Common wrist injuries

Author: Rebecca L. Morgan, Michael M. Linder
Date: Feb 15, 1997

Patients with wrist injuries often present to primary care physicians. Many times, mild clinical injury involves significant damage to carpal bones and soft tissue elements. The long-term outcome of these injuries depends on prompt diagnosis and appropriate therapy. Familiarity with the functional anatomy and physical examination of the wrist, accompanied by radiologic evaluation, may aid the physician in differentiating simple sprains from potentially debilitating wrist injuries.

The wrist is a complex joint that affects many activities of daily living. Commonly injured during athletic and leisure activities, patients may present with a swollen, painful wrist to the family physician. Often this type of injury is treated as a simple wrist sprain. However, many wrist injuries require further diagnosis and more aggressive treatment to ensure the patient's return to full function. This article discusses some of the more common diagnoses that may be mistaken for simple wrist sprains and addresses standard therapies for several common diagnoses.

Functional Anatomy

The wrist joint movements are flexion, extension, radial deviation, ulnar deviation, proration and supination. The wrist is composed of eight carpal bones, the distal articulation of the radius and the ulna, and articulations of the carpal and metacarpal bones. Various ligaments, articular cartilage and tendons assist in wrist movement and stability.

The carpal bones are arranged in two rows, with the proximal row consisting of the scaphoid, the lunate, the triquetrum and the pisiform. The scaphoid is unique in that it spans both carpal rows, accompanied in the distal row by the trapezium, the trapezoid, the capitate and the hamate. The carpal bones form a dorsally convex arch contiguous to the palmer arch of the hand formed by the metacarpals.[1]

Several ligaments hold the carpal bones in close articulation. The strongest ligaments are located on the volar side of the wrist. Interposed between the distal ulna and the proximal carpal row is a thick band of fibrous tissue that anchors an articular disc, known as the triangular fibrocartilage complex. This band serves to stabilize the wrist and provides a cushion against loading forces during ulnar deviation. It is often referred to as the homolog of the meniscus of the knee.[2]

The soft tissues of the wrist are grouped into zones known as compartments on the dorsal aspect and tunnels on the palmer aspect of the wrist. The six compartments of the wrist are numbered from the radial to the ulnar side and house the extensor tendons of the wrist and hand (Figure 1).

[Figure 1 ILLUSTRATION OMITTED]

The anatomic snuff box is an important landmark in the evaluation of wrist injury. It is bordered by the tendons of the first dorsal compartment on the radial side and by the tendon of the third compartment (the extensor pollicis longus) on the ulnar side. The scaphoid bone forms the floor of the snuff box, where the deep branch of the radial artery may often be palpated.

The palmer tunnels, located on the volar aspect of the wrist, consist of the carpal tunnel and the tunnel of Guyon. The carpal tunnel lies deep to the tendon of the palmaris longus and the transverse carpal ligament. The carpal tunnel houses the flexor tendons of the fingers and the median nerve. The tunnel of Guyon, located at the ulnar margin of the volar wrist, contains the ulnar artery and nerve.

The wrist has three basic planes of motion: flexion and extension, ulnar and radial deviation, and proration and supination. Supination and proration occur mainly at the distal radial ulnar joint in the wrist, but these movements also depend on normal function of the proximal articulation of the radius and ulna at the elbow. Flexion, extension and deviation occur at the articulations of the carpal bones with the radius, the ulna, the metacarpals and each other.

Radiologic Examination of the Wrist

The wrist is one of the more difficult radiographic examinations to interpret because of the multiplicity of overlapping shadows. Routine wrist radiographs include anteroposterior, lateral and oblique views. The anteroposterior view is taken with the dorsum of the hand against the plate, with the radial and ulnar styloid processes in alignment parallel to the film. The joint spaces between the carpal bones are of particular importance. If there is a normal relationship between the bones, the joint space should be a consistent width of lucency between the cortical margins of the articulating bones. Thus, the cortical margins form sets of parallel lines about the joint spaces (Figure 2). Disruption of the parallelism would indicate a dissociation of the involved bones.

[Figure 2 ILLUSTRATION OMITTED]

The lateral view is particularly helpful in identifying carpal dislocations. The relationship of the capitate, lunate and radius appear as three concavities resembling stacked dishes[3] (Figure 3). This relationship is best seen when the radial and ulnar styloids are perfectly superimposed on the lateral view. Any disruption of the "stack of dishes" indicates a carpal dislocation. Oblique views are obtained with the wrist prorated at a 45-degree angle from neutral. They are most helpful in identifying chip fractures of the carpal bones.

[Figure 3 ILLUSTRATION OMITTED]

Additional radiographic studies may be necessary to enhance the routine studies and better identify an abnormality. When fracture of the scaphoid is suspected, a posteroanterior projection with the wrist extended 30 degrees and in maximum ulnar deviation elongates the view of the scaphoid bone, often revealing a fracture not seen on routine films. Bone scans, fluoroscopy, arthrography, tomography, computed tomography and magnetic resonance imaging (MRI) are adjunct tools useful in the diagnosis of wrist injury when plain radiographs are not conclusive.[4]

Carpal Injury

SCAPHOID FRACTURE

The scaphoid is the most commonly fractured carpal bone, accounting for 70 to 80 percent of all carpal bone injuries and 8 percent of all sports-related fractures.[5] It is estimated that one in 100 college football players will have a scaphoid fracture.[6] The scaphoid is unique in that it spans both carpal rows and is firmly anchored by ligaments on the volar surface of the wrist. This position increases its susceptibility to injury when a loading force is applied to the dorsiflexed wrist, such as a fall on the outstretched hand, the most common mechanism of injury. A bending force is exerted on the waist of the scaphoid while the proximal pole remains stable in close proximity to the radius and capitate, resulting in a fracture.

Clinically, fracture of the scaphoid presents as a painful, swollen wrist after a fall. There may be limitation of motion and tenderness in the anatomic snuffbox. Swelling may also be localized to the snuffbox, obliterating its usual concavity. Any of these signs should raise clinical suspicion of a fracture.

Routine radiographs may not show acute fracture of the scaphoid. As previously mentioned, scaphoid views, by elongating the long axis of the bone, may provide a better view of the waist. The navicular (scaphoid) fat stripe, a radiolucent line parallel to the radial surface of the scaphoid bone on anteroposterior and oblique views (Figure 4), is laterally displaced or obliterated in 85 percent of scaphoid fractures but is not a specific sign of scaphoid fracture.[4] However, a negative radiograph does not rule out fracture.

[Figure 4 ILLUSTRATION OMITTED]

If suspicion of a fracture is high, the wrist should be immobilized in a thumb spice cast for 10 to 14 days and repeat radiographs obtained out of the cast at that time. Alternatively, a negative bone scan performed at 72 hours after the injury virtually excludes fracture of the scaphoid.[7] Adequate immobilization should be carried out until the bone scan is obtained.[4]

Prompt diagnosis and treatment are imperative to avoid potential complications of this injury. About 95 percent of undisplaced fractures unite if immobilized promptly in a short-arm thumb spice cast for six to 12 weeks. Displaced fragments are best treated by open reduction and internal fixation with Kirschner wires, followed by cast immobilization. Avascular necrosis through the waist of the scaphoid may occur in up to 30 percent of fractures, because of the limited blood supply by a singular interosseous vessel in most persons. Treatment of this complication can involve extended periods of cast immobilization, the use of electric bone stimulators and eventual surgery, with bone grafting.

Vascular injury in the upper extremity is most often caused by repetitive trauma. The ulnar artery is susceptible to injury in a short 2-cm segment between the distal margin of the tunnel of Guyon and the palmar aponeurosis, where the superficial palmar arch begins. At this segment, the artery is covered by the palmaris brevis muscle, subcutaneous tissue and skin. Repetitive impact over this area, as occurs in baseball catchers, touring cyclists and handball players, can cause aneurysm, thrombosis and vascular spasm. Aneurysm occurs secondary to trauma to the vascular media, thrombosis results from trauma to the intima and spasm results from mild repetitive trauma.[15]

Symptoms of vascular injury include one or more cold digits, pain, intermittent mottling, paresthesias and stiffness. Raynaud's phenomenon may be associated. A prominent hypothenar callus is often present, and an aneurysm may present with a palpable mass. Nerve palsy should not be found on examination if the problem is primarily vascular, because the motor branch of the ulnar nerve originates in the tunnel of Guyon, proximal to the affected area. Axillary or brachial arteriography is diagnostic. Complications in severe cases include focal necrosis and gangrene.[12] Treatment includes sensible hand care to protect the affected area, stellate ganglion block and resection of thrombosis.

MEDIAN NERVE

Nerve irritation from repetitive impact or continuous compression from adjacent structures is not uncommon, especially in persons who play racquet sports. Carpal tunnel syndrome is common in racquetball players, secondary to a flexor tenosynovitis from repetitive flexion and extension at the wrist.[12] It occurs less commonly in cyclists and in persons engaged in gripping and throwing sports. Patients typically experience episodic numbness of the thumb, the index finger and the long finger, accompanied by clumsiness that increases with athletic activity. Nocturnal intensification of symptoms is common. Physical examination findings include positive Tinel's and Phalen's tests. Loss of two-point discrimination and thenar wasting are later signs. Treatment is conservative, with relative rest, a volar wrist splint (especially at night), NSAIDs and corticosteroid injections. Surgical decompression is warranted when symptoms are protracted and conservative therapy has failed.

ULNAR NERVE

At the wrist, the ulnar nerve may be injured in the tunnel of Guyon from direct trauma, fractures of the hamate and the pisiform, and the repetitive power gripping that is inherent in certain sports, especially in cycle touring. Symptoms of pain, weakness and paresthesias in an ulnar sensory distribution with sparing of the dorsal sensory branch indicate compression of the ulnar nerve in Guyon's tunnel.[12] Longstanding compression neuropathy will result in intrinsic motor wasting. Treatment with NSAIDs and protective padding is sufficient if the condition is diagnosed early. If symptoms limit participation or evidence of motor involvement is found, surgical decompression of the tunnel is indicated.

Final Comment

Management of wrist injuries should include rehabilitation of muscles weakened by inflammation, pain and immobilization. Once painless range of motion is achieved, the patient should!be encouraged to embark on a strengthening program to return to activity in as good or better condition than before the injury. Other preventive measures, such as stretching programs, protective equipment and proper sports-specific technique, can assist the patient in returning to activities with less chance of reinjury.

REFERENCES

[1.] Hollinshead WH, Rosse C, eds. Textbook of anatomy. 4th ed. Philadelphia: Harper & Row, 1985:219-84.

[2.] Kursunoglu-Brahme S, Gundry CR, Resnick D. Advanced imaging of the wrist. Radiol Clin North Am 1990;28:307-20.

[3.] Carter PR. Common hand injuries and infections: a practical approach to early treatment. Philadelphia: Saunders, 1983.

[4.] Recht MP, Burk DL Jr, Dalinka MK. Radiology of wrist and hand injuries in athletes. Clin Sports Med 1987;6:811-28.

[5.] Posner MA. Injuries to the hand and wrist in athletes. Orthop Clin North Am 1977;8:593-618.

[6.] Zemel NP, Stark HH. Fractures and dislocations of the carpal bones. Clin Sports Med 1986;5:709-24.

[7.] Rosenthall L, Hill RO, Chuang S. Observation of the use of 99mTc-phosphate imaging in peripheral bone trauma. Radiology 1976;119:637.

[8.] O'Brien ET. Acute fractures and dislocations of the carpus. Orthop Clin North Am 1984;15:237-58.

[9.] Almquist EE. Kienbock's disease. Clin Orthop 1986;202:68-78.

[10.] Cordrey LJ, Ferrer-Torells M. Management of fractures of the greater multangular. J Bone Joint Surg [Am] 1960;42-A:1111-8.

[11.] Braun RM. The distal joint of the radius and ulna. Diagnostic studies and treatment rationale. Clin Orthop 1992;275:74-8.

[12.] Osterman AL, Moskow L, Low DW. Soft-tissue injuries of the hand and wrist in racquet sports. Clin Sports Med 1988;7:329-48.

[13.] Melone CP Jr, Nathan R. Traumatic disruption of the triangular fibrocartilage complex. Pathoanatomy. Clin Orthop 1992;275:65-73.

[14.] Stark HH, Jobe FW, Boyes JH, Ashworth CR. Fracture of the hook of the hamate in athletes. J Bone Joint Surg [Am] 1977;59:575-82.

[15.] Cabrera JM, McCue FC 3d. Nonosseous athletic injuries of the elbow, forearm, and hand. Clin Sports Med 1986;5:681-700.

The Authors

REBECCA L. MORGAN, M.D. is currently in private practice in Franklin, Tenn. She attended the University of South Alabama College of Medicine, Mobile, and completed a residency in family practice at the University of Alabama/Huntsville Hospital Family Practice Program and a fellowship in sports medicine at the University of Alabama School of Medicine, Huntsville.

MICHAEL M. LINDER, M.D. is an associate professor of family medicine, program director of the family medicine residency and director of the sports medicine program at the University of Alabama School of Medicine, Huntsville. He graduated from the University of Tennessee, Memphis, College of Medicine.

The authors thank Marcia Chesebro, M.D., and Tom Johnson, Ph.D., for editorial contributions to this manuscript.

Each year members of a different family practice department develop articles for "Problem-Oriented Diagnosis." This is the second in a series from the Department of Family and Community Medicine at the University of Alabama-Birmingham. Guest editors of the series are T. Michael Harrington, M.D., and Myra Crawford, Ph.D.

COPYRIGHT 1997 American Academy of Family PhysiciansCOPYRIGHT 2004 Gale Group

 
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