Lateral unicompartmental knee arthroplasty anatomy, indications, technique, and outcomes: a narrative review

Lateral unicompartmental knee arthroplasty (UKA) is an effective surgical option for isolated lateral compartment osteoarthritis, though it remains less common than medial UKA. The lateral compartment differs substantially from the medial compartment in osseous morphology, meniscal mobility, and reliance on soft tissue stabilizers, resulting in unique kinematics that require distinct implant designs and surgical strategies. While earlier guidelines delineated narrow indications, contemporary evidence supports expanded indications, with good outcomes even in younger patients, those with higher body mass index, or mild patellofemoral joint disease. Technical considerations include surgical approach, alignment goals, and implant choice, with fixed-bearing implants preferred due to lower dislocation risk and robotic-assisted techniques showing promise for optimizing implant positioning. Modern series demonstrate survivorship exceeding 90% at 10-15 years, with functional outcomes comparable to medial UKA and superior to total knee arthroplasty in some areas such as recovery, patient satisfaction, and wound infection and other complication rates. This review summarizes the anatomy and biomechanics of the lateral compartment of the knee, indications, surgical technique, implant options, and clinical outcomes of lateral UKA.