Muscle function around the hip after operation for Fibrous Dysplasia of Proximal Femur with Varus Deformity.

Objectives: This study aimed to analyse the clinical effect of surgery for patients with fibrous dysplasia (FD) of the proximal femur with varus deformity, detect the muscle function around the hip joint. Methods: This is a retrospective study. A total of 20 patients who underwent operation for FD of the proximal femur with varus deformity at West China Hospital, from January 2018 to October 2022 were included in this study. The peak torque (PT) of muscle strength during abduction, adduction, flexion and extension of bilateral hip joints was measured by an isokinetic muscle test and training system associated with the comparison of bilateral hip joints, to evaluate the function of muscles around the hip joint after operation. Results: The difference between the length of the affected limb and the healthy side was 1~2 cm in seven cases and <1 cm in 13 cases. The force line showed no abnormality in 15 affected limbs, which deviated from the center of the knee joint by 3-5 mm in five cases. The average PT during abduction of hip joints on the affected side of 20 patients was significantly lower than that on the healthy side, which was also reduced evidently during adduction and flexion of hip joints on the affected side compared with that on the healthy side. Conclusions: After effective recovery of the force line and length of the affected limb in patients with FD of the proximal femur with deformity, functional abnormalities of muscles are still present to a certain extent.