Correlation of Acromial Morphology With Risk and Direction of Shoulder Instability: An MRI Study.

BACKGROUND

The influence of bony morphology on the development of posterior shoulder instability is not well known.

PURPOSE

To determine if acromial morphology, as measured on magnetic resonance imaging (MRI), is associated with posterior or anterior shoulder instability.

DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

MRI measurements of posterior acromial coverage (PAC), posterior acromial height (PAH), posterior acromial tilt (PAT), and anterior acromial coverage (AAC) were completed for 3 separate matched groups who underwent surgical intervention: posterior instability, anterior instability, and a comparison group of patients who underwent arthroscopic surgery for snapping scapula. Inclusion criteria were patients with recurrent instability <40 years of age without multidirectional instability, glenoid bone loss >13.5%, or glenoid retroversion >10%.

RESULTS

Overall, 37 patients were included in each group. PAC was significantly less in the posterior instability group than in the anterior instability and comparison groups (68.3° vs 88.7° vs 81.7°;

CONCLUSION

A higher and flatter posterior acromion, as measured on preoperative MRI, appears to be associated with patients who require arthroscopic capsulolabral repair due to posterior shoulder instability. This information may help clinicians to both diagnose and predict the need for operative intervention for patients with posterior labral tears.

Déclaration de conflit d'intérêts

One or more of the authors has declared the following potential conflict of interest or source of funding: J.W.A. has received research support from Arthrex and DJO and hospitality payments from Mid-Atlantic Surgical Systems and Smith & Nephew. P.-C.N. has received support for education from Arthrex. M.T.P. has received consulting fees and royalties from Arthrex, consulting fees and honoraria from Joint Restoration Foundation Inc, consulting fees from Zimmer Biomet Holdings, honoraria from Flexion Therapeutics Inc, and royalties or license from Arthrosurface Inc and Anika Therapeutics. J.P.B. has received royalties and consulting fees from Arthrex and DJO. P.J.M. has received consulting fees and royalties from Arthrex. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.