The effect of magnetic resonance imaging scans on knee arthroscopy: randomized controlled trial.

PURPOSE: The purpose of this study was to investigate whether magnetic resonance imaging (MRI) in patients waiting for knee arthroscopy could reduce arthroscopy rates and improve patient outcome. METHODS: A prospective randomized controlled trial was conducted in a teaching hospital setting. All participating patients had knee MRI before arthroscopy. In the intervention group the MRI report was seen by surgeons, and in the control group it was not. The primary outcome measure was the proportion of patients who did not have an arthroscopy. Secondary outcome measures included the Short Form 36, EuroQol EQ-5D, Knee Injury and Osteoarthritis Score, and Knee Society Score. RESULTS: Surgeons changed both their diagnosis and management plan in 47% of patients in the intervention group compared with 1% in the control group, with no difference between groups in the proportion of patients who underwent an arthroscopy. In the intervention group 7 of 125 patients (5.6%) did not have an arthroscopy compared with 8 of 127 patients (6.3%) in the control group. In one instance a surgeon decided against arthroscopy based on the MRI report. There was no significant difference between groups in other outcome measures. CONCLUSIONS: We found no effect of MRI on the decision to perform arthroscopy or patient outcome. Performing MRI in patients already on the waiting list for arthroscopy may not be effective in reducing utilization of surgery. LEVEL OF EVIDENCE: Level I, therapeutic randomized controlled trial with no statistically significant difference but with narrow confidence intervals