Rockwood Children CH8

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SECTION TWO • Upper Extremity

A

by testing the abductor pollicis brevis (intrinsic) and flexor pol- licis longus (extrinsic) muscles. Ulnar nerve motor evaluation includes testing the first dorsal interosseous (intrinsic), abductor digiti quinti (intrinsic), and flexor digitorum profundus to the small finger (extrinsic) muscles. Radial nerve evaluation involves testing the common digital extensors for metacarpophalangeal joint extension as well as thumb extensor pollicis longus. Sen- sibility to light touch and two-point discrimination should be tested. Normal two-point discrimination is less than 5 mm but may not be reliably tested in children younger than 5 to 7 years of age. Pinprick sensibility testing will only hurt and scare the already anxious child and should be avoided. Radial Physeal Stress Fracture In contrast to the child with an acute, traumatic distal radius fracture, patients with distal radial physeal stress injuries typi- cally report recurring, activity-related wrist pain. Characteristi- cally, this pain is described as diffuse “aching” and “soreness” in the region of the distal radial metaphysis and physis. Pain may be reproduced in the extremes of wrist extension and flexion, and usually there is local tenderness over the dorsal, distal radial physis. Resistive strength testing of the wrist extensors will also reproduce the pain. There may be fusiform swelling about the wrist if there is reactive bone formation. The differential diag- nosis includes physeal stress injury, ganglion, inflammatory arthritis, ligamentous or TFCC injury, tendinosis or musculoten- dinous strain, carpal fracture, and osteonecrosis of the scaphoid (Preiser disease) or lunate (Kienbock disease). Diagnosis is made radiographically in the context of the clinical presentation. Radiographs are also usually diagnostic in cases of suspected distal radial physeal stress injuries. Physeal widening, cystic and sclerotic changes in the metaphyseal aspect of the distal radial physis, beaking of the distal radial epiphysis, and reac- tive bone formation are highly suggestive of chronic physeal stress fracture. In advanced cases, premature physeal closure or physeal bar formation may be seen, indicating long-stand- ing stress. 29,47,52,176,194,215 In these situations, continued ulnar growth leads to an ulnar positive variance with resulting pain B Figure 8-9.  Dorsal bayonet deformity. A: Typical distal metaphyseal fracture with dorsal bayonet showing a dorsal angulation of the distal forearm. B: Usually, the periosteum is intact on the dorsal side and disrupted on the volar side.

usually involves an ulnar physeal fracture rather than a soft tissue disruption of the DRUJ. Another ulnar physeal fracture is an avul- sion fracture off the distal aspect of the ulnar styloid. 1 Although an ulnar styloid injury is an epiphyseal avulsion, it can be asso- ciated with soft tissue injuries of the triangular fibrocartilage complex (TFCC) and ulnocarpal joint, though does not typically cause growth-related complications. Figure 8-8.  Coronal computed tomography (CT) image of an adoles- cent with ipsilateral distal radius and scaphoid fractures. (Courtesy of Children’s Orthopaedic Surgery Foundation.) Children with distal radial and/or ulna fractures present with pain, swelling, and deformity of the distal forearm (Fig. 8-9). The clinical signs depend on the degree of fracture displace- ment. With a nondisplaced torus fracture in a young child, med- ical attention may not be sought until several days after injury; the intact periosteum and biomechanical stability are protective in these injuries, resulting in minimal pain and guarding. Simi- larly, many of the physeal injuries are nondisplaced and present only with pain and tenderness at the physis. 144,156 With displaced fractures, the typical dorsal displacement and apex volar angu- lation create an extension deformity that is usually clinically apparent. Careful inspection of the forearm is critical to evaluate for possible skin lacerations, wounds, and open fractures. With greater displacement, physical examination is often lim- ited by the patient’s pain and anxiety, but it is imperative to obtain an accurate examination of the motor and sensory components of the radial, median, and ulnar nerves before treatment is initiated. Neurovascular compromise is uncommon but can occur. 205 A prior prospective study indicated an 8% incidence of nerve injury in children with distal radial fractures. 206 Median nerve irritability or dysfunction is most common, caused by direct trauma to the nerve at the time of injury or ongoing ischemic compression from the displaced fracture. Median nerve motor function is evaluated SIGNS AND SYMPTOMS OF FRACTURES OF THE DISTAL RADIUS AND ULNA Traumatic Fractures