Abstract
Soft tissue balancing in fixed genu valgum can be challenging and may lead to instability in flexion. Current techniques involve release of the tight secondary structures initially, with the fascia lata and the lateral capsule usually addressed first, and then the posterior capsule if necessary. If ligament testing does not permit neutral alignment in extension, release of the lateral collateral ligament becomes necessary.
The most common way of achieving neutral alignment is by lengthening the lateral structures through elevation of the proximal insertion of the lateral collateral ligament (LCL). This technique has two drawbacks: the lengthening affects both extension and flexion gaps and may give rise to excessive external rotation of the femoral implant, with too much offset of the rotational centre. Particularly when non-constrained prostheses are used, the resulting lateral instability in flexion can be a problem.
An alternative is to perform a release at the level of the distal insertion of the LCL, as advocated by Keblish and Buechel. However, this still induces undue external rotation of the femoral implant.
We think that if the situation in flexion before any release is satisfactory in terms of the patella, it should not be changed. This means that in order to maintain optimal patellofemoral function, the flexion gap should be addressed before any release. The task is then to achieve a good extension gap with a well-aligned knee. In fixed valgus deformities, this means distal translocation of the femoral insertion of the LCL by distal sliding lateral condylar osteotomy. This procedure aims to preserve the flexion condition and to allow distal slide of the lateral condylar osteotomised fragment. In doing the osteotomy, it is important to make the lateral fragment sufficiently large to allow relocation of the osteotomised fragment inside the prosthesis. This provides the immediate stability necessary for good healing. We have been using two simple cortical screws to ensure stability of the fragment.
This paper reports our experience in 100 cases.
Secretary: Dr H.J.S. Colyn, Editor: Professor M.B.E. Sweet. Correspondence should be addressed to SAOA, Box 47363, Parklands, Johannesburg, 2121, South Africa.
