To investigate the effect of a degradable high-purity magnesium screw in fixing the greater trochanter bone flap of a lateral circumflex femoral artery transverse branch in the treatment of ischemic necrosis of femoral head in young and middle-aged adults.

From February 2017 to February 2019, 12 cases (15 hips) of young and middle-aged patients with avascular necrosis of femoral head were treated in the Department of Orthopaedic of Affiliated Zhongshan Hospital of Dalian University. The age of patients was 30-53 years old. According to Association Research Circulation Osseous (ARCO), 2 hips were graded in stage II b, 4 in ARCO II c, 1 in ARCO III a, 5 in ARCO III b, 2 in ARCO III c and 1 in ARCO IV. The greater trochanter bone flap with a lateral circumferential vascular branch was used to fill the necrotic area, and fixed by a biodegradable high purity magnesium screw in the bone flap transfer. At 3, 6 and 12 months postoperation, the patient came to the hospital outpatient clinic for follow-up, and then were reviewed once a year. Imaging efficacy was evaluated by comparing preoperative and postoperative imaging. The Harris score and Visual Anoalogue Scale (VAS) score were tested at 12 and 24 months after surgery. The Harris score and VAS score before and after surgery were compared by Friedman test, and P<0.05 was considered statistically significant.

All 12 patients (15 hips) were entered in the 24-36 months of follow-up. At 12 and 24 months after surgery, Harris score was found at 87 (86, 92) and 90 (87, 92) respertively, which were both higher than that before surgery [59 (52, 74)] with a significant statistical difference (Z=-3.743, Z=-4.473, P<0.05). However, there was no significant difference in Harris scores between 12 and 24 months after the surgery (Z=-0.730, P>0.05). At the 12 and 24 months after surgery, VAS score was found at 3 (2, 3) and 2 (1, 3) respertively, which were both lower than that before surgery [6 (5, 6) ] with a significant statistical difference (Z=-3.560, Z=-4.656, P<0.05). There was no statistical difference in VAS scores between 12 and 24 months after surgery (Z=-1.095, P>0.05). X-ray and CT scan showed that the bone flaps healed well and the areas of osteonecrosis were repaired. Thirteen femoral heads were in good shape, and 2 femoral heads had further collapse of hips. No patients underwent joint replacement surgery at the time of last follow-up.

Fixation of the greater trochanter flap of lateral circumflex femoral artery transverse branch with a degradable high-purity magnesium screw can ensure the healing of the flap at the implantation site and avoid the displacement and shedding of the flap. It is a new therapeutic option to treat the avascular necrosis of femoral head of young and middle-aged people.

Avascular necrosis of femoral head; Greater trochanter bone flap; Lateral circumflex femoral artery transverse branch; Degradable high purity magnesium screw; Microsurgical technique