Revision of 33 unicompartmental knee prostheses using total knee arthroplasty: strategy and results

Abstract

The purpose of this study was twofold: to evaluate the radiological and clinical results of 33 total knee arthroplasties (TKA) implanted between January 1993 and March 2005, to replace failed medial unicompartmental knee arthroplasty (UKA), and to develop a strategy to deal with bone defects in the tibial plateau. Failure was due to: tibial loosening (15 cases), femoral loosening (five cases), femoral and tibial loosening (two cases), polyethylene wear (five cases), lateral compartment osteoarthritis (two cases), patellofemoral osteoarthritis (two cases), laxity and PE dislocation (one case), and sepsis in one case. In 12 cases the tibial bone defect was filled with a metallic wedge, in seven we used an allograft (femoral head), and in one we used both. We report the results of 27 cases (five patients died and one was lost to follow-up). The mean follow-up was 73+/-41.7 months (range, 8-153) and the global IKS score was 166.72+/-21.3 points (range, 128-200). X-rays of the eight allografts showed osteointegration in all cases and no radiolucency was noted.

Fig. 1

Severe bone loss at the level of the tibial plateau

Fig. 2

Step resection of the medial tibial plateau

Fig. 3

Preparation of the femoral head for bone grafting

Fig. 4

Temporary fixation of the bone graft in its proper position using Kirschner wires

Fig. 5

Placing the trial prosthesis on top of the reconstructed tibial plateau

Fig. 6

Postoperative X-ray to check the prosthesis and the bone graft