Itamoto Akihiro, Nishitani Kohei, Kuriyama Shinichi, Nakamura Shinichiro, Matsuda Shuichi
Department of Orthopaedic Surgery, Kyoto University Graduate School of Medicine, Kyoto, JPN.
Cureus. 2023 Aug 30;15(8):e44379. doi: 10.7759/cureus.44379. eCollection 2023 Aug.
Mid-flexion instability can be caused by patient-related, implant-related, or technique-specific factors and impairs the activities of daily living after total knee arthroplasty (TKA). In this study, we report a rare case of a patient with severe mid-flexion instability following tibial and femoral avulsion fractures after posterior-stabilized (PS) TKA for knee osteoarthritis. An 82-year-old female with bilateral knee osteoarthritis underwent staged bilateral TKA with a posterior-stabilized prosthesis. The course of the early postoperative period was good, and the patient was able to walk independently with a cane. Two months postoperatively, the patient fell and then experienced left knee pain and instability in the mid-flexion range. Radiographic images showed avulsion fractures of the articular capsule of the femur and tibia, and fluoroscopic examination showed severe posterior subluxation of the tibia between 40° and 60° of flexion. Conservative treatment with a functional knee brace and quadriceps training was initiated due to the patient's hesitation to undergo a second surgery; however, no improvement was observed. Eventually, revision surgery was planned three months after the fall incident (five months after the left primary TKA). At revision surgery, osteosynthesis of the tibial avulsion fracture and thickening of the PS insert did not sufficiently stabilize the instability, and revision TKA with a rotating-hinge prosthesis was needed. The postoperative course was uneventful, and she was able to walk with a cane within two weeks after revision TKA with no complaints of instability. Two years postoperatively, the patient recovered well and had no recurrence of instability, pain, or dysfunction. This case report shows that loss of support by the joint capsules due to avulsion fractures may cause significant anteroposterior instability in the mid-flexion position after posterior-stabilized TKA. In such a case, conservative treatment failed, and the revision of the rotating-hinge prosthesis provided stability and good improvement.
屈膝位不稳定可由患者相关、植入物相关或技术特定因素引起，并会影响全膝关节置换术（TKA）后的日常生活活动。在本研究中，我们报告了1例罕见病例，该患者因膝关节骨关节炎接受后稳定型（PS）TKA后发生胫股撕脱骨折，出现严重屈膝位不稳定。一名82岁双侧膝关节骨关节炎女性患者接受了分期双侧TKA，使用后稳定型假体。术后早期过程顺利，患者能够拄拐独立行走。术后两个月，患者跌倒，随后出现左膝疼痛和屈膝范围内的不稳定。影像学检查显示股骨和胫骨关节囊撕脱骨折，透视检查显示屈膝40°至60°时胫骨严重后脱位。由于患者对再次手术犹豫不决，开始使用功能性膝关节支具和股四头肌训练进行保守治疗；然而，未见改善。最终，在跌倒事件发生后三个月（左初次TKA术后五个月）计划进行翻修手术。在翻修手术中，胫骨撕脱骨折的骨固定和PS垫片增厚不足以稳定不稳定情况，需要使用旋转铰链假体进行翻修TKA。术后过程顺利，翻修TKA术后两周内她能够拄拐行走，无不稳定主诉。术后两年，患者恢复良好，无不稳定、疼痛或功能障碍复发。本病例报告表明，撕脱骨折导致关节囊失去支撑可能会在PS TKA后引起屈膝位明显的前后不稳定。在这种情况下，保守治疗失败，旋转铰链假体翻修提供了稳定性并取得了良好的改善。
