Abstract: BACKGROUND: Non-traumatic necrosis of the femoral head is a difficult joint disease, and preserving one’s own femoral head is of great significance for young patients. Currently, there is a lack of regular and unified functional exercise plans.
OBJECTIVE: To investigate the effect of hip abductor muscle exercise on the three-dimensional gait and collapse rate of patients with non-traumatic femoral head necrosis, and to provide theoretical basis for effective rehabilitation of patients with non-traumatic femoral head necrosis.
METHODS: Totally 81 non-traumatic and non-surgical patients with femoral head necrosis (81 hips) admitted to the Third Affiliated Hospital of Guangzhou University of Chinese Medicine from June 2020 to June 2022 were included. Patients were randomly divided into a control group (n=40) and a hip abductor muscle exercise group (n=41). The control group received routine physical therapy and medication treatment. The hip abductor muscle exercise group underwent hip abductor muscle exercise on the basis of the control group. The gait status (hip joint range of motion, step length difference, and ground contact time difference) of two groups of patients was evaluated using the Tecnobody balance assessment system before and 12 weeks after treatment. The BIODEX-S4 isokinetic muscle strength testing system was used to test the peak force distance of hip abduction isokinetic muscle strength. Gluteus medius width ratio was compared between two groups. The collapse rate was compared between two groups of patients 1 year after treatment.
RESULTS AND CONCLUSION: (1) There was no statistically significant difference between the hip abductor muscle exercise group and the control group in terms of age, gender, side profile, body mass index, and etiology (P > 0.05). (2) Before treatment, there was no significant statistical difference in the range of motion of the affected hip joint between the two groups (P > 0.05). After treatment, the range of motion of the affected hip joint in both groups improved compared to before treatment (P < 0.05), and the range of motion of the affected hip joint in the hip abductor muscle exercise group was significantly higher than that in the control group (P < 0.05). (3) Before treatment, there was no significant statistical difference in the step length and touchdown time between the two groups (P > 0.05). 12 weeks after treatment, the difference in step length and touchdown time between the two groups decreased compared to before treatment (P < 0.05), and the difference in step length and touchdown time between the hip abductor muscle exercise group after treatment was significantly greater than that of the control group (P < 0.05). (4) Before treatment, there was no significant statistical difference in gluteus medius width ratio between the two groups (P > 0.05). 12 weeks after treatment, the gluteus medius width ratio of both groups increased compared to that before treatment (P < 0.05), and the gluteus medius width ratio of the hip abductor muscle exercise group was significantly higher than that of the control group (P < 0.05). (5) At 1 year after treatment, the comparison of femoral head collapse rates between the two groups showed significant statistical significance (P < 0.05), and that in the hip abductor muscle exercise group (22%) was significantly lower than that in the control group (45%). (6) It is concluded that exercise of the hip abductor muscle effectively enhances hip joint function, improves gait, and reduces the rate of femoral head collapse in patients with non-traumatic femoral head necrosis. It is recommended to use hip abductor muscle exercise as one of the basic methods for hip preservation in non-traumatic femoral head necrosis.

Key words: femoral head necrosis, hip abductor muscle, gait, functional exercise, collapse