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.
The Unispacer knee system is a cobalt-chrome self-centring tibial hemiarthroplasty device for use in the treatment of isolated medial compartment osteoarthritis of the knee. The indications for use are similar to those for high tibial osteotomy, but insertion does not require bone cuts or component fixation, and does not compromise future knee replacement surgery. A prospective study of a consecutive series of 18 patients treated with the Unispacer between June 2003 and August 2004 was carried out to determine the early clinical results of this device. The mean age of the patients was 49 years (40 to 57). A total of eight patients (44%) required revision within two years. In two patients revision to a larger spacer was required, and in six conversion to either a unicompartmental or total knee replacement was needed. At the most recent review 12 patients (66.7%) had a Unispacer remaining This study demonstrates that use of the Unispacer in isolated medial compartment osteoarthritis is associated with a high rate of revision surgery and provides unpredictable relief of pain.
