The Acromioclavicular Joint

  • Ryan J. Warth
  • Peter J. Millett


The subcutaneous location of the acromioclavicular (AC) joint renders inspection and palpation relatively simple when compared to other structures around the shoulder. The recognition of acute AC joint injuries in clinical practice is straightforward; however, the underlying etiology may be more difficult to determine in patients with chronic pain related to the AC joint. This chapter serves to review the anatomy, biomechanics, and characteristic physical examination features common in patients with acute and chronic AC joint pathologies using an evidence-based approach.


Shoulder Acromioclavicular AC joint Coracoclavicular Separation Dislocation Physical exam Clinical exam 


  1. 1.
    Oki S, Matsumura N, Iwamoto W, Ikegami H, Kiriyama Y, Nakamura T, Toyama Y, Nagura T. Acromioclavicular joint ligamentous system contributing to clavicular strut function: a cadaveric study. J Shoulder Elbow Surg. 2013;22(10):1433–9.PubMedCrossRefGoogle Scholar
  2. 2.
    Oki S, Matsumura N, Iwamoto W, Ikegami H, Kiriyama Y, Nakamura T, Toyama Y, Nagura T. The function of the acromioclavicular and coracoclavicular ligaments in shoulder motion: a whole-cadaver study. Am J Sports Med. 2012;40(11):2617–26.PubMedCrossRefGoogle Scholar
  3. 3.
    Branch TP, Burdette HL, Shahriari AS, Carter II FM, Hutton WC. The role of the acromioclavicular ligaments and the effect of distal clavicle resection. Am J Sports Med. 1996;24(3):293–7.PubMedCrossRefGoogle Scholar
  4. 4.
    Ogata S, Uhthoff HK. The early development and ossification of the human clavicle – an embryologic study. Acta Orthop Scand. 1990;61(4):330–4.PubMedCrossRefGoogle Scholar
  5. 5.
    Iannotti JP, Williams GR. Disorders of the shoulder: diagnosis and management. Philadelphia: Lippincott Williams & Wilkins; 1999. p. 765–813.Google Scholar
  6. 6.
    Koch MJ, Wells L. Proximal clavicle physeal fracture with posterior displacement: diagnosis, treatment, and prevention. Orthopedics. 2012;35(1):e108–11.PubMedGoogle Scholar
  7. 7.
    Webb PA, Schuey JM. Epiphyseal union of the anterior iliac crest and medial clavicle in a modern multiracial sample of American males and females. Am J Phys Anthropol. 1985;68:457–66.PubMedCrossRefGoogle Scholar
  8. 8.
    Warner JJP, Beim GM, Higgins L. The treatment of symptomatic os acromiale. J Bone Joint Surg Am. 1998;80(9):1320–6.PubMedGoogle Scholar
  9. 9.
    Yammine K. The prevalence of os acromiale: a systematic review and meta-analysis. Clin Anat. 2014;27(4):610–21.PubMedCrossRefGoogle Scholar
  10. 10.
    Bosworth BM. Complete acromioclavicular dislocation. N Engl J Med. 1949;241(6):221–5.PubMedCrossRefGoogle Scholar
  11. 11.
    O’Brien SJ, Pagnani MJ, Fealy S, McGlynn SR, Wilson JB. The active compression test: a new and effective test for diagnosing labral tears and acromioclavicular joint abnormality. Am J Sports Med. 1998;26(5):610–3.PubMedGoogle Scholar
  12. 12.
    Rios CG, Arciero RA, Mazzocca AD. Anatomy of the clavicle and coracoid process for reconstruction of the coracoclavicular ligaments. Am J Sports Med. 2007;35(5):811–7.PubMedCrossRefGoogle Scholar
  13. 13.
    Colegate-Stone T, Allom R, Singh R, Elias DA, Standring S, Sinha J. Classification of the morphology of the acromioclavicular joint using cadaveric and radiological analysis. J Bone Joint Surg Br. 2010;92(5):743–6.PubMedCrossRefGoogle Scholar
  14. 14.
    DePalma AF. Surgery of the shoulder. 2nd ed. Philadelphia: LB Lippincott; 1973.Google Scholar
  15. 15.
    Urist MR. Complete dislocation of the acromioclavicular joint: the nature of the traumatic lesion and effective methods of treatment with an analysis of 41 cases. J Bone Joint Surg. 1946;28:813–37.PubMedGoogle Scholar
  16. 16.
    Emura K, Arakawa T, Miki A, Terashima T Anatomical observations of the human acromioclavicular joint. Clin Anat. 2014;27(7):1046–52.PubMedCrossRefGoogle Scholar
  17. 17.
    Bontempo NA, Mazzocca AD. Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries. Br J Sports Med. 2010;44(5):361–9.PubMedCrossRefGoogle Scholar
  18. 18.
    Collins DN. Disorders of the acromioclavicular joint. In: Rockwood Jr CA, Matsen 3rd FA, Wirth MA, Lippitt SB, editors. The shoulder, vol. 2. 4th ed. Philadelphia: Saunders; 2009. p. 453–526.Google Scholar
  19. 19.
    Rockwood Jr CA, Williams GR, Young D. Disorders of the acromioclavicular joint. In: Rockwood Jr CA, Matsen F, editors. The Shoulder. Philadelphia: Saunders; 1998. p. 483–553.Google Scholar
  20. 20.
    Heers G, Götz J, Schubert T, Schachner H, Neumaier U, Grifka J, Hedtmann A. MR imaging of the intraarticular disk of the acromioclavicular joint: a comparison with anatomical, histological and in-vivo findings. Skeletal Radiol. 2007;36(1):23–8.PubMedCrossRefGoogle Scholar
  21. 21.
    DePalma AF. The role of the discs of the sternoclavicular and acromioclavicular joints. Clin Orthop Relat Res. 1959;13:7–12.Google Scholar
  22. 22.
    Petersson CJ. Degeneration of the acromioclavicular joint: a morphological study. Acta Orthop Scand. 1983;54(3):434–8.PubMedCrossRefGoogle Scholar
  23. 23.
    Salter Jr EG, Nasca RJ, Shelley BS. Anatomical observations on the acromioclavicular joint and supporting ligaments. Am J Sports Med. 1987;15(3):199–206.PubMedCrossRefGoogle Scholar
  24. 24.
    Stine IA, Vangsness Jr CT. Analysis of the capsule and ligament insertions about the acromioclavicular joint: a cadaveric study. Arthroscopy. 2009;25(9):968–74.PubMedCrossRefGoogle Scholar
  25. 25.
    Corteen DP, Teitge RA. Stabilization of the clavicle after distal resection: a biomechanical study. Am J Sports Med. 2005;33(1):61–7.PubMedCrossRefGoogle Scholar
  26. 26.
    Fukuda K, Craig EV, An KN, Cofield RH, Chao EY. Biomechanical study of the ligamentous system of the acromioclavicular joint. J Bone Joint Surg Am. 1986;68(3):434–40.PubMedGoogle Scholar
  27. 27.
    Klimkiewicz JJ, Williams GR, Sher JS, Karduna A, Des Jardins J, Iannotti JP. The acromioclavicular capsule as a restraint to posterior translation of the clavicle: a biomechanical analysis. J Shoulder Elbow Surg. 1999;8:119–24.PubMedCrossRefGoogle Scholar
  28. 28.
    Lee KW, Debski RE, Chen CH, Woo SL, Fu FH. Functional evaluation of the ligaments at the acromioclavicular joint during anteroposterior and superoinferior translation. Am J Sports Med. 1997;25(6):858–62.PubMedCrossRefGoogle Scholar
  29. 29.
    Debski RE, Parsons II IM, Fenwick J, Vangura A. Ligament mechanics during 3 degree-of-freedom motion at the acromioclavicular joint. Ann Biomed Eng. 2000;28(6):612–8.PubMedCrossRefGoogle Scholar
  30. 30.
    Mazzocca AD, Arciero RA, Bicos J. Evaluation and treatment of acromioclavicular joint injuries. Am J Sports Med. 2007;35(2):316–29.PubMedCrossRefGoogle Scholar
  31. 31.
    Flatow EL. The biomechanics of the acromioclavicular, sternoclavicular, and scapulothoracic joints. Instr Course Lect. 1993;42:237–45.PubMedGoogle Scholar
  32. 32.
    Giphart JE, van der Meijden OA, Millett PJ. The effects of arm elevation on the 3-dimensional acromiohumeral distance: a biplane fluoroscopy study with normative data. J Shoulder Elbow Surg. 2012;21(11):1593–600.PubMedCrossRefGoogle Scholar
  33. 33.
    Inman VT, Saunders JB, Abbott LC. Observations on the function of the shoulder joint. J Bone Joint Surg. 1944;26:1–30.Google Scholar
  34. 34.
    Kennedy JC. Complete dislocation of the acromioclavicular joint: 14 years later. Trauma. 1968;8(3):311–8.Google Scholar
  35. 35.
    Ludewig PM, Phadke V, Braman JP, Hassett DR, Cieminski CJ, LaPrade RF. Motion of the shoulder complex during multiplanar humeral elevation. J Bone Joint Surg Am. 2009;91(2):378–89.PubMedCentralPubMedCrossRefGoogle Scholar
  36. 36.
    Sahara W, Sugamoto K, Murai M, Tanaka H, Yoshikawa H. 3D kinematic analysis of the acromioclavicular joint during arm abduction using vertically open MRI. J Orthop Res. 2006;24(9):1823–31.PubMedCrossRefGoogle Scholar
  37. 37.
    Rashid A, Christofi T, Thomas M. Surgical treatment of physeal injuries of the lateral aspect of the clavicle: a case series. Bone Joint J. 2013;95-B(5):664–7.PubMedCrossRefGoogle Scholar
  38. 38.
    Richards DP, Howard A. Distal clavicle fracture mimicking type IV acromioclavicular joint injury in the skeletally immature athlete. Clin J Sports Med. 2001;11(1):57–9.CrossRefGoogle Scholar
  39. 39.
    Zanca P. Shoulder pain: involvement of the acromioclavicular joint. (Analysis of 1,000 cases). Am J Roentgenol Radium Ther Nucl Med. 1971;112(3):493–506.PubMedCrossRefGoogle Scholar
  40. 40.
    Bearden JM, Hughston JC, Whatley GS. Acromioclavicular dislocation: method of treatment. J Sports Med. 1973;1(4):5–17.PubMedCrossRefGoogle Scholar
  41. 41.
    Tossy JD, Mead NC, Sigmond HM. Acromioclavicular separations: useful and practical classification for treatment. Clin Orthop Relat Res. 1963;28:111–9.PubMedGoogle Scholar
  42. 42.
    Rockwood CA. Injuries to the acromioclavicular joint. In: Rockwood CA, Green DP, editors. Fractures in adults, vol. 1. 2nd ed. Philadelphia: JB Lippincott Co; 1984.Google Scholar
  43. 43.
    Pauly S, Gerhardt C, Haas NP, Scheibel M. Prevalence of concomitant intraarticular lesions in patients treated operatively for high-grade acromioclavicular joint separations. Knee Surg Sports Traumatol Arthrosc. 2009;17(5):513–7.PubMedCrossRefGoogle Scholar
  44. 44.
    Pauly S, Kraus N, Greiner S, Scheibel M. Prevalence and pattern of glenohumeral injuries among acute high-grade acromioclavicular joint instabilities. J Shoulder Elbow Surg. 2013;22(6):760–6.PubMedCrossRefGoogle Scholar
  45. 45.
    Tischer T, Salzmann GM, El-Azab H, Vogt S, Imhoff AB. Incidence of associated injuries with acute acromioclavicular joint dislocations types III through V. Am J Sports Med. 2009;37(1):136–9.PubMedCrossRefGoogle Scholar
  46. 46.
    Canbora KM, Tüzüner T, Yanik SH, Görgeç M. Subcoracoid dislocation of the acromioclavicular joint. Acta Orthop Traumatol Turc. 2011;45(6):463–5.PubMedCrossRefGoogle Scholar
  47. 47.
    Gerber C, Rockwood Jr CA. Subcoracoid dislocation of the lateral end of the clavicle. A report of three cases. J Bone Joint Surg Am. 1987;69(6):924–7.PubMedGoogle Scholar
  48. 48.
    McPhee IB. Inferior dislocation of the outer end of the clavicle. J Trauma. 1980;20(8):709–10.PubMedCrossRefGoogle Scholar
  49. 49.
    Patterson WR. Inferior dislocation of the distal end of the clavicle. A case report. J Bone Joint Surg Am. 1967;49(6):1184–6.PubMedGoogle Scholar
  50. 50.
    Schwarz N, Kuderna H. Inferior acromioclavicular separation. Report of an unusual case. Clin Orthop Relat Res. 1988;234:28–30.PubMedGoogle Scholar
  51. 51.
    Arrigoni P, Brady PC, Zottarelli L, Barth J, Narbona P, Huberty D, Koo SS, Adams CR, Parten P, Denard PJ, Burkhart SS. Associated lesions requiring additional surgical treatment in grade 3 acromioclavicular joint dislocations. Arthroscopy. 2014;30(1):6–10.PubMedCrossRefGoogle Scholar
  52. 52.
    Blazar PE, Iannotti JP, Williams GR. Anteroposterior instability of the distal clavicle after distal clavicle resection. Clin Orthop Relat Res. 1998;348:114–20.PubMedCrossRefGoogle Scholar
  53. 53.
    Simovitch R, Sanders B, Ozbaydar M, Lavery K, Warner JJ. Acromioclavicular joint injuries: diagnosis and management. J Am Acad Orthop Surg. 2009;17(4):207–19.PubMedGoogle Scholar
  54. 54.
    Carbone S, Postacchini R, Gumina S. Scapular dyskinesis and SICK syndrome in patients with a chronic type III acromioclavicular dislocation. Results of rehabilitation. Knee Surg Sports Traumatol Arthrosc. 2014 (in press).Google Scholar
  55. 55.
    Gumina S, Carbone S, Postacchini F. Scapular dyskinesis and SICK scapular syndrome in patients with chronic type III acromioclavicular dislocation. Arthroscopy. 2009;25(1):40–5.PubMedCrossRefGoogle Scholar
  56. 56.
    Murena L, Canton G, Culcano E, Cherubino P. Scapular dyskinesis and SICK scapular syndrome following surgical treatment of type III acute acromioclavicular dislocations. Knee Surg Sports Traumatol Arthrosc. 2013;21(5):1146–50.PubMedCrossRefGoogle Scholar
  57. 57.
    Charron KM, Schepsis AA, Voloshin I. Arthroscopic distal clavicle resection in athletes: a prospective comparison of the direct and indirect approach. Am J Sports Med. 2007;35(1):53–8.PubMedCrossRefGoogle Scholar
  58. 58.
    Kassarjian A, Llopis E, Palmer WE. Distal clavicular osteolysis: MR evidence for subchondral fracture. Skeletal Radiol. 2007;36(1):17–22.PubMedCrossRefGoogle Scholar
  59. 59.
    Schwarzkopf R, Ishak C, Elman M, Gelber J, Strauss DN, Jazrawi LM. Distal clavicular osteolysis: a review of the literature. Bull NYU Hosp Jt Dis. 2008;66(2):94–101.PubMedGoogle Scholar
  60. 60.
    de la Puente R, Boutin RD, Theodorou DJ, Hooper A, Schweitzer M, Resnick D. Post-traumatic and stress-induced osteolysis of the distal clavicle: MR imaging findings in 17 patients. Skeletal Radiol. 1999;28(4):202–8.PubMedCrossRefGoogle Scholar
  61. 61.
    Fiorella D, Helms CA, Speer KP. Increased T2 signal intensity in the distal clavicle: incidence and clinical implications. Skeletal Radiol. 2000;29(12):697–702.PubMedCrossRefGoogle Scholar
  62. 62.
    Patten RM. Atraumatic osteolysis of the distal clavicle: MR findings. J Comput Assist Tomogr. 1995;19(1):92–5.PubMedCrossRefGoogle Scholar
  63. 63.
    Shaffer BS. Painful conditions of the acromioclavicular joint. J Am Acad Orthop Surg. 1999;7(3):176–88.PubMedGoogle Scholar
  64. 64.
    Stein BE, Wiater JM, Pfaff HC, Bigliani LU, Levine WN. Detection of acromioclavicular joint pathology in asymptomatic shoulders with magnetic resonance imaging. J Shoulder Elbow Surg. 2001;10(3):204–8.PubMedCrossRefGoogle Scholar
  65. 65.
    Needell SD, Zlatkin MB, Sher JS, Murphy BJ, Uribe JW. MR imaging of the rotator cuff: peritendinous and bone abnormalities in an asymptomatic population. AJR Am J Roentgenol. 1996;166(4):863–7.PubMedCrossRefGoogle Scholar
  66. 66.
    Mease PJ. Disease-modifying anti-rheumatic drug therapy for spondyloarthropathies: advances in treatment. Curr Opin Rheumatol. 2003;15(3):205–12.PubMedCrossRefGoogle Scholar
  67. 67.
    Day MS, Nam D, Goodman S, Su EP, Figgie M. Psoriatic arthritis. J Am Acad Orthop Surg. 2012;20(1):28–37.PubMedCrossRefGoogle Scholar
  68. 68.
    Huang GS, Bachmann D, Taylor JA, Marcelis S, Haghighi P, Resnick D. Calcium pyrophosphate dehydrate crystal deposition disease and pseudogout of the acromioclavicular joint: radiographic and pathologic features. J Rheumatol. 1993;20(12):2077–82.PubMedGoogle Scholar
  69. 69.
    Parperis K, Carrera G, Baynes K, Mutz A, Dubois M, Cerniglia R, Ryan LM. The prevalence of chondrocalcinosis (CC) of the acromioclavicular (AC) joint on chest radiographs and correlation with calcium pyrophosphate dehydrate (CPPD) crystal deposition disease. Clin Rheumatol. 2013;32(9):1383–6.PubMedCrossRefGoogle Scholar
  70. 70.
    Hong MJ, Kim YD, Ham HD. Acute septic arthritis of the acromioclavicular joint caused by Haemophilus parainfluenzae: a rare causative origin. Clin Rheumatol. 2015;34(4):811–4.Google Scholar
  71. 71.
    Noh KC, Chung KJ, Yu HS, Koh SH, Yoo JH. Arthroscopic treatment of septic arthritis of acromioclavicular joint. Clin Orthop Surg. 2010;2(3):186–90.PubMedCentralPubMedCrossRefGoogle Scholar
  72. 72.
    Hiller AD, Miller JD, Zeller JL. Acromioclavicular joint cyst formation. Clin Anat. 2010;23(2):145–52.PubMedGoogle Scholar
  73. 73.
    Kontakis GM, Karantanas AH, Pasku D, Alpantaki K, Katonis P, Hadjipavlou AG. Delayed diagnosis of a symptomatic osteochondroma of the distal clavicle. Orthopedics. 2006;29(8):734–6.PubMedGoogle Scholar
  74. 74.
    Sugi MT, Fedenko AN, Menendez LR, Allison DC. Clavicular eosinophilic granuloma causing adult shoulder pain. Rare Tumors. 2013;5(1):e8.PubMedCentralPubMedCrossRefGoogle Scholar
  75. 75.
    Walton J, Mahajan S, Paxinos A, Marshall J, Bryant C, Shnier R, Quinn R, Murrell GA. Diagnostic values of tests for acromioclavicular joint pain. J Bone Joint Surg Am. 2004;86-A(4):807–12.PubMedGoogle Scholar
  76. 76.
    Yelland M. A positive result on both the Paxinos test and bone scan ruled in a diagnosis of acromioclavicular joint pain. Evid Based Med. 2005;10(1):27.CrossRefGoogle Scholar
  77. 77.
    McLaughlin HL. On the frozen shoulder. Bull Hosp Joint Dis. 1951;12(2):383–93.PubMedGoogle Scholar
  78. 78.
    Moseley HF. Athletic injuries to the shoulder region. Am J Surg. 1959;98:401–22.PubMedCrossRefGoogle Scholar
  79. 79.
    Maritz NG, Oosthuizen PJ. Diagnostic criteria for acromioclavicular joint pathology. J Bone Joint Surg Br. 2002;78 Suppl 1:78.Google Scholar
  80. 80.
    Chronopoulos E, Kim TK, Park HB, Ashenbrenner D, McFarland EG. Diagnostic value of physical tests for isolated chronic acromioclavicular lesions. Am J Sports Med. 2004;32(3):655–61.PubMedCrossRefGoogle Scholar
  81. 81.
    Jacob AK, Sallay PI. Therapeutic efficacy of corticosteroid injections in the acromioclavicular joint. Biomed Sci Instrum. 1997;34:380–5.PubMedGoogle Scholar
  82. 82.
    Dawson PA, Adamson GJ, Pink MM, Kornswiet M, Lin S, Shankwiler JA, Lee TQ. Relative contribution of acromioclavicular joint capsule and coracoclavicular ligaments to acromioclavicular stability. J Shoulder Elbow Surg. 2009;18(2):237–44.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Ryan J. Warth
    • 1
  • Peter J. Millett
    • 2
  1. 1.Steadman Philippon Research InstituteVailUSA
  2. 2.The Steadman ClinicSteadman Philippon Research InstituteVailUSA

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