Everything You Need to Know About Acromioclavicular Joint Sprain
What is an AC Joint Sprain?
The term "acromioclavicular sprain" describes damage to one or more of the joint stabilizing ligaments to the joint which is at the junction of the collar bone and the shoulder blade. Acromioclavicular (AC) joint injuries are the most common reason for medical consult following an acute shoulder injury, yet remain a frequently overlooked problem due to diagnostic bias toward other shoulder problems.
AC joint injuries including Acromioclavicular joint sprain are responsible for 40-50% of all athletic shoulder injuries. Injuries are common in adolescents and young adults who participate in contact sports, such as rugby, hockey, football, and wrestling. The peak incidence of injury occurs in the second through fourth decade of life. Males are affected five times more often than females.
AC joint injuries most commonly occur following a fall onto the point of the shoulder with the arm in a crossbody or outstretched position. This direct force shears the joint causing one aspect to shift down as one stays elevated. Seat belt injuries during automobile accidents are another possible mechanism of AC joint sprain. It is crucial to seek proper AC Joint Injury Treatment to prevent further damage and facilitate a speedy recovery.
In general, ligamentous sprains may be graded based upon the degree of tissue damage: Grade 1 (mild strain with no fiber disruption), Grade 2 (partial fiber disruption), and Grade 3 (complete ligamentous rupture). In contrast, AC joint injuries are categorized based upon the following Rockwood classification:
Type I – mild, unseparated sprain of the AC ligaments with no disruption of the coracoclavicular ligaments.
Type II – complete disruption of the AC ligaments with joint separation (less than 4 mm or 40% difference) and sprained but intact coracoclavicular ligaments.
Type III – complete disruption of AC and coracoclavicular ligaments with joint separation and inferior displacement of the shoulder complex is commonly known as an AC joint sprain.
Type IV – complete disruption of AC and coracoclavicular ligaments with posterior displacement of the clavicle through the fibers of the trapezius, and detachment of deltoid and trapezius muscles from the distal clavicle.
Type V – complete disruption of the AC and coracoclavicular ligaments with significant inferior displacement of the shoulder complex from the clavicle as compared to a typical Type III injury.
Type VI – AC Joint Injury Treatment is necessary in cases where complete disruption of the AC and coracoclavicular ligaments, and the clavicle has dislocated inferiorly, below the coracoid process.
Radiographs of the shoulder are warranted in cases of trauma or significant clavicular displacement.
What Will an AC Joint Sprain Look and Feel Like?
The classic presentation involves pain and swelling on the upper aspect of the shoulder following acute trauma. Initially, symptoms are often generalized and widespread to the entire shoulder region but become progressively more localized to the AC joint as acute swelling improves. Symptoms may intensify with specific movements, including bench pressing, dips, or when the patient rolls onto the affected side at night.
Depending upon the severity of injury, one may demonstrate swelling, bruising, or a pronounced abnormality at the collar bone. Significant prominence at the end of the collar bone suggests at least a Type III injury Treatment. Marked prominence could also insinuate clavicular fracture. Range of motion testing will be painful and limited, particularly in raising the arm out to the side or across the body.
How Do We Treat an AC Joint Sprain?
AC joint injuries result in sport-specific disabilities, ranging from 10-64 days with an average of 18 days lost to sport. Grade I & II AC joint injuries treatment should be managed non-operatively through a succession of protection, immobilization, mobility, and strengthening. Protection of the AC joint via sling immobilization for 3-10 days may be appropriate. For Grade I & II injuries, sling use should be dictated by pain and discontinued when symptoms are manageable.
Under the guidance of a physical therapist, passive mobility exercises for Acromioclavicular Joint Sprain should be initiated early and gradually progress into full active ROM. Early on, patients should use caution in movements that increase stress on the AC joint, including reaching behind the back, cross-body reaching, and forward elevation. Long-term range of motion deficits are generally not associated with mild AC joint separations. When >90% of joint mobility is restored, strengthening will begin to take place with the goal of maximizing dynamic stability of the AC joint and return the patient to their prior level of activity.
Regarding Type III injuries, including AC joint sprain, there is a shift away from surgery toward conservative management. A large systematic literature review finds support for non-operative management over surgical intervention. 80% of orthopedic program residency directors opt for conservative management of Grade 3-type injuries. Conservative management is even more appealing considering potential complications associated with surgery. (37)
Rehab progression of AC joint injury treatment Type III injuries follows a similar pattern to a standard of care for Type I & II injuries. Immobilization is used solely to control symptoms, as there is no potential for ligamentous repair. Rehab begins with mobility and progresses to functional training. Type III injuries may require 6-12 weeks of conservative care to restore function.
If you have been suffering with an AC joint sprain or shoulder pain, schedule an appointment today to see how our doctors can help!