副肩峰骨

Overview

• In Thai patients with shoulder problems requiring MRI evaluation, the prevalence of os acromiale was 2.13% [1].
• Os acromiale is associated with rotator cuff injuries [5].
• A multicenter study aimed to determine the prevalence of and factors associated with os acromiale in the Japanese population [6].
• Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes [2].
• Surgical options for symptomatic os acromiale include arthroscopic sub-total excision [16].
• Surgical options for symptomatic os acromiale include arthroscopic subacromial decompression of stable fragments [16].
• Surgical options for symptomatic os acromiale include open reduction and internal fixation of unstable fragments [16].
• Surgical treatment is usually not indicated for os acromiale in the professional tennis player [7].
• Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate [12].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients after reverse total shoulder arthroplasty [3].
• Postoperative local tenderness at the os acromiale resolves spontaneously over time in the majority of patients after reverse total shoulder arthroplasty [3].
• The presence of os acromiale does not appear to have a negative impact on clinical outcomes after reverse total shoulder arthroplasty [4].
• The outcome of reverse total shoulder arthroplasty does not seem to be negatively affected by the presence of an os acromiale [9].

Anatomy & Pathophysiology

• The prevalence of os acromiale in Thai patients with shoulder problems requiring MRI evaluation is 2.13% [1].
• Os acromiale is associated with rotator cuff injuries [5].
• A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site [8].
• Fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting [10].
• Awareness of the os acromiale in the young athlete is crucial to confirm diagnosis through appropriate clinical examination and image studies [11].
• The synchondrosis of an os acromiale can be injured following trauma, though rarely [13].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients after reverse total shoulder arthroplasty [3].
• Postoperative local tenderness at the os acromiale resolves spontaneously over time in the majority of patients [3].
• The presence of os acromiale does not appear to have a negative impact on clinical outcomes after reverse total shoulder arthroplasty [4].
• The outcome of reverse total shoulder arthroplasty does not seem to be negatively affected by the presence of an os acromiale [9].
• Reverse shoulder arthroplasty improves range of motion, decreases pain, and increases patient satisfaction in patients with os acromiale and cuff tear arthropathy [24].
• Surgical treatment is usually not indicated for os acromiale in the professional tennis player [7].

Classification

• The prevalence of os acromiale in Thai patients with shoulder problems requiring MRI evaluation is 2.13% [1].
• Os acromiale is associated with rotator cuff injuries [5].
• A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site [8].
• Fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting [10].
• Awareness of the os acromiale in the young athlete, appropriate clinical examination, and image studies are crucial to confirm diagnosis [11].
• The synchondrosis of an os acromiale can be injured following trauma, though rarely [13].
• Meta-os acromiale is the rarest subtype of os acromiale [15].

Clinical Presentation

• The prevalence of os acromiale in Thai patients with shoulder problems requiring MRI evaluation was 2.13% [1].
• Os acromiale is associated with rotator cuff injuries [5].
• A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site [8].
• The presence of os acromiale does not appear to have a negative impact on clinical outcomes after reverse total shoulder arthroplasty (rTSA) [4].
• The outcome of reverse total shoulder arthroplasty (RTSA) does not seem to be negatively affected by the presence of an os acromiale [9].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients following rTSA [3].
• Postoperative local tenderness at the os acromiale resolves spontaneously over time in the majority of patients [3].
• Surgical treatment is usually not indicated for os acromiale in professional tennis players [7].
• Awareness of the os acromiale, appropriate clinical examination, and image studies are crucial to confirm diagnosis in young athletes [11].
• Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate [12].
• The synchondrosis of an os acromiale can be injured following trauma, though rarely [13].
• Fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting [10].
• Meta-os acromiale is the rarest subtype of os acromiale [15].
• Liberson reviewed 1800 shoulder girdles and identified an incidence of os acromiale of 1.4% [14].
• The lesion of os acromiale is bilateral in 62% of patients according to Liberson's review [14].

Investigations

• The prevalence of os acromiale in Thai patients with shoulder problems requiring MRI evaluation is 2.13% [1].
• Os acromiale is associated with rotator cuff injuries [5].
• A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site [8].
• Awareness of the os acromiale in the young athlete, appropriate clinical examination, and image studies are crucial to confirm diagnosis [11].
• The synchondrosis of an os acromiale can be injured following trauma, though rarely [13].
• Appropriate radiographic investigation for os acromiale injury includes axillary views [13].
• Fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting [10].
• Liberson reviewed 1800 shoulder girdles and identified an incidence of os acromiale of 1.4% [14].
• The lesion of os acromiale is bilateral in 62% of patients according to Liberson's review [14].

Treatment

• Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes [2].
• Surgical options for symptomatic os acromiale include arthroscopic sub-total excision, arthroscopic subacromial decompression of stable fragments, and open reduction and internal fixation of unstable fragments [16].
• Open reduction and internal fixation using cannulated screws or tension band wiring have superior outcomes in the literature in the treatment of symptomatic os acromiale [19].
• A new arthroscopic technique of fixation of os acromiale with absorbable screws provides promising clinical, cosmetic, and radiologic results with high patient satisfaction [17].
• A symptomatic os acromiale in a competitive female fastball pitcher was treated successfully with open reduction and internal fixation [21].
• Special consideration must be given to the type of tension-band construct used to achieve adequate compression and fixation for meta-os acromiale, the rarest subtype of os acromiale [15].
• Surgical treatment is usually not indicated for os acromiale in the professional tennis player [7].
• Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate [12].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients but resolves spontaneously over time in the majority of patients [3].
• The presence of os acromiale does not appear to have a negative impact on the clinical outcomes after reverse total shoulder arthroplasty (rTSA) [4].
• The outcome of reverse total shoulder arthroplasty (RTSA) does not seem to be negatively affected by the presence of an os acromiale [9].

Complications

• The prevalence of os acromiale in Thai patients with shoulder problems requiring MRI evaluation was 2.13% [1].
• Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes [2].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients following reverse total shoulder arthroplasty [3].
• Postoperative local tenderness at the os acromiale resolves spontaneously over time in the majority of patients [3].
• The presence of os acromiale does not appear to have a negative impact on clinical outcomes after reverse total shoulder arthroplasty [4].
• Reverse total shoulder arthroplasty remains a safe and effective treatment option in the presence of os acromiale [4].
• Os acromiale is associated with rotator cuff injuries [5].
• A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site [8].
• Surgical treatment is usually not indicated for os acromiale in professional tennis players [7].
• Fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting [10].
• The incidence of os acromiale identified by Liberson was 1.4% [14].
• The lesion of os acromiale was bilateral in 62% of patients in Liberson's review [14].

Recovery

• Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes [2].
• Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients but resolves spontaneously over time in the majority of patients [3].
• The presence of os acromiale does not appear to have a negative impact on the clinical outcomes after reverse total shoulder arthroplasty (rTSA) [4].
• Reverse total shoulder arthroplasty (rTSA) remains a safe and effective treatment option in patients with os acromiale [4].
• The outcome of reverse total shoulder arthroplasty (RTSA) does not seem to be negatively affected by the presence of an os acromiale [9].
• Surgical treatment is usually not indicated for os acromiale in professional tennis players [7].

Key Evidence

• [L3] In Thai patients with shoulder problems who required MRI evaluation, the prevalence of os acromiale was 2.13%. [1] (10.1177/23259671221078806)
• [L4] Operative management of a symptomatic os acromiale that has failed initial nonoperative treatment leads to decreased symptoms and improvement in clinical outcomes. [2] (10.1016/j.jse.2019.05.047)
• [L3] Postoperative local tenderness at the os acromiale can be expected in 1 out of 4 patients but resolves spontaneously over time in the majority of patients. [3] (10.1177/2325967120965131)
• [L4] The presence of os acromiale does not appear to have a negative impact on the clinical outcomes after surgery and rTSA remains a safe and effective treatment option. [4] (10.1016/j.xrrt.2025.01.002)
• [L3] The study supports previous findings that os acromiale is associated with rotator cuff injuries. [5] (10.1016/j.jseint.2025.05.015)
• [L3] This multicenter study aimed to determine the prevalence of and factors associated with os acromiale in the Japanese population. [6] (10.1016/j.jse.2025.01.008)
• [L4] Surgical treatment is usually not indicated for os acromiale in the professional tennis player. [7] (10.1177/2325967118773723)
• [L4] A tear of the rotator cuff may often be associated with os acromiale, likely due to impingement from abnormal motion at the fibrous union site. [8] (10.2106/00004623-198466080-00029)
• [L4] The outcome of RTSA does not seem to be negatively affected by the presence of an os acromiale. [9] (10.1016/j.jse.2017.02.012)
• [L4] An anatomical study showed that fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting. [10] (10.2106/00004623-200003000-00010)
• [L4] Awareness of the os acromiale in the young athlete, appropriate clinical examination, and image studies are crucial to confirm diagnosis. [11] (10.1016/j.jseint.2020.02.008)
• [L4] Ipsilateral os acromiale may be a relative contraindication to the clavicle hook plate. [12] (10.1186/s12891-021-04841-1)
• [L4] This case highlights that the synchondrosis of an os acromiale can be injured following trauma, though rarely, and emphasizes the need for appropriate radiographic investigation including axillary views and a flexible surgical approach. [13] (10.1016/j.jse.2008.02.012)
• [L4] Meta–os acromiale is the rarest subtype of os acromiale, and special consideration must be given to the type of tension-band construct used to achieve adequate compression and fixation. [15] (10.1177/03635465211028238)
• [L5] Surgical options for symptomatic os acromiale include arthroscopic sub-total excision, arthroscopic subacromial decompression of stable fragments, and open reduction and internal fixation of unstable fragments. [16] (10.5435/jaaos-d-17-00011)
• [L4] This new arthroscopic technique of fixation of os acromiale with absorbable screws provides promising clinical, cosmetic, and radiologic results with high patient satisfaction. [17] (10.1016/j.jse.2011.12.011)
• [L4] Open reduction and internal fixation using cannulated screws, or tension band wiring have superior outcomes in the literature in the treatment of symptomatic os acromiale. [19] (10.1302/2058-5241.4.180100)
• [L4] A symptomatic os acromiale in a competitive female fastball pitcher was treated successfully with open reduction and internal fixation. [21] (10.1177/0363546506288305)
• [L4] Reverse shoulder arthroplasty improved ROM, decreased pain, and increased patient satisfaction in patients with os acromiale and cuff tear arthropathy. [24] (10.5397/cise.2019.00409)

References

[1] Prevalence of Os Acromiale in Thai Patients With Shoulder Problems: A Magnetic Resonance Imaging Study. Orthopaedic Journal of Sports Medicine. 2022. DOI: 10.1177/23259671221078806 [2] Os acromiale: systematic review of surgical outcomes. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2019.05.047 [3] Os Acromiale in Reverse Total Shoulder Arthroplasty: A Cohort Study. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120965131 [4] Clinical implications of reverse total shoulder arthroplasty with an os acromiale: a systematic review. JSES Reviews, Reports, and Techniques. 2025. DOI: 10.1016/j.xrrt.2025.01.002 [5] Prevalence and factors associated with os acromiale: a multicenter study. JSES International. 2025. DOI: 10.1016/j.jseint.2025.05.015 [6] The prevalence and associated factors of os acromiale: a multicenter study. Journal of Shoulder and Elbow Surgery. 2025. DOI: 10.1016/j.jse.2025.01.008 [7] Os Acromiale in Professional Tennis Players. Orthopaedic Journal of Sports Medicine. 2018. DOI: 10.1177/2325967118773723 [8] Rotator cuff tears associated with os acromiale.. The Journal of Bone & Joint Surgery. 1984. DOI: 10.2106/00004623-198466080-00029 [9] Reverse shoulder arthroplasty in patients with os acromiale. Journal of Shoulder and Elbow Surgery. 2017. DOI: 10.1016/j.jse.2017.02.012 [10] Os Acromiale: Frequency, Anatomy, and Clinical Implications. The Journal of Bone and Joint Surgery-American Volume. 2000. DOI: 10.2106/00004623-200003000-00010 [11] The unstable os acromiale: a cause of pain in the young athlete. JSES International. 2020. DOI: 10.1016/j.jseint.2020.02.008 [12] Os acromiale may be a contraindication of the clavicle hook plate: case reports and literature review. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04841-1 [13] Fracture of an os acromiale with associated rupture of the coracoclavicular ligaments. Journal of Shoulder and Elbow Surgery. 2008. DOI: 10.1016/j.jse.2008.02.012 [14] Types of os acromiale according to Liberson. 2006. [15] Rare Symptomatic Meta–Os Acromiale in an Athlete. The American Journal of Sports Medicine. 2021. DOI: 10.1177/03635465211028238 [16] Symptomatic, Unstable Os Acromiale. Journal of the American Academy of Orthopaedic Surgeons. 2018. DOI: 10.5435/jaaos-d-17-00011 [17] Arthroscopically assisted internal fixation of the symptomatic unstable os acromiale with absorbable screws. Journal of Shoulder and Elbow Surgery. 2012. DOI: 10.1016/j.jse.2011.12.011 [19] Os acromiale: a review of its incidence, pathophysiology, and clinical management. EFORT Open Reviews. 2019. DOI: 10.1302/2058-5241.4.180100 [21] Surgical Stabilization of Os Acromiale in a Fast-Pitch Softball Pitcher. The American Journal of Sports Medicine. 2006. DOI: 10.1177/0363546506288305 [24] Reverse shoulder arthroplasty with os acromiale. Clinics in Shoulder and Elbow*. 2020. DOI: 10.5397/cise.2019.00409