Role of alignment in successful clinical outcomes following medial unicompartmental knee arthroplasty: current concepts

Unicompartmental knee arthroplasty (UKA) has become increasingly more common, indicating the necessity to better understand factors that may impact outcomes and survivorship. Overcorrection or undercorrection of a varus deformity can increase the risk of postoperative complications including contralateral, lateral compartmental osteoarthritis, component loosening, and component wear following medial UKA. There is no general consensus on the amount of alignment correction to optimise outcomes. The purpose of this article is to provide an overview of the current literature related to alignment, intraoperative alignment correction, and the impact on outcomes and survivorship following medial UKA as well as to explore alternative surgical techniques including patient-specific instrumentation and robotic assistance when managing the varus-malaligned knee with medial UKA. Understanding each of these factors and how they interact is vital in providing patients with promising outcomes following UKA. The ideal alignment is unknown; however, the key is to avoid severe undercorrection and overcorrection of varus malalignment for superior outcomes following medial UKA.