A grade III AC joint separation is characterized by complete disruption of the AC and coracoclavicular ligaments (coronoid and trapezoid ligaments). The injury is often obvious with 25% to 100% displacement of the distal clavicle, which can be seen tenting the skin. The AC ligaments provide support with horizontal shoulder motion and anterior-posterior stability. The coracoclavicular ligaments provide restraint against cephalad migration of the clavicle.

Most grade III AC joint separation injuries can be treated without surgery despite the obvious deformities of the shoulder. In general, most patients will have good functional recovery without loss of strength or motion long term. Competitive athletes and heavy laborers have also been shown to have comparable results both with and without surgery. Outcomes of nonsurgical treatment largely depend on participation in physical therapy to regain strength and motion. Surgical reconstruction may offer high-level throwing athletes some benefit as these patients were found to have an altered throwing motion without surgery. Loss of AC stability is thought to decrease the stability of the scapula and subsequently weaken the shoulder girdle. With that said, current literature overwhelmingly supports nonoperative treatment in most, if not all, patients with a grade III AC joint separation.1,2

Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).

References

  1. Virk MS, Apostolakos J, Cote MP, Baker B, Beitzel K, Mazzocca AD.  Operative and nonoperative treatment of acromioclavicular dislocation: a critical analysis review. JBJS Rev. 2015;3(10).
  2. Bassett A, Farmer K. Acromio-clavicular injuries (AC separation). Available at: https://www.orthobullets.com/shoulder-and-elbow/3047/acromio-clavicular-injuries-ac-separation. Accessed September 25, 2018.
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