The greater tuberosity angle: a new predictor for rotator cuff tear

Area of Science:

• Orthopedic Surgery
• Radiology
• Shoulder Biomechanics

Background:

• Scapular morphology's role in rotator cuff tears is well-established.
• The significance of greater tuberosity (GT) morphology warrants further investigation.
• A novel radiographic marker, the GT angle (GTA), is proposed to assess GT position relative to the humeral head's center of rotation.

Purpose of the Study:

• To introduce and validate the GT angle (GTA) as a new radiographic marker.
• To investigate the association between GTA values and the presence of rotator cuff tears.
• To test the hypothesis that higher GTA values correlate with an increased likelihood of rotator cuff tears.

Main Methods:

• Prospective recruitment of 71 participants (33 with rotator cuff tears, 38 controls) over one year.
• Exclusion of individuals with proximal humerus abnormalities.
• Measurement of GTA on anteroposterior shoulder X-rays in neutral rotation by three observers at two separate times.

Main Results:

• Mean GTA was significantly higher in patients (72.5°) compared to controls (65.2°) (P < .001).
• A GTA exceeding 70° was associated with a 93-fold increased odds of detecting a rotator cuff tear (P < .001).
• High interobserver and intraobserver reliability were demonstrated for GTA measurements.

Conclusions:

• Greater tuberosity morphology plays a role in rotator cuff tears.
• The GT angle (GTA) is a reliable radiographic marker for rotator cuff tear detection.
• A GTA greater than 70° is highly predictive of rotator cuff lesions.