膝置换术后假体周围骨折内固定后再骨折一例

A Subsequent Femoral Fracture after Internal Fixation for Periprosthetic Fracture Following Total Knee Arthroplasty: A Case Report

摘要: 全膝关节置换术(Total Knee Arthroplasty, TKA)后假体周围骨折内固定治疗后再次发生股骨骨折较为少见，其病因判断受局部力学环境、骨质疏松及抗骨吸收药物治疗等多因素影响。文章报道1例76岁女性骨质疏松患者，长期接受地舒单抗治疗，因左膝骨关节炎行左侧TKA。术后侧位X线片示股骨前方皮质切迹样改变。术后第16天在伸直位压腿锻炼时发生左股骨远端假体周围螺旋形骨折，行切开复位股骨远端外侧锁定钢板内固定。内固定术后两月余，患者由坐位转为卧位时突发左大腿疼痛，X线示左股骨干近端骨折，位于原钢板近端邻近区域，原内固定物及假体未见松动或断裂，考虑为钢板近端应力集中相关围内固定物骨折，长期地舒单抗治疗及骨质疏松为背景因素。采用保留原内固定物的Ortho-Bridge System (OBS)长节段桥接固定，术后近四个月骨折愈合良好。此类骨折不宜仅归因于单一因素，应综合评估钢板端部应力集中、内固定稳定性、骨质疏松及抗骨吸收治疗背景，并与非典型股骨骨折鉴别。

Abstract: A subsequent femoral fracture after internal fixation for a periprosthetic fracture following total knee arthroplasty (TKA) is uncommon, and its etiology is influenced by multiple factors, including the local mechanical environment, osteoporosis, and antiresorptive therapy. This article reports a 76-year-old woman with osteoporosis who had received long-term denosumab therapy and underwent left TKA for osteoarthritis of the left knee. Postoperative lateral radiographs showed a notch-like change of the anterior femoral cortex. On postoperative day 16, she sustained a spiral periprosthetic fracture of the distal femur during straight-leg knee extension exercise and underwent open reduction and internal fixation with a lateral distal femoral locking plate. More than 2 months later, she developed sudden left thigh pain while moving from a sitting to a supine position. Radiographs showed a proximal femoral shaft fracture adjacent to the proximal end of the previous plate, without loosening or breakage of the fixation or the prosthesis. This was considered a peri-implant fracture related to stress concentration at the proximal end of the plate, with long-term denosumab therapy and osteoporosis as background factors. Long-segment bridge fixation using the Ortho-Bridge System (OBS) was performed while retaining the previous internal fixation, and the fracture healed well nearly 4 months postoperatively. Such fractures should not be attributed to a single factor; stress concentration at the plate end, fixation stability, osteoporosis, and antiresorptive therapy should be comprehensively evaluated, and differentiation from atypical femoral fracture is warranted.