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 The arm is connected to the body through this small joint. There are 2 groups of ligaments which provide the stability between these bones:
- coraco-clavicular - 2-3 cms medial to the joint, passing between the finger like projection of the shoulder blade and the clavicle. Major stabiliser!
- acromioclavicular joint capsule - passing between the 2 bone ends. Very minor contribution to the stability.
Acute Instability
When a person falls on the point of the shoulder the ligaments between the 2 bones may tear if the bones do not break. The severity of the injury depends if only the capsule is stretched (subluxation or grade 1) or if the capsular ligaments are torn but the coracoclavicular ligs remain intact (grade 2) or both groups of ligaments tear and there is a large disruption with a large lump forming on top of the shoulder (actually the end of the collar bone sticking up under the skin).
Conservative treatment
Especially with grade 1 & 2 instability treatment may be non operative with:
- sling supporting the weight of the elbow and arm for comfort
- pain relief - analgesia
- ice to reduce swelling initially
- movements at an early stage with strengthening exercises at 2 weeks
Operative treatment
At surgery an internal sling is passed around the finger like projection (coracoid) of the shoulder blade and then around the collarbone providing immediate stability. The sling is made of an absorbable material and is often taken through a hole in the collarbone.
Stitches may be used to approximate the ends of the torn ligaments.
The actual end of the collar bone (about 0.5 cm) is often removed as the cartilage may be damaged or perfect alignment is not possible and may lead to painful joint or arthritis later.
Post operative
- usually one night in hospital - rarely 2 for pain relief
- sling for 6 weeks
- no sport or lifting for 3 months
- good results generally but often slightly more prominent lump than other non injured side
Chronic A-C Instability
If the original injury was missed or a decision was made to treat it without surgery initially, some people will require additional treatment later because
- gross instability - don't like the very large mobile lump (end of collarbone)
- clunk as the outer end of collarbone catches on the edge of acromion
- feeling of arm not connected - dragging sensation
Surgery
Not only is a synthetic ligament used around the collarbone and coracoid but also the outer end of collarbone is excised and a ligament is transferred into the end to provide a biological stabilising ligament. This additional ligament is taken off the front edge of acromion and left attached to the coracoid process.
Postoperatively
- usually one night in hospital - rarely 2 for pain relief
- sling for 6 weeks
- no sport or lifting for 3 months
- good results generally
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