At present, total hip arthroplasty (THA) is the primary treatment for hip diseases such as femoral head necrosis and developmental dysplasia of the hip. It has good effects in reducing pain and improving joint function. The appearance of modular hip prosthesis facilitates adjustment of limb length and femoral offset. However, the wear between the interface of hip prosthesis can lead to inflammatory pseudotumor, osteolysis and other adverse reactions. To explore the risk factors of wear between hip prosthesis interface is helpful to improve the design and manufacturing concept of the product, improve the product performance, help surgeons optimize the operation technology and reduce the impact of human factors on the wear of the prosthesis. Many literatures have reported the mechanism of wear between the head-acetabula interface of prosthesis. The mechanism of wear between the interfaces has been described relatively clearly. In addition to the head-acetabula interface, the wear between the head-neck interface is another major cause of unexplained pain around the joint and prosthesis loosening after hip replacement. Many factors affect head-neck wear. The design of prosthesis (such as prosthesis material and prosthesis taper), surgical technology (such as impact strength and prosthesis mismatch) and patient factors (such as age, gender and activity) have important impact on head-neck wear. Adverse reactions caused by head-neck wear have also been widely concerned. However, there is no considerable solution for wear prevention. Thus, we should optimize the design of prosthesis, improve the surgical technology, and guide the rehabilitation of patients to prevent wear. In order to improve the attention of joint surgeons, the present paper reviews the literatures and analyzes the risk factors of head-neck interface wear and the clinical manifestations caused by head-neck wear.

Objective:To evaluate the clinical efficacy of biplane osteotomy in the treatment of malunion of Stephens-Sanders type Ⅱ calcaneal fracture.Methods:A retrospective study was conducted to analyze the clinical data of 31 patients who had been treated by biplane osteotomy at Sports Medicine Center, The First Affiliated Hospital of Army Medical University for malunion of Stephens-Sanders type Ⅱ calcaneal fracture from January 2019 to January 2022. There were 21 males and 10 females, with an age of (41.4±13.9) years and a duration from injury to diagnosis of (12.8±8.9) months. Functional and image scores were compared before surgery, 6 months after surgery, and at the last follow-up. Functional scores included the visual analogue scale (VAS) score, the American Orthopedic Foot and Ankle Society (AOFAS) score, and the pain interference (PI) and physical function (PF) indices in the Patient-Reported Outcomes Measurement Information System (PROMIS). Image scores included the Gissane angle, B?hler's angle, calcaneal pitch angle, length of the calcaneus, absolute foot height, and axial calcaneal width as measured on X-rays.Results:The operation time was (106.6±29.9) minutes for this cohort. All the 31 patients were followed up for (18.4±5.8) months. At 6 months after surgery and the last follow-up, the VAS scores [3 (2, 3), 2 (1, 3)], AOFAS scores [83 (76, 87), 85 (83, 87)], PI scores [(57±9), (48±6)], PF scores [53 (39, 61), 56 (54, 66)], Gissane angles (109.6°±14.1°, 109.3°±14.9°), B?hler angles (26.5°±11.6°, 26.9°±11.8°), calcaneal pitch angles [19.1° (14.5°, 23.9°), 19.9° (14.5°, 23.9°)], absolute foot heights [(76.5±9.6) mm, (76.0±9.9) mm], and axial calcaneal widths [(38.5±4.1) mm, (38.3±4.1) mm] were all significantly improved compared to the preoperative values [5 (4, 6), 62 (56, 67), (62±6), 47 (38, 51), 126.8°±13.1°, 11.8°±10.9°, 13.8° (8.2°, 18.7°), (71.0±9.1) mm, (42.8±5.5) mm] (all P<0.05). However, there was no statistically significant difference in the length of the calcaneus among pre-surgery, 6 months after surgery, and the last follow-up ( P>0.05). Conclusion:Biplane osteotomy is a surgical technique that demonstrates good clinical efficacy in the treatment of malunion of Stephens-Sanders type Ⅱ calcaneal fracture so that it should be promoted in clinic.