Pediatric Acromioclavicular Joint Injuries: Epidemiology, Anatomy, Evaluation, and Treatment
Learn about pediatric acromioclavicular joint injuries, including their epidemiology, anatomy, mechanism of injury, clinical and radiographic evaluation, classification, treatment options, and potential complications.
Epidemiology
- Rare in children <16 years of age.
- The true incidence is unknown because many of these injuries actually represent pseudodislocation of the acromioclavicular joint.
Anatomy
- The acromioclavicular joint is a diarthrodial joint; in mature individuals, an intra-articular disc is present.
- The distal clavicle is surrounded by a thick periosteal sleeve that extends to the acromioclavicular joint.
Mechanism of Injury
- Athletic injuries and falls comprise the majority of acromioclavicular injuries, with direct trauma to the acromion.
- Unlike acromioclavicular injuries in adults, in children, the coracoclavicular (conoid and trapezoid) ligaments remain intact. Because of the tight approximation of the coracoclavicular ligaments to the periosteum of the distal clavicle, true dislocation of the acromioclavicular joint is rare.
- The defect is a longitudinal split in the superior portion of the periosteal sleeve through which the clavicle is delivered, much like a banana being peeled from its skin.
Clinical Evaluation
- The patient should be examined while in the standing or sitting position to allow the upper extremity to be dependent, thus stressing the acromioclavicular joint and emphasizing deformity.
- A thorough shoulder examination should be performed, including assessment of neurovascular status and possible associated upper extremity injuries. Inspection may reveal an apparent step-off deformity of the injured acromioclavicular joint, with possible tenting of the skin overlying the distal clavicle. Range of motion may be limited by pain. Tenderness may be elicited over the acromioclavicular joint.
Radiographic Evaluation
- A standard trauma series of the shoulder (AP, scapular-Y, and axillary views) is usually sufficient for the recognition of acromioclavicular injury, although closer evaluation includes targeted views of the acromioclavicular joint, which requires one-third to one-half the radiation to avoid overpenetration.
- Ligamentous injury may be assessed via stress radiographs, in which weights (5 to 10 lb) are strapped to the wrists and an AP radiograph is taken of both shoulders for comparison.
Classification (Dameron and Rockwood)
| Type | Description |
|---|---|
| Type I | Mild sprain of the acromioclavicular ligaments without periosteal tube disruption; distal clavicle stable to examination and no radiographic abnormalities |
| Type II | Partial disruption of the periosteal tube with mild distal clavicle instability; slight widening of the acromioclavicular space appreciated on radiographs |
| Type III | Longitudinal split of the periosteal tube with gross instability of the distal clavicle to examination; superior displacement of 25% to 100% present on radiographs as compared with the normal, contralateral shoulder |
| Type IV | Posterior displacement of the distal clavicle through a periosteal sleeve disruption with buttonholing through the trapezius; AP radiographs demonstrating superior displacement similar to type II injuries, but axillary radiographs demonstrating posterior displacement |
| Type V | Type III injury with >100% displacement; distal clavicle may be subcutaneous to palpation, with possible disruption of deltoid or trapezial attachments |
| Type VI | Infracoracoid displacement of the distal clavicle as a result of a superior-to-inferior force vector |
Treatment
- For types I to III, nonoperative treatment is indicated, with sling immobilization, ice, and early range-of-motion exercises as pain subsides. Remodeling is expected. Complete healing generally takes place in 4 to 6 weeks.
- Treatment for types IV to VI is operative, with reduction of the clavicle and repair of the periosteal sleeve. Internal fixation may be needed.
Complications
- Neurovascular injury: This is rare and is associated with posteroinferior displacement. The intact periosteal sleeve is thick and usually provides protection to neurovascular structures underlying the distal clavicle.
- Open lesion: Severe displacement of the distal clavicle, such as with type V acromioclavicular dislocation, may result in tenting of the skin, with possible laceration necessitating irrigation and debridement.
1. What is the incidence of pediatric acromioclavicular joint injuries?
Answer: B. Rare in children aged <16 years. The true incidence is unknown, as many of these injuries are actually pseudodislocation of the acromioclavicular joint.
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2. What is the mechanism of injury for pediatric acromioclavicular joint injuries?
Answer: B. Falls and athletic injuries. Direct trauma to the acromion is the most common mechanism of injury.
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3. What is the recommended treatment for types I to III pediatric acromioclavicular joint injuries?
Answer: B. Immobilization with a sling, ice, and early range-of-motion exercises. Remodeling is expected, and complete healing typically takes 4 to 6 weeks.
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4. What is the radiographic evaluation for pediatric acromioclavicular joint injuries?
Answer: C. Standard shoulder trauma series (AP, scapular-Y, and axillary views). Closer evaluation may require targeted views of the acromioclavicular joint.
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5. What is the complication associated with posteroinferior displacement of the distal clavicle?
Answer: A. Neurovascular injury. The intact periosteal sleeve usually provides protection to neurovascular structures underlying the distal clavicle.
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