Shoulder Series - Part 3

Shoulder Series

PART 3

Acromioclavicular joint injuries

What is the Acromioclavicular Joint?

The Acromioclavicular joint (ACJ) is at the top of the shoulder and describes the articulation  between the acromion process of the scapula, and the distal end of the clavicle.

The ACJ is filled with a thick cartilaginous disc (meniscus) and entwined with several ligaments for support including the acromioclavicular and coracoacromial. It is further aided in stability by the trapezoid and conoid coracoclavicular ligaments that connect the coracoid process of the scapula to the distal clavicle.

The ACJ is a pivot joint and aids the scapula in rotation thereby allowing an overall greater range of motion to the glenohumeral joint. It moves when the arm is overhead or horizontally across the body.

What types of injury can occur at the ACJ?

The ACJ is susceptible to several injuries due to its relatively weak connection. The most common injuries are:

·       Osteoarthritis – like any articulating joint in the body, the ACJ can become arthritic as general joint wear and tear occurs. This process can be accelerated dependant on the individual’s lifestyle, general health, occupation, posture and activities.

·       ACJ disclocation – occurs following a direct fall onto the shoulder or extended arm. These type of injuries are most common during sporting activity including; rugby, skiing, snowboarding, football, skating, etc.

An ACJ dislocation can be classified based on a 4 point grading system quantified by the amount of separation of the acromion from the clavicle when a distraction force is applied to the arm.

o      Grade I – slight displacement of the ACJ and a slackened / partially torn acromioclavicular ligament.

o      Grade II – a complete tear of the ACJ and partial damage to the coracoclavicular ligament – leading to a partial dislocation of the ACJ.

o      Grade III – a complete dislocation of the ACJ as a result of the rupture to the acromioclavicular and coracoclavicular ligaments.

o      Grade IV – A more prominent dislocation with detachment and movement of the clavicle that is evident on Xray and physical assessment.

Treatment of ACJ injuries and Pilates

ACJ arthritis is best managed like any arthritic joint;

·       Pain relief

·       Joint mobility exercises (Pilates)

·       Physiotherapy – manual therapy

·       Heat

·       Reduction of aggravating activities – above head activities

In cases where the ACJ has been sprained / partially dislocated (Grades I – III) then the initial treatment will follow a similar course to that of ACJ arthritis above. Most clients will fully recover and those who further strengthen the shoulder with Pilates will be able to return the majority of their activities.

Pilates in ACJ rehab should focus predominantly on correct muscle patterns around the scapula, particularly on educating good scapulohumeral rhythm. Starting with good foundations and trunk control then gradually extending the lever through arm movements can help to restore stability around the injured area.

Clients who have suffered a Grade IV or worse ACJ dislocation will require surgery to reduce it first and then be able to follow the same course of rehab as above.