1244 Wound Dehiscence and Infection of a Total Knee Replacement Secondary to Postoperative ‘Dorsal Fin’ Intra-Articular Vertical Patella Dislocation

Abstract

Abstract A 75-year-old man presented to our emergency department with a bleeding wound 19 days following a primary hinged left total knee replacement, performed elsewhere, for lateral tibiofemoral osteoarthritis. Examination revealed a knee held in fixed flexion of 30°, with partial dehiscence of the wound, implant exposure and a visible patella. Radiographs revealed an abnormally raised joint line with a vertical appearance of the patella on the lateral image. The decision was made to proceed with a two-stage revision. At operation, the patella was confirmed to be vertically positioned in the trochlea groove of the femoral component and identified as the likely cause for the wound dehiscence. There was evidence of a large lateral release having been performed during the primary surgery. A joint orthoplastic wound debridement was performed, together with implant removal, and static cement spacer insertion. Following an eight-week interval of IV antibiotics, the second stage was performed. A new hinged implant was implanted, with metaphyseal sleeves and stems. A tibial tubercle osteotomy was required to address the lateral tracking patella and a gastrocnemius flap was necessary to address a distal soft tissue defect. This case study highlights an unusual cause for wound dehiscence following total knee arthroplasty. Patella dislocation with vertical axis rotation has been described in the native knee1, but to our knowledge, this is the first report of this phenomenon following arthroplasty. This was almost certainly secondary to component malpositioning and emphasizes the significance of restoring the native joint line and correct implant rotation during knee replacement surgery.