Related Experiment Video
Updated: Jul 29, 2026
10:10
Reverse Total Shoulder Arthroplasty
Published on: July 5, 2011
43.1K
The Critical Shoulder Angle as a Highly Specific Predictor of a Full-Thickness Rotator Cuff Tear: A Case-Control
Erik Gerlach1, Richard W Nicolay1, Rusheel Nayak1
1Department of Orthopaedic Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
The American Journal of Sports Medicine
|October 23, 2024
Summary
The critical shoulder angle (CSA) is significantly larger in patients with rotator cuff tears (RCTs). An increased CSA is an independent risk factor for RCTs, aiding in diagnosis.
Area of Science:
- Orthopedic Surgery
- Radiology
- Biomedical Engineering
Background:
- The critical shoulder angle (CSA) is studied in rotator cuff tears (RCTs).
- Conflicting data exists on CSA's ability to differentiate between normal shoulders and full-thickness RCTs on radiographs.
Purpose of the Study:
- To define the relationship between full-thickness RCTs and CSA.
- Hypothesized that patients with full-thickness RCTs would have an increased CSA compared to controls.
Main Methods:
- Retrospective case-control study of 532 patients (266 RCTs, 266 controls) with MRI-confirmed RCTs.
- Propensity score matching controlled for age, sex, BMI, and tobacco use.
- Two independent observers measured CSAs on anteroposterior shoulder radiographs.
Main Results:
- Mean CSA was 33.6°± 4.2° for the cohort.
- Mean CSA for RCT group (36.2°± 3.3°) was significantly higher than control group (30.9°± 3.3°).
- CSA ≥35° showed 67.7% sensitivity and 89.4% specificity for full-thickness RCTs (AUC=0.88).
Conclusions:
- Patients with RCTs have significantly higher CSAs.
- Increased CSA is an independent risk factor for RCTs (OR=1.7 per degree).
- CSA is an accurate, simple, and reproducible measurement aiding clinical decision-making for full-thickness RCTs.
