Posterior Dislocation after Right Total Knee Replacement Treated with Full Constrained Total Knee Replacement: A Case Report

Total knee replacement (TKR) is commonly performed for severe knee arthritis and usually yields positive outcomes. However, posterior knee dislocation, though rare, is a serious complication that can arise postoperatively. Neglected posterior dislocation, where the condition is not promptly addressed, can lead to chronic pain and functional impairment. The purpose of this case study is to detail the results of the TKR revision in neglected posterior dislocation of knee after TKR. A 63-year-old female presented with right knee pain for seven months before admission, which worsened with walking and prolonged standing. A right TKR was performed in April 2019. Physical examination revealed a postoperative scar, varus deformity of 15 degrees, tenderness at the lateral patella, and limited range of motion (ROM). The assessment concluded with a diagnosis of implant failure of the right knee post-TKR and left knee osteoarthritis. The planned intervention was a total knee replacement revision. A full-constrained TKR with a modular knee prosthesis system was implanted. Varus, valgus, extension, and flexion stability were satisfactory. Postoperative X-ray showed a medial distal femoral angle (MDFA) of 92.67° (N: 80-95°), medial proximal tibia angle (MPTA) of 88.50° (N: 85-90°), combined MDFA and MPTA of 181.17° (N: 165-185°), and a posterior condyle offset (PCO) ratio of 0.50 (N: 0.44-0.47). No notching was found on the femoral component. Timely recognition and intervention are crucial to prevent complications and improve outcomes. Proper surgical techniques and the use of a full-constrained prosthetic system were key in restoring knee stability and function. Keywords: total knee replacement, knee revision surgery, prosthetic system, implant failure, case report