Mini-invasive knee unicompartmental arthroplasty: bone-sparing technique.

Total knee replacement (TKR) has been well accepted as the definitive knee- salvage procedure. Existence of a predictable, reproducible, salvage procedure has allowed for re-evaluation of other surgical techniques, such as unicompartmental arthroplasty, to prolong or preserve knee function. Knee osteoarthritis has been described as highly segmental, primarily medial, and slowly progressive. Loss of articular cartilage is compensated by development of sclerotic bone, which although it supports weight, it deforms with weight-bearing and produces pain. Ligament imbalance is not compensated. A mini-invasive knee arthroplasty has been developed that features the following three criteria: (1) minimizes physiologic damage, (2) minimizes interference in life style, and (3) avoids interference with future treatment options. Unicompartmental knee arthroplasty can, therefore, be performed as a low-morbidity outpatient procedure while preserving bone for future TKR--in essence, a pre-TKR procedure. Techniques include limited surgical exposure, internal landmarks for prosthetic insertion, and pain management to facilitate out-patient status.