Conversion of Unicompartmental to Total Knee Replacement: A Comprehensive Review of Technical Considerations and Surgical Outcomes.

» Unicompartmental knee arthroplasty (UKA) has seen significant growth and development over the last 15 years with improved outcomes for patients, but many of these patients may require subsequent surgeries to address failure of their UKA.

» There are 3 main strategies for treatment of a failed UKA: (1) revision UKA (rUKA), (2) staging to a bicompartmental knee arthroplasty (sBiKA), and (3) conversion of UKA to total knee arthroplasty (cTKA).

» Each has specific indications and contraindications, but currently, the cTKA is the gold standard for surgical treatment, and the goal of that surgery is to have equivalent outcomes to primary TKA.

» There are several technical difficulties that have historically made this procedure more challenging than primary TKA with the literature showing inconsistent outcomes in terms of equivalence to primary TKA. sBiKA and rUKA are much less frequently used and more rarely represented in the literature.

» Each surgical option has its own drawbacks and unique difficulties, and these surgeries likely do not yield equivalent outcomes to simple primary TKAs yet. There are a number of emerging technologic tools and modern techniques that can be implemented in the hopes of improving outcomes for this cohort of patients and have shown preliminary promise in this area.