Minimally Invasive Unicompartmental Knee Arthroplasty
Unicondylar knee arthroplasty (UKA) has seen a very significant revival in interest in the past 3–4 years in the United States. Results in the 1980s and 1990s were not very encouraging and the surgical procedure was almost abandoned. With the dawn of minimally invasive surgical (MIS) techniques, there is more interest in the procedure. The indications for the surgery have been clearly defined and the surgical technique has been significantly changed. UKA should not be performed as a total knee arthroplasty (TKA). The MIS approach is a limited one and the soft tissues must be managed so proper visualization and technique are still possible. Alignment and balancing are different because the surgery is performed on only one side of the knee. The knee must not be overcorrected and flexion and extension balancing must be established without significant ligament releases. The slope of the tibial cut and the distal femoral cut can be used to a certain extent to adjust the balance. The technique demands accuracy but it is not difficult to master. The early results of MIS UKA are very encouraging and mimic the published results of TKA and of UKA performed with open arthrotomy. The future of knee surgery will include more partial knee replacements and will certainly progress to MIS total knee replacement.