We performed 82 primary unicompatental, medial knee replacements in patients under the age of 50, using a fixed bearing, metal backed tibial design and a conforming anatomic femoral component. Patients were followed prospectively for a minimum of 2 years (range, 24 to 48 months). All patients were rated both clinically and radiographically using Knee Society Scores, SF-36 and standard radiographic instruments. Patients also completed a validated questionnaire that examined activity level, functional outcomes and ability to return to sports.

Methods: The senior author performed all procedures using a minimally invasive technique with subvastus approach to the medial aspect of the joint. Inclusion criteria were patients under 50 with documented, medial compartment osteoarthritis and a retained ACL. All patients received the same fixed bearing, metal backed design implanted with cement. All patients had osteophytes removed from the medial border of the patella if present.

Results: At last follow up, the mean Knee Society functional score was 96. There was one early infection that was converted to a total knee replacement without further complication. There were no fractures, thromboembolic events or other major complications in this group. Patients reported excellent pain relief and few activity limitations. There was no loss of radiographic alignment or signs of loosening on the most recent radiographs.

Conclusion: Unicompartmental medial knee arthroplasty in a younger patient population can be performed with excellent results. Functional outcomes were superior to total knee replacement designs previously reported in this patient population. The authors can recommend this design in younger patients with medial osteoarthritis that is resistant to non-operative treatment, but full evaluation of this prosthesis will require longer-term results.