Today's News

Sunday, February 07, 1999

MRIs most accurate in high grade partial tears

A review of acute knee injuries in poster exhibit 396A Saturday showed that the greatest accuracy in magnetic resonance imaging (MRI) diagnosis was in cases with high grade partial tears.

According to co-author Jon L. Hyman, MD, resident, department of orthopaedics, Hospital for Special Surgery, New York, an MRI of a chronic partial tear of the anterior cruciate ligament (ACL) is generally not detectable on gross inspection during arthroscopy, and does not correlate with clinical examination of the knee under anesthesia. "However, magnetic resonance imaging may show remodeling or progressive tearing of the acutely injured ligament before arthroscopy or indicate chronic, partial ACL tears that are surgically or clinically undetectable," said Dr. Hyman.

Eighty-two patients who had a partial tear of the ACL, were diagnosed by MRIs in a standardized technique by a single radiologist, and underwent subsequent knee arthroscopy. The radiographic findings were compared to the gross findings at arthroscopy and correlated with exam under anesthesia.

The study found that 23 of the 82 patients had partially torn ACLs at surgery and 12 of these cases demonstrated a positive pivot shift under anesthesia. Forty-nine of the 82 patients had grossly intact ACLs and none of them had instability. Ten of the 82 patients had completely torn ACLs. Eight of nine complete tears demonstrated positive pivot shifts. Twenty-four patients had acute injuries (38 percent partial tears) and 58 were chronic injuries (24 percent partial tears). The mean age of the patients was 41 years. The mean time between MRI and arthroscopy was 2.1 months.

Co-authors of the study with Dr. Hyman, all from the department of orthopaedics, Hospital for Special Surgery, are Hollis Potter, MD, chief, magnetic resonance imaging division; Thomas L. Wickiewicz, MD, chief of shoulder and sports medicine service; Jo A. Hannafin, MD, PhD, attending sports medicine physician; Russell F. Warren, MD, surgeon-in-chief; Timothy S. Johnson, MD, resident; and Tamara Rosenthal, BS, medical student.

1999 Academy News Feb. 7 Index A
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Last modified 07/February/1999