Acromioclavicular Joint Injury
1. Introduction
The acromioclavicular (AC) joint – which may be described as the ‘tip’ of the shoulder – is formed by the outside end of the collar bone (clavicle) and part of the shoulder blade known as the acromion. This joint assists with movement of the shoulder blade on the chest and maximises shoulder range of movement and stability. Like all synovial joints, it has a joint capsule and ligaments (acromioclavicular, coracoacromial and coracoclavicular) which provide stability.
Injury to this joint almost always occurs as a result of trauma to the shoulder. In the process of the injury, the collar bone will lift up relative to the acromion. This will cause strain or tearing of these ligaments which is often what causes the pain.
Frequently Asked Questions
- Acromioclavicular joint injuries involve damage to the joint between the collar bone and the shoulder blade. Typically, this follows a fall on an outstretched hand, elbow, and direct impact onto the tip of the shoulder .
- Acromioclavicular joint injuries involve damage to the joint between the collar bone and the shoulder blade.
- Typically, this follows a fall on an outstretched hand, elbow, and direct impact onto the tip of the shoulder.
- Acromioclavicular joint injuries make up approximately 9% of all shoulder injuries (3, 6).
- This is less than 1% of all adult injuries.
- No.
- Most acromioclavicular joint injuries are treated with physiotherapy and will make a full recovery.
- There are different grades of the injuries from type I – VI.
- Lower grade injuries are treated with immobilisation for a few weeks followed by exercise rehabilitation.
- Higher grade injuries may require surgery (6). However, these more serious cases are rare.
- Athletes account for 40% of acromioclavicular joint injuries.
- Athletes from contact and high-speed sports such as hockey, rugby, skiing, football, snowboarding and cycling (4).
- It is seen 5 times more in men than in women.
- It most commonly occurs in people between the ages of 20-30 (5).
- Pain on the top of the shoulder which may radiate into the neck and upper arm.
- Symptoms aggravated by heavy lifting, overhead and across body movements.
- Swelling/bruising.
- Loss of shoulder movement.
- A visible deformity can often be seen on the tip of the shoulder (3), called a ‘step deformity’ as it can look like a step. Do not worry as this is common with this injury and does not indicate a serious problem.
- Advice from a qualified health professional would help to determine the extent of injury and employ the best management strategy.
- Sling immobilisation is commonly recommended for type I – III injuries (7).
- Once the pain has reduced, a progressive exercise programme will help to ensure you return to normal shoulder function.
- This will depend upon several factors including existing injuries/problems, severity of injury, adherence to rehabilitation, etc.
- In a type I injury, returning to normal activity should take 2-4 weeks (7).
- In a type II, typically 4-6 weeks (7).
- In a type III, typically 6-12 weeks (7).
- It should be noted that most people will make a full recovery from the injury despite the fact that the visual (step) deformity may often remain.
We recommend consulting a musculoskeletal physiotherapist to ensure exercises are best suited to your recovery. If you are carrying out an exercise regime without consulting a healthcare professional, you do so at your own risk.
2. Signs and Symptoms
- Pain on the top of the shoulder which may radiate into the neck and upper arm.
- Swelling, bruising and tenderness with palpation of the injured area – around the ‘tip’ of the shoulder.
- Visual deformity on the ‘tip’ of the shoulder – commonly referred to as a ‘step deformity’, indicating displacement of the acromioclavicular joint.
- Limited range of motion and function.
- Aggravated by heavy lifting, overhead and across body movements (3).
3. Causes
- Fall onto an outstretched hand or elbow.
- A direct blow or fall onto the point of the shoulder.
- A road traffic accident.
- Acromioclavicular joint injuries are commonly seen in contact sports such as football, rugby, hockey, cycling, skiing/snowboarding and road traffic accidents (4).
4. Risk Factors
This is not an exhaustive list however these factors could increase the likelihood of someone sustaining an acromioclavicular joint injury. It does not mean everyone with these risk factors will develop symptoms.
- Active individuals in their 20s and 30s.
- Gender – the incidence is 5 times higher in males.
- Athletes are more prone to this type of injury due to their higher risk of impact/falls.
- In particular contact and high-speed sports such as hockey and rugby, skiing, football, snowboarding and cycling (4,5).
5. Prevalence
Acromioclavicular joint injuries account for approximately 9% of all shoulder injuries (6). This accounts for less than 1% of all adult injuries. The extent of acromioclavicular joint injury can range from a mild ligament sprain to complete ligament tear resulting in ‘separation’ of the acromioclavicular joint or ‘dislocation’ (although this is rare). In athletes, injury of the joint is seen in 40% of shoulder girdle injuries. Grade I and II injuries are far more common, accounting for up to 90% of cases (3).
6. Assessment & Diagnosis
Your musculoskeletal physiotherapist will take a detailed history to understand how the injury occurred and what your symptoms are. Following this, a comprehensive physical assessment will be completed to establish your function and test specific structures to assist with the accurate diagnosis so that the most appropriate and effective treatment can begin straight away.
In cases where the function is relatively well maintained, there are several physical tests that will help establish the grade of the injury – usually I – III. However, in some cases, an X-ray is utilised to assist with grading and to guide ongoing treatment and management.
Your musculoskeletal physiotherapist will work with you to develop a set of individualised goals to help direct your treatment and facilitate optimal recovery with a successful return to normal activity/sporting performance. We value reassessment to ensure you are making progress and to allow adjustments in your treatment to be made.
7. Self-Management
Alongside a referral within 48 hours if deemed appropriate:
- A sling/brace is advised to immobilise the shoulder; this can be used in tandem with taping to provide the joint with additional support (7). Elevating the shoulder to a comfortable height is also suggested when resting. A sling can be used until symptoms diminish and function returns.
- For grade I – III injuries, patients typically return to normal function at 2-4, 4-6 and 6-12 weeks respectively (3). Optimal treatment remains uncertain for type III injuries as favourable outcomes have been observed in both conservative and surgical management. For overhead athletes and those with physical jobs that require higher functional demands for the shoulders, surgical intervention is recommended for greater restoration of function and as such, treatment options should be individualised (2, 5, 7).
- For type IV injuries and upwards, surgery is often indicated to restore normal anatomy and stability through ligament reconstruction (2, 5, 9).
- Your physio will help explain the injury and what structures are involved so that you can understand your symptoms and help support your own recovery. As you recover, we provide ongoing guidance so that you can effectively return to your normal activities whilst minimising the likelihood of future complications.
8. Rehabilitation
In most cases, rehabilitation will be the main solution to you getting back to full function following this type of injury.
Below are three rehabilitation programmes created by our specialist physiotherapists targeted at addressing acromioclavicular joint injury. In some instances, a one-to-one assessment is appropriate to individually tailor targeted rehabilitation. However, these programmes provide an excellent starting point as well as clearly highlighting exercise progression.
9. Acromioclavicular Joint Injury
Rehabilitation Plans
Our team of expert musculoskeletal physiotherapist have created rehabilitation plans to enable people to manage their condition. If you have any questions or concerns about a condition, we recommend you book an consultation with one of our clinicians.
What Is the Pain Scale?
The pain scale or what some physios would call the Visual Analogue Scale (VAS), is a scale that is used to try and understand the level of pain that someone is in. The scale is intended as something that you would rate yourself on a scale of 0-10 with 0 = no pain, 10 = worst pain imaginable. You can learn more about what is pain and the pain scale here.
This programme focuses on maintaining range of movement within the shoulder and maintenance of scapular control (9). We suggest you carry this out once a day for approximately 2-4 weeks as pain allows. As with the early programme, some discomfort is to be expected but the pain should not exceed 4/10 on your perceived pain scale whilst completing this exercise programme.
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This is the next progression. More focus is given to progressive upper limb strengthening with closed kinetic exercises towards open chain resistance exercises. As with the early programme, some discomfort is to be expected but, ideally, pain should not exceed 4/10 whilst completing this exercise programme.
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- 910
This programme is a further progression of exercises to increase the strength and stability of the shoulder. When the full range of motion is achieved alongside comparable strength to the non-affected limb, return to activity can take place (2). Pain should not exceed 4/10 whilst completing this exercise programme.
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- 910
10. Return to Sport / Normal life
For patients wanting to achieve a high level of function or return to sport we would encourage a consultation with a musculoskeletal physiotherapist as you will likely require further progression beyond the advanced rehabilitation stage. Before returning to sport, a rehabilitation programme should incorporate plyometric based exercises; this might include things like tossing and catching a plyometric ball, throw overhead side to side and plyometric push ups.
As part of a multi-modal treatment approach, your physio may also use a variety of other pain-relieving treatments to support symptom relief and recovery. Whilst recovering, you might benefit from further assessment to ensure you are making progress and establish appropriate progression of treatment. Ongoing support and advice will allow you to self-manage and prevent future reoccurrence.
11. Other Treatment Options
In severe and traumatic cases, grade IV – VI, there is a high likelihood that surgical intervention will be required as the preferred treatment approach (4). Despite continuous advances in surgical procedures – with up to 160 various techniques described (9) – the gold standard for surgical intervention remains elusive, however, the evidence recommends that each surgeon’s expertise – alongside deliberating the associated benefits and risks – should dictate the procedure used (5, 9).
Surgery will restore normal anatomy and stability to the joint. Post-surgical management is very similar to that of lower grade injuries beginning with increasing range of motion before moving on to strengthening exercises and graded exposure to higher level exercise for return to baseline function.
References
- Kim, S., Blank, A., & Strauss, E. (2014). Management of Type 3 Acromioclavicular Joint Dislocations. Bulletin of the Hospital for Joint Diseases, 72(1).
- Li, X., Ma, R., Bedi, A., Dines, D. M., Altchek, D. W., & Dines, J. S. (2014). Management of acromioclavicular joint injuries. JBJS, 96(1), 73-84.
- Culp, L. B., & Romani, W. A. (2006). Physical therapist examination, evaluation, and intervention following the surgical reconstruction of a grade III acromioclavicular joint separation. Physical therapy, 86(6), 857-869.
- Johansen, J. A., Grutter, P. W., McFarland, E. G., & Petersen, S. A. (2011). Acromioclavicular joint injuries: indications for treatment and treatment options. Journal of shoulder and elbow surgery, 20(2), S70-S82.
- Sirin, E., Aydin, N., & Mert Topkar, O. (2018). Acromioclavicular joint injuries: diagnosis, classification and ligamentoplasty procedures. EFORT open reviews, 3(7), 426-433.
- Gorbaty, J. D., Hsu, J. E., & Gee, A. O. (2017). Classifications in brief: Rockwood classification of acromioclavicular joint separations.
- Reid, D., Polson, K., & Johnson, L. (2012). Acromioclavicular Joint Separations Grades I–III. Sports medicine, 42(8), 681-696.
- Beitzel, K., Mazzocca, A.D., Bak, K., Itoi, E., Kibler, W.B., Mirzayan, R., Imhoff, A.B., Calvo, E., Arce, G., Shea, K. and of ISAKOS, U.E.C. (2014). ISAKOS upper extremity committee consensus statement on the need for diversification of the Rockwood classification for acromioclavicular joint injuries. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 30(2), 271-278.
- Deans, C. F., Gentile, J. M., & Tao, M. A. (2019). Acromioclavicular joint injuries in overhead athletes: A concise review of injury mechanisms, treatment options, and outcomes. Current reviews in musculoskeletal medicine, 12(2), 80-86.
Other Conditions in
Shoulders
Whiplash Disorders
An injury which typically occurs following a road traffic collision, often affecting the soft tissues of the neck.
Thoracic Outlet Syndrome
A condition presenting with pain in the arm as a result of compression of structures around the neck/shoulder.
Shoulder Osteoarthritis (OA)
Age and activity related changes to the joints of the shoulder which can lead to pain and stiffness.
Shoulder Impingement
Shoulder impingement is an umbrella term used to describe a variety of conditions that can cause pain in the shoulder.
Shoulder Dislocation
An injury in which your upper arm bone ‘pops out’ of the cup-shaped socket of your shoulder blade.
Rotator Cuff Tendinopathy
Pain and weakness affecting the shoulder and limiting function.
Frozen Shoulder
An insidious (no clear cause), painful/stiff condition of the shoulder persisting for more than 3 months.
Calcific Tendinopathy
A rare condition causing pain and loss of free movement in tendons and joints.
Biceps Tendinopathy
A tendon-related issue affecting the long bicep tenon at the front of the shoulder.
Benign Joint Hypermobility Syndrome
Common age related changes to the structure of the knee joint which may be associated with pain, stiffness and loss of function.
Acute Torticollis
Sometimes referred to as “wry neck”, this is a condition causing muscle spasms and associated neck pain.