The investigation and treatment of disorders of the knee: indications and a cost-comparison of arthroscopy and magnetic resonance imaging.

Results of a year-long prospective audit of all arthroscopies of the knee in one NHS Trust hospital indicate that selective magnetic resonance imaging (MRI) would be cost-effective in up to 40% of patients. However, to achieve such savings, at least 14% of patients who would otherwise need diagnostic arthroscopy would need to be excluded from surgery, the cost of MRI must be low, and the success rate of interpreting the scans should be known.