Anteromedial Osteoarthritis and UKA

UKA is a successful and popular procedure for the treatment of end-stage knee osteoarthritis, but its primary indication is anteromedial osteoarthritis of the knee. The presence of an intact ACL is intact in all knees with anteromedial arthritis. ACL rupture allows posterior femoral subluxation, posterior tibiofemoral contact, and posterior progression of medial compartment wear, suggesting that deficient ACLs may eventually disappear. Chronic ACL rupture in knee osteoarthritis is likely caused by direct physical and vascular damage, leading to spread of wear areas posteriorly on the medial tibial plateau and to the lateral compartment. UKA has been used to prevent pain in osteoarthritis since 1940, with good results in single compartment disease. However, some groups reported poor outcomes due to inadequate patient selection or material failures. UKA requires full thickness preservation of the lateral tibial plateau articular cartilage, varus deformity to be fully correctable in 20 degrees of flexion, and intact posterior cartilage within the medial tibial plateau. It is also permissible in flexion deformity of up to 15°. UKA allows preservation of bone stock and soft tissues, reduced blood loss, shorter length of stay, lower readmission rate, and improved range of motion and ambulatory function. UKA is 2.1–2.8 times more likely to be revised than TKA, largely due to a lower threshold for revision and a larger difference in revision rates between high and low volume surgeons. Outcomes and mechanisms of failure vary for different types of UKA. Limitations to UKA use. UKA is more challenging than TKA, and patient selection is controversial. Kozinn and Scott recommendations for eligibility criteria are often applied. UKA is a potential alternative to total knee arthroplasty for isolated anteromedial osteoarthritis, with improved clinical outcomes and lower revision rates.