The TRAC-PS dual radius total knee arthroplasty : Disappointing medium and long terms results

The TRAC prosthesis is a dual radius, mobile bearing, posterior stabilized prosthesis, to increase stability by optimizing contact area and control wear using a mobile polyethylene. Between February 1995 and January 2000, a single surgeon performed a continuous series of 85 TRAC-PS TKAs in 85 patients at the University Hospital Brussels. A retrospective review on patient charts was performed. Patients available were scored clinically using the Knee Society Score, WOMAC osteoarthritis index, SF 36 and a Visual Analogue Scale for pain. 43 patients had died at time of evaluation, three were unavailable for examination due to bad general health and five were lost to follow up. The remaining 35 patients were examined with a mean follow-up of 13 years. The mean age of the patients at follow up was 83 years. The mean WOMAC score was 78,4(SD 17,9). The mean Knee Society Score was 86.8(SD 8,4) clinical and 42,6(SD 28) functional. The mean range of flexion was 105°. The mean SF-36 score was 59,8(SD 15,4). The VAS for pain was 6(SD 9). With revision (8 cases) as endpoint, survival rate of the prosthesis was estimated to be 92% at 13 years. Twenty-three Serious Adverse Events (28%) in 17 patients, related to the prosthesis were registered in this patient group. Long term results of this prosthesis were satisfying but a large number of serious adverse events led to abandonment of the TRAC-prosthesis.