A Narrative Review of Long-Term Outcomes and Imaging-Based Failure Analysis in Lateral Unicompartmental Knee...

Lateral unicompartmental knee arthroplasty (UKA) remains an underutilized treatment option for isolated lateral compartment osteoarthritis, despite growing evidence supporting its effectiveness. Historically, concerns regarding technical complexity, implant design limitations, and higher revision rates limited its adoption. However, advances in implant technology and surgical techniques have substantially improved outcomes. We conducted a comprehensive literature search for studies including outcomes of UKA. Inclusion prioritized but was not limited to studies published in 2020 and onwards, systematic reviews, meta-analyses, and clinical trials. We summarized the available literature on long-term clinical outcomes, survivorship, and failure patterns following lateral UKA, with particular emphasis on the role of imaging-based failure analysis. Contemporary cohort studies and registry data demonstrate excellent survivorship at long-term follow-up comparable to medial UKA and, in appropriately selected patients, total knee arthroplasty. Imaging modalities, including radiography, computed tomography, fluoroscopy-based kinematic analysis, and magnetic resonance imaging, play a critical role in evaluating component positioning and alignment, along with early signs of failure that may not be clinically apparent. These imaging-based assessments have contributed to refinements in surgical planning and patient selection. Overall, modern lateral UKA has evolved into a reliable and durable procedure when performed with meticulous techniques and appropriate imaging-guided evaluation, supporting its expanded role in contemporary knee arthroplasty practice.