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Wheeless' Textbook of Orthopaedics

Acromioclavicular Joint

- Discussion: 
   - AC joint is situated between the clavicle and acromion; 
   - acromion has two ossification centers which fuse at age 22 yrs; 
   - it permits motion in three planes:
           - AP gliding of acromion during protraction & retraction of scapula;
           - tilting of acromion during abduction & adduction of arm;
           - rotation of the clavicle;
           - rotation occurs during abduction & adduction of shoulder.

- Anatomy: 
    - innervation: provided by the suprascapular and lateral pectoral nerves
    - joint is reinforced by two sets of ligaments:
         - AC ligament
                - directed horizontally, and functionally the AC joints control horizontal stability;
                - palpable shallow depression between end of clavicle & acromion;
                - superior AC lig is most important ligament in stabilizing AC joint for normal daily activities;
         - coracoclavicular ligaments:
                - stronger, vertically directed contains conoid and trapezoid ligaments help to control vertical stability;
                - coracoclavicular lig are suspensory ligaments of upper limb;
                - conoid:
                        - is the most important ligament for support of the joint against significant injuries and superior displacement;
                        - cone shaped which extends between the conoid tubercle on the posterior clavicle and the base of the coracoid;
                - trapezoid:
                        - resists AC joint compression;
                        - begins anteriorly and laterally to the conoid ligament on the clavicle and inserts on the coracoid process; 
         - references: Biomechanical study of the ligamentous system of the acromioclavicular joint. 

    - Sternoclavicular joint:
         - see S.C. joint injury in the adolescent;
         - inherently more stable than AC joint;
         - because of this stability & its more protected medial location;
         - it is injured less frequently than the acromioclavicular joint.



- Radiology:
    - classification of AC separation:
    - acromioclavicular joint stresses views
          - type I and type II injuries can be differentiated on stress radiographs;
          - w/ pt standing, 10 lb weight is secured to affected upper limb;
          - w/ grade II injury, suspended  wt displaces AC joint articulation, which increases distance between clavicle & acromion;
                 - grade I injuries remain nondisplaced;
    - zanca view
    - scapular outlet view
    - references: Radiological evaluation of the acromioclavicular joint. 


- Exam:
    - palpate the AC joint during flexion and extension of shoulder;
    - distract the arm as it is placed in adduction;
         - significant prominence of the distal clavicle indicates type V injury;
         


- Management of Specific Injuries:
    - AC joint arthrosis / distal clavicle excision 
          - The influence of distal clavicle resection and rotator cuff repair on the effectiveness of anterior acromioplasty. 
    - AC joint septic arthritis:
         - Septic arthritis of the acromioclavicular joint - a report of four cases
         - Septic arthritis of the acromioclavicular joint.
         - Sonographic detection, evaluation and aspiration of infected acromioclavicular joints.
         - Primary septic arthritis of the acromio-clavicular joint: case report and review of literature  

- AC Joint Separation: 
       - non operative treatment:
               - in the report by TF Schlegel MD et al, the authors prospectively studied natural history of untreated acute grade III  AC  separations;
               - 25 patients were treated nonoperatively with a sling for comfort through progressive early range of motion as tolerated;
               - 10 additional uninjured subjects underwent strength testing to evaluate difference between dominant and nondominant sides;
               - one patient underwent a surgical procedure at 2 weeks after injury because of cosmetic concerns;
               - 20 of the 25 patients completed the 1-year evaluation and strength-testing protocol;
               - 4 of the 20 patients (20%) thought that their long-term outcome was suboptimal, although for 3 of them it was not enough to warrant surgery;
               - testing of the 20 patients revealed no limitation of shoulder motion in injured extremity and no diff between sides in rotational shoulder muscle strength;
               - bench press was the only strength test that showed a significant short-term difference, with the injured extremity being an average of 17% weaker;
               - ref: A Prospective Evaluation of Untreated Acute Grade III AC Separations.  TF Schlegel MD. Am Jour of Sports Med 29:699-703 (2001) 

       - operative treatment:
                 - surgical precautions:
                       - attempt to keep fixation over the anterior third of the clavicle (avoid more anterior translation);
                       - consider some technique to defray pressure over the clavicle (endo button, plate ect) to avoid cut through;

                       - Surgery about the coracoid: neurovascular structures at risk. 

                 - reconstruction w/o tendon graft:
                       - consider a direct verticle suture limb(s) and a second suture limb running more lateral to engage the latera edge
                               of the clavicle (to reproduce the trapezoid ligament);

                          - Technique of Reconstruction for Complete Acromioclavicular Dislocation. A Prospective Study. 
                          - Stability of acromioclavicular joint reconstruction: biomechanical testing of various surgical techniques in a cadaveric model.
                           - A cadaveric study examining acromioclavicular joint congruity after different methods of coracoclavicular loop repair.
                           - Consistency of long-term outcome of acute Rockwood grade III acromioclavicular joint separations after K-wire transfixation.
                           - Mid-term outcome comparing temporary K-wire fixation versus PDS augmentation of Rockwood grade III acromioclavicular joint separations.           
                           - Treatment of Tossy III acromioclavicular joint injuries using hook plates and ligament suture.

                 - reconstruction with tendon graft:
                           - Reconstruction of the Coracoclavicular Ligaments with Tendon Grafts. A Comparative Biomechanical Study. 
                           - AC joint dislocation: A comparative study of palmaris-longus tendon graft reconstruction with other augmentative methods in cadaveric models.
                           - Anatomical acromioclavicular ligament reconstruction: a biomechanical comparison of reconstructive techniques of the acromioclavicular joint.
                           - Clinical outcomes of coracoclavicular ligament reconstructions using tendon grafts.
                           - Acromioclavicular joint reconstruction using peroneus brevis tendon allograft.





                              


                 - modified weaver dunn procedure: (for chronic injuries) 



The acromioclavicular joint in rheumatoid arthritis.

Osteolysis of the distal part of the clavicle in male athletes. 

Arroscopic distal clavicle excision. Technique and early results. 




      

 




Original Text by Clifford R. Wheeless, III, MD.

Last updated by Clifford R. Wheeless, III, MD on Tuesday, October 27, 2009 10:13 am