Design and clinical application of the distal femur spherical motion axis hinge knee prosthesis / 中华骨科杂志

ABSTRACT

Objective:To investigate the feasibility and early clinical efficacy of spherical motion axis hinge knee prosthesis to reconstruct distal femoral bone defects.Methods:A retrospective analysis was performed on 16 patients admitted to PLA 960th Hospital and Tianjin Hospital from October 2019 to November 2021, including 8 males and 8 females, with an average age of 43.3±17.8 years (range, 15-71 years). There were 13 patients of primary tumors of the distal femur and 3 patients of postoperative revision of knee joint prostheses. Among the 13 patients with distal femur tumors, there were 6 cases of osteosarcoma, 5 cases of giant cell tumor of bone, 1 case of leiomyosarcoma and 1 case of chondrosarcoma. The reasons for revision after prosthesis replacement in 3 cases were 2 cases of aseptic loosening after tumor-type prosthesis and 1 case of periphery fracture of surface artificial knee prosthesis. A spherical shaft rotary hinged knee prosthesis was designed and fabricated to reconstruct postoperative femoral defects in 16 patients. Follow up regularly after the operation, recheck the X-ray film to evaluate the lower limb force line, evaluate the quality of life after the operation with the Chinese version of 36-item short-form (SF-36), and evaluate the postoperative limb function with the Musculoskeletal Tumor Society (MSTS) 93 evaluation system.Results:All 16 patients were successfully placed with prostheses, and except for 2 patients undergoing total femoral replacement, the length of bone defects was 18.2±11.7 cm (range, 8.6-47.1 cm) in other 14 patients, and the operation time was 138±19 min (range, 110-170 min), the intraoperative blood loss was 211±118 ml (range, 100-500 ml). The postoperative full length orthostatic X-ray film of the lower limbs showed that the distance between the mechanical axis of the lower limb and the center of the knee joint was 0.1 (0, 0.7) cm in 16 patients, and the hip-knee ankle angle was 179.0°±2.3°(range, 173.3°-182.2°). The patients were followed up for 12-36 months. No prosthesis complications were found in 16 patients. The SF-36 score was 56.7±7.0 (range, 42.7-67.4) for physiological function and 54.1±7.6 (range, 40.5-66.3) for psychological function. The maximum knee flexion angle was 120.0°±15.6° (range, 95°-130°). The MSTS 93 score of 15 patients with tumor was 25.0±1.7 (range, 22-28), including 7 excellent and 8 good. One patient developed liver and lung metastases 10 months after surgery and died 18 months after surgery. The remaining patients, as of the last follow-up, were alive and had no local recurrence or distant metastases. Tumor-free survival time was 25.8±8.4 months (range, 12-36 months).Conclusion:The spherical motion axis hinge knee prosthesis reconstruction for distal femoral bone defects is simple and fast in intraoperative prosthesis installation, and there are no prosthetic related complications during short-term follow-up. The clinical efficacy is satisfactory.