Total knee arthroplasty for arthritis of the knee with extra-articular deformity

Background: Simultaneous corrective osteotomy of angular deformity and total knee arthroplasty has been considered the treatment of choice for patients with arthritis of the knee associated with ipsilateral extra-articular deformity. However, this procedure is technically demanding, and the functional outcome of the total knee arthroplasty may be jeopardized if the osteotomy fails. This retrospective study was performed to evaluate the clinical results of total knee arthroplasty combined with intra-articular bone resection, without osteotomy, in patients with extra-articular deformity and arthritis of the knee. Methods: Fifteen patients with arthritis of the knee and extra-articular deformity underwent total knee arthroplasty with bone resection and soft-tissue balancing. All deformities had resulted from fracture malunion. There were ten uniplanar, three biplanar, and two triplanar deformities. The deformity was in the tibia in eight patients and in the femur in seven. The average angle of the femoral deformities was 15.1degrees in the coronal plane and 8.1degrees in the sagittal plane. Two femora had a rotational deformity, consisting of 200 of internal rotation in one and 100 of external rotation in the other. The average angle of the tibial deformities was 190 in the coronal plane. Results: The duration of follow-up averaged thirty-eight months. The average Knee Society knee score improved from 22.3 points preoperatively to 91.7 points at the time of the last follow-up, and the average Knee Society function score improved from 28.0 points preoperatively to 87.3 points at the time of the last follow-up. The average arc of knee motion improved from 77.7degrees preoperatively to 103.7degrees postoperatively. The average mechanical axis of the knee improved from 22.7degrees of varus preoperatively to 0.3degrees of varus at the time of the last follow-up. Two patients had an unsatisfactory clinical result, which was not related to the total knee arthroplasty. There were no complications such as infection, ligament instability, or component loosening. Conclusions: Total knee arthroplasty in conjunction with intra-articular bone resection is an effective procedure for patients with arthritis of the knee and extra-articular varus deformity of <20degrees in the femur or : less than or equal to30degrees in the tibia in the coronal plane.