SHOULDER
Acromioclavicular stabilization
Injuries to the acromioclavicular joint are caused by a direct blow to the shoulder, or a fall onto the shoulder, resulting in axial loading of the shoulder and downward movement of the acromion, while the clavicle moves upwards. This movement can disrupt the joint and surrounding ligaments. The degree of injury can vary from a minor sprain to complete rupture of the joint, depending on the force applied.
Prevalence
Injuries to the acromioclavicular (AC) joint are common, accounting for around 9% of all shoulder girdle injuries. These injuries are more common in men and athletes, due to their high-risk activities. The incidence of AC joint injuries is relatively high in contact and collision sports, such as soccer, field hockey and rugby. Other sports, such as skiing, cycling and wrestling, also present a risk of acromioclavicular joint injury.
Symptoms and diagnosis
Lesions of the acromioclavicular joint usually present with pain, which is usually felt over the acromioclavicular joint, but can also be referred to the trapezius. Physical examination usually reveals tenderness of the lateral clavicle or acromioclavicular joint, and an abnormal contour of the shoulder compared to the contralateral side. Stability assessment consists of evaluating both the horizontal (anterior-posterior) and vertical (superior-inferior) stability of the joint. Exacerbation tests, such as the O’Brien test, may also be performed.
X-rays play an essential role in the diagnosis and management of lesions. Fractures can mimic acromioclavicular separations, such as the base of coracoid fractures or Neer 2A-type distal clavicle fractures (ligaments remain attached to the distal fragment while the proximal fragment moves), making it important to correctly diagnose the type of injury for appropriate management.
Categorization of acromioclavicular joint instability
The Rockwood classification is a widely used system for categorizing acromioclavicular joint instability. It classifies joint injuries according to severity and joint displacement. It helps guide treatment decisions and provides prognostic information on acromioclavicular joint instability:
- Type I: This is a mild injury in which the joint is sprained but remains stable. There is no significant joint displacement.
- Type II: In this type, there is a partial tear of the acromioclavicular ligaments, resulting in some degree of joint separation. The joint remains stable, but there is significant displacement of the clavicle in relation to the acromion.
- Type III: This type involves complete tearing of the acromioclavicular ligaments, resulting in significant joint separation. The coracoclavicular ligaments may also be partially torn, causing further instability. The joint is unstable and the clavicle is significantly elevated in relation to the acromion.
- Type IV: This type represents a more severe injury where the acromioclavicular and coracoclavicular ligaments are completely torn. The clavicle is displaced posteriorly, behind the acromion.
- Type V: This type involves complete tearing of the acromioclavicular and coracoclavicular ligaments, similar to type IV. However, in Type V injuries, the clavicle is displaced downwards.
- Type VI: This is the most severe type, characterized by complete rupture of the acromioclavicular and coracoclavicular ligaments, and detachment of the clavicle from the acromion. The clavicle may be displaced downwards, backwards or forwards of the acromion.
Management of acromioclavicular joint injuries
Conservative management with brief sling immobilization, rest, ice and physical therapy is indicated for types I, II and type III in most individuals, particularly when the clavicle is displaced by less than 2 cm. Rehabilitation generally involves early mobilization of the shoulder to regain functional movement at 6 weeks, and return to normal activity at 12 weeks. In certain chronic cases associated with osteoarthritis, corticosteroid injections may be considered. Studies have shown that type III injuries treated conservatively have higher functional scores than those treated surgically. Complications of non-operative management may include arthritis, chronic subluxation and instability.
Arthrex GmbH 2024
Surgical management of acromioclavicular joint injuries involves two main techniques: open reduction with internal fixation or coracoclavicular ligament reconstruction. Surgical indications include acute type IV, V or VI injuries, and acute type III injuries in workers, high-level athletes or patients with aesthetic problems. In addition, chronic Type III injuries that have failed conservative treatment may also benefit from surgical intervention. Techniques for coracoclavicular ligament reconstruction include autograft or allograft reconstruction. Fixation, if carried out within the first 3 weeks, can avoid the use of a tendon graft with a plate-and-wire system (TightRope®/FiberTape®). Only in cases where the coracoid does not represent a solid fixation point can the hook plate be used.
Arthrex’s Twin Tail TightRope® technique is a minimally invasive procedure using a suture-building implant. Through an incision in the acromioclavicular joint, tunnels are created in the clavicle and acromion (part of the scapula), enabling the implant to be placed. After adjusting the tension on the implant to restore joint alignment and stability, special buttons are used to fix the implant in place on both sides of the joint. This technique results in less tissue damage and potentially faster recovery than traditional open surgery.
Post-operation
After the operation, patients are immobilized in a sling for two weeks without moving the shoulder. Controlled active mobilization is often possible by the third week after surgery. Full activity, including shoulder-impact competitions, can be resumed after six months of rehabilitation. As with any surgical procedure, surgical treatment of acromioclavicular joint lesions carries risks and potential complications. A common complication is residual joint pain, which occurs in 30-50% of cases. Arthritis is also more common with surgery than with conservative treatment.
