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Degenerative rotator cuff tears most often found in a posterior location
Kim HM. JBJS. 2010; 92:1088-1096.
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Investigators have identified the specific posterior location of degenerative rotator cuff tears: near the junction of the supraspinatus and infraspinatus.
According to existing theories, the most common rotator cuff lesion type, degenerative rotator cuff tears, usually involve the supraspinatus tendon. The tears start at the anterior portion of the supraspinatus insertion and propagate posteriorly, according to H. Mike Kim, MD, of Washington University School of Medicine in St. Louis, Mo. For their study, Kim and his colleagues investigated the most common location of degenerative cuff tears as well as tear location patterns linked with different tears sizes.
The investigators examined ultrasonograms of 360 shoulders (233 patients) with either a full-thickness rotator cuff tear (272) or a partial-thickness tear (88). They measured the tear width and length and the distance from the biceps tendon to the tear’s anterior margin, according to the study abstract. The investigators grouped the tears based on anteroposterior width and whether they were partial- or full-thickness. Then, they identified each tear numerically as a column of consecutive numbers that represented width and distance to the biceps tendon.
Kim and his colleagues pooled all tears to illustrate the width and location within groups. From the pooled data, the investigators generated frequency histograms and determined the mode for each histogram representing various tear groups.
Mean patient age was 64.7 ± 10.2 years. The mean tear width was 16.3 ± 12.1 mm, and the mean length was 17.0 ± 13.0 mm. The mean distance from the biceps tendon to the anterior tear margin was 7.8 ± 5.7, the investigators wrote in their study.
According to the histograms, the most commonly torn location within posterior cuff tendons was 15 mm to 16 mm posterior to the biceps tendon.
“The histograms of small tears (a width of <10 mm) and partial-thickness tears showed similar distributions of tear locations, indicating that the region approximately 15 mm posterior to the biceps tendon may be where rotator cuff tears most commonly initiate,” Kim and colleagues wrote.