AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Background

Acromioclavicular (AC) joint injuries most commonly occur in active or athletic young adults. Although uncommon, pediatric AC injuries are increasing because of the rising popularity of dangerous summer and winter sporting activities.

For a related CME/CE activity, see CME/CE - Management of Chronic Shoulder Disorders Reviewed.

Pathophysiology

The AC joint is composed of the articular surfaces of the clavicle and the acromion, a surrounding capsule, and 2 sets of ligaments (AC and coracoclavicular [CC] ligaments). The AC ligament is composed of stronger superior and inferior ligaments as well as weaker anterior and posterior ligaments. The AC ligament is the principle restraint to anteroposterior translation between the clavicle and the acromion. The CC ligament is composed of the conoid and trapezoid ligaments, which together form a strong, heavy band that provides vertical stability. The AC joint has minimal mobility.

Classification of injury

The degree of clavicular displacement depends on the severity of injury to the AC and CC ligaments, the AC joint capsule, and the supporting muscles of the shoulder (trapezius and deltoid) that attach to the clavicle.

Allman and Tossy initially proposed a 3-grade classification that Rockwood expanded to 6 types of injury. Grades I and II are the same in both classification schemes with grade III injuries in the Tossy classification subdivided into grades III, IV, V, and VI in the Rockwood classification.

The Rockwood classification is as follows:

• Type I - Minor sprain of AC ligament, intact joint capsule, intact CC ligament, intact deltoid and trapezius
• Type II - Rupture of AC ligament and joint capsule, sprain of CC ligament but CC interspace intact, minimal detachment of deltoid and trapezius
• Type III - Rupture of AC ligament, joint capsule, and CC ligament; clavicle elevated (as much as 100% displacement); detachment of deltoid and trapezius
• Type IV - Rupture of AC ligament, joint capsule, and CC ligament; clavicle displaced posteriorly into the trapezius; detachment of deltoid and trapezius
• Type V - Rupture of AC ligament, joint capsule, and CC ligament; clavicle elevated (more than 100% displacement); detachment of deltoid and trapezius
• Type VI (rare) - Rupture of AC ligament, joint capsule, and CC ligament; clavicle displaced behind the tendons of the biceps and coracobrachialis

Pediatric AC injury

AC joint injuries in children are uncommon, and they differ anatomically from such injuries in adults. The immature clavicle is encased in a periosteal tube. The CC ligament is within this tissue, while the AC ligament is exterior to it. This anatomic relationship explains why the AC ligament is frequently injured with direct trauma, while the CC ligament remains intact. When evaluating a pediatric radiography, remember that incomplete closure of or failure of an ossification center may appear to be a fracture.

The pediatric Rockwood classification is as follows:

• Type I - Clavicle stable; joint radiographically normal
• Type II - Partial tear of the periosteal tube, allowing for some mobility of the distal clavicle; AC ligament disrupted
• Types III-VI - Larger tear through the periosteal tube, allowing for greater clavicle mobility and gross instability with clavicle positioning; CC ligament remains attached to the clavicle periosteal tube

Frequency

United States

The true incidence of AC injury is not known, as many affected do not seek treatment. Approximately 12% of all dislocations involving the shoulder affect the AC joint.

Mortality/Morbidity

Mortality is not commonly associated with AC injuries. Significant morbidity is negligible with type I and II injuries. Types IV, V, and VI do well with surgical repair. Morbidity is highest with type III injuries due to the controversy surrounding management.

Race

No difference in injury patterns exists among various racial or ethnic backgrounds.

Sex

Males sustain significantly more AC injuries due to larger participation in high-risk activities.

Age

Younger patients (<35 y) sustain more AC injuries due to higher participation in risky activities.

CLINICAL

Section 3 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

History

AC injury often involves a fall onto the apex of the shoulder, usually with the arm in adduction. Severe forces resulting from significant falls are often associated with type III-VI injuries. Patients usually present with pain at the top of the shoulder at the acromioclavicular joint and can often be seen carrying the affected arm close to the side of their bodies. Alternatively, patients use the unaffected arm to splint the injured extremity. Abrasions and ecchymoses are common at the site of impact.

Physical

While examining the stability of the affected shoulder, the midshaft of the clavicle should be manipulated rather than the AC joint itself. The patient should be asked to place the hand of the affected side on the opposite shoulder while the examiner applies downward force on the affected elbow, trying to elicit pain at the AC joint. Patients may also experience pain upon direct palpation of the AC joint. Several techniques to directly assess the AC joint are discussed in the orthopaedic literature, although none of these maneuvers has been shown to have a high sensitivity or specificity.

Palpating the bony structures of the shoulder for any stepoff that might suggest occult fracture as well as noting any displacement of the clavicle are important. A thorough neurovascular examination to rule out brachial plexus injury is also essential, although concomitant neurovascular injury is relatively rare in AC joint injuries.

Causes

Downward blunt force on the acromion results in variable injury to the AC and CC ligaments. Other injuries, depending on the force of injury, may include tears of the deltoid and trapezius attachments at the clavicle and fractures of the acromion, clavicle, and coracoid (or of their cartilaginous attachments).

Athletes participating in contact sports, such as football and martial arts, are at increased risk of AC joint injuries. Patients involved in motor vehicle collisions with direct trauma to the apex of the shoulder are also at risk for AC injuries.

DIFFERENTIALS

Section 4 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

Septic arthritis
Erb-Duchenne injury
Distal clavicle osteolysis

WORKUP

Section 5 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Imaging Studies

• Standard radiographs of the shoulder should be obtained. To optimally image the AC joint, a cross body adduction radiograph should be obtained. A radiograph of the entire upper thorax is useful to compare the vertical distance between the clavicle and the coracoid process on both sides. Radiographic results according to severity of injury are as follows:
• • Type I - Normal
  • Type II - Subluxation of AC joint space less than 1 cm; normal CC space
  • Type III - Subluxation of AC joint space more than 1 cm; widening of the CC space more than 50%
  • Types IV-VI - Subluxation of AC joint space more than 1 cm, widening of the CC space more than 50%; associated displacement of the clavicle
• Stress radiographs (10-lb weight in each hand) may help distinguish type I from type II injuries, but many authorities consider such studies unnecessary. Stress views are of limited value as any involuntary splinting by the patient prevents full visualization of the AC joint and may simply serve to increase the patient's pain.
• With complete AC/CC ligament rupture, cross body adduction films will show the scapula rotated anteromedially and the acromion will migrate medially.
• Assess the clavicle and scapula for associated fractures.
• For pediatric injuries, plain radiographs may reveal fractures at the base of the coracoid.
• Obtain a chest radiograph if concern exists with regard pulmonary involvement.
• Research has looked at the additional information provided by ultrasonographic examination of the AC joint in suspected high-grade injuries. Heers and Hedtmann showed that ultrasonographic examination of the AC joint in experienced hands had 100% sensitivity for diagnosis of deltoid muscle detachment and fascial disruption.¹ The study also showed 80% sensitivity and 100% specificity for disruption of the trapezius muscle. More studies are necessary to evaluate the potential for ultrasonography in the routine examination of suspected AC injury.
• MRI should be considered to further delineate the extent of AC joint injury, particularly in highly competitive athletes.

Procedures

• Reduction of AC injuries is rarely attempted in the emergency department. Such maneuvers should only be performed in cooperation with an orthopedic surgeon.

TREATMENT

Section 6 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Prehospital Care

• Distinguishing AC injuries from other shoulder injuries (ie, clavicular fractures, shoulder dislocations, proximal humeral fractures) is difficult.
• Prehospital providers should splint suspected AC injuries in a position of comfort. Neurovascular status of the injured extremity should always be checked after application of a splint.
• Assess and immobilize the spine, if indicated.

Emergency Department Care

• Type I
• • These injuries involve minimal disruption of the AC joint and are intrinsically stable. Treatment involves application of a sling for comfort, ice, and analgesic agents.
  • Athletes can usually return to sports in 1-2 weeks. For patients whose symptoms do not improve within this time frame, intra-articular steroid injections may be indicated. Patients with persistent pain for extended amounts of time may be candidates for a distal clavicle excision.
• Type II
• • In these patients, the AC ligament is completely torn. For the most part, these patients receive the same treatment as those with type I injuries. However, patients with type II injuries take longer to improve. With significant instability, strap immobilization for 2-4 weeks and no heavy lifting for 6-8 weeks are appropriate.
  • A Kenny-Howard shoulder harness may be used for strap immobilization, although this device frequently is uncomfortable for the patient and may not change the outcome.
  • Late management of these injuries may require intra-articular steroids or surgery. Distal clavicle excision has been noted to produce inferior results compared with the same surgery in patients with type I injury due to increased instability of the AC joint.
• Type III
• • Patients with type III AC injuries have complete tearing of the coracoclavicular ligament in addition to a complete tear of the AC ligament. This injury results in superior displacement and greater instability of the clavicle.
  • Controversy exists regarding the optimal management of this injury. Most studies suggest that conservative therapy produces better functional results than operative repair. Comparison trials between operative and nonoperative management have suffered from insufficient numbers of patients, a retrospective design in most cases, heterogenous patient groups, or a lack of objective evaluation in the follow-up period. Furthermore, a variety of different surgical techniques have been developed making comparison between conservative management and general operative management difficult.
  • Nissen and Chatterjee recently published a survey of members of the American Orthopaedic Society for Sports Medicine and ACGME accredited residency directors; they found that conservative therapy is still the recommended first line of care (>90%).²
  • In 1998, Philips et al performed a meta-analysis of all studies looking at outcomes of AC separations.³ This study looked at 24 papers, 5 of which directly compared surgical and nonsurgical management of type III AC injury. They concluded that nonsurgical intervention yielded improved strength, range of motion, and fewer complications than operative intervention.
  • Other authorities point out that individuals in certain active occupations, such as baseball pitchers, manual laborers, and soldiers, may disproportionately benefit from an operative intervention.
• Type IV
• • In patients with type IV injury, the deltotrapezial fascia is disrupted in addition to complete tears of the AC and CC ligaments. This injury complex allows posterior displacement of the clavicle into the trapezius and requires reduction, usually operative.
  • In theory, a closed reduction could be possible to convert the injury into a type III AC injury, which could then be managed conservatively. Barring this possibility, surgery with an open reduction and internal fixation is necessary.
• Type V and VI: These forms of AC injury are the most severe and will universally require open reduction and internal fixation (ORIF).
• AC joint injection may be considered in the patient with recurrent ED visits for AC pain. However, this is not recommended in the acute setting as any fluid injected may complicate MRI evaluation of the joint.
• Pediatric injuries
• • For types I-III, closed reduction can be effective, although surgical intervention for selected cases may be indicated to achieve better functional results.
  • Types IV and V commonly require ORIF.

Consultations

• Orthopedic surgery
• • Pediatric cases
  • Types III-VI in adults

MEDICATION

Section 7 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The goals of therapy are to reduce pain and inflammation.

Drug Category: Nonsteroidal anti-inflammatory agents (NSAIDs)

These agents are used for both anti-inflammatory and analgesic effects. Acetaminophen (with or without an opiate) is the most commonly used analgesic.

Drug Category: Nonopioid analgesics

These agents are used for mild-to-moderate analgesic effects.

Drug Category: Opioid analgesics

These agents are used for moderate-to-strong analgesic effects.

Drug Name	Hydrocodone bitartrate and acetaminophen (Vicodin ES)
Description	Indicated for the relief of moderate to severe pain.
Adult Dose	1-2 tab or cap PO q4-6h prn for pain
Pediatric Dose	<12 years: 10-15 mg/kg/dose acetaminophen PO q4-6h prn; not to exceed 2.6 g/d of acetaminophen >12 years: 750 mg acetaminophen PO q4h; not to exceed 10 mg of hydrocodone bitartrate per dose; not to exceed 5 doses/d
Contraindications	Documented hypersensitivity; HACE; elevated ICP
Interactions	Coadministration with phenothiazines may decrease analgesic effects; toxicity increases with CNS depressants or TCAs
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Tabs contain metabisulfite, which may cause hypersensitivity; caution in patients dependent on opiates, since this substitution may result in acute opiate withdrawal symptoms; caution in severe renal or hepatic dysfunction

Drug Name	Acetaminophen and codeine (Tylenol with Codeine)
Description	Indicated for the treatment of mild to moderate pain.
Adult Dose	30-60 mg/dose based on codeine content PO q4-6h or 1-2 tab PO q4h; not to exceed 12 tab/d
Pediatric Dose	0.5-1 mg/kg/dose based on codeine PO q4-6h; 10-15 mg/kg/dose based on acetaminophen content; not to exceed 2.6 g/d of acetaminophen
Contraindications	Documented hypersensitivity
Interactions	Toxicity increases with CNS depressants or TCAs
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Caution in patients dependent on opiates, since this substitution may result in acute opiate-withdrawal symptoms; caution in severe renal or hepatic dysfunction

Drug Category: Corticosteroids

These agents have both anti-inflammatory and salt retaining properties. Glucocorticoids have profound and varied metabolic effects. In addition these agents modify the body's immune response to diverse stimuli.

Drug Name	Methylprednisolone (Depo-Medrol, Solu-Medrol)
Description	Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
Adult Dose	30-40 mg intra-articular injection
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity; viral, fungal or tubercular skin infections
Interactions	Coadministration with digoxin may increase digitalis toxicity secondary to hypokalemia; estrogens may increase levels of methylprednisolone; phenobarbital, phenytoin, and rifampin may decrease levels of methylprednisolone (adjust dose); monitor patients for hypokalemia when taking medication concurrently with diuretics; grapefruit juice increases prednisolone concentrations; methylprednisolone and cyclosporine mutually inhibit one another resulting in increased plasma levels of each drug
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions	Most common side effect is postinjection flare, which manifests as pain at injection site and can be relieved with oral NSAIDs; this pain is due to crystal deposition of the steroid preparation in joint space and usually lasts <24 h Other side effects are related to poor technique and include skin atrophy, hypopigmentation, and tendon rupture rare side effects include infection of joint space and anaphylaxis; side effects such as Cushing syndrome, osteoporosis, and menstrual irregularities are rare and only occur when multiple injections are given over a relatively short time period A percentage of injected drug might be absorbed systemically; if application is repeated, some systemic effects of the corticosteroids may occur; most common side effect is postinjection flare due to crystal deposition of steroid preparation in joint space (lasts <24 h; can be relieved with oral NSAIDs); other side effects are related to poor technique and include skin atrophy, hypopigmentation, and tendon rupture

FOLLOW-UP

Section 8 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Further Inpatient Care

• AC injuries requiring ORIF should be repaired within 2 weeks of the time of injury. Unless other injuries are sustained, these patients do not require admission on the day of injury.

Further Outpatient Care

• Following discharge, orthopedic surgical follow-up is mandatory for type III-VI injuries and is recommended in all pediatric injuries.

Deterrence/Prevention

• General safety precautions are the best method of preventing AC injuries. Football shoulder pads may decrease the extent of an injury but by no means prevent AC injuries.

Complications

• Cosmetic deformity
• Accelerated osteoarthrosis
• Decreased shoulder range of motion/upper extremity strength
• Distal clavicle osteolysis

Prognosis

• Patients with type I injuries may usually return to sports in 1-2 weeks.
• Patients with type II injuries usually require a longer period of recovery, but patients can usually return to sports in 2-4 weeks. Reports exist of patients with type II injuries who continue to experience some subjective loss of strength up to 3 years after injury.

MISCELLANEOUS

Section 9 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to document neurological, vascular, or other associated injuries is the primary error in the assessment of AC joint injuries.

Special Concerns

• Although the majority of studies comparing surgical management to conservative management of type III AC injuries have suggested that conservative management produces superior functional results, additional consideration for surgical intervention should be given to specific patient groups such as throwing athletes, manual laborers, and soldiers, who may receive greater benefit from an operative intervention than the general population.

ACKNOWLEDGMENTS

Section 10 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Cappi Lay, MD, to the development and writing of this article.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Media file 1:  Anteroposterior (AP) radiograph of right shoulder showing step-off of acromioclavicular (AC) joint.
	View Full Size Image
Media type:  X-RAY

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

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Article Last Updated: Apr 1, 2008