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Biomechanics and treatment of acromioclavicular and sternoclavicular joint injuries
  1. Nicholas A Bontempo,
  2. Augustus D Mazzocca
  1. Department of Orthopaedic Surgery, University of Connecticut Health Center, Medical Arts and Research Building, Farmington, Connecticut, USA
  1. Correspondence to Augustus D Mazzocca, Associate Professor, Department of Orthopaedic Surgery, University of Connecticut Health Center, Medical Arts and Research Building, 263 Farmington Avenue, Farmington, Connecticut 06030, USA; mazzocca{at}


Acromioclavicular (AC) joint injuries are more common than sternoclavicular (SC) joint injuries. There is a spectrum of AC joint traumatic injuries that ranges from a ligament sprain to a complete dislocation. The majority of AC joint injuries are successfully treated non-operatively with a period of sling immobilisation followed by progressive physical therapy and shoulder range of motion exercises. In patients who have symptomatic AC joint injuries that are recalcitrant to non-operative treatment there exists a variety of surgical treatment options to reconstruct and stabilise the joint. The SC joint, like the AC joint, can suffer a spectrum of ligamentous injuries; however, when it comes to dislocation it can only dislocate anteriorly or posteriorly. Anterior dislocations are often successfully treated with closed reduction. Posterior dislocations have significant clinical implications because of the proximity of surrounding vessels and nerves. Any attempt at reduction of a posterior dislocation requires the presence of a cardiothoracic surgeon. The majority of AC and SC joint injuries typically result in ligamentous sprain and heal uneventfully with a period of immobilisation. If, however, patients remain symptomatic after non-operative treatment or have a dislocated joint, there are reduction manoeuvres and surgical techniques that allow joint stabilisation.

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The acromioclavicular (AC) joint is the articulation between the distal clavicle and scapula and injuries of this joint represent 9% of all shoulder girdle injuries. It has been previously reported that 43.5% of AC joint injuries occur in patients in their twenties. AC joint injuries are five times more common in men and are twice as likely to be incomplete, rather than complete.1 AC joint separations have been found to be the third most common injury in division 1 college hockey teams and account for as many as 40% of the shoulder injuries seen in National Football League quarterbacks.2 3

Injuries to the sternoclavicular (SC) joint, by contrast, are very rare. In one large study conducted by Rowe and Marble, out of 1603 shoulder girdle injuries there was only a 3% incidence of SC joint injuries.4 This is in comparison to an 85% incidence of glenohumeral injuries and a 12% incidence of AC dislocations.

In this article we will present a current review of the biomechanics, evaluation and treatment of AC and SC joint injuries.

AC joint

Anatomy and biomechanics

The articulation of the acromion and the distal clavicle represents a diarthrodial joint with four planes of motion: anterior/posterior and superior/inferior. The AC joint is surrounded by a capsule and has intra-articular synovium and an articular cartilage interface. The hyaline cartilage becomes fibrocartilage by age 17 on the acromial side of the joint and by age 24 on the clavicular side.1 A meniscal homologue, which has a large variation in both shape and size, is present within the joint. DePalma et al, Petersson and Salter et al have shown that as one ages the meniscal homologue degenerates rapidly and is no longer functional after the fourth decade.5,,7 The average size of the adult AC joint is 9 mm by 19 mm, but tremendous variation has been documented.8 The true articular portion of the distal clavicle varies in both location and size. Articular cartilage can cover the entire distal clavicle or it can cover a smaller percentage, which can complicate the fixation and treatment of AC joint injuries.

Stability at the AC joint is achieved through a combination of both static and dynamic stabilisers. There are four AC ligaments: superior, inferior, anterior and posterior. The AC joint capsule and the AC ligaments resist movement of the distal clavicle primarily in the horizontal plane (anterior to posterior direction) with respect to the scapula.9 Resistance to posterior translation is important because instability of the distal clavicle in the posterior direction can lead to abutment with the spine of the scapula (figure 1).10

Figure 1

Anatomical drawing of the ligamentous (L) structures surrounding the glenohumeral and acromioclavicular joints.

The coracoclavicular (CC) ligament complex is the primary restraint to vertical (superior to inferior) translation at the AC joint, but it has significant influence in the horizontal plane as well.11 This complex is comprised of the conoid and trapezoid ligaments. In addition to stabilising the AC joint in the vertical plane, the CC ligaments also strengthen the AC articulation and mediate scapulohumeral motion by attaching the clavicle to the scapula. The osteology of the clavicle and anatomy of the CC ligaments have been studied in cadavers and can aid in reconstruction.12 The radiographic anatomical distance between the coracoid and the clavicle has been found to range between 1.1 and 1.3 cm.13 This anatomical distance is important when reviewing radiographs of a suspected AC joint injury and when trying to restore normal functional anatomy during reconstruction of the CC ligaments.

Fukuda et al determined that, with small displacements at the AC joint, the AC ligaments are the primary restraint to posterior (89%) and superior (68%) translation of the clavicle.9 As displacement at the AC joint increases, the AC ligaments maintain their role in resisting posterior translation but the conoid ligament becomes the primary restraint to superior (62%) translation. The trapezoid ligament primarily functions to restrain compression at the AC joint with both small and large displacements, making it an important factor when considering operative reconstruction.

Mechanism of injury

Two common mechanisms account for AC joint injury: direct and indirect. The most common mechanism is a result of a direct force to the AC joint. A direct injury occurs when a person falls onto the AC joint with their arm at their side in an adducted position, as is commonly seen in collision sports such as hockey, football, rugby and karate. An indirect injury to the AC joint can also occur as the result of a fall on an outstretched hand. The fall typically drives the humeral head superiorly into the acromion.

Radiographic evaluation

One of the most important things to remember when obtaining an x-ray for evaluation of an AC joint injury is to reduce the penetration by one-third to one-half of that used for a standard glenohumeral x-ray. The axillary view is particularly helpful in visualising a type IV AC joint injury with a posteriorly displaced distal clavicle. When there is a normal CC interspace, but a complete dislocation of the AC joint, a coracoid fracture should be suspected. The best view to visualise a coracoid fracture is the Stryker notch view, which is taken with the patient supine and the palm on the affected side placed on the patient's head. The x-ray beam is then tilted 10° cephalad.

The Zanca view is the most accurate view to visualise the AC joint. This view is achieved by tilting the x-ray beam 10–15° cephalad and using one-half of the standard penetrance (figure 2A). Because of the significant variation in AC joint anatomy from one side to another, a bilateral Zanca view is recommended to visualise both AC joints on a single x-ray cassette while maintaining the same orientation of the x-ray beam. By visualising both AC joints on the same cassette, the CC distance can be compared from side to side, pre and postoperatively (figure 2B–D).

Figure 2

(A) Proper positioning of patient in relation to the x-ray beam for a Zanca view. To obtain this view the x-ray beam is angled 10–15° cephalad and the penetrance is reduced by half. (B) Bilateral Zanca view in a patient with increased left coracoclavicular distance. (C) Bilateral Zanca view in a patient 2 days after undergoing an anatomic coracoclavicular reconstruction and overcorrection of coracoclavicular distance. (D) Bilateral Zanca view in a patient 2 months after undergoing an anatomic coracoclavicular reconstruction and maintenance of coracoclavicular distance.

Basmania has described a cross arm adduction view of the AC joint.14 This view is taken with the arm forward elevated to 90° and adducted across the body. If the clavicle overrides the acromion on this view, the injury is considered unstable.

On standard x-rays, it has been reported by Zanca that the AC joint space is between 1 and 3 mm, but decreases with age.15 Bearden et al reported that an increase in the CC interspace by 25–50%, when compared with the uninjured side, indicates complete disruption of the CC ligaments.13

Physical examination, classification and diagnosis

Patients will complain of pain in the superior anterior aspect of the shoulder. Examination of the patient with a suspected AC injury should be done with the patient standing or sitting which allows the weight of the arm to stress the AC joint and exaggerate any deformity. Traumatic pathology of the AC joint is identified by pain, swelling and point tenderness at the AC joint. If a patient has more pain than is expected for a simple AC joint injury, then there should be high suspicion for a coronoid fracture or a type IV injury with displacement of the clavicle through the trapezial fascia.

The radiographic classification of AC joint injuries, as originally described by Tossy et al and Rockwood et al, represents a continuum of increased soft tissue injury (figure 3).1 16 In type I the AC ligaments are sprained, but the joint is intact. In addition there is no palpable displacement of the joint itself. These injuries result in minimal to moderate tenderness and swelling over the AC joint. Patients typically have only minimal pain with movement of the arm. Radiographically there may be mild soft tissue swelling, but there is no widening, separation, or deformity at the AC joint.

Figure 3

Acromioclavicular joint injuries, types I–VI.

With type II injuries, the AC ligaments are torn, but the CC ligaments are intact. Type II injuries are characterised by moderate to severe pain at the AC joint. The distal end of the clavicle may be palpated to be slightly superior to the acromion and shoulder motion produces more pain at the AC joint. The distal clavicle is also found to be unstable in the horizontal plane if grasped and moved anterior to posterior. A bilateral Zanca view may demonstrate that the distal clavicle is slightly elevated, but the CC interspace is the same in both the injured and uninjured shoulders.

Patients with type III injuries present with the upper extremity in a supported, adducted and elevated position to help relieve pain. In type III injuries both the AC and CC ligaments are torn, but the deltoid and trapezial fascia are intact. The distal clavicle may be prominent enough to tent the skin and is unstable in both the vertical and horizontal planes. These patients have a severe amount of pain with tenderness to palpation at the AC joint. Any movement of the arm, especially abduction, creates pain and discomfort, especially for the first 1–3 weeks. Both plain and bilateral Zanca x-rays reveal that the distal clavicle is 100% displaced superiorly in relation to the acromion. In actuality, the position of the clavicle is not altered by the injury. The weight of the upper extremity causes the acromion to displace inferiorly in relation to the horizontal plane of the lateral clavicle. In obvious cases of dislocation the clavicle is displaced superiorly from the acromion and the CC interspace will be greater in the injured shoulder. A shrug test has been described to differentiate a type III injury from a type V injury. If when the patient shrugs his or her shoulders the joint reduces, then the deltotrapezial fascia is intact and a type V injury can be ruled out.

Type IV injuries are characterised by complete dislocation with posterior displacement of the distal clavicle into or through the fascia of the trapezius. Physical examination of these patients reveals a greater amount of pain as compared with patients with type III injuries, and the pain is located more posteriorly. Examination of the seated patient from above will reveal that the distal clavicle is displaced posteriorly when compared with the uninjured shoulder. It is possible for the distal clavicle to become ‘button-holed’ in the trapezius and tent the skin posteriorly. With a type IV injury it is also important to examine the SC joint for a concomitant anterior dislocation. The posteriorly displaced clavicle is best appreciated on an axillary view of the shoulder.

Type V injuries represent a greater degree of soft tissue damage with the deltotrapezial fascia being stripped off the acromion and the clavicle. These injuries present as a more severe type III injury with more pain and a greater amount of displacement at the AC joint. The distal end of the clavicle appears to be grossly displaced superiorly towards the neck. The scapula is translated anteriorly and inferiorly as it migrates around the thorax. On bilateral Zanca view there is 100–300% increase in the CC interspace. Patients with a type V injury may have pain in the neck or trapezius due to the disruption of the deltotrapezial fascia.

Type VI injuries are inferior AC joint dislocations into a subacromial or subcoracoid position. Three cases have been described by Gerber and Rockwood and other cases have been described by Patterson, McPhee, and Schwarz and Kuderna.17,,20 None of the cases described in the literature had accompanying vascular injuries. Type VI injuries are usually seen in high energy polytrauma patients. The mechanism of injury is extreme hyperabduction and external rotation of the arm combined with retraction of the scapula. Associated injuries include clavicle and upper rib fractures and upper root brachial plexus injuries. It is not uncommon for these patients to have transient paraesthesias that subside after reduction.

Non-operative treatment

The goal of treatment for AC joint injuries is pain-free shoulder movement with full range of motion and stability. Non-operative treatment is typically indicated in type I and type II injuries. Type III injuries are evaluated on a case-by-case basis with regard to treatment. Management of AC joint problems is dictated by the severity and chronicity of the injury and the patient's needs and expectations.21 The trend in recent literature is towards the initial non-operative management of these injuries. However, consideration of other factors such as type of sport, timing of injury relative to athletic season, or the throwing demands in an uninjured dominant arm may play a role in the decision-making process.22 Rockwood has previously reported that, in patients who participate in contact sports (football, hockey, soccer and lacrosse) where the risk of reinjury is high, non-operative treatment is recommended.1 In the small group of patients who have persistent pain and are unable to return to work or sports after non-operative treatment, then surgical stabilisation is encouraged.

Most non-operative treatment is centred on a brief period of immobilisation in a sling accompanied by ice and oral analgesic medication if tolerated. If a patient is in the acute phases of injury and is experiencing significant pain and discomfort, a sling may be utilised to reduce stress on the AC joint. Early initiation of range of motion activities assists in reducing pain and inflammation and expedites discharge from the sling. Mobility exercises are initiated within the first week of injury in an effort to decrease associated morbidity, followed by strengthening exercises. Full rehabilitation should be achieved within 6–12 weeks.

Particularly in patients with type III injuries, surgery may be indicated if symptoms persist after a complete course of rehabilitation (figure 4).23 It is important, however, to remember that, at 2-year follow-up, non-operatively versus operatively treated type III injuries have no difference in strength.24 In a prospective study of type III injuries conducted by Larsen and Hede, rates of persistent symptoms were similar between the operative (2/25, 8%) and non-operative (3/29, 10%) groups.25

Figure 4

An algorithm that can be used when treating a patient with an acromioclavicular joint injury.

Operative treatment

Operative treatment is generally the accepted method of management of type IV–VI injuries because of the associated morbidity of a displaced clavicle. There are four basic types of surgical procedures that have been described for treatment of these injuries. These include:

  1. primary repair of the AC joint with pins, screws or rods;

  2. distal clavicle excision with soft tissue reconstruction (Weaver Dunn);

  3. anatomic coracoclavicular reconstruction (ACCR);

  4. arthroscopic suture fixation.

Expanding upon the four basic types of procedures, some authors promote the combination of procedures as the appropriate treatment. Many of the procedures used today are combinations, modifications, or modifications on modifications of previously described procedures.

Primary AC joint repair

AC ligament repair was first advocated in 1963 by Sage and Salvatore, who also recommended reinforcement of the superior AC ligament with joint meniscus.26 Supplementation of this repair with transarticular smooth or threaded pins was subsequently advocated by many surgeons.13 27,,37 A plate across the AC joint has been described by several other authors, with good to excellent results ranging from 60% to 94%.38,,41

Distal clavicle excision with soft tissue reconstruction

Distal clavicle excision with soft tissue reconstruction was initially described in 1972 as the Weaver–Dunn technique (figure 5).42 The procedure involves resection of the distal clavicle followed by release of the CC ligament from its attachment on the acromion. The detached end of the ligament is then attached to the distal clavicle to help hold it in a reduced position. Transfer of the conjoined tendon, where the lateral half of the tendon is transferred to the distal clavicle, has recently (in 2007) been described (figure 6).43 Transfer of the conjoined tendon has been argued to be superior to the original Weaver–Dunn technique because the functioning CC ligament is left intact.

Figure 5

Weaver–Dunn procedure, which includes distal clavicle excision, followed by release of the CC ligament from its attachment on the acromion and reattachment of the ligament to the distal clavicle.

Figure 6

Transfer of the lateral half of the conjoined tendon to the distal clavicle as a soft tissue reconstruction of the acromioclavicular joint.

Anatomic coracoclavicular ligament reconstruction

ACCR was developed with the use of free grafts (figure 7).11 The ACCR procedure entails a diagnostic shoulder arthroscopy and arthroscopic distal clavicle excision. The AC ligament is detached from its acromial insertion and tied to the distal clavicle through two drill holes. A gracilis or semitendinosis autograft or allograft is then looped underneath the coracoid and through two drill holes in the clavicle. The graft is then tied to itself in a figure-of-eight fashion or fixed to the clavicle with interference screws. Several biomechanical studies have been completed which illustrate that ACCR more closely approximates the stiffness of the CC ligament complex and produces less anterior to posterior translation at the AC joint as compared with the Weaver–Dunne procedure.44,,47

Figure 7

Anatomic coracoclavicular ligament reconstruction where a free graft is looped around the coracoids and fixed to the clavicle through two drill holes.

Arthroscopic suture fixation

Recently in the literature two techniques for restoring the CC ligaments without a graft have been described. The first technique involves using two suture anchors through four drill holes in the clavicle for fixation.48 The suture anchors are fixed in the coracoid and tied over a bone bridge in the clavicle. As part of this procedure the CC ligament is transferred as well. Previously a technique was described using a single suture anchor.49 In a controlled laboratory study on cadaveric shoulders, two tightrope devices were used to reconstruct the CC ligaments through two single tunnels in the clavicle and coracoid (figure 8). Both studies report anatomic restoration of the AC joint with favourable biomechanical results.48 50

Figure 8

Single or double mini graft-ropes have also been used to reconstruct the coracoclavicular ligaments in an acromioclavicular joint injury.

SC joint

Anatomy and biomechanics

The SC joint is the only true joint connecting the axial skeleton to the shoulder girdle. Despite having such an important role, the SC joint lacks inherent bony stability and relies solely on ligamentous and capsular attachments. The SC joint articulation is held in place by the SC capsular ligaments, the costoclavicular ligaments and the interclavicular ligaments. Within the SC joint there is an intra-articular disc and the articular surface of the medial clavicle is covered with fibrocartilage. Of the ligaments surrounding the SC joint, the capsular ligament is the strongest and most important structure preventing upward displacement of the medial clavicle.51 The intra-articular disc resists medial displacement of the clavicle with compression. The SC joint is incongruous, as the medial clavicle is enlarged, bulbous and saddle-shaped, whereas the clavicular notch of the sternum is concave. Less than half of the medial clavicle actually articulates with the sternum. It has been shown that, in 2.5% of patients, the inferior aspect of the medial clavicle actually articulates with the superior aspect of the first rib (figure 9).52 A relatively large amount of motion is seen at the SC joint. There is approximately 30–35° of upward elevation, 35° of translation in the anterior to posterior plane and 50° of rotation around the longitudinal axis of the clavicle.53 54

Figure 9

Ligamentous anatomy surrounding the sternoclavicular joint.

Mechanism of injury

Traumatic injury to the SC joint is the most common cause of SC joint dislocations. Motor vehicle collisions and sports participation are the top two causes of traumatic SC joint injury.55,,57 Posterior dislocations of the SC joint typically occur as the result of a direct force to the anteromedial clavicle. Posterior dislocations also occur when a force is applied to the posterolateral shoulder, causing the shoulder to roll forward. Anterior dislocations, on the other hand, rarely occur as a result of direct trauma. Instead anterior dislocations can occur when an anterolateral force is applied to the clavicle and the shoulder is rolled backward. In three separate studies looking at SC joint dislocations, an indirect force was the most common mechanism of injury (figure 10).58,,60

Figure 10

The clavicular head can dislocate anteriorly or posteriorly in relation to the sternum.

Radiographic evaluation

A standard anteroposterior x-ray of the chest or SC joint may suggest an injury to the SC joint, however, this is not the best view for visualising the joint. Rockwood was the first to describe the serendipity view to assess SC joint injuries.58 The serendipity view is a bilateral view of the SC joints achieved by tilting the x-ray tube 40° cephalically and centred on the sternum (figure 11). A CT scan performed with the patient supine is the best modality for visualising and assessing for any SC joint injury (figure 12). With a CT scan, axial sections can be viewed of both the injured and uninjured sides on one image. Subtle differences from side to side can be picked up more easily by the physician looking at the axial views.

Figure 11

Positioning of a patient in relation to the x-ray beam for a serendipity view. The patient is supine and the x-ray beam is angled 40° cephalad to the patient.

Figure 12

Axial sternal CT scan image depicting a right posterior sternoclavicular joint dislocation.

Physical examination, classification and diagnosis

Often with an acute dislocation, either anterior or posterior, a palpable stepoff at the SC junction can be appreciated. Posterior dislocations, although rare, have more significant symptoms and implications. Posterior dislocations can be associated with venous congestion present in the neck or ipsilateral upper extremity from compression on the subclavian vessels. The posteriorly displaced clavicle can also compress the trachea or oesophagus and patients may complain of dyspnoea, choking, difficulty swallowing, or a tight feeling in the throat. In the most severe cases the posterior dislocation can result in complete shock or a pneumothorax.

For patients with a type I injury (mild sprain) there is usually mild to moderate pain associated with movement of the upper extremity. Instability is usually absent but the SC joint may be tender to palpation and slightly swollen. With this injury the ligaments remain intact, so the joint is not unstable. Type II injuries (moderate sprain) are associated with partial disruption of the ligaments. The joint may subluxate when manually stressed, but it is not grossly dislocatable. These patients usually have more swelling and pain than patients with type I injuries and the SC joint is more tender to palpation.

Type III (severe sprain) injury results in complete dislocation, either anterior or posterior, of the SC joint. Patients with this injury present with severe pain that is exacerbated by any movement of the upper extremity. The ipsilateral shoulder may appear protracted in comparison with the contralateral uninjured shoulder. Patients will often hold the affected arm across the chest in an adducted position and support it with the contralateral arm. The head may be tilted towards the side of the injured clavicle. Examination of the patient lying supine on the examining table will lead to a worsening of symptoms and the involved shoulder will not lie flat on the table.

Non-operative treatment

Type I and II injuries are often treated non-operatively. Non-operative treatment consists of a short period of immobilisation in a sling, oral analgesic medication and ice. After a short period of immobilisation the patient can gradually return back to activities based upon his or her own level of comfort. As in type II injuries where the clavicle is subluxated, the joint can be reduced by retracting the shoulders in a figure-of-eight brace. This treatment modality can be incorporated whether the subluxation is anterior or posterior. Both plaster and soft figure-of-eight braces have been described.61 62 McLaughlin recommends that, in addition to the figure-of-eight brace, the patient be given a sling to support the affected arm.63

When the SC joint is completely dislocated, as seen in a type III injury, an attempt can be made at closed reduction. For an anterior dislocation the patient should be placed supine with a roll in the centre of the back between the shoulder blades. This positioning allows the scapula to assume a retracted position and pull the clavicle laterally. A gentle pressure can then be applied to the anteromedial clavicle in order to reduce. Anterior dislocations are often easy to reduce; however, they are usually unstable and will dislocate once the pressure is released. If, however, the SC joint maintains reduction after closed means the patient should be immobilised in a soft figure-of-eight brace for a period of 6 weeks. Persistent pain at the SC joint can be managed by an ultrasound-guided corticosteroid injection.

Prior to any attempt at closed reduction of a posteriorly displaced clavicle, injury to local vessels, heart and lung needs to be ruled out. Closed reduction of a posterior dislocation should be done in the operating room with the patient under general anaesthesia. Similarly to an anterior dislocation, the patient should lay supine with a roll between the scapulae. Traction should then be applied to the abducted arm while it is slowly extended. Oftentimes the joint will reduce with this manoeuvre; if not the clavicle can be manipulated with the aid of a towel clip. Unlike anterior dislocations, posterior dislocations are usually stable once reduced. The patient with a reduced SC joint should then be placed in a figure-of-eight brace for 4–6 weeks while the ligaments heal. It is important to have a cardiothoracic surgeon present if the patient is taken to the operating room for an attempted closed reduction because of the potential complications that may arise as a result of the injury or the attempted reduction.

Operative treatment

Most SC joint dislocations are best managed non-operatively; either they may be left unreduced or an attempt at closed reduction may be made. Surgical stabilisation of the clavicle is not recommended by most authors.64 65 In most cases the benefits of surgery are outweighed by the risks. Numerous complications have been reported in the literature, including infection, recurrence, poor cosmetics and hardware migration. If patients develop symptomatic SC joint instability, then several surgical options exist. Good long-term outcomes have been reported in patients who have medial clavicle excision or SC joint reconstruction for SC joint instability.66 In a biomechanical analysis of reconstructions for SC joint instability, Spencer and Kuhn tested three SC joint fixation methods in a cadaveric study.67 They concluded that the figure-of-eight semitendinosus reconstruction provided superior biomechanical properties to subclavius tendon reconstruction and intramedullary ligament reconstruction (figure 13). Any surgery being performed for a posterior SC joint dislocation should be done with a cardiothoracic surgeon present due to risk of injury to surrounding structures.

Figure 13

Reconstruction of the sternoclavicular joint using a figure-of-eight semitendinosus graft provides superior biomechanical properties compared with subclavius tendon reconstruction and intramedullary ligament reconstruction.


In conclusion, both AC and SC joint injuries represent a spectrum of soft tissue injury ultimately leading to dislocation. Specific radiographic views are helpful in visualising these joints and it is sometimes necessary to get bilateral views to compare the injured side with the uninjured side. Both type I and type II AC and SC joint injuries can be treated non-operatively and patients have a good outcome. The treatment of these joint injuries differs as the amount of soft tissue disruption increases. Type IV and V AC joint injuries often require surgical intervention for successful outcomes. A grey area, however, exists for the treatment of type III AC joint injuries and multiple patient factors must be taken into account. Patients with type III AC joint injuries can be managed non-operatively, but data exist to support surgical management of these injuries as well. Surgical treatment involves stabilisation of the joint via pins and screws, or soft tissue construction of the AC or CC ligaments. Type III SC joint injuries (dislocations) can be treated successfully without closed reduction and the joint can be left unreduced. Patients with a dislocated SC joint often are asymptomatic after the soft tissues calm down. Appropriate precautions must be taken if an attempt is made to reduce a posterior dislocation.

What is already known about this topic

  • Most acromioclavicular and sternoclavicular joint injuries are ligamentous sprains and can be treated non-operatively with a period of sling immobilisation and pain control followed by physical therapy.

What this study adds

  • A variety of surgical options exists for the treatment of acromioclavicular (AC) joint injuries if non-operative modalities fail. Appropriate treatment of type III AC joint injuries must take into account the patient's work status, physical activity level, handedness and time during the season. Treatment of sternoclavicular (SC) joint injuries rarely requires surgical intervention.


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  • Competing interests None.

  • Provenance and peer review Commissioned; not externally peer reviewed.