Darus Lee Bennett MD, Presenter: Nothing to Disclose

Wesley Ferley, Abstract Co-Author: Nothing to Disclose

Kenjirou Ohashi MD, Abstract Co-Author: Nothing to Disclose

Georges Yousef El-Khoury MD, Abstract Co-Author: Nothing to Disclose

Commonly, occult meniscal tears (not even seen in retrospect on MRI) have been reported to be most commonly found in the setting of an associated ACL tear. Our purpose was to identify bone contusion patterns that have a high association with occult meniscal tears in patients with an acute ACL tear and compare them to patients without an ACL tear.

486 patients who had preoperative MRI and knee arthroscopy at our institution were examined. The reports for both procedures were retrospectively reviewed, and 44 cases were found that had meniscal tears missed on MRI but discovered at surgery. Two experienced musculoskeletal radiologists, blind to the initial reports, independently reviewed the 44 MRI exams that had missed meniscal tears, which yielded 28 patients with occult meniscal tears by MRI. These 28 patients with an occult meniscal tear were independently reviewed by the above two radiologists to determine the bone contusion pattern and to evaluate for the presence of an ACL tear by MRI.

There were 7 females and 21 males with an average age of 33 years (range of 19-48 years). 16/28(57%) had an acute ACL tear; 12/28(43%) did not. In the group of patients with an ACL tear, 12/16(75%) had a classic pivot shift injury bone contusion pattern. The other patterns seen included isolated contusions of the peripheral aspect of the medial femoral condyle (2/16), entire anterior aspect of both tibial plateaus (1/16), and the posterior aspect of the medial tibial plateau (1/16). In the group of patients without an ACL tear, 6/12(50%) had no bone contusions even though they had an acute knee injury. 2/12 had a pivot shift injury bone contusion pattern. 2/12 had contusions of the peripheral aspect of the medial tibial plateau. The other two patients in this group had isolated bone contusions of the patella (lateral aspect) and the lateral femoral condyle (anterior aspect).

The pivot shift bone contusion pattern was the most commonly seen. It can be seen in conjunction with an occult meniscal tear even when the ACL is intact; therefore, it should raise suspicion for an occult meniscal tear even if the ACL is intact.

Bennett, D, Ferley, W, Ohashi, K, El-Khoury, G, Knee MRI Study of Occult Meniscal Tears: Bone Contusion Patterns Seen with Occult Meniscal Tears.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4418502.html