The acromioclavicular joint is an important hub between the shoulder girdle and the trunk, and the stresses acting on the upper extremity are transmitted through the acromioclavicular joint. Therefore, injury to the acromioclavicular joint is one of the most common shoulder injuries. Injuries to the acromioclavicular joint can cause dysfunction of the entire upper extremity and seriously affect the quality of life of the patient. However, the choice of treatment for acromioclavicular joint injuries is still very controversial. Whether surgical or conservative treatment is used, the acromioclavicular joint will remain dysfunctional to varying degrees. Therefore, the choice of treatment modality and the corresponding rehabilitation are crucial for the functional recovery of the acromioclavicular joint. In this article, we will review the treatment strategies for the acromioclavicular joint.
I. Anatomical overview of the acromioclavicular joint
The acromioclavicular joint consists of the acromion and the distal clavicle in terms of bony structure. The acromioclavicular ligament mainly maintains stability in the horizontal direction; the rostral ligament mainly maintains stability in the vertical direction. The rostral collar ligament is more important for the function of the acromioclavicular joint. The rostral ligament consists of two parts, the medial conical ligament and the lateral rhomboid ligament. The tapered ligament starts at the medial rostral root and ends vertically upward at the lower surface of the clavicle; the rhomboid ligament starts above the rostral root and ends obliquely laterally at the lower surface of the clavicle.
1. An articular disc exists within the acromioclavicular lock, and the articular disc can be classified into three types.
(1) Complete articular disc.
(2) Semilunar discs.
(3) Absent articular disc.
The articular disc has a protective effect on the articular cartilage, and according to the literature, there is no degeneration of the articular cartilage when the disc is normal. With age, the articular disc gradually wears out. In the case of shoulder lock joint injury, especially shoulder lock joint dislocation, along with the damage to the soft tissues around the joint, mainly ligaments, the articular disc is also damaged.
Second, the subtypes of acromioclavicular joint dislocation.
The most commonly used subtype of acromioclavicular dislocation is the Rockwood subtype. According to this type, acromioclavicular dislocation can be divided into 6 types: Type I is a contusion or partial rupture of the acromioclavicular ligament, with no significant instability of the acromioclavicular joint and no widening of the joint space visible on imaging; Type II is a complete rupture of the acromioclavicular ligament and a contusion of the rostral ligament, but the shape is intact, and only the widening of the rostral joint space without the upward displacement of the distal clavicle; Type III is a complete rupture of the rostral ligament, with the acromioclavicular joint in the vertical position. In type IV, the clavicle is dislocated posteriorly into the trapezius muscle; in type V, the clavicle is dislocated upward to 100%-300% of the clavicle thickness; and in type VI, the clavicle is dislocated inferiorly to the sub rostral process. In this type, the clavicular end is dislocated inferiorly to the rostral process. Type I, type II and type III injuries are common.
Treatment strategies for acromioclavicular joint dislocation
1. Type I and II dislocations.
The main conservative treatment, type I injury can generally resume normal activities in 1-3 weeks. Type I injuries can generally resume normal activities in 1-3 weeks, while type II injuries generally resume normal activities in 2-12 weeks. Conservatively treated acromioclavicular dislocations were followed up for 10.2 years, and at the last follow-up, about half of the patients had functional impairment of the acromioclavicular joint. Thus the long-term outcome of type I and type II acromioclavicular dislocations is very uncertain.
2. Type III injury.
It is very controversial in terms of treatment and generally tends to be treated conservatively.
In recent years, a large number of clinical studies have shown that surgical treatment is not better than conservative treatment, and that surgical treatment has more complications, longer recovery time and longer return to work. In a meta-analysis of the literature on grade III acromioclavicular dislocation, Phillips et al. concluded that conservative treatment is significantly better than surgical treatment in terms of patient satisfaction, shoulder mobility, and postoperative complications. The only advantage of surgical treatment is anatomical repositioning and reduction of shoulder deformity. However, the degree of shoulder deformity does not correlate well with the long-term pain and mobility of the shoulder.
While some authors advocate surgical treatment in some specific cases, Gstettner et al. studied 24 patients who underwent surgical treatment and 17 patients who underwent conservative treatment for type III acromioclavicular dislocation in a comparative study with a 34-month follow-up. the authors used clavicular hook plate fixation and applied a sling brake for 4 weeks after surgery, after which the patients were allowed to perform supination and abduction activities. The results showed better functional recovery with surgical treatment than with conservative treatment. The authors concluded that surgical treatment should be performed for type III acromioclavicular dislocation, especially in young, active patients.
3. For type IV, V and VI, surgical treatment is generally adopted.
IV. Treatment methods
1.Conservative treatment.
Mainly for the application of sling suspension fixation. Apply painkillers and physical therapy to reduce pain. Conduct functional exercises until full-amplitude movement is achieved.
2.Surgical treatment.
(1) Apply K-wire or clavicle hook plate fixation.
Key points of surgery: the torn joint disc needs to be excised. Repair the acromioclavicular and rostral ligaments, and repair the torn deltoid and trapezius fascia.
(2) Weaver-Dunn surgery.
Reconstruction of the rostral collar ligament using transposition of the rostral shoulder ligament. A wire or outline cable is also used for fixation between the rostral process and the clavicle.
(3) Dynamic reconstruction surgery
Dynamic reconstruction is a surgical method in which the short head of the rostro-humeral muscle and biceps muscle are chiseled down at the attachment point of the rostral process together with part of the bone and fixed superiorly on the clavicle. This method is more suitable for young adults because they have more developed muscles and can reposition the acromioclavicular joint by traction with the movement of the upper arm. This method has a low recurrence rate of re-dislocation, but it causes more damage, and when the affected limb is lifted up, the two ends of the joint surface are prone to friction and collision, which will accelerate the degeneration of the acromioclavicular joint and lead to acromioclavicular arthritis. Therefore, the distal clavicle was removed 0.5~1 cm on the basis of this operation to reduce the occurrence of acromioclavicular arthritis.
(4) The principles that should be followed in the surgery of acromioclavicular dislocation are
(1) Remove the scar tissue and blood clot from the dislocation to achieve anatomical repositioning;
(2) Repair and reconstruct the corresponding ligaments and joint capsule to maintain the muscle balance of the shoulder joint;
(3) Reliable fixation to achieve firm healing of the ligament;
(3) Reliable fixation to achieve firm healing of the ligaments; (4) Early and painless functional exercise to prevent the occurrence of periarticular histopathy.