This study was designed to evaluate the performance of a new patient specific interpositional knee device. Treatment of osteoarthritis is evolving, allowing surgical treatment options at an earlier stage. The interpositional knee device is a recently developed patient specific implant used for the treatment of mild to moderate uni-compartmental osteoarthritis. The benefits over traditional methods of surgical management are: it's less invasive, can be a day procedure and does not limit future options. Young Adults with early uni-compartmental arthritis are suitable. A MRI scan of the patient's knee is reviewed by local and US radiologists to decide if the patient is suitable for the implant. A bespoke implant is produced. Prior to insertion an arthroscopic procedure is undertaken to allow proper positioning of the implant.

We treated 27 patients with the iForma Conformis interpositional knee implant in South Wales at the Princess of Wales Hospital, Bridgend and the Royal Glamorgan Hospital, Llantrisant since November 2007. The pre- and post-operative WOMAC scores were recorded. The average age was 54.7 years, BMI 32; 10 females and 20 males. The average pre-operative WOMAC score was 42.2 improving to 62.9 post-operatively. 35 implants were used. 7 patients experienced post-operative problems. No dislocations were reported. Average follow-up was 12.6 months.

Our early experience suggests patient selection plays a role in the outcome following surgery. It indicates that this device is a viable and safe alternative to a uni-compartmental knee replacement.