Understanding Acromial Stress Fractures After Reverse Shoulder Arthroplasty: Insights from Recent Research

Wiemer et al. Acromial stress fractures and reactions after reverse total shoulder arthroplasty: a case-control study¹

Reverse total shoulder arthroplasty (rTSA) has revolutionized the management of complex shoulder pathologies, offering excellent pain relief and restoring function for diverse patient populations. Its success is highlighted by its usage compared to anatomic shoulder replacements as its indications have greatly expanded.² Yet, as its popularity grows, representing 70% of all total shoulder arthroplasties,³ so too does the need to address rare but significant complications. One of the most challenging to treat is the acromial stress fracture (ASF), which can profoundly impact patient satisfaction and long-term outcomes. While our understanding of this pathology has significantly increased over the past decade, there is still much yet to be understood including patient and implant risk factors, treatment modalities, non-operative and post-operative management, etc.

Study Spotlight: Incidence and Risk Factors for ASF

A new case-control study published in the Journal of Shoulder and Elbow Surgery by Wiemer and colleagues brings important clarity to this topic. Assessing 220 rTSA patients at a single Australian center, the authors found that acromial stress fractures or reactions (ASF/ASR) occurred in 11% of cases—a higher rate than previously reported in multicenter reviews.⁴

What’s driving this elevated risk? The study identified two key, independent risk factors:

• Corticosteroid Use: Patients on oral corticosteroids (often for systemic conditions like rheumatoid arthritis) were nearly 10 times more likely to develop ASF/ASR.
• Previous Shoulder Surgery: Prior procedures—especially arthroscopic rotator cuff repairs with acromioplasty—raised the risk over sevenfold.

Notably, most fractures occurred spontaneously, especially in female patients, while a minority followed minor trauma. Advanced imaging (including SPECT-CT) allowed early identification of stress reactions before progression to displaced fractures, pointing toward the value of modern diagnostics for personalized management.

Why ASF Matters: Impact on Patient Outcomes

Functionally, patients who experienced ASF/ASR saw significantly worse outcomes at follow-up compared to matched controls:

• American Shoulder and Elbow Surgeons (ASES) scores were lower.
• Higher pain and disability indexes (SPADI, DASH).
• Reduced forward elevation and internal rotation.

These findings reinforce the need for vigilant follow-up and innovative solutions to improve implant longevity and consistently deliver the clinical results patients demand.

The Inlay vs. Onlay Debate: What Does the Data Show?

There is considerable debate whether implant design—specifically “inlay” vs “onlay” humeral components—plays a role in ASF risk. Drawing from a larger analysis of over 3,000 rTSA procedures across multiple institutions, Marigi et al. explored this exact question in another recent publication. They found no significant association between humeral component style and fracture rates, suggesting that other patient- or technique-specific factors take precedence when it comes to ASF prevention.⁵

Moving Forward: Surgical Practice and Implant Innovation

While not all risk factors are modifiable, these studies empower clinicians to better preoperatively counsel patients at elevated risk (e.g., chronic steroid use or prior shoulder surgery) and plan for proactive postoperative surveillance. For implant manufacturers, such research can inform ongoing innovation, whether through refined biomechanical testing, enhanced fixation methods, or next-generation materials.

The challenge of acromial stress fracture may persist, but with research-driven insights, industry partnership, and surgical collaboration, the orthopedic community is poised to further improve outcomes in reverse shoulder arthroplasty.

References:

1. Wiemer F, Coghlan JA, Bell SN. Acromial stress fractures and reactions after reverse total shoulder arthroplasty: a case-control study. J Shoulder Elbow Surg. 2025;34:1897–1903.
2. Best MJ, Aziz KT, Wilckens JH, McFarland EG, Srikumaran U. Increasing incidence of primary reverse and anatomic total shoulder arthroplasty in the United States. J Shoulder Elbow Surg. 2021 May;30(5):1159-1166. doi: 10.1016/j.jse.2020.08.010. Epub 2020 Aug 26. PMID: 32858194.
3. Australian Orthopaedic Association National Joint Replacement Registry 2023 Annual Report. p306. Available at: https://aoanjrr.sahmri.com/documents/10180/1579982/AOA_NJRR_AR23.pdf.
4. Moverman MA, Puzzitiello RN, Glass EA, Swanson DP, Efremov K, Lohre R, Bowler AR, Mahendraraj KA, Le K, Dunn WR, Cannon DJ, Friedman LGM, Gaudette JA, Green J, Grobaty L, Gutman M, Kakalecik J, Kloby MA, Konrade EN, Knack MC, Loveland A, Mathew JI, Myhre L, Nyfeler J, Parsell DE, Pazik M, Polisetty TS, Ponnuru P, Smith KM, Sprengel KA, Thakar O, Turnbull L, Vaughan A, Wheelwright JC, Abboud J, Armstrong A, Austin L, Brolin T, Entezari V, Garrigues GE, Grawe B, Gulotta LV, Hobgood R, Horneff JG, Hsu JE, Iannotti J, Khazzam M, King JJ, Kirsch JM, Levy JC, Murthi A, Namdari S, Nicholson GP, Otto RJ, Ricchetti ET, Tashjian R, Throckmorton T, Wright T, Jawa A; ASES Complications of RSA Multicenter Research Group. Implant-Positioning and Patient Factors Associated with Acromial and Scapular Spine Fractures After Reverse Shoulder Arthroplasty: A Study by the ASES Complications of RSA Multicenter Research Group. J Bone Joint Surg Am. 2024 Aug 7;106(15):1384-1394. doi: 10.2106/JBJS.23.01203. Epub 2024 Jun 5. PMID: 40305832.
5. Marigi E et al. Acromial and scapular fractures after reverse shoulder arthroplasty: comparison of 3018 reverse total shoulders by inlay and onlay humeral component design. J Shoulder Elbow Surg. 2024.