Os Acromiale in Reverse Total Shoulder Arthroplasty: A Cohort Study

Area of Science:

• Orthopedic Surgery
• Shoulder Arthroplasty
• Biomedical Engineering

Background:

• Increased passive deltoid tension post-reverse total shoulder arthroplasty (RTSA) may cause os acromiale displacement.
• Os acromiale presence can complicate RTSA outcomes.

Purpose of the Study:

• To compare outcomes and complications in RTSA patients with and without os acromiale.
• To analyze the impact of os acromiale on RTSA success.

Main Methods:

• A matched cohort study (Level 3 evidence) comparing 45 RTSA patients with os acromiale to 133 controls.
• Mean follow-up of 52 months, assessing Constant Score (CS), Subjective Shoulder Value (SSV), and radiological outcomes.
• Matching criteria included sex, surgery type, follow-up duration, and age.

Main Results:

• Both groups showed significant improvement in CS, SSV, and range of motion post-RTSA.
• Patients with os acromiale had comparable CS and SSV but significantly reduced active flexion at 1 year and abduction at 2 years.
• Postoperative os acromiale tenderness occurred in 27% of cases, resolving spontaneously in most.

Conclusions:

• RTSA provides reliable patient satisfaction irrespective of os acromiale presence, with minor range of motion deficits.
• Postoperative tenderness at the os acromiale is common but generally self-limiting.
• Os acromiale should be considered in RTSA planning, but does not preclude successful outcomes.