The purpose of this study is to compare non-operative treatment versus operative treatment in patients who suffer a complete, acute acromioclavicular (AC) joint dislocation. This study will show if one method is superior to the other and will also show advantages and disadvantages associated with each treatment method.

All patients presenting to the hospital with a Type III, IV or V acute acromioclavicular (AC) joint dislocation and meeting the eligibility criteria will be approached and asked to enter this prospective, randomized clinical trial. After obtaining consent, the subject will be managed in accordance with one of the two randomized treatment strategies. The first treatment strategy will involve conservative (nonoperative) management of the AC joint dislocation. The second treatment strategy will involve operative fixation (i.e. ORIF) of the dislocation with a hook plate and screws.

The subjects in both treatment groups will receive post-operative care according to the same standards and protocol. The surgeon and research staff will be responsible for study follow-up (clinical and radiological assessment) of the patient on admission (baseline), on discharge from the hospital and at post-operative intervals of six weeks, three months, six months, one year and two years. Primary and secondary outcomes will be monitored at these post-operative intervals.

Inclusion Criteria:

• Men or women aged 16 to 65 years of age
• Grade III (3), IV (4) or V (5) dislocation of the acromioclavicular (AC) joint (evidenced by no contact between the distal clavicle and the acromion as seen in standardized radiographs)
• Closed injury
• AC joint dislocations within 28 days post injury
• Provision of informed consent

Exclusion Criteria:

• Grade I(1), II (2), or VI (6) subluxation/dislocation of the AC joint
• Open AC joint separation
• Scapulothoracic dissociation
• Presence of vascular injury
• Dislocations over 28 days post-injury
• Limited life expectancy due to significant medical co-morbidity
• Medical contraindication to surgery (including pregnancy)
• Inability to comply with rehabilitation or form completion
• Inability to provide informed consent
• Likely problems, in the judgement of the investigators, with maintaining follow-up (i.e., patients with no fixed address, patients not mentally competent to give consent, etc.)