A unicompartmental knee replacement (uni) resurfaces one of the knee's three articular compartments with prosthetic surfaces made of metal and plastic. A total knee replacement (TKR) resurfaces all three compartments with similar materials. Patients with osteoarthritis that is limited to just one part of the knee are candidates for this procedure. For these individuals (approximately 30 percent of patients), a uni offers quicker recovery, less pain after surgery and the potential for a "normal" knee in that no ligaments are sacrificed. All total knee replacements are cruciate deficient post-op thus limiting vigorous activities due to the resultant abnormal kinematics.
A successful uni requires both a well designed prosthesis and its accurate implantation; the lack of either can lead to the procedure's failure. Advancements including improved implants and refined surgical technique have produced results that challenge and often eclipse those of total knee replacements.
A recent improvement of an established successful implant design utilizes oxidized zirconium for a bearing surface with less friction, resulting in diminished wear and enhanced durability. This device is designed to be combined with a specific surgical technique developed to ensure proper knee alignment and soft tissue balance with the least possible surgical exposure, thus reducing surgical morbidity and allowing for a quicker recovery.
Patients with degenerative arthritis limited to a single compartment who may be contemplating surgical repair should consider a uni or partial knee replacement. Because of the benefits outlined above it is often the better choice.