Shoulder lock joint dislocation is a common traumatic disorder in clinical practice, and there are various treatment methods, but there is no uniformity in the choice of treatment method among physicians. For larger dislocations, most physicians prefer surgical treatment. The clinical treatment should not only consider the patient’s condition and the classification of the fracture dislocation, but also consider the patient’s economic status and occupation, age and subjective desire, etc., to carry out individualized treatment. The following is a discussion of some of the issues of conservative treatment.
Dislocation of the acromioclavicular joint is one of the common injuries to the shoulder, mostly caused by direct violence, and its incidence accounts for 4.4% to 5.89% of all fractures and dislocations. Dislocation of the acromioclavicular joint accounts for about 12% of shoulder injuries.
Anatomical features
The acromioclavicular joint is a joint that consists of the inner edge of the acromion and the outer end of the clavicle, and its joint stability is maintained by three parts: (1) the acromioclavicular ligament formed by the joint capsule and its thickened part; (2) the tendon attachment part of the deltoid and trapezius muscles; and (3) the rostral ligament (trapezius ligament and tapered ligament) from the rostral process to the clavicle. The average distance between the clavicle and the rostral process is 1.2 cm (1.1 to 1.3 cm).
The acromioclavicular joint is functionally a micromotor joint with three basic forms of motion: up and down, anterior and posterior, and rotation. The acromioclavicular joint is a force transmission joint and is the support point for the flexible movement of the shoulder joint. Therefore, when a dislocation of the acromioclavicular joint occurs, it not only produces symptoms such as pain and abnormal movement of the acromioclavicular joint, but also greatly affects the strength and flexibility of movement of the entire upper limb.
Biomechanics
Klassen et al[ 1] studied the strength and stiffness of the ligaments around the acromioclavicular joint and found that the strength and stiffness of the acromioclavicular capsule ligament complex (the joint capsule and the superior, inferior, anterior and posterior acromioclavicular ligaments) were the strongest, followed by the conical ligament and finally the oblique ligament; the most frequent location of ligament rupture was in the central part of the ligament, and simple ligament attachment point avulsions were rare, and even if they existed, they were mostly accompanied by rupture in the central region If it is present, it is usually accompanied by rupture of the central region.
The acromioclavicular ligament Fukuda et al [2] found that the acromioclavicular ligament is mainly resistant to stress during minor displacement (physiological stress during daily range of motion) and the conical ligament is mainly resistant to stress during significant displacement (stress during injury); the acromioclavicular ligament is the main force against posterior displacement and posterior axial rotation in both minor and significant stress displacements. Debski et al [3] demonstrated that after severing the acromioclavicular capsule, 100% of the clavicle underwent anterior-posterior movement.
The rostral clavicular ligament Fukuda et al [2] found that the tapered ligament mainly resists the forces of forward and upward rotation and displacement. It is subjected to a significant increase in stress during significant displacement. Although the oblique ligament plays a small role in horizontal displacement and resistance to upward displacement, it is responsible for the majority (75%) of the stresses against the acromioclavicular joint compression. After cutting the acromioclavicular capsule and ligaments, the oblique ligament increased its resistance to posterior stress by 66% (50% greater than the tapered ligament).
After cutting the capsule, the tapered ligament increased by a factor of 2 in resistance to forward stress, while the rhomboid ligament increased by a factor of 1. Harris et al [30] measured the fracture loads of the rostral locking ligament (tapered and rhomboid ligaments), tapered ligament, and rhomboid ligament under uniaxial loading, which were 500, 394, and 44O N, respectively, with the tapered ligament having the greatest stiffness (105 N/mm). They concluded that simply cutting the tapered or rhomboid ligaments had no effect on the total tension strength of the rostral locking ligaments.
Rockwood et al [4] found that although there was 40-500 rotation of the clavicle during upper extremity supination, the true acromioclavicular motion was only 5-80 due to simultaneous scapular and clavicular motion.Some authors concluded that there should be a slight axial rotation of the distal clavicle during normal shoulder supination and that any acromioclavicular fusion would affect and limit upper extremity supination, therefore after fusion or after strong After fixation (rostral locking screws, plates) of the clavicle and scapula, high intra-articular stresses can occur, clinically manifested by fracture or displacement of the internal fixation, and loss of repositioning after internal fixation.
Mazzocca AD et al [5] used 42 cadaveric models to evaluate the biomechanics of different procedures of rostral-clavicular ligament reconstruction and concluded that anatomical reconstruction of the rostral-clavicular ligament maintains a stable position and less anterior-posterior displacement than the modified Weaver-Dunn procedure, which is closer to the physiological condition and better maintains the function of the acromioclavicular joint.
Mechanism of injury
Most dislocations of the acromioclavicular joint are caused by direct violence. The result is that if the clavicle is not fractured, the acromioclavicular and rostral ligaments rupture and the acromioclavicular joint dislocates. A few are caused by indirect violence, with fractures and dislocations caused by the conductive stresses generated during a fall on the elbow or hand in the extended position, commonly seen in ball and punching sports injuries [6, 17].
Injury classification system
Type I: incomplete rupture of the acromioclavicular ligament, intact rostral ligament, and mild displacement of the clavicle on X-ray; Type II: complete rupture of the acromioclavicular ligament and strain on the rostral ligament, with half of the diameter of the outer end of the clavicle protruding upward beyond the acromion on stress X-ray; Type III: complete rupture of the acromioclavicular ligament and rostral ligament, with a piano key-like sign ( Type III: complete rupture of the acromioclavicular ligament and rostral collarbone ligament, with piano sign and complete displacement of the distal clavicle on X-ray.
Post grading: there are 6 grades: grade I: mild injury, partial ligament injury of acromioclavicular joint; grade II: moderate injury, rupture of acromioclavicular capsule and acromioclavicular ligament rupture, often causing subluxation; grade llI: severe injury, rupture of acromioclavicular and rostral ligaments, complete dislocation of acromioclavicular joint; grade 1V: acromioclavicular joint dislocation combined with rostral fracture, severe soft tissue injury, or the external end of the clavicle breaks the joint capsule Grade V: posterior dislocation of the lateral end of the clavicle, located behind the acromion; Grade VI: downward dislocation of the lateral end of the clavicle and rupture of the rostral ligament. This classification tends to be more detailed and accurate in terms of pathologic anatomy.
The acromioclavicular dislocation can be divided into three types according to the Allman method: type I refers to partial tearing of the acromioclavicular capsule and acromioclavicular ligament, and the acromioclavicular joint is still stable; type II has a complete rupture of the acromioclavicular capsule and acromioclavicular ligament, while the rostral ligament remains intact and anterior-posterior instability occurs; type III has a complete rupture of the acromioclavicular capsule and acromioclavicular ligament rostral ligament, and the external end of the clavicle is separated from the acromion [28].
Currently, Rockwood classification [8] is mostly used, with six levels, which tends to be more detailed and accurate for pathologic anatomy. grade I: acromioclavicular ligament injury with intact rostral ligament and acromioclavicular joint remains stable; grade II: acromioclavicular ligament rupture and rostral ligament injury, often causing subluxation; grade III: complete rupture of both acromioclavicular capsule and rostral ligament, with 25% to 100% increase in rostral gap compared to normal; grade IV: for grade III Grade IV: Grade III with avulsion of the rostral clavicle ligament from the clavicle, accompanied by posterior displacement of the distal clavicle into or through the trapezius muscle; Grade V: Grade III with vertical displacement of the clavicle from the rostral clavicle gap of the scapula by 100% to 300% more than normal, with the clavicle located subcutaneously; Grade VI: Grade III with dislocation of the lateral end of the clavicle downward, located under the rostral process, this type is rare.
There is also a variant of type III injury, namely Salter-Harris injury [27], which includes distal clavicular epiphysis injury, rostral fracture and acromioclavicular joint dislocation. Because of the late closure of the distal clavicular epiphysis (18-22 years of age), this injury can also occur in young people. In this case, the acromioclavicular joint is intact, the rostral ligament is attached to the intact periosteal sheath, and the clavicle epiphysis and cadaver are displaced upward through the musculoperiosteal rupture.
Radiographic examination
X-ray examination of the acromioclavicular joint includes: anteroposterior, axillary and Zanca oblique views of the acromioclavicular joint, and stress X-rays can be taken in special cases. CT examination can better show the degree of posterior displacement of the clavicle in case of type IV injury. If the axillary radiograph does not clearly reflect the rostral fracture, a Stryker notch position (patient in supine position with the upper limb raised over the head in forward flexion and the tuberosity tilted l0 degrees to the side of the head, projected from above and downward) radiograph should be taken. If the rostral fracture involves the glenohumeral joint, CT can be performed to determine the degree of intra-articular displacement; if a child is suspected of acromioclavicular dislocation and the radiograph shows an enlarged rostral gap, the presence of a Salter-Harris fracture should be examined, and CT or MR examination can help diagnose such fractures.
Current status of conservative treatment methods
In the past, conservative treatment for mild and moderate acromioclavicular dislocation usually achieved satisfactory results; however, there are differences in the treatment of severe acromioclavicular dislocation between authors, and most of them believe that non-operative treatment is difficult to be effective, and the effect of appropriate conservative treatment has yet to be evaluated, and no detailed evaluation data are available.
It is not difficult to reset the dislocated shoulder, but it is not easy to maintain the position after external fixation.
The most commonly used method is the adhesive tape fixation method, in which the lateral end of the high convexity of the clavicle is pressed downward and forward with a soft roll under the axilla, and the affected limb is suspended and braked for 3 weeks and then active or passive exercise is performed. This method has the disadvantage that the adhesive tape falls off and the fixation strength is not enough. More commonly used is also the plaster strip fixation method, but this method is prone to complications such as skin pressure sores, which are difficult for many patients to tolerate. The above methods are generally used for patients with partial dislocation, but they do not maintain the alignment relationship well for total dislocation.
Huang Gongyi et al. first used ZERO position fixation to treat 23 cases of fresh acromioclavicular dislocation and achieved good results. The principle is that the upper arm abduction and forward elevation in this position reach 155° each, so that the acromion end of the scapula and the lateral end of the clavicle come together to achieve repositioning and fixation of the acromioclavicular joint, thus facilitating the repair of the injured ligaments and joint capsule. This method is suitable for patients with fresh partial dislocation of the acromioclavicular joint and partial complete dislocation, confirming appropriate external fixation, and can also treat severe fresh acromioclavicular joint dislocation. However, the elevation of the affected arm is required to reach 130°, the patient should have good tolerance, and attention should also be paid to vascular and neurological complications.
Zhang Xishan et al. treated 34 cases of acromioclavicular joint dislocation with an adjustable abduction frame. 23 cases had excellent efficacy, 9 cases had good efficacy, and 1 case could be treated according to Imatani’s scale. None of the cases had complications such as skin and neurovascular injury, and the comparison showed that the shorter the duration of the disease, the better the treatment effect, providing a treatment method for fresh acromioclavicular dislocation with postural repositioning. The benefits of this method are overcoming the weight of the upper limb, reducing the tendency to separate the distal end of the acromioclavicular joint or clavicle, and having the effect of bringing the distal side of the injury closer to the proximal side.
Beijing Luo Youming Hospital of Traditional Chinese Medicine [17] used double “∞” bandages with special spacers to treat patients with various types of acromioclavicular dislocations and distal clavicle fractures. The method is to cut a cardboard according to the shape of the distal clavicle, usually crescent-shaped, with the length equivalent to the length of the clavicle, and tape it on both sides. The cardboard is then placed under the axilla with a cotton ball wrapped in a square towel and tied with an oblique “∞” bandage. Then use the posterior “∞” bandage to keep the chest posture. Suspend the affected limb in front of the chest and fix it for 3-8 weeks.
Liu Wei of Luoyang Orthopaedic Hospital in Henan, China made the elastic repositioning band of clavicle to treat 68 cases of acromioclavicular joint dislocation and distal clavicle fracture, and the tensile force of the elastic repositioning band was 3.65 KG for every 10 MM extension within the elastic range. Zhang Yajun used the elastic repositioning fixation belt to treat 14 cases of acromioclavicular joint dislocation and distal clavicle fracture, 11 cases were anatomically repositioned, 2 cases were partially repositioned, and 1 case did not adhere to the treatment and the deformity healed.
Chen Wanguo et al. applied homemade shoulder and elbow elastic fixation belt to treat various types of acromioclavicular joint dislocation with an excellent rate of 90%. Cui Xiquan et al. treated Tossy type II acromioclavicular joint dislocation with the application of shoulder and chest belt fixation, and the excellent rate was 100%.
Jiang Tao et al. of Guangdong Provincial Hospital of Traditional Chinese Medicine used their own patented shoulder locking belt to maintain a certain degree of abduction and pressure on the distal clavicle to treat acromioclavicular dislocation, which also achieved good results, especially for Rockwood V type cases.
Indications for conservative treatment of acromioclavicular joint dislocation
Rockwood type I and II, suspension and fixation for 1-3 weeks.
Bradley and Elkousyt [13] concluded that all grade III injuries should be treated conservatively first, regardless of the patient’s occupation, and then surgically if they fail. The duration of suspension and immobilization is 3-4 weeks. The indications for type III injuries requiring one-stage surgery are (1) high aesthetic requirements or thin shoulder skin, (2) jobs involving repetitive heavy lifting, and (3) work with the shoulder in a prolonged forward flexion >90º position.
Patients with Rockwood V refuses to undergo surgery for various reasons, and it is confirmed by X-rays or the C-arm machine in revision that it can be repositioned by manipulation/ or postural repositioning, external fixation can maintain repositioning, and local conditions allow for conservative treatment, for example, no neurovascular injury and no obvious local pressure sores. Some patients with multiple traumas requiring bed rest due to compound injuries can also be treated conservatively with suspension and immobilization for up to 7-8 weeks if bedside revision and X-rays confirm repositioning.
For Rockwood IV/ or VI type, because the muscle is interlocked with the distal clavicle, most of them cannot be closed and reset, so it is better to be treated surgically; if the X-ray orthogonal film and axillary film in the revision confirm that they can be reset, they can also be treated conservatively, but they need to review the X-ray position several times at intervals, and the suspension and fixation time is up to 7-8 weeks, for adults 5-6 weeks external fixation, the fixation time is up to 7-8 weeks. In adults, 5-6 weeks of external fixation is insufficient and most patients remain dislocated.
Mouhsine et al. treated 37 cases of acute Tossy grade I-II acromioclavicular dislocation conservatively and found pain with activity in 7 cases, tenderness at the acromioclavicular joint in 12 cases, and degenerative changes at the acromioclavicular joint in 13 cases on radiographs. In 13 cases, the radiographs showed degenerative changes in the acromioclavicular joint. For Rockwood’s grade IV, V and VI injuries, surgery is currently advocated.
Rehabilitation after revision
The duration of braking in a cervical wrist sling varies according to the subluxation type, but for Rockwood I-III, small pendulum-like movements and passive external rotation exercises can be started 1 week after the injury under protection (with the patient pressing the distal clavicle with the opposite hand) and continued for 2-3 weeks. For Rockwood IV and above, the neck and wrist sling is applied for 7-8 weeks, during which time the physician directs functional activities. When the mobility reaches 80%-85% of the normal side. Sports are allowed to resume at 4 to 6 months postoperatively.
Patients with Rockwood type IV and above have been externally fixed for a long time, and because of the fear of aggravation of dislocation, the doctor ordered the patient to be more conservative in their activities, and the possibility of shoulder stiffness is relatively higher.
Complications of conservative treatment
1. Post-traumatic arthritis: Many scholars report that joint degeneration can occur after Tossy type I and II injuries, and the probability of developing symptoms is 48% with X-ray changes up to 75%. However, there is no clear relationship between the occurrence of symptoms and radiographic performance. If conservative treatment is not effective, distal clavicle resection can be considered. Type III injury may result in instability of the acromioclavicular joint if the distal clavicle is removed alone, so acromioclavicular joint stabilization (such as rostral ligament reconstruction, etc.) should be performed at the same time.
2, distal clavicle osteolysis: mainly manifested as pain (mostly occurs during abduction and flexion), but has a self-limiting tendency. osteolysis, osteoporosis, bone redundancy formation and distal clavicle acromegaly are seen on X-ray [23].
3, neurovascular injury: mostly due to brachial plexus nerve pulling caused by scapular band instability; or due to compression by too tight external fixation belt. If thoracic outlet syndrome is caused then vascular symptoms will occur. Generally, the symptoms can be improved by scapuloclavicular joint stabilization without releasing the nerve.
4.Osseous ossification of the rostral-clavicular space: whether treated conservatively or surgically, ossification of the rostral-clavicular space may occur. Ectopic calcification may occur around the injury area, or a bridge may be formed between the rostral process and the clavicle. The ossification of the rostral-clavicular space does not have much effect on function.
5. Postoperative loss of repositioning and re-dislocation: The rate of re-dislocation / or partial dislocation is high, but most patients with gradual loss of repositioning do not have obvious symptoms and mostly do not need reoperation. Only acute re-dislocations, especially those with fractures or broken internal fixations, require reoperation.
Although most patients with Tossy’s subtype I and II injuries can regain motion, they may also have residual symptoms. In a study of naval school students, 30% of Type I and 42% of Type II injuries complained of mild symptoms that did not interfere with activity; an additional 9% of Tossy Type I and 23% of Type II injuries had significant symptoms that could cause persistent pain or interfere with activity. Other studies have shown that patients with type II injuries are more likely to have degeneration of the acromioclavicular joint with weakness in rapid horizontal abduction and increased anterior-posterior motion. If the pain does not resolve within a few weeks, steroid hormone injections can be given into the acromioclavicular joint .
For old type III or greater acromioclavicular dislocations that are symptomatic and painful, the treatment is currently considered the same as for acute type IV acromioclavicular dislocations.
By experimentally measuring the effective pressure range required for the external fixation band to maintain the repositioning, observing the local sensation of the shoulder and the effect on the neurovascularity of the upper extremity when different pressure levels are applied, and observing the comfort and tolerance of the human body after external fixation to avoid complications such as skin pressure sores and neurovascular injury due to excessive pressure, we finally arrive at quantitative data that are effective and within the safe range. The design can also be used for standardized training of clinicians in the use of this external fixation method, i.e., with the premise of determining a reasonable amount of pressure applied to the shoulder, the physician can train and guide the required force in the use of the external fixation belt by feeling the pressure on the shoulder, etc.
We observed the repositioning and maintenance of repositioning of patients with V-degree acromioclavicular dislocation after fixation with the shoulder locking fixation belt under the C-arm-X machine to study the effect of upper limb position on repositioning.
We verified that in three patients with V degree dislocation, the same tourniquet pressure was applied after manual repositioning, and if the tourniquet pressure reached 4 KPa, the V degree injury could be reset to II-III degree under the surveillance of C-arm machine, at which time the position could be maintained by lightly moving the shoulder joint under the protection of suspension triangle scarf . In addition, for abduction supination of the forearm around 70º (for cases of V degree dislocation, the dynamic observation of 0-155º position is currently underway) can help reset the acromioclavicular joint dislocation to some extent in patients with type III and V dislocation; however, reset is difficult in cases of type IV dislocation, and the possible cause may be the interlocking clavicle such as the trapezius muscle If the distal clavicle can be unlocked and reset by manipulation, it may be possible to maintain the position.
In fact, we also have 2 cases of inpatients with type V who were successfully repositioned to type I-III with conservative treatment. We used them as study subjects and confirmed that both the shoulder lock fixation band and the postural position had some degree of repositioning effect.
In one of these 2 cases, there was mild skin reddening on the fourth day, and the pressure sore disappeared after keeping the forearm abducted and supinated in 70º position after adding a slight cushion and reducing pressure, so the key is whether the follow-up was followed up.
There are various treatment methods for shoulder clavicle dislocation, and scholars have different views, which focus on the final efficacy of non-surgical treatment versus surgical treatment. Some scholars believe that due to the complex local anatomical relationship of the distal clavicle and the imbalance of muscle strength after fracture, external fixation is difficult to achieve a lasting and stable fixation, and the only effective fixation method is internal fixation.
The procedure of external fixation must pay attention to whether the fresh dislocation can be repositioned manually and whether the repositioning is complete? How much pressure should be applied to reset? Can the repositioning be maintained by X-ray or C-arm machine during/after repositioning? If the subtype is a Rockwood IV or VI dislocation, manual repositioning is inherently difficult because of muscle interlocking, and it is unrealistic to hope for external fixation. In a patient over Rockwood IV in his 50’s, surgery is recommended; if external fixation is performed for 4-8 weeks, some patients will develop frozen shoulder after improvement of the dislocation.
In clinical practice, we have also treated patients who refused surgery for acromioclavicular dislocation type V with external fixation to turn a type V patient into a type II. The key is timely follow-up using an abduction 70º shoulder brace can reduce the tendency of dislocation. The other most critical issue is pressure sores, which are not a concern if used during hospitalization; the key is compliance.
Through clinical studies, we have realized that physician practice and patient compliance are critical issues in the treatment process. We have conducted a lot of experimental and clinical studies to standardize the practice of physicians and to avoid complications and other adverse events. However, the patient’s compliance is the guarantee of the follow-up treatment. The patient should be clearly explained while using external fixation, including the education on the use of external fixation apparatus and precautions, etc.
The treatment of shoulder injury is influenced by multiple factors, such as the patient’s economic status, the patient’s wishes, occupation, age, gender, physician’s level, medical unit conditions, and in China, probably mainly the cost, and how to obtain the best treatment with limited cost, which is also the problem of evidence-based orthopedic medicine.
Problems and Prospects
For example, the standardization of external fixation belt pressure, further improvement of apparatus, and whether external fixation can treat severe acromioclavicular dislocation injury; how to observe the biomechanics of external fixation on a living human body without harming the patient’s interests, which involves the ethics of medical research, these will be our next research topics.
Under the premise that China is not yet fully medically insured, such shoulder injuries are extremely common in small and medium-sized cities, such as in Wendeng Orthopaedic Hospital and Luoyang Orthopaedic Hospital, where there are a large number of such patients, so research on treatment options that meet Chinese conditions still has a broad development prospect.