Total knee replacement in osteoarthritis associated with extra-articular deformity

Abstract

Background Long-term results on total knee replacement (TKR) depend on the restitution of the limb’s mechanical axis, the correct placing of the prosthesis, and the appropriate balance of soft tissue. Patients with osteoarthritis of the knee associated with femoral or tibial extra-articular deformity, require thorough preoperative planning in order to decide if the axis correction could be made through “unusual” intra-articular bone cuts, or if it should be associated with an osteotomy.MethodsTwenty two TKR were performed in 20 patients with osteoarthritis of the knee associated with extraarticular deformity of post-traumatic etiology in 8 cases and post-osteotomy in 14 (8 femoral and 6 tibial). Minimal follow-up was 5 years. In all cases the limb axis was corrected through a TKR with “unusual” intra-articular bone cuts, without the need of an osteotomy.ResultsTwenty of 22 operated patients achieved good results with this technique. The clinical and functional evaluation was made through the Knee Society scoring system. The average clinical score was 24.3 points in the preoperative period and 86 points one year after surgery. The functional score changed from an average of 34 points in the preoperative period to 85.3 points after one year.ConclusionsThere is no an undisputable criterion regarding the treatment of patients with symptomatic osteoarthritis of the knee associated with severe extra-articular deformity. Correction of the extra-articular deformity by intra-articular “unusual” bone cuts at the time of TKR is indicated if these cuts do not affect the femoral insertions of the collateral ligaments of the knee. This method can be applied to angular deformities up to 20º in the femur and up to 30º in the tibia.