The Role of Preoperative Magnetic Resonance Imaging in Surgical Decision-making for Total Versus Medial Unicompartmental Knee Arthroplasty

Unicompartmental knee arthroplasty (UKA) is considered favorable over total knee arthroplasty (TKA) due to quicker recovery and high postoperative function; however, UKA failure rates remain high. The purpose of this study was to investigate the role of preoperative magnetic resonance imaging (MRI) in surgical decision-making for medial UKA versus TKA. Ninety-four knees of 85 patients who underwent knee replacement surgery were analyzed retrospectively. Patients deemed candidates for UKA based on stress-view radiographs and physical exam underwent MRIs to assess candidacy. Exclusion criteria included lateral meniscus tears, loose bodies, grade 3 – 4 chondromalacia, anterior cruciate ligament (ACL) tears, sclerosis, and osteoarthritis in more than one compartment. Based on exclusion criteria in the MRI, 47.87% of patients who were initially candidates for UKA were deemed TKA-only candidates. Therefore, although MRIs pose an additional cost, high failure rate of UKA and cost of conversion to TKA make it a beneficial solution. (Journal of Surgical Orthopaedic Advances 34(1):011-014, 2025)

Key words: magnetic resonance imaging, unicompartmental knee arthroplasty, total knee arthroplasty, osteoarthritis, surgical planning