[The Physician and Sportsmedicine]

Office Management of Scaphoid Fractures

Greg Gutierrez, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 24 - NO. 8 - AUGUST 96

In Brief: A dull, deep pain in the wrist after a fall on an outstretched hand is the hallmark of a scaphoid fracture. Pain with maneuvers that stress the scaphoid can suggest fracture on physical exam. Radiographs are crucial: Determining the location, stability, and orientation of the fracture guides treatment and predicts outcome. Distal fractures and horizontally oriented fractures generally heal well and can be managed by immobilization in a short-arm thumb spica cast. Proximal fractures and vertically oriented fractures have the most morbidity, and open reduction should be considered. When prolonged immobilization is required, range-of-motion and strengthening exercises are prescribed to restore hand function after cast removal.

The scaphoid bone is crucial to the intricate function of the wrist. It endures a myriad of complex forces, including a common injury in active people--a fall on an outstretched hand, particularly when the wrist is radially deviated. The scaphoid is the most frequently injured carpal bone. In the wrist, only distal radius fractures are more common. Scaphoid injuries are most commonly seen in young men, are often misdiagnosed as sprained wrists, and are rarely seen in children because the distal radial physis usually fails first.

Scaphoid fractures have a warranted reputation for needing close attention. Fractures of this bone can be complicated by a tenuous blood supply and a tendency for some of the fractures to be unstable. Certain scaphoid fractures require prolonged immobilization and have an increased risk of poor results. However, 60% to 70% of scaphoid fractures are stable and 90% will heal with prompt diagnosis and proper immobilization (1,2).

Family physicians handle a broad range of fractures with good clinical results (3,4). By understanding the unique characteristics of the scaphoid, certain fractures of this bone can be managed with confidence.

A Delicate Anatomic Balance

The scaphoid is shaped like a cashew. Eighty percent of the surface is covered by articular cartilage; therefore, most fractures are intra-articular except at the tubercle. The scaphoid is a strong mechanical link between the proximal and distal carpal rows and can be regarded as an extension of the thumb ray into the wrist (figure 1). It is subjected to shearing, rotational, and compression forces from several surrounding structures.

[FIGURE 1]

Its umbilical-cord-like blood supply enters at the waist; some smaller arteries enter distally, but none enters proximally. Retrograde flow from the distal vessels supplies the proximal pole. A fracture proximal to the waist can sever communicating vessels and deprive the proximal fragment of its blood supply.

A Comprehensive Wrist Exam

History. The history usually involves a fall on an outstretched hand. Patients may not report severe pain and may even continue to use the wrist. Scaphoid fracture pain is usually described as a dull, deep discomfort in the wrist on the thumb side. The swelling and ecchymosis of an isolated scaphoid fracture is usually mild, but fullness in the anatomical snuffbox may suggest a wrist effusion (5).

Physical exam. Physical examination of the wrist should be done with one fingertip, carefully palpating the major structures of the wrist: the flexor and extensor tendons and their insertions, the distal radius and ulna, and the carpal bones.

Maneuvers that elicit pain when the scaphoid is injured are shown in figure 2. Results should be compared to the opposite wrist. A false positive may be obtained, for example, when compression of the sensory branch of the radial nerve, which passes along the palmar aspect of the snuffbox, causes pain. Absence of pain on axial compression of the thumb has been shown to be reassuring that a fracture is not present (6).

[FIGURE 2]

Radiographs. Routine radiographs of the scaphoid include anteroposterior (AP), lateral, and oblique (45° from horizontal) views. The AP view is done with the fist mildly clenched and the wrist in ulnar deviation. (An AP view with a tightly clenched fist and ulnar deviation can be ordered to screen for ligament injury.) The lateral view is done with the wrist in neutral position. When the scaphoid is injured in the normal wrist, the lateral view shows a line of concentric arcs formed by the distal radius, lunate, and capitate. The longitudinal axis of these bones should be collinear. Disruption of this alignment suggests a ligament injury or dislocation, displacement, or angulation of a fracture.

If radiographs are negative despite clinical suspicion of a scaphoid fracture, the patient's wrist is immobilized and radiographs are repeated in 2 weeks. If plain films continue to be negative but clinical suspicion remains, further imaging should be pursued. Bone scan and computed tomography have been used with about equal accuracy to detect occult fractures. Polytomography and magnetic resonance imaging (MRI) can also be used though they are more expensive. MRI can demonstrate much more anatomy and, because of increasing affordability, may soon become the standard for visualizing occult fractures and ligament disruptions.

Classification. Treatment decisions and outcome predictions are based on the location and stability of the scaphoid fracture. Acute, nondisplaced fractures are generally seen as a single lucent line through the scaphoid. A fracture is considered unstable if more than 1 mm of displacement is seen between fragments or if the fragments are angled. In addition, the fracture is considered unstable if the lateral radiographic view shows malalignment of the carpal bones suggestive of fracture dislocation, or if the anteroposterior view shows carpal widening suggestive of ligament disruption.

Fractures are localized within the proximal, middle (waist), or distal third of the bone. The incidence of avascular necrosis increases as fractures are located more proximally in poorly vascularized areas. Most scaphoid fractures occur at the waist, followed by the proximal pole and then the distal pole (1). Orientation of the fracture is a clue to its stability (figure 3). The most stable fracture orientation is the horizontal oblique, wherein the axis of the load is perpendicular to the fracture line. Transverse fractures may be unstable. The most unstable fracture has a vertical oblique orientation; fragments are vulnerable to longitudinal shearing forces from the radius.

[FIGURE 3]

Detecting Other Injuries

Checking for a scaphoid fracture is only one part of the wrist trauma evaluation, which should also focus on other structures that might be injured. The differential diagnosis of radial wrist pain includes fracture of the scaphoid, distal radius, or base of the first metacarpal, radioulnar joint injury, perilunate ligament disruption, and injury of the extensor carpi radialis (brevis and longus) or flexor carpi radialis tendons.

A history of severe pain and disability and an exam that demonstrates significant swelling raises the examiner's suspicion of a complex injury, which can include fracture-dislocation, ligamentous disruption, and injury to bones other than the scaphoid. In complex injuries, the mechanism is usually severe, such as falling at high speed, a powerful twisting injury, or a football injury. Companion fractures and ligament injuries that occur with a complex injury can cause significant carpal instability that requires surgical correction.

A missed ligament rupture can be as devastating as a problematic fracture (7). A complete ligament disruption on x-ray will show increased joint space between the affected carpal bones (figure 4). A clenched-fist AP view may demonstrate subtle intercarpal widening. Other imaging studies such as arthrography and MRI may be needed (7). Pain in the wrist after apparent scaphoid healing also suggests a ligament disruption.

[FIGURE 4]

Orientation Guides Treatment

Wrist and thumb immobilization is the first step in acute treatment for nondisplaced distal scaphoid fractures and is an option for treating some of the more complex scaphoid fractures. Scaphoid fractures that present more than 3 weeks after the injury may need more aggressive treatment, and orthopedic consultation is suggested (2). An adaptation of Herndon's algorithmic approach to treatment and patient counseling is shown in figure 5 (not shown). Though patient and environment variability may require deviation from the steps outlined, this is a good conservative starting point.

Because of the multiple forces on the scaphoid, many different positions of wrist immobilization have been used; however, healing rates of 90% have been achieved with all methods and most types of scaphoid fractures, suggesting that the position of the wrist may be irrelevant (3,4). Immobilization of the elbow is controversial. The long-arm cast includes the elbow at 90°, the wrist in neutral position, and the thumb immobilized at the metacarpophalangeal (MCP) joint. Appropriate conclusions can be drawn from recent studies using long-arm casting (8). Long-arm casting of nondisplaced, stable scaphoid fractures healed 3 weeks faster than other methods in one study (9). The most improvement was seen in patients who had proximal and middle third fractures. Though no significant loss of motion in the elbow occurred with less than 6 weeks of immobilization, functional and economic hardships were increased.

Acute, nondisplaced fractures of the tubercle and distal third of the scaphoid can be treated with a short-arm cast (figure 6a) for 6 to 8 weeks. The wrist is placed in neutral flexion-extension and neutral-to-slight radial deviation. The thumb MCP joint should be included in the cast, and the interphalangeal joint can be left out (1,2). Molding of the cast is as important as its position. Slight wrist movements in a loose case can move the scaphoid. The casting material should be molded snugly (figure 6b). Because casts loosen over time, regular cast checks and changes are necessary every 3 to 4 weeks for effective immobilization.

[FIGURE 6]

Waist fractures should be considered for open reduction; however, nondisplaced, horizontal oblique fractures of the waist have the best chance of successful nonsurgical treatment. Though closed treatment has less surgical risk, prolonged immobilization and nonunion are other risks to consider. Closed treatment consists of 6 weeks in a long-arm cast, followed by a short-arm cast worn until healing is seen on radiographs. Waist fractures require a total of 8 to 12 weeks of immobilization. Vertical oblique fractures of the waist should be referred to an orthopedist.

Closed treatment of stable, nondisplaced fractures on the proximal pole can be attempted; however, orthopedic referral is suggested because open treatment is preferable. Proximal pole fractures require 12 to 24 weeks of immobilization for closed treatment.

Complications Require Vigilance

During immobilization, x-rays should be obtained at 3 to 4 week intervals to monitor healing and detect signs of delayed union, nonunion, malunion, or avascular necrosis. Risk factors for complications in scaphoid fractures include delayed treatment, greater than 1 mm of displacement, carpal instability (ligament disruption), vertical oblique fracture, proximal pole fracture, and fracture-dislocations. Orthopedic consultation is needed as soon as any of these risk factors is detected. After immobilization, follow-up x-rays should be done at 3, 6, and 12 months.

Healing of the fracture is recognized radiographically by a decrease in the fracture lucency with trabeculae crossing the fracture line.

Delayed union is defined as no healing (no trabeculae crossing the fracture line) at 3 months. Nonunion is defined as no healing at 6 months. Other signs of delayed healing on x-ray include resorption at the fracture site, sclerosis, and displacement. Surgical treatment is necessary, and good results can be achieved (1).

Malunion occurs when the fracture fragments heal with angulation, causing a dorsal "humpback" deformity. X-rays show a foreshortened scaphoid. Views of the opposite wrist should be compared if foreshortening is suspected. Malunion of this bone causes an abnormal link in the intricate chain of carpal bones. Since 80% of the scaphoid surface is articular cartilage, arthrosis and arthritis are eventual consequences. Regular x-ray follow-up during immobilization is crucial because it will help detect the development of angulation and other abnormalities.

Avascular necrosis occurs after injury of the retrograde arteries within or entering the proximal scaphoid. Signs of avascular necrosis on x-ray include sclerosis and cyst development (figure 7). In waist fractures the incidence of avascular necrosis is 30% to 50%. In proximal third fractures, the incidence ranges from 14% to 100% with treatment, and in proximal fifth fractures the incidence with treatment is nearly 100% with treatment. The distal third of the scaphoid nearly always heals without complications (1).

[FIGURE 7]

Why Is Rehab Important?

Because of the long immobilization time needed to treat most scaphoid fractures, a rehabilitation program should be instituted after immobilization. A thumb spica splint can be used for protection until range of motion and strength improve. If a long-arm cast is used and flexion contractures are evident, physical therapy is recommended. Physical therapy is required for elderly patients because of their increased risk of losing strength and range of motion.

Range-of-motion exercises for the wrist can be started after immobilization, followed by progressive strengthening exercises for the wrist flexors and extensors. Supination, pronation, and grip exercises can also be added.

Return-to-play decisions are multifactorial and are based on fracture location, patient age, sport, and level of competition. At a minimum, the fracture should exhibit healing and be properly immobilized and protected before return is considered.

Teamwork Reduces Disability

Scaphoid fractures will probably always be common in active patients; however, physicians can greatly reduce the complications that result by instituting appropriate treatment and close follow-up. Physicians can enlist patient support toward the goal of reducing complications by teaching them to monitor their pain and symptoms and to observe the importance of follow-up and compliance.

References

  1. Herndon JH: Scaphoid fractures and complications. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994
  2. Taleisnik J: Fracture of the carpal bones, in Green DP (ed), Operative Hand Surgery, ed 2. New York City, Churchill Livingstone, 1988
  3. Eiff MP, Saultz JW: Fracture care by family physicians. J Am Board Fam Pract 1993;6(2):179-181
  4. Hatch RL, Rosenbaum CI: Fracture care by family physicians: a review of 295 cases. J Fam Pract 1994; 38(3):238-244
  5. Barton NJ: Twenty questions about scaphoid fractures. J Hand Surg (Br) 1992;17(3):289-310
  6. Powell JM, Lloyd GJ, Rintoul RF: New clinical test for fracture of the scaphoid. Can J Surg 1988;31(4):237-238
  7. Atkinson LS, Baxley EG: Scapholunate dissociation. Am Fam Physician 1994;499(8):1845-1850
  8. Cooney WP III, Linscheid RL, Dobyns JH: Fractures and dislocations of the wrist, in Rockwood CA Jr, Green DP, Bucholz RW (eds), Rockwood and Green's Fractures in Adults, ed 3. Philadelphia, JB Lippincott Co, 1991
  9. Gellman H, Caputo RJ, Carter V, et al: Comparison of short and long thumb-spica casts for nondisplaced fractures of the carpal scaphoid. J Bone Joint Surg (Am) 1989;71(3):354-357

The author would like to thank Mary Zavadil-Gutierrez, MD, for her assistance with the revision of this manuscript.

Dr Gutierrez is in private practice at The Denver Center for Sports and Family Medicine in Denver. He is director of sports medicine education for the St Joseph Hospital family practice residency and is a clinical instructor at the University of Colorado Health Sciences Center, both in Denver. He is a member of the American Medical Society for Sports Medicine and holds a certificate of added qualification in sports medicine. Address correspondence to Greg Gutierrez, MD, Denver Center for Sports and Family Medicine, 210 University Blvd, Suite 210, Denver, CO 80206; e-mail to [email protected].


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