A modified surgical method for the treatment of ONFH: quadratus femoris muscle pedicle bone flap transplantation with preservation of posterior superior retinacular artery
Authors: San Changmeng , Xu Yongqing , Lee Mingjun , Pu Luqiao , Wang Teng , Shi Xiangwen , Lu Siyu , Cheng Qi 
Published: April 2022

Abstract
Background: Osteonecrosis of the femoral head(ONFH) can lead to pain and loss of function of the hip joint, which brings a greater burden to patients and society. Surgery is the main treatment for osteonecrosis of the femoral head, and the quadratus femoris muscle pedicle bone flap has a definite therapeutic effect as one method of surgery for the treatment of ONFH. However, the posterior superior retinacular artery is often injured during the operation of quadratus femoris muscle pedicle bone flap. There is evidence that this artery is extremely important to the femoral head, once the artery is injury will seriously affect the blood supply of the femoral head. Therefore, this restricts the clinical application effect of quadratus femoris muscle pedicle bone flap. We intend to explore a new surgical method of quadratus femoris muscle pedicle bone flap, which can preserve the integrity of the posterior superior retinacular artery.Methods：We modified the traditional quadratus femoris muscle pedicle bone flap and preserved the integrity of the posterior superior retinacular artery. In order to explore the safety and feasibility of the operation, we simulated the operation on 6 fresh frozen cadavers (12 hips) and measured the related data. We have tried this modified surgical method in clinical and collected the detailed data of the patients.Results: Through the study of simulating the modified quadratus femoris muscle pedicle bone flap on the hip joints of fresh frozen cadavers, we found that the posterior superior retinacular artery existed in all cadaver specimens, the sources may be different(MFCA or IGA). The modified operation does not need to cut the joint capsule during the operation, therefore, the integrity of the posterior superior retinacular artery is preserved. The quadratus femoris muscle was exposed via the posterior approach of the hip joint, and then chisel the quadratus femoris muscle pedicle bone flap. After the stop of the quadratus femoris muscle is loosened properly, the migration distance of the quadratus femoris muscle pedicle bone flap can reach (5.89 ± 0.45)cm (c±s). Trim the bone flap properly and place it to one side. Next step, we will drill a bone tunnel from the intertrochanteric outside of the capsule stop of the hip joint, and the bone tunnel will break through the sclerosing zone and go straight to the necrotic area of the femoral head. Remove the dead bone with ring saw and arc bone knife, autogenous bone or allogeneic bone was filled in the bone groove according to the situation, the cancellous bone in the bone groove is tamped by percussion. Then insert the bone flap into the bone groove and give appropriate pressurization. The depth of the bone groove was determined by the location of osteonecrosis of the femoral head. We found that the furthest distance between the bone groove and the femoral head (4.76 ± 0.07)cm (c±s), the length of the bone flap is (4.91 ± 0.23) (c±s). This means that when the depth of the bone groove reaches the area of osteonecrosis of the femoral head, the quadratus femoris muscle pedicle bone flap has sufficient length and migration distance to be embedded in the area of osteonecrosis of the femoral head and fixed firmly, and the quadratus femoris does not have much tension. The closest distance between the posterior superior retinacular artery and the bone groove was (1.11 ± 0.96)cm (c±s) ,when the bone groove is made in this area, the edge of the bone groove has a safe distance of 1cm at least from the posterior superior retinacular artery of the femoral head.Clinically, we have tried to implement this modified operation. During the operation, the quadratus femoris muscle pedicle bone flap was embedded into the drilled bone groove and fixed with magnesium nail. There was no sliding of the bone flap after operation, and the posterior superior retinacular artery was intact. We followed up the patient for 3 months and found that the patient recovered well and the affected limb still had no weight-bearing. The operation time of the modified operation was shorter than the traditional quadratus femoris muscle pedicle bone flap, the amount of bleeding was significantly reduced, and the postoperative pain was lighter and no special discomfort was complained. Postoperative imaging examination showed that the collapse of the femoral head had been partially corrected and the bone flap gradually fused with the surrounding bone.Conclusions: Through this experimental study, we confirmed the feasibility of the modified moehod of the quadratus femoris muscle pedicle bone flap with the posterior superior retinacular artery preserved. This new operation not only retains the integrity of the posterior superior retinacular artery of the femoral head, but also reduces the difficulty of the operation and shortens the operation time, which is of great clinical significance.