Role of magnetic resonance imaging in the diagnosis of the painful unicompartmental knee arthroplasty

Background: Unicompartmental knee arthroplasty (UKA) is a well established method for the treatment of single compartment arthritis; however, a subset of patients still present with continued pain after their procedure in the setting of a normal radiographic examination. This study investigates the effectiveness of magnetic resonance imaging (MRI) in guiding the diagnosis of the painful unicompartmental knee arthroplasty. Methods: An IRB-approved retrospective review identified 300 consecutive UKAs performed over a three years period with 28 cases of symptomatic UKA (nine percent) with normal radiographic images. Results: MRI examination was instrumental in finding a diagnosis that went undetected on radiographs. Based on MRI findings, 10 (36%) patients underwent surgery whilst 18 (64%) were treated conservatively. Conclusion: This study supports the use of MRI as a valuable imaging modality for managing symptomatic unicompartmental knee arthroplasty. Level of evidence: Case series.