Acromio-Clavicular (AC) Joint Injuries
There are two main types of injuries affecting the AC joint: acute and chronic.
Acute AC Injuries
Acute AC joint injuries are very common injuries to the shoulder. These are injuries to the outer end of the collar bone (clavicle), usually from a traumatic episode, ie falls while playing sport, from a bicycle or motor bike. Injuries lead to disruption of the joint itself.
Normally the end of the collar bone is in line with another bone called the acromion, and this forms a joint. Following an injury, the collar bone can separate and move upwards by varying degrees. The true mechanism of injury is a disruption of the coraco-clavicular ligaments, which are the ligaments between the front of the shoulder blade, which is what houses the joint of the shoulder, and the under surface of the clavicle.
These ligaments are what suspend the arm and the shoulder blade from the clavicle, and the clavicle is suspended from the chest girdle. Following an injury these ligaments are disrupted and whilst it would appear that the clavicle is sitting upwards, what actually occurs is that the shoulder and shoulder blade falls off the clavicle and actually sit inferior or downwards. The amount of disruption of these ligaments determines how far the shoulder blade falls inferiorly.
There are several types of injuries. A sprain or a bruising to the ligaments and the joint capsule itself, will lead to a partial disruption of the AC joint and leads to minimal movement of the clavicle. When it is significantly disrupted the whole shoulder blade and acromion falls off the end of the clavicle.
Thus, simple sprains are known as grades 1 or 2 and more significant sprains are grades 3-6.
Minimal injuries or the simple sprains can be treated quite simply with pain relief, a sling for comfort, mobilisation as required and early return to sport and activities.
More significant sprains sometimes take a lot longer to settle and will lead to a permanent bump on the end of the clavicle, which is not only cosmetically unsightly but more importantly means that the shoulder support has to be undertaken more by the muscles of the neck. This can develop into an aching sensation of the whole shoulder itself and base of the neck.
What treatment options are there?
Firstly it is important, as with any injury, to diagnose the condition. In any injury to the shoulder or upper arm following a fall which does not result in a fracture, one needs to be concerned about an AC joint injury. Best assessment is done by a qualified person such as a doctor with a sports injury interest or physiotherapist, and they may seek referral to an orthopaedic surgeon.
X-rays will help confirm the diagnosis and these may involve hanging x-rays which involve holding on to a weight or strapping it to the wrist such that it puts traction or downward pressure on the arm.
Once the diagnosis is made, the level of severity determines what the best treatment options are. For the simpler injuries analgesics and anti-inflammatories are worthwhile and sometimes this may be supplemented by a steroid injection if not settling over a period of time. This is done under ultrasound guidance, where the radiologist, using ultrasound, injects the joint of the acromio-clavicular area with a small dose of steroid.
For more significant sprains often surgical intervention is offered to try to reduce the shoulder back on to the end of the clavicle, allowing the ligaments to heal in the best position. If this surgery is undertaken more than 2-4 weeks after injury, then often the ligaments need to be supplemented with some of the patient’s own ligaments to allow the tendon to heal.
How is the AC joint repair surgery undertaken?
In our experience, the best option is to tie the clavicle and the coracoid process together by drilling a hole through the clavicle and placing extremely strong suture band or tape around the clavicle four times in a strapping fashion. This is done through a small 6cm incision in oblique fashion from the front of the clavicle. It can lead to a high success rate – 95% of people see significant improvement. It does require the use of a sling for a six week period and avoiding carrying weights for a three to four month period until the tissues heal. There is a risk of the tape tearing or loosening off, leading to slight recurrence of subluxation, although this risk is low.
What is undertaken in those cases which are delayed for more than four weeks?
In cases that are over a month old often a ligament is transferred across. We undertake a Weaver Dunn procedure which involves transfer of a ligament which normally runs between the coracoid and acromion, transferring it to the end of the clavicle. This is secured using a suture anchor which is placed in the end of the clavicle. As part of this process the end of the clavicle is excised to allow the ligament to heal to the end of the clavicle.
Are there other techniques of repairing the acromio-clavicular joint injury which has been delayed?
Yes, there are. There are numerously described techniques, some involve using tendon harvested from the leg as you would for an anterior cruciate reconstruction in the knee. Others use other ligaments such as the Lars ligament which has been used in knees. However, in our experience, we have seen no advantage in doing this.
What are the long term concerns about acromio-clavicular injuries?
Certainly in an acromio-clavicular injury that is not causing the patient any problems such as pain or concern about function, this does not need to be treated. Often AC joint sprains, whether they are minor sprains or the more severe ones, can lead to AC joint symptoms such as clicking joints or arthritis. Arthritis is more likely to develop in the simpler sprains but this is easily treated with an arthroscopic debridement of the joint. This could be undertaken at any stage later in life if this becomes a chronic issue.
At Glenelg Orthopaedics, we take the time to make sure that you get the best advice and options for your situation, and the treatments offered have the best chance of achieving the desired outcome. Call us on 08 8376 9988, or send your x-rays to email@example.com, and we’ll help you find the best treatment options for your shoulder injury.
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