Medial unicompartmental arthroplasty of the knee. Use of the L-cut and comparison with the tibial inset method.

Forty-four medial unicompartmental arthroplasties were performed between August 1982 and August 1985 using the L-cut resection and guides. These were compared with 19 medial unicompartmental arthroplasties performed between September 1974 and August 1982 in which the tibial plateau was prepared by the conventional tibial inset method. The L-cut was more precise due to the use of guides. This method allowed the tibial component to be seated directly on the cortical rim of the medial proximal tibial plateau for better support. There was a direct relationship between the placement of the tibial component and the clinical results. In both groups, those patients approaching a tibial prosthesis placement of 90 degrees in the coronal plane and 80 degrees in the sagittal plane had the best clinical results.