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Acromioclavicular joint

Arthritis and Injury 

1. Acromioclavicular Joint Arthritis 

What is it?

The acromioclavicular (AC) joint connects your collarbone to your shoulder blade.  It is the bony lump you can feel at the outer end of your collarbone on the top of your shoulder.  Signs of joint degeneration in the AC joint on X-ray is common in people over 40yrs old, but it is often completely asymptomatic.  Sometimes it can cause significant pain and need treatment. 

What are the Symptoms?

Typically patients report a gradual onset of symptoms with pain when raising their arm to its maximum height or across their body.  Often there is a constant pain like ‘toothache’ in the shoulder, which worsens with movement.  Sometimes it can affect your sleep and often patients cannot lie on their affected side.  Most patients locate their pain accurately to the top of the shoulder. Sometimes patients feel grinding in the AC joint as it moves

Why does it happen?

Despite the AC joint being small, large forces pass through it every time you use your arm.  These forces tend to cause the joint to wear out over time, so arthritis of the AC joint is commonly seen on shoulder x-rays or scans of patients over the age of 40.  In some patients, this degeneration causes pain as the joint lining gets inflamed or as the worn out surfaces of the joint rub against each other.  Sometimes, joint degeneration can occur after an injury to the joint.

How is it diagnosed?

Your symptoms and clinical examination will be suggestive. Shoulder x-rays (usually two images) are routinely taken and help make the diagnosis. You may also require Ultrasound or MRI scans, although these are often to look at the other structures in your shoulder alongside your AC joint.   Occasionally, if the precise area of your shoulder that is causing pain remains in doubt, a targeted local anaesthetic injection can be helpful in localising the causative area. (These injections sometimes require image guidance (usually ultrasound) to ensure precise placement) 

What are the non-surgical treatment options?

Physiotherapy.  Correction of postural and strength issues can reduce the burden placed on your AC joint during daily activities and therefore improve your symptoms. A physiotherapy programme will take 8-12 weeks to have an enduring effect, so keeping motivated is important.  Your physiotherapist will advise and support you through your rehabilitation.

Acromioclavicular joint Cortisone Injection. Your surgeon may recommend an injection into your AC joint. This may be performed in the clinic, but sometimes image guidance (with X-ray or ultrasound) is required to ensure the injection gets to the right place. The injection has very low risk of harm and is moderately sore but well tolerated by patients.  You can drive home afterwards. Most patients enjoy significant symptom relief for three months or more, giving an excellent window of opportunity for the physiotherapist to help you rehabilitate your shoulder. 

What are the Surgical Options?

If your symptoms remain significant after an injection and a good quality rehabilitation programme, you may decide it’s time to consider surgery. In most cases, this will involve a keyhole operation called acromioclavicular joint excision, (also called distal clavicle resection).  More information is available under the treatments section. acromioclavicular joint excision

What is the prognosis for AC joint arthritis?

Many patients will improve their symptoms resolve with a combination of physiotherapy and cortisone injection.  Of those who go on to have surgery, 85% will be happy with their outcome, but it can take several months (6-9 months) for the full benefit of surgery to be realised. Approximately 10% may experience on-going symptoms in their shoulder. It is rare (<5%) for patients to be made worse.


2. Acromioclavicular Joint Injury

What is it?

The AC joint is the only bony connection of your shoulder blade and it is important for maintaining normal dynamics in  your shoulder.

The AC joint relies on three main structures for stability: Your AC joint capsule, the coraco-clavicular ligaments and the delto-trapezial fascia.  These structures are illustrated below.

With direct force, normally a fall onto the tip of the shoulder, the joint can be injured and become painful and unstable.   In some cases this pain and/or instability requires surgery. The x-ray below shows a high-grade dislocation of the AC joint. 



What are the Symptoms of an AC joint injury?

You will likely recall a specific injury – e.g. fall off a bike/rugby tackle. There will be acute pain and swelling over the top of your shoulder and you may notice a step (dislocation of AC joint).  Initially you will have reduced function due to pain,  but this often settles over the first couple of weeks. However, it may continue and limit your shoulder function and dynamics.

Who gets AC joint injuries?

This is typically an injury that occurs in 18-45 year olds; it is much more common in men and is particularly common in collision sports, such as rugby.  Other sports with risk of falling onto the shoulder, such as cycling, skiing and riding are also higher risk. 

What do the 'grades' of injury mean?

 Different grades of injury can occur, ranging from a capsular sprain of the AC joint, through to rupture of all stabilizers and gross displacement of the AC joint.  The grade of injury does not necessarily predict the functional impairment you will experience.  It is possible for low grade sprains to cause on-going issues, while patients with obvious deformity can sometimes suffer few  symptoms. There spectrum of injury has been divided into 6 grades.  This grade is determined by x-rays and clinical examination.   It can help us understand which structures have been damaged.

Grades 1 and 2 - you will not have a significant step and your AC joint will be stable.   Your joint capsule has been injured, but  your important coraco-clavicular ligaments will be intact.  90% will recover without surgery.  10% will develop ongoing pain that may require treatment.

Grade 3 - you will have a step over your shoulder.  On x-ray your collarbone will have moved out of its socket by approximately 100%.  Your coraco-clavicular ligaments have been injured, but it is probable that your delto-trapezial fascia remains intact. Repeated studies suggest that most (85%) of patients do well without surgery and a recent review confirmed no obvious superiority of early fixation for these injuries. If you are coping well at 10 days or so after injury, it is best not to have an operation.  If you are still struggling at this point then you may decide that surgery is indicated. 

Grade 4 - as for Grade 3, but your collarbone is unstable posteriorly.  This causes the collarbone to penetrate the trapezius muscle behind the AC joint as you move your arm across your body.  Patients are normally very sore and limited by this and most will opt for early surgery.

Grade 5 - In this case, the overlying delto-trapezial fascia has also ruptured and the collarbone has displaced yet further from it's original position.  Most surgeons would offer early surgery to restore stability in this group. 

Grade 6 - An extremely rare injury pattern where the collarbone comes to rest beneath the coracoid process.  

 What non-surgical treatments are there?

Rest, activity modification, painkillers and anti-inflammatories are the first step, as for many injuries.  Physiotherapy helps to reduce swelling, restore range of motion and muscle control to your shoulder.  

Intra-articular (Cortisone) Steroid Injection can be helpful if symptoms persist in low grade sprains, but they are not indicated if you have significant deformity.

Will I need Surgery for my AC joint injury?

If your shoulder settles down within the first two weeks then you may do well without surgery, regardless of your injury 'grade'. However, if you shoulder is still very troubling, and your AC joint is unstable, you may choose to have surgical repair.  Depending on the time from injury, this may be either an arthroscopic repair procedure or an open reconstruction.  Both can achieve excellent outcomes with 90% satisfaction.

You may have injured your AC joint some time ago.  If it’s still causing problems, you may require surgery, either to resect the joint (low grade sprain), or to reconstruct the torn ligaments (higher grade injury).  Chronic cases with instability require an open reconstruction where an artificial ligament is implanted to replace the damaged ones and the degenerate distal end of your collarbone can be resected.

This link will take you to a page on acromioclavicular joint stabilisation

Below is an algorithm  designed to help you understand what might be required after an ACJ injury:: 


Recovery from AC joint injury

Many patients with 'sprains' settle down quickly and return to sports between one and three weeks from injury.  A minority of low grade sprains will need further treatment. Unstable (grade 3 or higher) AC joint injuries may also settle (especially grade 3) albeit with a visible step, but more will require surgery.  If higher grade injuries settle down, you can return to play as soon as you’re comfortable without restriction.  If your dislocated AC joint does not settle down within two  weeks, and you remain significantly limited, you may need surgery. 

If you have chosen to follow a non-operative initial course and your symptoms persist, you may then decide to undergo treatment. 

What is my Prognosis?

Most low grade sprains recover without surgery, but a small proportion (10%)  will cause on-going pain and require treatment. Higher grade sprains may also do well without surgery, but many will require stabilisation.  The rehabilitation after surgical reconstruction or repair of the ligaments involves a period of protected motion, increasing to full range of motion before strength training.  Sporting return will take place after three to six months depending on your sport. If you do require surgery, outcomes in terms of return to sport and symptom resolution are very good with over 85% returning to their sport.  

Making the right choice about the best treatment for you means getting the right information. During your consultation, please do feel free to ask Mr Granville-Chapman to explain anything that you do not fully understand, and for his advice about the pros and cons of any treatment.