Bilateral fatigue fracture of the femoral components in a cruciate-retaining cementless total knee prosthesis.

Full article available online at ORTHOSuperSite.com. Search: 20110826-26 This article reports a case of bilateral fatigue fracture of the femoral components in a cruciate-retaining uncemented total knee arthroplasty (TKA). A 75-year-old woman (height, 158 cm; weight, 72 kg; body mass index, 29.2) had undergone one-stage bilateral TKA for osteoarthritis 11 years previously at the author’s institution. Surgery was performed using an uncemented Flexible Nichidai Knee. Equal tension of the collateral ligaments and normal mechanical axis were achieved during the primary procedure. The patient was an ardent lover of the game of badminton and had higher activity levels with daily playing. At 8 years postoperatively, she started complaining of mild pain in both knees. The pain gradually increased, and at 11 years postoperatively, she had diffi culty walking. Anteroposterior radiographs showed narrowing of the medial joint space, indicating wear of the polyethylene insert. Lateral radiographs showed signs of broken implants in both knees. There were no signs of gross implant loosening or osteolysis. One-stage revision surgery was performed, and the knees were converted to cemented posterior-stabilized TKAs. At revision, the bilateral femoral components were found to be fractured at the junction between the trochlear fl ange and the medial condyle, anteriorly to the medial peg. The polyethylene insert showed mild wear at the medial middle portion. In the majority of case reports, stress fractures of the femoral component have predominantly affected the medial condyle, following uncemented implantation of fi xed-bearing knees. In this case, failure of bone ingrowth in uncemented components, higher body mass index, and a higher athletic activity led to fatigue fracture of the femoral components. Drs Saito, Tokuhashi, Ishii, Mori, Hosaka, Ryu, and Suzuki are from the Department of Orthopedic Surgery, Nihon University School of Medicine, Tokyo, Japan. Drs Saito, Tokuhashi, Ishii, Mori, Hosaka, Ryu, and Suzuki have no relevant fi nancial relationships to disclose. Correspondence should be addressed to: Shu Saito, MD, Department of Orthopedic Surgery, Nihon University School of Medicine, 30-1 Oyaguchi, Kami-machi, Itabashi-Ku, Tokyo 173-8610 Japan (ssaito@med.nihon-u.ac,jp). doi: 10.3928/01477447-20110826-26 Bilateral Fatigue Fracture of the Femoral Components in a Cruciate-retaining Cementless Total Knee Prosthesis SHU SAITO, MD; YASUAKI TOKUHASHI, MD; TAKAO ISHII, MD; SEI MORI, MD; KUNIHIRO HOSAKA, MD; KEINOSUKE RYU, MD; GEN SUZUKI, MD e688 Figure: Preoperative weight-bearing standing AP radiographs of the right (A) and left (B) knees show severe destruction of the articular cartilage in the medial compartment with a varus deformity. A B