Abstract
Introduction:
Unicompartmental knee arthroplasty (UKA) is a well established method for 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. We propose the use of magnetic resonance imaging (MRI) as a useful modality in determining the etiology of symptoms in symptomatic unicompartmental knee arthroplasties.
Materials & Methods:
An IRB-approved retrospective analysis of 300 consecutive unicompartmental knee arthroplasties between 2008–2010 found 28 cases symptomatic for continued pain. Magnetic resonance imaging was performed with a 1.5 T Surface Coil unit after clinical and radiographic assessment. MRI evaluation included assessment for osteoarthritis, synovitis, osteolysis, and loosening. Validated questionnaires including PAQ, WOMAC and UCLA Activity Score were used for clinical assessment
Results:
The average age at surgery was 56.1 ± 10.9 years (34–79). Imaging results indicated progressive arthritis in 28 patients (100%), synovitis in 17 patients (61%), osteolysis in 9 patients (32.0%), and loosening in 3 patients (11%). Based on these results and other clinical findings, a revision or conversion to a TKR was advised for 10 patients and 18 were recommended for nonoperative therapies. One patient received treatment at a separate hospital, and another was lost to follow-up. At post-operative follow-up of 1.4 ± 0.9 years, 7 of the 10 patients (70%) in the operative group experienced improvement in pain and function. The mean PAQ, UCLA and WOMAC index scores for these patients were 8.0 ± 1.4 (7–9), 5.5 ± 6.4 (1–10), and 2.0 ± 2.8 (0–4), respectively. In the nonoperative group, 11 of the 18 patients (61%) experienced improvement in pain and function. Among these patients, the mean PAQ, UCLA and WOMAC index scores were 7.6 ± 3.7 (0–10), 5.9 ± 3.2 (1–10) and 8.9 ± 12.0 (0–28), respectively.
Conclusion:
The use of MRI as an imaging modality for symptomatic arthroplasty patients is becoming more commonly used. This study shows how MRI with sound clinical judgment can influence treatment decisions and supports the use of high quality MRI as a diagnostic tool for the symptomatic unicompartmental knee arthroplasty.
