Can physical signs or magnetic resonance imaging substitute for diagnosticarthroscopy in knee osteoarthritis patients with suspected internal derangements? A pilot study

This pilot study was developed to compare the relative diagnostic accuracie s of physical findings, magnetic resonance imaging (MRI) and arthroscopy fo r internal derangements in knee osteoarthritis (OA) patients. Nine patients with locking and/or giving way in 10 knees underwent MRI and arthroscopy; the relative diagnostic accuracies for meniscal tears were studied and comp ared with physical findings. Eleven meniscal and no cruciate ligament tears were noted by MRI and/or art hroscopy. Using arthroscopy as the comparison standard, the sensitivity of MRI for meniscal tears was 33.3%, specificity was 96.6%, and diagnostic acc uracy was 75.0%. No significant correlations between physical findings and MRI or arthroscopy findings were found. It seemed that participants with no rmal radiographs had false positive MRIs more frequently. These preliminary data suggest that physical findings may not be adequate f or the diagnosis of meniscal tears in patients with associated knee OA. A l arger study may be warranted to further test this hypothesis. Because the p resence of a meniscal tear may change therapy toward specific physical ther apy modalities and/or meniscal repair, knee OA patients with mechanical sym ptoms may require an MRT or arthroscopy to establish the presence of a meni scal tear. Further testing is required to confirm the suggestion from these cases that patients with normal or minimally abnormal radiographs may requ ire a diagnostic arthroscopy rather than an MRI to demonstrate a meniscal t ear.