Revision surgery for a dislocated constrained total knee arthroplasty.

Knee dislocation after revision total knee arthroplasty (TKA) is a dangerous, albeit rare, injury that can lead to neurovascular compromise and permanent disability. A paucity of peer-reviewed literature exists regarding this complication after revision TKA. Tibiofemoral dislocation commonly occurs with minimal trauma, such as rising from a seated position, and is commonly associated with a flexion-extension gap mismatch. Prompt diagnosis and expedited treatment of this complication is necessary to minimize the risk of adjacent neurovascular structures. Acute management involves attempted reduction, knee stabilization, and thorough neurovascular workup. Long-term management may require revision surgery, with the level of articular constraint necessary being determined intraoperatively. This article describes 2 cases of relatively atraumatic knee dislocations after revision TKA involving the same semiconstrained components. Patient 1 was a 68-year-old man who sustained an atraumatic posterior knee dislocation 2 months after revision TKA. Patient 2 was a 55-year-old woman who presented after an atraumatic posterior knee dislocation 6 months after revision TKA. In both patients, a semiconstrained construct was used with corresponding revision components prior to dislocation. This article includes a synopsis of solutions for flexion-extension gap balancing and a review of the literature regarding this uncommon complication.