AC Joint sprain
The term, “acromioclavicular sprain” describes damage to one or more of the acromioclavicular joint stabilizing ligaments- leading to pain, instability, and/or separation. (1) Acromioclavicular (AC) joint injuries are the most common reason for medical consult following an acute shoulder injury, yet remain a frequently overlooked. (1,2) The AC joint is the junction between the clavicle and acromion process of the scapula. The normal joint width varies from 1-3 mm in young adults, narrowing to less than 0.5 mm in seniors(3). The joint is held together by a thin capsule and four ligaments (3,4). AC joint injuries may involve any or all of the ligaments.
How are AC joint sprains categorized?
AC joint sprains are defined by type, with I being the most mild and VI being the most severe:
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.
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 – complete disruption of the AC and coracoclavicular ligaments, and the clavicle has dislocated inferiorly, below the coracoid process.
What percentage of shoulder injuries involve the AC joint?
AC joint injuries are responsible for 40-50% of all athletic shoulder injuries (7).
Who most commonly gets AC joint injuries?
Injuries are common in adolescents and young adults who participate in contact sports, such as rugby, hockey, football, and wrestling (7,8). The peak incidence of injury occurs in the second through fourth decade of life (1,7). Males are affected five times more often than females. (7)
How do AC joint injuries occur?
AC joint injuries most commonly occur following a fall onto the point of the shoulder with the arm at the side (42,43,44). This direct force to the acromion shears the acromion inferiorly in relation to the clavicle. Another often reported mechanism of injury involves a fall onto an outstretched hand (FOOSH) (9,10,42,43,44). Seat belt injuries during automobile accidents are another possible mechanism of AC sprain. (11)
Symptoms of AC joint sprain:
The classic clinical presentation involves pain and swelling on the superior aspect of the shoulder following acute trauma (12). Initially, symptoms are often generalized to the trapezius and entire shoulder region but become more localized to the AC joint as acute swelling improves (12). Symptoms may intensify with specific movements, including bench pressing, dips, or when the patient rolls onto the affected side at night (3,12).
Signs of AC joint injury:
AC point tenderness demonstrates high sensitivity for AC involvement (14). Palpation of the distal clavicle may demonstrate a feeling of “giving way” (Piano key sign). Significant distal clavicle prominence suggests a Type III type injury. Range of motion testing will be painful and limited, particularly in abduction.
Is imaging necessary or recommended for AC joint sprains?
X-rays of the shoulder are warranted in cases of trauma or significant clavicular displacement. The detail provided by an MRI is often unnecessary for the assessment of AC joint injuries, although an MRI may be appropriate for differentiation of rotator cuff lesions (15).
Are slings recommended for AC joint injuries?
This depends on severity of the injury. Generallly speaking, immobilization for 3-10 days may be appropriate (18). Grade I & II AC joint injuries should be managed non-operatively through a succession of protection, immobilization, mobility, and strengthening (12,18-24). Sling use should be dictated by pain and discontinued when symptoms are manageable (25).
Should I be cautious with certain movements with an AC joint injury?
Patients should use caution in movements that increase stress on the AC joint, including behind the back internal rotation, cross-body adduction, and forward elevation (27). These movements are not expressly prohibited but should be approached with caution and performed within the patient’s pain tolerance (27).
Is the AC joint important?
Although often underappreciated, the AC joint is a “keystone” link for normal coordinated movement of the shoulder girdle (33). Normal elevation of the arm requires 30-40 degrees of clavicular elevation, and any dysfunction involving the clavicle or scapula may lead to secondary problems, like impingement or rotator cuff strain (34).
Do I need surgery to repair the AC joint?
There is a shift away from surgery toward conservative management in type III and below AC joint injuries (34). A large systematic literature review finds support for non-operative management over surgical intervention (36). 80% of orthopedic program residency directors opt for conservative management of Grade 3-type injuries. (5) Conservative management is even more appealing considering potential complications associated with surgery (37). Surgical consultation should be considered for patients with Type II-III injuries who do not respond to a six-week trial of conservative care and for all Type IV-VI injuries (41) Patients with separations above Type II are sometimes surprised by the level of permanent aesthetic deformation. Surgery for low-grade injury is indicated after a minimum of six months of failed conservative care (40).
What are my treatment options?
Conservative care generally takes 6-12 weeks to recover an AC joint injury.
NSAIDs may provide palliative benefit.
Clinicians will address concurrent biomechanical issues, including joint manipulation to restrictions in the cervical, thoracic, glenohumeral,and sternoclavicular joints. Focus on correction of postural deficits, particularly scapular dyskinesis and upper crossed syndrome have been helpful.
Passive mobility exercises should be initiated early and gradually progress into full active ROM.
Muscle strengthening is beneficial for AC joint sprains. The goal of strengthening is to maximize dynamic stability of the AC joint and return the patient to their prior level of activity (18). Strength training should begin with closed chain scapular stabilization exercises, progressing to isotonic strengthening, and eventually sport-specific training. Pain tolerance should dictate progression during the flexibility and strengthening phases of care (27).
AC joint injections may be appropriate for stable joints with recalcitrant pain. (39).
Steroid injections do not however, alter the natural progression of AC injury. (40)
At Creekside Chiropractic & Performance Center, we are highly trained to treat AC joint sprains. We are the only inter-disciplinary clinic in Sheboygan county that provides chiropractic, myofascial release, ART (Active Release Technique), massage therapy, acupuncture, physiotherapy, rehabilitative exercise, nutritional counseling, personal training, and golf performance training under one roof. Utilizing these different services, we can help patients and clients reach the best outcomes and the best versions of themselves. Voted Best Chiropractor in Sheboygan by the Sheboygan Press.
Evidence Based-Patient Centered-Outcome Focused
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