Practice Essentials
The carpus, or wrist, is a complex joint that provides abduction and adduction in the frontal plane of the upper extremity, extension and flexion for hand movements, and supination and pronation in the coronal plane.
In the early 1800s, Colles was the first to differentiate between wrist fractures and wrist dislocations.
Signs and symptoms
In a patient with a wrist dislocation, the pain is usually localized to the dorsum of the wrist over the radioulnar joint. Pronation or supination against resistance causes pain, and occasionally, a click may be heard when the wrist is rotated.
Although ecchymosis is not always present, edema and point tenderness around the wrist should alert the clinician to the likelihood of a fracture (thereby preventing the misdiagnosis of a sprain or dislocation). Perform a thorough range-of-motion examination with pronation and supination to access pain and limitation of motion.
See Presentation for more detail.
Diagnosis
The majority of wrist fractures can be assessed adequately with good-quality anteroposterior (AP) and lateral radiographic images. A bone scan or magnetic resonance imaging study may be necessary to detect occult fractures that may not be visualized on plain radiographs.
See Workup for more detail.
Treatment
Accurate and timely fracture reduction is essential to obtaining good functional results. Early reduction lessens morbidity and improves patient comfort. Obtain anatomic reduction by manipulation and plaster fixation.
Open fractures and joint-capsule injuries require extensive irrigation, administration of antibiotics, emergent operative treatment, and hospital admission.
See Treatment and Medication for more detail.
Etiology
Causes
Causes include the following:
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Sports-related injuries
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Chronic overuse injuries
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Trauma
Carpal fractures most frequently occur after a fall onto an outstretched hand. [1]
Scaphoid navicular
Other mechanisms of injury have recently come to light in addition to a fall on the outstretched hand with hyperextension. These include forced palmar flexion of the wrist with axial loading of the wrist in a fixed position and hyperpronation. [2]
Epidemiology
United States statistics
The frequency of carpal bone injuries cannot be specifically determined because they encompass a range and variety of injuries near and around the wrist joint. Additionally, retrospective analysis by diagnosis category grossly underestimates the number of incidents.
The author's perspective is from a personal observation made one weekend day during a 12-hour shift several years ago in Wildomar, California. Seven fractures or fracture-dislocations of the wrist presented to the emergency department; all were related to roller blades, and all involved children aged 5-16 years.
The rate of chronic overuse injuries and other sports-specific injuries approaches 35-50% of all carpal injuries in the sports world. Fractures of the distal radius account for one sixth of all fractures seen and treated in the emergency department. These injuries are most common in patients aged 6-10 years and those aged 60-69 years.
International statistics
International rates approximate the US rate.
Functional Anatomy
The wrist joint, or carpus, is a complex arrangement between the forearm and the carpal bones, stabilized by strong, ligamentous attachments. [3, 4] The average wrist movement is 80º in flexion, 70º in extension, 30º in ulnar deviation, and 20º in radial deviation. Pronation and supination occur at the radioulnar articulation in the forearm, not at the wrist. The majority of injuries to the wrist occur with the wrist in the flexed position.
The muscles of the hand originate primarily in the forearm and pass over the wrist; the flexor carpi ulnaris inserts into the pisiform bone and is the only muscle that inserts into the wrist. The second and third metacarpals are fixed at the base and are immobile.
Carpal bones
The 8 carpal bones are arranged in 2 rows and are cuboid, with 6 surfaces. Of these 6 carpal surfaces, 4 are covered with cartilage to articulate with the adjacent bones, and 2 are roughened for ligament attachments. The proximal row, which contains the scaphoid, lunate, triquetrum, and pisiform, articulates with the radius and triangular cartilage to form the carpus. The distal row contains the trapezium, trapezoid, capitate, and hamate.
The ulnar nerve runs deep to the flexor carpus ulnaris tendon through the canal of Guyon. The median nerve lies between the flexor carpus radialis and the palmaris longus tendon in the carpal tunnel. Blood is supplied via the radial and ulnar arteries, which form the dorsal palmar arch. The scaphoid bone receives its blood supply from the distal part of this arch, which is prone to injury.
Anatomic considerations
The carpus is composed of the interval between the distal end of the radius and ulna and the proximal end of the metacarpal bones. A complex system of articulations works in unison to provide a global range of motion for the wrist joint. As noted above (see Functional Anatomy, Carpal bones), 8 carpi are arranged in 2 rows to form a compact, powerful unit. The distal row articulates with the proximal surface of the metacarpal bones. The proximal row articulates with the distal end of the radius and the fibrocartilaginous end of the ulna. The ulna does not articulate with the carpus.
The wrist has 5 large joint cavities in addition to the intercarpal joint spaces: (1) radiocarpal joint, (2) distal radioulnar joint, (3) midcarpal joint, (4) large carpometacarpal joint (between the carpus and the second, third, fourth, and fifth metacarpals), and (5) small carpometacarpal joint (between the first metacarpal and trapezium).
Motion at the wrist joint occurs between the radius and carpal bones. The size, position, and relation to the radius and surrounding carpal bones render the wrist joint vulnerable to injury. With dorsiflexion and radial deviation of the wrist, the joint is impinged by the radius; because of its narrow mid portion, the wrist joint is predisposed to injury. Healing depends on blood supply to the area; at this joint, blood enters the bone along the dorsal surface near its mid portion. Thus, the scaphoid is prone to avascular necrosis.
Sport-Specific Biomechanics
Sport-specific biomechanics focus on the unique characteristics that place the carpal bones at risk for injury during a sporting activity. This can be as obvious as a fall onto an outstretched hand during a roller sport to the hand plant that is involved in a gymnastics move.
Chronic use and movements in racquet sports, golf, and baseball require the carpus to resist torque stress. Depending on the strength of the weakest link, acute or chronic injury can ensue, which can be especially true in the hyperpronation-supination activity that is involved in the modern golf swing. The key to wrist injury prevention is to improve strength and flexibility in all planes of motion.
Prognosis
The prognosis depends on the severity of the injury and whether surgical correction is required. For example, simple, nondisplaced fractures of the distal radius require approximately 6 weeks of immobilization and 4-6 weeks of rehabilitation for a return to the full, premorbid condition. However, fracture-dislocations of the wrist that require open reduction and internal fixation require 8-12 weeks for the initial treatment phase and a similar amount of time for rehabilitation.
The prognosis following wrist fractures is influenced by many variables, including the complexity of the injury. Open fractures with large soft-tissue injuries have a much poorer prognosis. Additionally, timely and appropriate care can improve the prognosis. Appropriate follow-up monitoring and aggressive rehabilitation are essential.
Complications
Most complications from wrist fractures occur when the distal radius is fractured.
Colles fractures may result in radial shortening and angulation deformity, subluxation of inferior radioulnar joint, reflex sympathetic dystrophy, median nerve injury, osteoarthritis, or ulnar impaction syndrome.
Radiocarpal fracture-dislocation may cause entrapment of tendons or the ulnar nerve and/or artery.
A Hutchinson fracture may result in scapholunate dislocation, osteoarthritis, or ligament damage.
A Smith fracture may result in a complication similar to that of a Colles fracture.
Ulnar styloid fractures often result in nonunion.
Patient Education
When a patient is reintroduced to a sporting activity, in order to avoid reinjury and protect the injury site, take into account the patient's overall athletic strength when formulating an approach. For example, a tennis player with a carpus injury must regain full strength before attempting full use of the injured wrist during play. Specific care to the wrist-supporting ligaments and muscles is necessary to prevent overuse injuries during recovery and return of function.
Advise patients that wrist protection with support in the axial plane (with volar and dorsal hard-surface materials) is vital to prevent carpal injures in such sports as inline skating (ie, rollerblading).
For patient education resources, see the Hand, Wrist, Elbow, and Shoulder Center, Arthritis Center, and Breaks, Fractures, and Dislocations Center, as well as Carpal Tunnel Syndrome and Wrist Injury.
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Total volar displacement of distal radius fracture from patient fall; mechanism consistent with Smith fracture. Posteroanterior (PA) view of left wrist shows complex comminuted fracture deformity of the distal radius with overlap of the fracture fragments and antipalmar angulation of the fracture apex.
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Total volar displacement of distal radius fracture from patient fall; mechanism consistent with Smith fracture. Anteroposterior (AP) external rotation view of left wrist shows complex comminuted fracture deformity of the distal radius with overlap of the fracture fragments and antipalmar angulation of the fracture apex.
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Total volar displacement of distal radius fracture from patient fall; mechanism consistent with Smith fracture. Lateral view of left wrist shows ulnar sided subluxation of the ulna in relation to the distal carpal bones.
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Reduction obtained by volar inversion of hand on forearm and axial traction. Posteroanterior (PA) view of left wrist post-reduction shows interval reduction of the comminuted fracture of the distal radius with probably extension of fracture lines to the articular surface.
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Reduction obtained by volar inversion of hand on forearm and axial traction. Lateral view of left wrist post-reduction shows interval reduction of the ulnar subluxation.
