Management of fixed deformities in total knee arthroplasty.

Total knee arthroplasty (TKA) has developed significantly since the early 1970s. The basic principles have not changed over the past 30 years; however, the techniques and prostheses have improved a great deal. The TKA must correct deformity while balancing the ligaments and equalizing the flexion and extension gaps. Deformity can be a result of bone angulation or ligament imbalance. Bone deformity must be isolated out to the diaphysis, metaphysis, or articular surface of the knee. The latter two areas can be managed at the same time as the arthroplasty. Diaphyseal changes that are greater than 20 degrees of angulation most often require a separate operative procedure. Ligament imbalance can be managed with either lengthening of the tightened ligament or tightening of the lax ligament. While lengthening is the easier of the two approaches, both techniques are acceptable when performed correctly. Deformity of the knee can be a challenging problem, but with proper planning, the results are very acceptable and rewarding both for the patient and the operating surgeon.