Aggressive proximal tibio-fibular joint ganglion cyst after a total knee arthroplasty--a case report.

Although the knee is a common location, a ganglion cyst arising from the proximal tibio-fibular joint (PTFJ) is relatively rarer. Unique diagnostic and management difficulties are encountered as these can extend into subcutaneous tissue, or spread along peroneal muscles and nerve, or erode adjacent bone. We report here a PTFJ ganglion cyst which was indolent for at least 12 years and then caused destructive and expansile changes in the fibula over a period of 6 years after a total knee arthroplasty (TKA), simulating a malignancy. Although no wear or foreign body reaction could be shown, this alarming progression of a PTFJ ganglion cyst in the fibula after the TKA is a noteworthy association, and has not been recognized and reported before. Awareness of such a lesion can aid in the diagnosis and prevent unnecessary aggressive management.