Abstract
Purpose: For many years, single-compartment knee inserts have been one of our most frequent operative indications, but the uncertain nature of the results and early deterioration have led us to revisit the failure cases and modalities for total knee arthroplasty.
Material and methods: From 1994 to 2001, we reoperated 33 single-compartment knee inserts (28 medial and five lateral inserts). Mean delay from initial implantation was 4.3 years (range nine months to ten years). Clinical and radiological assessment was done with the IKS score. Peroperative exploration searched for the underlying cause.
Results: All single-compartment inserts were replaced with a total knee arthroplasty. The mean HSS improved from 42.8±15 to 83.6±18% good and very good results. The causes of failure were loosening in 22 cases including four cases of implant fracture or displacement. We had three stress fractures of the tibial plateau. The revision procedure required compensation blocks for the tibia in two cases, and a bone graft in four. Finally, a tibial stem extension was needed in nine cases. There were two mechanical complications after revision, one recurrent stiff knee and one recurrent dislocation of a posterior stabilised prosthesis.
Discussion: Ligament tension and balance both in extension and flexion remains an important problem in revision procedures on single-compartment inserts. The difficulty in setting the femoral rotation is well known due to the loss of posterior condyle tissue. Tibial stem extensions can be useful, particularly if a graft of the medial compartment is used. Use of adapted instrumentation facilitates revision of these single-compartment knee inserts and may provide further confidence in first intention total knee arthroplasty.
The abstracts were prepared by Pr. Jean-Pierre Courpied (General Secretary). Correspondence should be addressed to him at SOFCOT, 56 rue Boissonade, 75014 Paris, France
