A-C Joint Injuries
The Acromio-Clavicular or ‘A-C’ Joint is formed by the junction of the clavicle and the acromion process of the scapula. It is supported by ligament structures (the A-C capsule and the two branches of the coraco-clavicular ligament), and also via dynamic muscular stabilisation provided by the upper trapezius, deltoid and pectoralis major. Because of its orientation, the A-C joint is vulnerable to downward shearing stress, so injuries are common in contact sports like AFL and rugby, but also any sport where there is risk of a heavy blow to the point of the shoulder—a fall off a bike for instance. In many directions the A-C joint is very strong; it needs to be in order to transmit forces from the arm to the trunk and vice versa! However, if sufficient downward force is applied to the tip of the acromion, the joint can injure easily, tearing the ligaments and driving a separation of the two bones.
Grades of injury vary, as does both their treatment and recovery time. Low grade injuries settle well and relatively quickly, but the highest grades may require stabilisation surgery and obviously imply longer rehab time.
Some points of interest:
- Injuries to young males outnumber females by 5:1
- Incidence is highest in 2nd decade of life
- There is usually a history of acute injury
- Injury results in pain and loss of range of movement, especially above 90° of elevation
- The clavicle is curved so that it can absorb impact and stress.
Lower Grade strains:
- These are treated conservatively. Treatment is steered by your Physio and includes techniques to reduce pain, stabilise the joint, progressively regain ROM, and re-establish strength in the longer term.
- A period of immobility may be required initially to allow ligament healing.
- Manual therapy can assist in maintaining shoulder, scapula, neck and thoracic mobility.
- Graded exercise is essential, facilitating your range of movement and lightly strengthening the shoulder and scapula musculature as comfortable.
- Electrotherapeutic modalities (interferential & ultrasound) may help stimulate tissue repair and reduce pain.
- Recovery is usually within 2-8 weeks.
Higher Grade injuries (dislocations):
- Surgical vs conservative treatment remains controversial and you should discuss this with you Physiotherapist
- Research suggests ultimately there is no difference in outcome between surgical and non-surgical management of 'typical' A-C dislocations at 12 months post injury. Recovery time following a dislocation is often 12+ weeks regardless of whether it is surgically repaired or not. Conservative treatment allows for the formation of a functional scar ‘bridge’ which is very effective, but aesthetically there is usually a permanent 'lump' that will remain visible.
- There are some uncommon sub-types of a full dislocation, and all of these require surgical fixation due to the high grade displacement of the clavicle seen.
What is the Conservative Management for a dislocation?
- Non steroidal anti-inflammatory medication and analgesia is usually required/recommended in the early stages of recovery.
- Physio treatment may include strapping and immobilisation over the first 1-4 weeks, coupled with local electrotherapy, ultrasound and soft tissue techniques to assist and facilitate repair. A graduated exercise program is required once the acute phase of the injury has passed, with particular care taken above 90°.
- Strapping of the A-C aims to support the damaged structures & prevent further injury, as well as attempting to more closely approximate the acromion and clavicle.
- From experience, continual strapping of the A-C improves comfort, aids sleep, and provides valuable position feedback to reduce the risk of further injury. However, its effect on reducing the A-C separation is questionable. Certainly, those who have experienced an A-C dislocation managed without surgery will have some degree of long term cosmetic deformation; we hope that strapping in some ways decreases this but it is obviously difficult to assess.
Surgical fixation of A-C joint disruptions has been debated for many years, its popularity waxing and waning. In the 1970’s surgical fixation was deemed the most popular choice amongst orthopaedic surgeons, however by the 1990’s this had reversed and 72% of those surveyed favoured conservative management. Some believe that the high degree of disruption seen with Grade 3 leads to muscular fatigue and difficulty coping with loads overhead. Therefore, in sub-groups of patients who are involved with heavy manual labour, throwing sports, or are of an age where they are uncertain as to their future career, surgical fixation and/or reconstruction of the A-C complex will be considered.
A minority of cases will suffer from longer term instability and/or pain, particularly with overhead activities. Acceleration of degenerative change in the A-C joint is also frequently seen. For these patients, surgery may be warranted, usually taking the form of excision of the distal clavicle, A-C stabilisation and reconstruction of the coraco-clavicular ligaments. Variations on this may be favoured depending on the surgeon.
**Our Principal Physiotherapist at Belmont City Physiotherapy Clinic has been through the same injury process - sometimes first hand experience is unwanted but invaluable! If you have any queries, don't be afraid to ask!