Acromial Morphology: Reliability of CT-based Assessment and Relationship With Age in a Series of 420 Patients

This is a retrospective monocentric observational study conducted at Strasbourg University Hospitals including 420 patients who underwent shoulder CT or arthro-CT between 2009 and 2023. Acromial morphology is assessed using the Bigliani classification on 3D reconstructions. The study evaluates intra- and inter-observer reliability using kappa coefficients and explores the relationship between acromial shape and patient age. Data are collected retrospectively from medical records and imaging software, with repeated assessments performed at 3 and 6 months to evaluate reproducibility.

Primary outcomes

• Intra-Rater and Inter-Rater Reliability of the Bigliani Classification of Acromial Morphology [Initial assessment, with repeat assessments at 3 and 6 months after the initial assessment.]: Acromial morphology will be classified as Type I (flat), Type II (curved), or Type III (hooked) according to the Bigliani classification, using 3D-reconstructed shoulder CT scans or CT arthrography images. Intra-rater and inter-rater reliability will be assessed using kappa agreement coefficients (Cohen's kappa and Fleiss' kappa). Five evaluators will assess the images, with repeat evaluations at 3 and 6 months after the initial assessment.

Sex: All, ages: 20 Years to 98 Years

Inclusion Criteria:

* Subjects aged 20 to 89 years
* Shoulder CT or arthro-CT performed at Strasbourg University Hospitals
* Examination performed between 02/01/2009 and 11/12/2023
* Independent indication for imaging
* No documented opposition to reuse of medical data for research

Exclusion Criteria:

* Imaging not performed
* Poor image quality
* Inability to perform 3D reconstruction
* Duplicate examination within the same age group
* History of acromial fracture
* Previous surgery interfering with acromial analysis (arthroplasty, acromioplasty, osteosynthesis, arthrodesis)
* Shoulder pathology interfering with acromial analysis (severe acromioclavicular arthropathy, humeral head osteonecrosis, glenohumeral dysplasia)