Improved range of motion with the Y/S total knee arthroplasty system.

A total knee arthroplasty system (total knee system) was developed by the authors (Y/S) with instrumentation for controlled soft-tissue balancing both in flexion and extension. The prosthesis was designed to take into consideration the kinematic aspect of full flexion. Vigorous daily postoperative rehabilitation was continued for four weeks. Results were good to excellent in all but two of 50 consecutive knee operations on 39 patients. A minimum of 90 degrees flexion was achieved in all cases, with a better average range of motion than those reported in the past. Four patients (six knees), achieved full squatting. The combination of three elements, prosthetic geometry, well-controlled soft tissue balancing for flexion and extension phases, and vigorous rehabilitation, is important for the recovery of range of motion.