©1997 British Editorial Society of Bone and Joint Surgery 0301-620X/97/47911 $2.00

Arthroscopy and MRI for the knee In its early days arthroscopy was used mainly for diagnosis; it saved many knees from unnecessary arthrotomy. Today, MRI is available to save knees from unnecessary arthro-scopy; internal derangements can then be treated by arthro-scopic surgery. Arthrotomy for internal derangement is now obsolete and the debate has moved on to the relative roles of arthroscopy and MRI in the management of knee disorders. MRI is non-invasive, free from known morbidity and is safer and less expensive than arthroscopy. The sensitivity of MRI for meniscal lesions may exceed 90%,1-3 but despite this, diagnostic arthroscopy is often advised too readily. One study showed that 51 % of patients on a waiting-list for arthroscopy for a suspected meniscal lesion were remove