis were enrolled in this study. The gait data and CT images of the hip and knee joints were obtained before and 3 months after operation. The changes of plantar gait before and after operation were compared, and the correlation between postoperative femoral anteversion angle and acetabular anteversion angle and postoperative gait data were analyzed. The postoperative acetabular anteversion angle was significantly higher than that before operation (p = 0.032), and there was no significant change in the femoral anteversion angle (p = 0.221). Compared with the preoperative, the postoperative gait speed (p = 0.002), stride frequency (p = 0.010), stride length (p = 0.013), touchdown angle (p = 0.011) and ground beat speed (p = 0.009) were significantly improved, and the postoperative foot offset angle was significantly reduced (p = 0.002). Spearman correlation analysis was used to analyze the correlation between postoperative femoral anteversion angle, acetabular anteversion angle and postoperative plantar gait data. The results showed that the magnitude of postoperative femoral anteversion angle was correlated with postoperative beat ground speed (p = 0.035) and postoperative step frequency (p = 0.027). For patients with unilateral femoral head necrosis undergoing primary THA, the postoperative acetabular anteversion angle was significantly correlated with postoperative foot offset angle and postoperative touchdown angle. The larger the postoperative acetabular anteversion angle was, the larger the postoperative foot offset angle was and the smaller the postoperative touchdown angle was.