Injury to the AC Joint (Acromioclavicular Joint)
I had an accident and sustained an AC joint injury
The AC joint is the junction between the outer end of the collar bone (clavicle) and the roof of the shoulder (acromion - part of the shoulder blade). There is only little motion in this joint but the forces are huge as the clavicle suspends the shoulder against the sternum. Stability is maintained via the joint capsule and the two ‘coraco-clavicular’ ligaments which connect the outer end of the clavicle with a bony hook (coracoid process) that extends from the shoulder blade.
What are the symptoms of AC joint injury?
There will be a visible lump at the shoulder and pain especially when trying to raise the arm.
Who gets a AC joint injury?
A fall, usually a high energy trauma to the shoulder can disrupt the joint capsule and also the coraco-clavicular ligaments. This is a common cycling or winter sports injury. It also occurs in contact athletes.
How is AC joint injury diagnosed?
The trauma history and the visible deformity are first diagnostic clues. Once the pain has settled the level of joint instability can be assessed. X-rays in comparison often with some weight at the hands will image the joint disruption. There are several degrees to the injury where the level of instability and joint displacement in the X-ray determine which structures are torn and which treatment should be chosen.
Treatment for AC joint injuries
Based on the clinical findings and X-rays in consideration with the activity level of the injured person, AC joint injuries can be managed non-operative or with surgical fixation. Where non-operative management is suggested the arm is immobilised for two weeks in a broad arm sling followed by physiotherapy for range of motion exercises. Higher degrees of AC joint injuries require reduction and fixation in order to regain a normal shoulder function.
Surgery for AC joint injuries
Surgery for AC joint injuries of higher grade require reduction of the outer end of the clavicle and fixation to the coracoid process. The coracoid process is a bony prominence arising from the front of the shoulder blade. There are strong ligaments between the the coracoid process and the clavicle which are disrupted in AC joint injuries of higher degree. Surgery aims to reduce the clavicle and bring the iron ligaments back together in order for them to heal. Timing is crucial as this injury is considered acute in the first three weeks. During this time the torn ligaments can heal reliably. In chronic cases, cases beyond the three weeks mark, tendon grafting is required. It is my preference to perform these surgery mainly via arthroscopy (keyhole surgery). A tensioning device is used to reduce the clavicle and maintain reduction until the ligaments have healed. In chronic cases which require tendon grafting one incision is slightly larger and the procedure is assisted by arthroscopy. Often these cases can be managed a s day surgery.
Preparing for surgery for AC joint injury
Prior to the procedure, we will arrange for one preconditioning physiotherapy session where we fit a shoulder immobiliser, explain some simple exercises and give you an ice bladder with icing instructions. If required we will also arrange for a bulk billed pre-admission clinic at the hospital. This is run by a specialist anaesthetist who will gather information and request investigations that are required for safe anaesthesia. Our reception staff will advise of costs, hospital and admission details.
Recovery from surgery for AC joint injury
After surgical fixation sling immobilisation is necessary for roughly six weeks. This is the time ligaments need to heal. The shoulder immobiliser neutralises gravity forces of the arm and keeps the AC joint rested. Physiotherapy can commence within a few days following the procedure mainly for elbow and wrist motion but also passive shoulder motion. Once comfortable active assisted exercises for the shoulder joint will be added. The surgical incision will be closed with internal sutures and the wound will have healed when you will have your scheduled two week postoperative appointment with me. X-ray will follow at the six week mark before sling immobilisation can be discontinued. This marks a change in rehabilitation where the focus will shift towards increasing range of motion and strength. Recovery of full range of motion and strength can be expected at the 12 week mark following surgery.