This study will evaluate the non-inferiority of conservative management for acromioclavicular clavicle disjunction, compared with surgical management. Half of patients will be treated with a specific standardized rehabilitation protocol, and the other half will be treated with coracoclavicular and acromioclavicular fixation, followed by a another specific standardized rehabilitation protocol.

Outcomes:

The primary outcome is the non-inferiority of the conservative management over surgical management of Rockwood III-V Acute acromioclavicular joint dislocation (ACJD) without PICCAT with American Shoulder and Elbow Surgeons (ASES score) at one year. If the non-inferiority is reached, the non-inferiority of the conservative management over surgical the management of Rockwood III-V ACJD with PICCAT using ASES score at one year will be evaluated.

Secondary outcomes were radiological criteria (i.e. comparison of ipsilateral and contralateral coracoclavicular distance on anterior view; and dynamic posterior shaft of the cross-body adduction Basamania/Alexander view) return to sports, work absenteeism, complication rate, cosmetic results, patients satisfaction, Constant score, Single Assesment Numeric Evaluation (SANE) score, Acromioclavicular Joint Instability (ACJI) score, ASES score at others timepoints, and range of motion of the implicated shoulder. Finally, multivariable regression analysis will be performed in order to evaluate the impact of predictors of interest on ASES score at one year.

Background and rationale:

ACJD can be either managed conservatively or surgically. Concerning functional outcomes, it usually accepted that ACJD Rockwood state I and II should be treated conservatively.It is still debated whether grade III should be treated surgically or not, and only experts opinion suggest that grade IV and V has better surgical outcome than conservative. The main literature failed to demonstrate the superiority of the surgical management for functional outcomes. Despite this, operative management results in a better cosmetic outcome, but conservative management is associated with a lower duration of sick leave and lesser costs. It has been purposed by a worldwide expert consensus (ISAKOS consensus) that dynamic posterior clavicle impaction into the trapezius muscle (PICCAT) could be a predictive factor of poor functional outcome in case of conservative management.

Hypothesis:

H0: ASES score at one year of follow-up is better with surgical management than with conservative management.

H1: one year ASES score after conservative management is not inferior as after surgical management. H1 will be first tested without PICCAT. If H1 is validated, it will then be tested again including all patients, PICCAT or not.

Study design:

This multicentric case-control study is randomized 1:1 between conservative and surgical treatment of ACJD. It is a non-inferiority trial that includes 176 patients that suffers from acute ACJD Rockwood grade III-V. Conservative management will consist of a sling for 10 days followed by a standardized physical therapy program, (Cote et al. 2010) and surgical management will consist of coracoclavicular and acromioclavicular fixation and specific rehabilitation. Clinical follow-up will last one year.

Statistical analysis

Non-inferiority statistical analysis will be performed upon appropriate unilateral 95% confidence interval margin (Z = -1.645), with a non-inferiority margin of 6.4, corresponding to ASES minimal clinically important difference. Analysis is planned in case of "intention to treat" method, but, if patients of the conservative management group undergo surgery because they are unsatisfied, ASES score will be measured prior surgery instead of at one year of follow-up. No statistical adjustments on potential confounders are planned.

Sample size calculation:

ASES score minimal clinically important difference has been estimated to 6.4. ASES standard deviation after surgical management of ACJD has been estimated to 9.7. If there is truly no difference between the surgical and conservative treatments, then 80 patients are required to be 90% sure that the lower limit of a one-sided 95% confidence interval (or equivalently a 90% two-sided confidence interval) will be above the non-inferiority limit of -6.4. Mazzoca, one of the main authors of ISAKOS consensus (ISAKOS), has reported operating 50% of Rockwood type III-V ACJD. From this, we can strongly suppose that 50% of Rockwood type III-V ACJD presents PICCAT. Considering a 10% of drop-outs, we therefore need 80/(50%)*110% = 176 patients.

Inclusion Criteria:

• acute (less than 10 days) ACJD , with possibility to perform surgery within 10 days after the trauma

Exclusion Criteria:

• Rockwood grade I, II, or IV ACJD
• Significant other trauma of the involved upper member requiring surgery
• Associated scapula or clavicle fracture
• Polytrauma inducing significant limitation of rehabilitation process
• Inability to follow properly conservative management or post-surgery recommendations
• Patients suffering from symptomatic anaemia, or patients with severe cardiorespiratory insufficiency
• Known or suspected non-compliance, drug or alcohol abuse
• Patients incapable of judgement or under tutelage
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant
• Enrolment of the investigator, his/her family members, employees and other dependent persons