SHOULDER INJURY – AC JOINT
Acromioclavicular (AC) joint injury is a source of
significant morbidity for individuals, especially for athletes in over-head sports. The AC joint is a diarthrodial joint, only 1 of the 5 joints that make up the complex arrangement of the shoulder. Together with the sternoclavicular joint, the AC joint provides the upper extremity with a connection to the axial skeleton.
Injury to the ACJ can easily mimic other shoulder conditions so we must understand the anatomy and biomechanics of the shoulder in order to perform a systematic clinical evaluation and identify the injury.
Careful clinical evaluation allows the clinician to categorize the individual’s AC joint injury and institute appropriate treatment in a timely fashion. This will assist in getting the patient back to sport or life in a more timely and fully functional manner.
“Codman observed that AC joint motion was minimal and generally equivalent to the pliability of the ligaments. He noted that the AC joint “swings a little, rocks a little, twists a little, slides a little, and acts like a hinge”
“Rockwood described a synchronous, 3-dimensional linkage of clavicular and scapular rotation: the clavicle does rotate, but the scapula rotates with it, so that there is very little relative motion of the clavicle and scapula. Thus, most scapulothoracic motion occurs through the sternoclavicular joint. The clinical significance of this is that AC fixation may be rigid without necessarily producing an obligate loss of shoulder motion.”
Direct injury to the AC joint most commonly occurs as a result of straight force produced by the patient falling on the point of the shoulder onto the ground with arm in adducted orientation. The most common events associated with AC injuries include contact sports such as hockey and football. “Webb and Bannister noted a 45% incidence of AC injuries in first-class rugby players, and most did well with conservative treatment. The direct force of striking the point of the shoulder drives the acromion downward.”
“Indirect forces to the AC joint may also be responsible for injury. An upward force to the AC joint can occur from a fall on an outstretched hand transmitting up the arm through the humeral head into the acromion process. The strain is referred only to the AC ligaments and not to the coracoclavicular ligaments, thus producing isolated AC joint injury. A downward force by a pull through the upper extremity while carrying a heavy load may also cause AC joint injury; however, this is a very uncommon mechanism.”
TYPE I: Sling for 5 to 7 days, Ice for 48 to 72 hours, NSAIDS may be recommended. Immediate Isometric and gentle ROM encouraged. A more structured therapeutic program in a skilled PT clinic should be initiated as soon as symptoms begin to resolve. Most patients will return to full activities within 2 weeks.
TYPE II: Essentially the same as Type I with more extensive approach. Sling for 1-2 weeks, Ice for 48 to 72 hours, NSAIDS may be recommended. Immediate Isometric and gentle ROM encouraged. A more structured therapeutic program in a skilled PT clinic should be initiated as soon as symptoms begin to resolve. Most patients will return to full activities within 2-3 weeks. If these patients develop symptoms unresponsive to conservative management, they may do quite well with an arthroscopic or open distal clavicle resection based on research findings.
TYPE III: Commonly treated non-operatively except for the elite throwing athlete in whom the extremes of motion and biomechanics loads placed on the shoulder at high levels may cause substantial difference in performance. Essentially the same treatment as Type I and II such as sling, ice and NSAIDS until symptoms subside then isometric and gentle ROM encouraged within 1-2 weeks. A more structured therapeutic program in a skilled PT clinic should be initiated as soon as symptoms begin to resolve. Devices designed to reduce the AC joint are not recommended currently. Hughston and colleagues (J.C. Hughston, MD, unpublished data, 1999) have advocated early operative repair of type III AC dislocations. They have had excellent clinical results with this form of treatment and feel that restoration of normal anatomy is essential for a good functional result, especially in the contact athlete.
TYPES IV, V, VI: Most surgeons recommend early surgical treatment for type IV, V, and VI AC dislocations. A wide variety of operative procedures have been recommended for the open treatment of both acute and chronic complete AC dislocations.
Wright Physical Therapy DPTs train every week, month and quarter through our Joint Spine Sport University to ensure cohesive alignment with physician diagnosis and to ensure proper treatment is administered to your patients. Please call Bryan at 208-736-2574 or email firstname.lastname@example.org if you have any questions.
Content adapted from Journal of Athletic Training 2000;35(3);261-267 Gloria M Beim MD