Acromioclavicular Joint Pain

What is the Acromioclavicular joint?

• The acromioclavicular (AC) joint is a planar diarthrodial joint located between the acromion of the scapula and the clavicle. It is stabilized by the acromioclavicular and coracoclavicular ligaments, and dynamic stability is provided by the
  deltoid and trapezius muscles [Flores et al, 2020].
• AC joint pain localizes to the top of the shoulder, which is exacerbated by overhead and cross-body activities. This pain is distinct from the diffuse shoulder pain and stiffness seen in glenohumeral (GH) OA.
  
• AC joint pain can coexist with GH OA, complicating the clinical picture [Menge et al, 2014; Mall et al, 2013].
  

What Are the Most Common Acromioclavicular (AC) Joint Conditions?

• AC Osteoarthritis (OA): Osteoarthritis is due to degeneration of the fibrocartilaginous disk within the AC joint, often due to repetitive stress and mechanical load, particularly in middle-aged individuals.
• Distal Clavicle Osteolysis: Osteolysis is a condition where the bone at the end of the collarbone (clavicle) undergoes degeneration and breakdown. Osteolysis is often due to repetitive microtrauma leading to bone resorption at the distal clavicle. Athletes will often present with shoulder pain that localizes to the acromioclavicular (AC) joint, with tenderness to palpation over the joint and exacerbated by specific tests on physical examination.
• Acromioclavicular Joint Sprain: Sprains of the AC joint ligamentous are due to direct trauma to the acromion with the arm adducted, leading to ligamentous damage and joint displacement. Injuries can range from a mild sprain to complete tears of the ligaments.
  

How are Acromioclavicular (AC) Joint Conditions treated?

• AC Osteoarthritis (OA): Initial management can include NSAIDs, acetaminophen, and activity modification. Corticosteroid injections can provide short-term relief.
  
  • If conservative measures fail:
    • Platelet rich plasma (PRP) therapy involves drawing a small amount of the patient's blood, spinning it to separate platelets, and then injecting the concentrated platelet-rich plasma into the affected AC joint. Platelets contain growth factors that potentially reducing pain and inflammation. In a pilot study, 13 patients (16 AC joints) with AC joint arthritis were followed for 8 months and patients experienced significant improvement in pain and function when compared to the pre-injection score [Raja et al, 2020].
    • For persistent symptoms, surgical options such as distal clavicle resection (open or arthroscopic) are considered [Bontempo et al, 2010; Li et al, 2014; Turnbull, 1998; Flores et al, 2020].
• Distal Clavicle Osteolysis: Activity modification is the primary treatment.
  
  • If conservative measures fail:
    • Platelet rich plasma (PRP) therapy is a concentrated solution of a patient's own blood platelets, which contain growth factors. In the case of distal clavicle osteolysis, PRP could potentially stimulate bone regeneration and reduce inflammation, leading to pain relief and improved function, and has been shown to be effective in case reports [Kim & Covey, 2024].
    • The surgical management options for distal clavicle osteolysis primarily include distal clavicle resection, which can be performed using either open or arthroscopic techniques [Simovitch et al, 2009; Frank et al, 2019].
• Acromioclavicular Joint Sprain: Lower grade type I and II sprains are treated with sling immobilization and early functional rehabilitation.
  
  • If the injury is a higher grade sprain then surgical management may be required:
    
    • Type III injuries are controversial, with both non-surgical and surgical options. High-grade injuries (Type IV-VI) usually require surgical intervention for stabilization and repair [Ma et al, 2024; Frank et al, 2019; Bontempo et al, 2010; Li et al, 2014].

References:

1. Bontempo NA, Mazzocca AD. Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries. Br J Sports Med. 2010 Apr;44(5):361-9.
   
2. Flores DV, Goes PK, Gómez CM, Umpire DF, Pathria MN. Imaging of the Acromioclavicular Joint: Anatomy, Function, Pathologic Features, and Treatment. Radiographics. 2020 Sep-Oct;40(5):1355-1382.
3. Frank RM, Cotter EJ, Leroux TS, Romeo AA. Acromioclavicular Joint Injuries: Evidence-based Treatment. J Am Acad Orthop Surg. 2019 Sep 1;27(17):e775-e788.
   
4. Kim AR, Covey CJ. Distal Clavicular Osteolysis Treated With Platelet-Rich Plasma: A Case Report. Clin J Sport Med. 2024 May 1;34(3):310-311.
5. Li X, Ma R, Bedi A, Dines DM, Altchek DW, Dines JS. Management of acromioclavicular joint injuries. J Bone Joint Surg Am. 2014 Jan 1;96(1):73-84.
   
6. Ma Y, Ma Z, Guo J, Ma X, Lv S, Cheng S. Surgical Advances in the Treatment of Acromioclavicular Joint Injury: A Comprehensive Review. Med Sci Monit. 2024 Nov 16;30:e942969.
   
7. Mall NA, Foley E, Chalmers PN, Cole BJ, Romeo AA, Bach BR Jr. Degenerative joint disease of the acromioclavicular joint: a review. Am J Sports Med. 2013 Nov;41(11):2684-92.
   
8. Menge TJ, Boykin RE, Bushnell BD, Byram IR. Acromioclavicular osteoarthritis: a common cause of shoulder pain. South Med J. 2014 May;107(5):324-9.
9. Raja C R, Sudhakar T, Jambukeswaran PST, Ugeneshwaran M, Manivannan AG. PRP in acromio-clavicular jointarthritis – A prospective analysis. IP Int J Orthop Rheumatol 2020;6(2):80-83.
10. Simovitch R, Sanders B, Ozbaydar M, Lavery K, Warner JJ. Acromioclavicular joint injuries: diagnosis and management. J Am Acad Orthop Surg. 2009 Apr;17(4):207-19.
11. Turnbull JR. Acromioclavicular joint disorders. Med Sci Sports Exerc. 1998 Apr;30(4 Suppl):S26-32.