Magnetic resonance imaging of the knee: assessment of effectiveness.

OBJECTIVES: To quantify how magnetic resonance imaging (MRI) influences clinicians' diagnoses, diagnostic confidence and management plans in patients with knee problems. To investigate whether these changes can bring about an improvement in health.

METHODS: This was a prospective observational study on all patients referred to a regional unit for MRI of the knee over a 6-month-period. Data on diagnosis, diagnostic confidence and proposed management before MRI was compared with diagnoses and actual management after MRI. In addition, short form 36 item (SF-36) health survey data was collected at referral and again 6 months later.

RESULTS: Three hundred and thirty-two patients were entered into the study. MRI led to previously unsuspected diagnosis in 69 of 269 patients with available data. When MRI confirmed the clinical diagnosis, significant improvements in clinicians' diagnostic confidence were found (P < 0.01 for medical meniscus, P < 0.05 lateral meniscus, P < 0.05 anterior cruciate). MRI led to a change in management in 180 (63%) of 288 patients (where data available). There was a significant shift away from surgical management after MRI (P < 0.01). SF-36 results were available in 206 patients. There was a significant improvement over time in five of the eight SF-36 scales (four at P < 0.001, one at P < 0.01).

CONCLUSIONS: Magnetic resonance imaging significantly influences clinicians' diagnoses and management plans. These patients, examined by MRI, also recorded an improvement in health related quality of life.