The O'Donoghue triad revisited

Abstract

We identified 60 consecutive patients with combined anterior cruciate and medial collateral ligament (ACL- MCL) disruptions that were incurred during athletic endeavors. Each underwent acute reconstruction of the ACL. The arthroscopic data obtained at the time of reconstructive surgery was reviewed in order to deter mine the incidence of O'Donoghue's triad (the "unhappy triad"), consisting of ACL, MCL, and medial meniscus tears.

Patients were subdivided into two groups for analysis based upon the degree of MCL injury at time of pres entation (Group I, 35 patients with a second-degree sprain; Group II, 25 patients with a complete, or third- degree injury). Medial meniscus tears were an uncom mon finding. Lateral meniscus tears significantly out numbered medial meniscus tears in both groups, oc curring in 25 (71 %) of Group I patients and 8 (32%) of those in Group II. Even chondral fractures of the lateral femoral condyle outnumbered medial meniscus tears [6 (17%) versus 4 (11 %)] in patients with a second- degree MCL sprain. Furthermore, when present in Group I patients, tears of the medial meniscus were associated with a concomitant lateral meniscus injury. Group II patients were more likely (60%) than Group I not to have any meniscal abnormality at all.

We conclude that the classic O'Donoghue triad is, in fact, an unusual clinical entity among athletes with knee injuries; it might be more accurately described as a triad consisting of ACL, MCL, and lateral meniscus tears. This injury combination appears to be more common when an incomplete, or second-degree, tear of the medial collateral has occurred. Third-degree MCL injuries in conjunction with ACL disruptions seem to "protect" joint surfaces, as patients with these injuries most commonly demonstrate an absence of further intraarticular abnormality (meniscal or chondral).