A quantitative assessment of degenerative changes acceptable in the unoperated compartments of knees undergoing unicompartmental replacement.

Thirty-five unicondylar knee arthroplasties were performed on 32 patients. In the unresurfaced compartments, degenerative cartilaginous changes were observed intraoperatively and recorded. The Outerbridge grading scale was used to assess the degree of arthritic change. In addition, the surface area involved was estimated. Grade III and limited grade IV changes in the unresurfaced tibiofemoral compartment and the patellofemoral joint did not preclude excellent results at a follow-up interval of 2 to 4 years.