MR imaging: effectiveness and costs at triage of patients with nonacute knee symptoms.

Purpose: To prospectively evaluate the cost and effectiveness of magnetic resonance (MR) imaging performed to exclude the need for arthroscopy in patients with nonacute knee symptoms who are highly suspected clinically of having intraarticular knee abnormality.

Materials And Methods: The study was approved by the institutional review boards of three hospitals; informed patient consent was obtained. All 584 included patients (406 male, 178 female; mean age, 31.1 years+/-8.0 [standard deviation]) underwent MR imaging. Patients with an MR result positive for the diagnosis of intraarticular knee abnormality underwent arthroscopy (group A). Patients with a negative MR result were randomly assigned to undergo either conservative (group B) or arthroscopic (group C) treatment. Treatment was considered effective if the Noyes function score had increased 10% or more at 6 months. A cost analysis was performed from a societal perspective to compare the treatment strategy involving MR imaging with the strategy not involving MR imaging.

Results: Of the 584 patients, 294 (50.3%) were assigned to group A; 149 (25.5%), to group B; and 141 (24.1%), to group C. At 6 months, the number of patients effectively treated in group B (conservative treatment) was a mean of 5.1%+/-10.0 larger than the number of patients effectively treated in group C (arthroscopy). Owing to savings in productivity costs, total societal costs were lower with use of the strategy involving MR imaging by a mean of $153+/-488 (P=.54).

Conclusion: MR imaging can be used without additional costs or disadvantageous effects on function to obviate arthroscopy in patients with nonacute knee symptoms who are highly suspected of having intraarticular knee abnormality.