ACJ Instability/Dislocation

Surgery may be necessary depending on the classification of the condition. The degree of damage to the joint is classified by the joint displacement and injury to the ligaments which support the AC joint.

Surgery may be necessary depending on the classification of the condition.

These are described using the Tossy classification with the Rockwood modification:

I – ACJ sprain
II – ACJ ligaments tear. CC ligaments intact
III – All ligaments torn. Up to 100% dislocation
IV – Clavicle displaced posteriorly
V – >100% dislocation
VI – Clavicle displaced under coracoid

Type I & II are treated conservatively with either Physiotherapy to ‘retrain’ the shoulder muscles or with painkillers and anti-inflammatories. If pain remains a problem, then ACJ excision arthroplasty may be necessary. Types IV-VI are usually treated surgically. Type III remains controversial with some surgeons advocating conservative management and others surgical.

In the chronic cases, a modified Weaver Dunn procedure is carried out. This utilises the transfer of the CA ligament to the excised end of the distal clavicle. This transfer is then protected with fixation between the clavicle and the coracoid.

The introduction of the tightrope (Arthrex) gives the option of treatment in the acute phase without the transfer of the CA ligament.

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