Osteotomy versus unicompartmental arthroplasty: an algorithm for anteromedial knee osteoarthritis

Knee arthritis occupies a significant proportion of the musculoskeletal burden in the UK. Total knee arthroplasty currently comprises the mainstay of treatment. There has been a shift towards treating isolated unicompartmental osteoarthritis with bone-preserving surgical techniques, in the form of realignment osteotomy or unicompartmental arthroplasty. There are significant data regarding the survivorship of unicompartmental knee arthroplasty from the National Joint Registry data. Similar registry data are not available for osteotomy surgery yet, but the evidence suggests that unicompartmental knee arthroplasty has greater survivorship. Osteotomies can, however, deliver higher functional return. For both techniques to succeed, it is imperative that rigorous surgical decision-making, with regards to patient selection, should be followed. This paper discusses the basis for these principles and their importance in delivering optimal care. Often, these two surgical techniques are promoted as being mutually exclusive; this paper argues that, in fact, they are part of a complementary algorithm that can deliver the best outcome to the appropriately selected patient.