Delayed peroneal nerve palsy after total knee arthroplasty--a rare complication of tibial osteolysis.

We present a case of peroneal nerve palsy which occurred 12 years after primary total knee arthroplasty as a result of extensive tibial osteolysis. The tibial osteolytic cyst extended through a cortical defect in the proximal tibia into the anterolateral compartment of the leg causing compressive neuropathy of the peroneal nerve. Imaging included radiographs, CT scan and MRI. At revision surgery, the tibial component was found loose with significant proximal tibial osteolysis. The cyst in the leg was decompressed through the cortical defect in the proximal tibia and analysis of cystic fluid revealed polyethylene debris. At 7-year follow-up after revision, the osteolytic cyst had resolved but the peroneal palsy did not recover.