A rare case of bilateral large osteolysis following cemented and cementless total knee arthroplasties

A 66-year old woman (BMI 36) presented for routine follow-up after undergoing total knee arthroplasty (TKA) in the right knee 12 years ago, and TKA in the left knee 4 years ago. The right TKA was a cementless cruciate-retaining prosthesis (Encore Medical Foundation Knee, femoral component porous coated CoCrMb alloy, tibial component Ti-alloy with 4 screws, PE insert 9 mm). The left TKA was a cemented cruciate-retaining prosthesis (Zimmer Natural Knee II, femoral component CoCrMb alloy, tibial baseplate component Ti-alloy, PE insert 9 mm). The patient reported only mild problems (knee score 88 points, function score 60 points).

Radiographs and CT scans revealed extensive osteolysis at the proximal medial tibia of both knees (Figures 1 and 2). There was a mild varus malalignment (4°) of both legs. Rotational alignment measured on the CT scans showed a rotational mismatch between femoral and tibial components of 8° (femoral internal rotation) in the right knee and no mismatch (1° of femoral internal rotation) in the left knee.