Unicondylar knee prosthesis: our experience

AIM OF THE STUDY: To compare unicompartmental knee arthroplasty with "all poly" tibial component and "metal back" from a clinical and functional point of view.

MATERIALS AND METHODS: We evaluated prospectively 50 patients who underwent unicompartmental knee replacement at the Orthopedic Clinic of the University of Trieste. Patients were split into two groups (A and B); in patients from group A has been implanted a Mitus prosthesis (Link) with "all poly" tibial component, in patients from Group B has been implanted an Allegretto prosthesis (Zimmer) with a "metal back" tibial component. The mean follow-up was 36 months. All patients were evaluated using the Knee Society Score.

RESULTS: The mean preoperative Knee Society Score (objective and functional) was found to be respectively 48 and 49 or the group A and group B; post-operative score was found to be of 95 and 94 respectively for Group A and group B. The average post-operative ROM was 125 degrees (range, 85-140 degrees) for group A and 130° (range 90°-145°) for group B.

CONCLUSIONS: No differences were found between implants with "all poly" tibial component (thickness to be used must be greater than 6 mm) and those with the "metal back". We believe that to achieve positive results over time is important the carefully selection of the patients and the accurate positioning of components.