Fracture of femoral component in a resurfacing total knee arthroplasty.

We present a case of an unusual complication after a resurfacing total knee arthroplasty. Fracture of the uncemented porous-coated femoral component occurred 4 years after its implantation. The mechanical axis was restored and collateral ligament balance was achieved at the primary procedure. At revision, the femoral component was found fractured at the junction of the trochlea with the medial condyle, anteriorly to the medial peg. A thin layer of fibrous tissue was interposed between bone and metal under the fracture area. Metallurgical analysis of the fractured component revealed fatigue failure but no structural defect. Lack of bony support and excessive cyclic loading led to fracture of the implant.