Usefulness of Tc-99(m)-MDP knee SPET for pre-arthroscopic evaluation of patients with internal derangements of the knee

The aim of this study was to ascertain whether knee SPET can localize lesio n sites in patients with internal derangements of the knee. We performed kn ee SPET as a pre-arthroscopic examination in 63 consecutive patients. SPET imaging was performed with a triple-headed SPET camera 4 h after the inject ion of Tc-99(m)-methylene diphosphonate. Arthroscopic diagnoses were as fol lows: 28 medial meniscus injuries, 24 lateral meniscus injuries, 31 anterio r cruciate Ligament (ACL) injuries, three posterior cruciate ligament injur ies and one medial collateral ligament injury. Of 30 patients with crescent -shaped increased activity at the medial tibial plateau, 22 had medial meni scus injuries (positive predictive value: PPV 73%); of 17 patients with cre scent-shaped activity at the lateral tibial plateau, 13 had lateral meniscu s injuries (PPV 76%). Of 18 patients with increased activity at ACL attachm ent sites (primary sign), 17 had ACL injuries (PPV 94%). Of 27 patients wit h increased activity at bone impaction sites of ACL, injury (secondary sign ), 22 had ACL injuries (PPV 81%). Of 32 patients who had either a primary o r secondary sign, 26 had ACL injuries (PPV 81%). We conclude that knee SPET is very useful in the management of internal derangements of the knee, par ticularly in determining the need for arthroscopy by localizing lesion site s. ((C) 2000 Lippincott Williams & Wilkins).