ONFH is a common disease in young or active patients and may be related to alcoholism, hormones, trauma, or other risk factors. For young patients, long-term efficacy and years of use of THA are still fraught with uncertainty; therefore, preserving the patient’s joints is of great importance. Current interventions include core decompression, various types of osteotomies, and vascularized or non-vascularized bone grafts [11]. Core decompression is a popular treatment for early ONFH but it cannot effectively remove all dead bones and cannot provide support for subchondral bone [12]. Osteotomy changes the anatomy of the proximal femur, which may cause difficulties for THA in the future. In addition, it has a higher complication rate, including the nonunion or delayed union of bone at the osteotomy, failure of internal fixation, etc [13-15]. Vascularized bone grafts require a high surgical technique, long operation time, extensive trauma, and have highly variable long-term success rates [16-18]. Therefore, many orthopedic surgeons choose non-vascularized bone grafts to treat ONFH, such as fenestration of the femoral head and neck (bulb technique).
In the head and neck fenestration technique, the OCM approach was utilized to treat pre-collapse femoral head necrosis. The average intraoperative blood loss was 220.64 ± 75.63 ml and the average operation time was 116.70 ± 14.19 min, which had certain advantages. The OCM approach is a modification of the Watson-Jones approach. As a minimally invasive approach, it enters through the gap between the gluteus medius muscle and the tensor fascia lata muscle to reduce muscle damage [19]. This approach has the advantages of less trauma, less blood loss, and the ability to reveal the femoral head and neck. It can effectively scrape the anterior, anterolateral, and anteromedial necrotic bone tissue of the femoral head, facilitate the reconstruction of the lateral column of the femoral head and effectively support the subchondral bone. In addition, the subcutaneous soft tissue was isolated from the proximal end of the surgical incision, which could be cut directly from the iliac bone to be used as a bone grafting material, thereby reducing skin incision, decreasing pain, and improving patient satisfaction. When long-term joint preservation fails, the OCM approach can also be used for THA, avoiding additional surgical incisions, which may be more important for female patients.
In this study, autologous iliac bone mixed with tricalcium phosphate porous bioceramic bone was selected as the bone graft. Autologous bone while providing mechanical support, but also promote the formation of bone and blood vessels, effectively repairing bone defects. However, autogenous bone has some adverse factors such as rapid bone absorption, which may affect the curative effect of ONFH. Tricalcium phosphate porous bioceramic bone is characterized by biocompatibility, good mechanical strength, degradation and absorption in vivo, and tissue conduction. In addition, it is non-toxic and non-carcinogenic, and its degradation product composition is close to the inorganic composition of human bone, which is conducive to the mineralization of bone matrix and has good osteoinductive properties. Mixed with autogenous bone can better repair the defect of ONFH.
Fenestration of the head and neck was first reported by Rosenwasser [20], where the average follow-up time was 12 years and the success rate was about 81%. Mont [21] showed that the follow-up time was 4 years and the success rate was 86%. Postoperative HHS was significantly improved. Skeler [9] reported that joint preservation technology used autologous bone combined with BMP-7, with an average follow-up time of 3 years, and the success rate was 67%. Wang [22] reported 138 cases of ONFH with a success rate of 68%. Sun [23] reported that the femoral head survival rate in patients with early ONFH was more than 90%. In our study, head and neck fenestration via the OCM approach was performed to remove necrotic bone tissue. The cortical bone and cancellous bone of the autologous iliac bone are mixed with tricalcium phosphate porous bioceramic bone graft to improve the healing process of the femoral head, with a 63.83% hip preserving success rate and 36.17% functional excellent rate. About 78.72% of patients did not show radiographic progression postoperatively. The results of the current study suggest that clinical success is not entirely consistent with radiographic success.
Several studies have shown that bone repair response, especially excessive bone resorption in bone remodeling, may lead to secondary collapse. Vitamin D plays a major role in calcium absorption and bone health, which is involved in the regulation of bone and mineral metabolism and can effectively promote bone mineralization, increase intestinal absorption of calcium and phosphate, and has a direct effect on bone cells to optimize bone remodeling. Serum 25(OH)D in bone metabolism markers is an intermediate product of vitamin D metabolism and its level can reflect the nutritional status of vitamin D in the body [24-27]. Univariate analysis of data from this study identified 25(OH)D deficiency and preoperative ARCO stage as risk factors for postoperative clinical failure. The results of the Cox multivariate risk analysis suggested that stage ⅢA was an independent risk factor for postoperative clinical failure. The postoperative clinical failure rate of 25(OH)D deficient patients was 51.52% and the postoperative clinical failure rates of patients with stages IIB, IIC, and IIIA were 10%, 14.29%, and 60.87%, respectively. Therefore, we believe that whether the patient’s femoral head collapses or not affects bone healing after surgery. For patients with 25(OH)D deficiency, increasing the level of vitamin D may be beneficial for bone healing after surgery and improve the clinical success rate.
This study has some limitations. First, prospective randomized controlled studies are lacking. All patients were admitted to the hospital after complete imaging tests to determine the surgical plan, which leads to inevitable bias. Second, No comparative studies between non-vascularized bone grafts and other surgical approaches have been performed. Third, analysis of other markers of bone metabolism is missing. Bone metabolic markers can be used to monitor dynamic changes between bone formation and bone resorption. Fourth, our follow-up period was relatively short and the sample size was relatively small, which requires increased follow-up time and expanded sample size.