What is an AC joint sprain?

An AC joint sprain is a relatively common sporting injury affecting the shoulder and is characterized by tearing of the connective tissue and ligaments of the Acromio-Clavicular joint. The shoulder blade gives rise to a bony prominence known as the acromion. The acromion attaches to the collar bone (clavicle) via strong ligaments and connective tissue. This joint is known as the AC joint and is situated at the point of the shoulder.                                                                  

The AC joint is responsible for connecting the shoulder blade with the clavicle and allows for some shoulder movement. During certain activities, stretching forces are placed on the AC joint. When these forces are excessive and beyond what the AC joint can withstand, tearing of the ligaments and connective tissue of the AC joint may occur. This condition is known as an AC joint sprain.  An AC joint sprain can range from a small sprain resulting in minimal pain and allowing ongoing activity, to a severe AC joint sprain resulting in significant pain, deformity and disability.

Causes of an AC joint sprain

An AC joint sprain typically occurs following a direct blow to the point of the shoulder. This commonly occurs in contact sports due to a collision with another player. Occasionally an AC joint sprain may occur following a fall onto the point of the shoulder.

Signs and Symptoms of an AC joint sprain

Patients with an AC joint sprain typically experience pain on the top of the shoulder at the time of injury. In minor cases of an AC joint sprain, patients may be able to continue activity only to experience an increase in pain, swelling and stiffness in the shoulder after activity with rest (particularly first thing in the morning).

In more severe cases of an AC joint sprain, pain may prevent the patient from continuing activity and cause them to cradle the arm. Patients with an AC joint sprain may also experience a rapid onset of swelling and may notice a 'step' deformity or bump in their shoulder with the tip of their collar bone sticking up. This occurs due to tearing of the connective tissue holding the AC joint together and the accumulation of swelling and bleeding around the joint.

It is often painful for patients with an AC joint sprain to perform overhead activities, lie on the affected side, move their arm across their body or perform heavy pushing or pulling movements.

Diagnosis of an AC joint sprain

A thorough examination from an MD Health Physiotherapist is usually sufficient to diagnose an AC joint sprain. Investigations such as an X-ray, MRI scan or CT scan may occasionally be required to confirm diagnosis of an AC joint sprain and determine the extent of damage or involvement of other structures in the shoulder. This is important to exclude the possibility of a fracture.

Treatment for an AC joint sprain

Most patients with an AC joint sprain heal well with appropriate physiotherapy. The success rate of treatment is largely dictated by patient compliance. A vital aspect of treatment is that the patient rests sufficiently from any activity that increases their pain (a sling may be required initially). Activities placing large amounts of stress on the AC joint should also be minimized, particularly lifting, pushing, pulling, overhead activities, lying on the affected side and movements taking the arm across the body. Resting from aggravating activities ensures the body can begin the healing process in the absence of further damage to the AC joint. Once the patient can perform these activities pain free a gradual return to these activities is indicated provided there is no increase in symptoms.

Ignoring symptoms or adopting a 'no pain, no gain' attitude is likely to lead to the AC joint sprain becoming chronic. Immediate, appropriate treatment in patients with an AC joint sprain is essential to ensure a speedy recovery. Once the condition is chronic, healing slows significantly resulting in markedly increased recovery times and an increased likelihood of future AC joint injury.

Patients with an AC joint sprain should follow the R.I.C.E. Regime in the initial phase of injury. The R.I.C.E regime is beneficial in the first 72 hours following an AC joint sprain or when inflammatory signs are present (i.e. morning pain or pain with rest). The R.I.C.E. regime involves resting from aggravating activities (this may include the use of a sling), regular icing, and keeping the arm elevated (e.g. lying on the unaffected side). Anti-inflammatory medication may also significantly hasten the healing process in patients with an AC joint sprain by reducing the pain and swelling associated with inflammation.

Patients with an AC joint sprain should perform pain-free flexibility and strengthening exercises as part of their rehabilitation to ensure an optimal outcome. The treating physiotherapist can advise which exercises are most appropriate for the patient. Upon return to sport (especially contact sports), patients with an AC joint sprain can tape the shoulder to protect and support the AC joint and decrease the likelihood of re-injury.

Prognosis of an AC joint sprain

With appropriate management, most patients with a minor to moderate AC joint sprain can return to sport or normal activity within 2 – 8 weeks. Patients with severe AC joint sprains will require a longer period of rehabilitation to gain optimum function.

Physiotherapy for an AC joint sprain

Physiotherapy for patients with an AC joint sprain is vital to hasten the healing process, ensure an optimal outcome and reduce the likelihood of future recurrence. Treatment may comprise:

• soft tissue massage of surrounding muscles
• joint mobilization
• ice or heat treatment
• protective taping
• the use of a sling
• anti-inflammatory advice
• exercises to restore flexibility and strength
• education & training
• activity modification advice
• a gradual return to activity program

Other intervention for an AC joint sprain

Despite appropriate physiotherapy management, a small percentage of patients with an AC joint sprain may not improve adequately. When this occurs, the treating physiotherapist can advise on the best course of management. This may involve pharmaceutical intervention, corticosteroid injection, further investigation such as an X-ray, CT scan or MRI, or a review by a specialist who can advise on any procedures that may be appropriate to improve the AC joint sprain.