Fractures of the Distal Radius
Because of the close proximity to the radiocarpal joint, fractures of the distal radius are considered wrist injuries. In children the most common injury is the buckle, or torus, fracture, which occurs with a fall onto an outstretched hand. Radiographic findings may be subtle, with only a slight cortical disruption of the extra-articular radius seen on the lateral film (Fig. 2.3). Treatment is a short arm cast for three weeks; functional return is excellent.20
When a child presents with a "sprained wrist," evaluation must be done carefully, as the growth plates are weaker than ligaments during this period of rapid growth. With normal roentgenograms and tenderness over the epiphyseal plate, a Salter I fracture is presumed, and a short arm cast is applied for two to three weeks.20
In adults the most common radial fracture is a Colles' fracture, which occurs when patients over age 50 fall onto an outstretched hand. The "silver fork" deformity is caused by dorsal displacement of the distal fragment. The ulnar styloid may also be fractured. Reduction of a Colles' fracture may be attempted, but the physician must be aware of potential complications of this fracture, including median or ulnar nerve compression, damage to the flexor or extensor tendons, and radioulnar joint arthritis.
Nondisplaced distal radial fractures that are nonarticular can usually be treated with cast immobilization for six weeks in adults. Low-impact intra-articular nondisplaced fractures in the elderly may also require only cast immobilization, although the patient is advised that some residual arthritis may occur.16 For other displaced fractures or intra-articular radial fractures in young patients, treatments such as percutaneous pinning or open reduction internal fixation may be required to minimize long-term problems in the joint.
Sixty percent of carpal bone fractures involve the scaphoid (or carpal navicular) bone. The injury mechanism is a fall on an outstretched hand, usually in an adolescent or young adult. The location of the fracture determines the likelihood of complications. Distal (5%) and middle (waist) scaphoid fractures (80%) carry a good prognosis for healing, whereas proximal (15%) fractures have an incidence of nonunion or avascular necrosis as high as 30% to 50% due to a poor blood supply.
Although a scaphoid fracture is usually identified on a posteroante-rior view with the wrist in ulnar deviation, occasionally the fracture is not evident on the initial films. Patients with a "wrist sprain" who have tenderness over the scaphoid tubercle (palmar hand surface) or pain in the anatomic snuffbox, located between the extensor pollicis brevis and extensor pollicis longus tendons, should be immobilized in a short arm cast or splint for seven to ten days, at which time repeat films usually demonstrate the fracture. If tenderness continues but plain films remain negative, a bone scan or tomograms may be needed to confirm a suspected fracture. Because of the high risk of nonunion, scaphoid fractures require prolonged immobilization. Clinical opinion varies regarding use of a long arm cast versus a short arm cast, but in general a short arm cast applied for 8 to 12 weeks is acceptable for uncomplicated nondisplaced middle or distal fractures of the scaphoid.16 The longer time frame is necessary to allow adequate bone healing and to prevent nonunion or avascular necrosis. For patients with a proximal fracture or for those with a treatment delay, orthopedic consultation may be wise because of the high incidence of long-term sequelae.21 Any scaphoid fracture with displacement more than 1 mm or angulation more than 20 degrees is regarded as unstable and should also be referred for surgical treatment.
Other fractures of the carpal bones are uncommon and frequently require special radiographic views or tomograms for identification. A meticulous examination of the painful area indicates which carpal bones are likely to be involved. Because serious sequelae are common, including ulnar or median neuropathy and chronic wrist stability, orthopedic intervention is usually needed.
Although fractures of the carpal bones are unusual, sprains and other minor traumatic wrist injuries are common. A number of serious wrist injuries and carpal instabilities have been described as physicians have gained greater appreciation for the complex interactions of other ligaments and multiple articulations within the carpal complex. Roentgenography may be helpful for delineating certain problems, such as lunate and perilunate dislocations and scapholunate dissocia-tions.10 More sophisticated procedures, such as arthrography or MRI, may be required to identify other complex problems. Because there may be difficulty distinguishing a serious wrist injury from a minor sprain, the physician should be suspicious of wrist injuries that fail to resolve within a three- to four-week period. In these circumstances an orthopedic consultation is wise to ensure that no significant injury has been overlooked.
The triangulofibrocartilage complex (TFCC) is a small meniscus located distal to the ulna. This tissue serves to absorb impact to forces on the ulnar aspect of the wrist. Injuries can be acute, due to a sudden impact, or chronic, due to repetitive loading such as gymnastics. As with carpal instability, the physician should be suspicious of TFCC injuries when ulnar wrist pain does not respond to three to four weeks of splinting. Orthopedic consultation, frequently with MRI, may be required to identify the specific problem.22
De Quervain's Tenosynovitis
A stenosing tendonitis, de Quervain's tenosynovitis, occurs in the first extensor compartment of the wrist, comprising the abductor pollicis longus and extensor pollicis brevis. As these tendons cross the radial styloid, thickness and swelling may occur. The patient complains of radial wrist pain, and there is often an occupational or vocational history of repetitive hand motion, such as knitting or sewing.
The diagnosis is confirmed by the Finkelstein test, as follows. After passive adduction of the thumb into the palm, ulnar deviation of the wrist elicits a sharp pain that reproduces the patient's symptoms. Initial treatment should include a corticosteroid injection into the tendon sheath. Other treatment options include rest, anti-inflammatory medications, and a thumb spica splint. On occasion, surgical release of the tendon sheath is required for symptomatic relief.23
Inflammation can also occur at the crossover of the first and second extensor compartments of the wrist, located 4 to 8 cm proximal to the distal radius.24 Pain and tenderness are noted in this region, and the problem occurs as an overuse syndrome from repeated wrist extension. This anatomy should be distinguished from the more distal de Quervain's tenosynovitis. Initial treatment should include a thumb spica splint and anti-inflammatory medications. Corticosteroid injection is useful for those who do not respond to splinting.25 This is a contrast to de Quervain's tenosynovitis where injection is the preferred initial treatment.
Carpal Tunnel Syndrome
The most common compression neuropathy of the upper extremity, carpal tunnel syndrome, is discussed in Reference 35, Chapter 67.
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