A 9-year-old boy fell on his left arm while skating and injured his elbow. Heexperienced no loss of consciousness or associated injury.
9-year-old boy fell on his left arm while skating and injured his elbow. Heexperienced no loss of consciousness or associated injury.When he arrives at the emergency department, he complains of pain inhis left elbow and holds his injured arm in extension with pronation. He is unableto recall the position of his arm during the fall.
Before the accident, the boy was healthy. He has no history of underlyingdiseases or serious illnesses, and he takes no medications regularly.
The only abnormal findings are related to the left elbow.The area over the distal humerus and elbow is tender to palpation. There is nobreach in the skin or swelling in the area. The left shoulder and wrist are nottender. Evaluation of distal neurovascular status shows capillary refill of lessthan 2 seconds' duration. The results of the Allen test indicate perfusion inboth the radial and the ulnar arteries. Radial, ulnar, and median nerve sensoryand motor functions are normal and intact.Radiographs of the left elbow are obtained. The anteroposterior view inextension and the lateral view in 90 degrees of flexion are shown here.
What clues in these films point to the extent of the boy's injury?
Mechanism of injury.
Sixty percentof all elbow fractures in childrenare supracondylar fractures. This fractureis most commonly seen in childrenbecause the medial and lateralepicondylar ligaments are strongerthan the bone in the epiphyses andsupracondylar area of the humerusuntil about age 12 or 13. At that time,the bony structures gain strength toresist fracture.Posterior dislocation of theelbow occurs in adolescents andadults following the same mechanismthat produces supracondylar fracturein children. The typical mechanisminvolves falling on an outstretchedhand.In more than 95% of patients, thefractured bone fragment of the distalhumerus is displaced posteriorly.The force of the fall or other injury istransmitted up the forearm bones tothe supracondylar area of the humerus.In extension, the force fracturesthe supracondylar area, pushing thedistal fragment posteriorly and upward.The fracture line traverses thecondyles horizontally, traveling acrossboth the coronoid fossa and the olecranonfossa.
Vascular compromiseis a serious complication ofsupracondylar fracture. The brachialartery can be pinched or entrappedin the fracture site, which produces avolar compartment syndrome of theforearm. Because of the risk of compartmentsyndrome, evaluation of distalneurovascular function is evenmore important than examination ofthe fracture site. Pain, poor perfusion,absent radial pulse, paresthesias, andparalysis (the 5 Ps) of the forearmsuggest ischemia.Bear in mind that the radialpulse can be reconstituted from arterialflow which bypasses the volarcompartment; thus, ischemic injuryto the compartment can occur even in the presence of a radial pulse. Increasingpain in the forearm warrantsimmediate vascular evaluation. Passiveextension of the fingers may be auseful finding that indicates vascularcompromise.Prolonged ischemia can lead toVolkmann's contracture; infarction ofthe forearm musculature is completeafter 12 to 24 hours of vascular insufficiency.Fixed flexion of the elbow,pronation of the forearm, and wristflexion are evidence of necrosis andfibrosis. The incidence of Volkmann'sischemic contracture associated withsupracondylar fracture has decreasedwith greater awareness of the risk ofcompartment syndromes and properemergency care.Radial, median, or ulnar nerveinjuries occur in 5% to 10 % of supracondylarfractures. The nerve may bedamaged at the time of injury, duringfracture reduction, as a result of ischemia,or through entrapment of thenerve in fracture callus.
Management of asupracondylar fracture consists ofsplinting the elbow in extension. Excessiveflexion of the elbow can compromiseperfusion. Avoid excessivelytight splinting, and reassess the neurovascular status of the injured armafter immobilization.Many orthopedists admit allchildren with supracondylar fracture--even if nondisplaced--to observethem for swelling and vascularcompromise during the first 24 to 48hours. The child with a greenstick ornondisplaced supracondylar fractureand minimal swelling may be treatedas an outpatient provided that closefollow-up observation is assured. Thearm should be splinted in flexion withthe forearm in a neutral or pronatedposition. Perfusion is reassessed aftersplinting, and the patient must beseen by an orthopedic surgeon within24 hours after the injury. If such follow-up care cannot be assured or ifthere is any displacement of the fractureor significant swelling, inpatienttreatment is required.Immediate reduction is necessaryif signs of vascular compromiseappear. If the symptoms and signs ofischemia are severe and no orthopedistis immediately available, the fracturecan be reduced with traction,supination of the forearm, and directpressure on the displaced fragmentdownward and anteriorly. If elbow extension,fracture reduction, and removalof constricting bandages fail torestore perfusion within 6 to 8 hours,fasciotomy and arterial explorationmay be necessary.
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