Carpal Fractures Management


Practice Essentials

A carpal fracture is a fracture of one or more of the carpal bones of the wrist. [1] Because treatment varies depending on the carpal element involved, fractures of the various bones are discussed individually.

The accepted indications for surgical intervention in the treatment of carpal fractures include an unstable or displaced fracture, an open fracture, and failure of nonoperative treatment with established nonunion. Treatment of carpal fractures has no absolute contraindications. The key to treatment is to obtain and maintain anatomic alignment with the most appropriate method.

Wilhelm Conrad Roentgen's discovery of x-rays, for which he was later awarded the Nobel Prize in physics, was a major turning point in the understanding and categorization of wrist fractures. One year after Roentgen obtained the first radiograph of the hand in 1895, Sir Robert Jones published the first report on the clinical use of a radiograph to locate a bullet in the wrist. By the early 20th century, radiography allowed for the description of almost every currently known wrist fracture.

Radiography provided insights into fracture fixation that proved particularly valuable by the mid-20th century. Treatment of war injuries has always played a significant role in the development and refinement of surgical principles and procedures. The knowledge obtained from treating casualties during World War I played an important role in the treatment of fracture fixation during World War II, when military surgeons developed a number of fixation procedures with the intent of expediting the return of soldiers to the battlefield.

Martin Kirschner was a German surgeon known for his fixation methods, particularly the development of the Kirschner wire (K-wire) fixation technique. Contemporary surgeons continue to favor this fixation method in the treatment of unstable fractures. The K-wire fixation method is technically easy to perform and probably the least traumatic method of fixing bones.

In the years following the war, advances in the treatment of carpal fractures included refinements in surgical techniques and improvements in prosthetic implants available for reconstruction.

Wrist arthroscopy is a minimally invasive technique that has an established role in the diagnosis and staging of wrist pathology. Diagnostic wrist arthroscopy is becoming the standard against which other diagnostic techniques are being compared. Similarly, staging arthroscopy has found an appealing role in evaluating and documenting the progression of disease and in tailoring treatment options accordingly. [2, 3]

The latter half of the 20th century also witnessed the development of new devices for rigid internal fixation. The Herbert bone screw has been a useful device. It provides highly secure internal fixation that allows for early mobilization. Originally designed to treat scaphoid fractures, this method of fixation has expanded to include fixation of other small osseous fractures as well. The Acutrak bone screw is a fully threaded, conically shaped implant with variable pitch threads.

Subsequently, the bone screw was developed for use in cancellous applications in which good compression and a headless design are desired. The unique combination of variable thread pitch, along with a fully threaded and tapered profile, provides excellent compression and holding power. In addition, bioresorbable implants are now being evaluated for fracture fixation. Studies to refine and improve the torsional strength and rigidity of such materials continue and may perhaps play a role in improving the treatment of unstable carpal fractures.

Anatomy

Located between the forearm and hand, the wrist extends from the insertion of the pronator quadratus on the radius and ulna proximally to the carpometacarpal (CMC) joints distally. The wrist contains eight carpal bones, all of which are associated with a network of tightly interwoven ligamentous connections.

The vascular supply to the wrist begins with the radial and ulnar arteries, as well as the anterior and posterior interosseous arteries. These vessels contribute to the formation of palmar and dorsal vascular arches that provide circulation to the carpal bones.

The pattern of blood flow to the scaphoid is of particular importance. The scaphoid receives its blood supply through two small branches that primarily arise from the radial artery. The palmar scaphoid branch enters the cortex at the distal pole of the scaphoid and the dorsal scaphoid branch enters along the dorsal ridge. Circulation to the proximal pole is maintained in a retrograde fashion by the intraosseous vessels.

Because the vascular supply of the proximal pole primarily relies on vessels entering the scaphoid, more distal injuries to the wrist of the scaphoid may disrupt the blood flow, thereby making the proximal pole particularly susceptible to ischemic changes. A fracture of the wrist may interfere with the proximal flow, placing the scaphoid at risk for avascular necrosis (AVN). [4]

Pathophysiology

Scaphoid fractures

Scaphoid fractures are the most frequent fractures in bony trauma to the carpus, with an incidence of about 60-70%. The reason for the high incidence of scaphoid involvement is that the scaphoid acts as a bridge between the proximal and distal bones of the carpus and is more easily put under stress. [5]

Two thirds of scaphoid fractures occur at the wrist, an area of the bone that can be impinged upon by the styloid process of the radius during a radial deviation maneuver. This fracture is usually associated with a force applied to the distal pole of the scaphoid, often with the wrist hyperextended. The radiostyloid essentially functions as a fulcrum against the center of the scaphoid, resulting in the predominance of fractures at the wrist level. The mechanism of injury usually consists of a fall on the palm of an outstretched hand.

On clinical examination, pain is elicited when pressure is exerted on the distal pole or on the scaphoid at the anatomic snuffbox on the radial aspect of the wrist.

Triquetral fractures

The mechanism of triquetral injury usually consists of either a direct blow to the dorsum of the hand or extreme dorsiflexion of the hand. The fracture is thought to result either from the hamate being forced against the triquetrum or from the ulnar styloid creating a volar compressive force on the dorsal aspect of the triquetrum.

On clinical examination, palpation of the triquetrum is facilitated by radial deviation of the hand. This maneuver allows direct palpation of the triquetrum as it moves away from the ulnar styloid process. Point tenderness is usually elicited directly over the triquetrum.

Lunate fractures

The mechanism of lunate fracture involves either chronic repetitive trauma leading to multiple microfractures or a direct traumatic blow resulting in a primary fracture. The etiology of AVN of the lunate or Kienböck disease has long been debated. [67The arterial blood supply of the lunate is variable, and it may be predominately derived from a single vessel. Other evidence, however, suggests that venous stasis may be more of an etiologic factor than an inadequate arterial supply.

The diagnosis should be suspected in the patient who reports central dorsal wrist pain, loss of motion at the wrist, and diminished grip strength. Tenderness is demonstrated with direct palpation of the dorsal aspect of the lunate.

Pisiform fractures

Pisiform fractures usually involve either a direct blow to the ulnar aspect of the wrist or forceful hyperextension, as in a fall on an outstretched hand.

On clinical examination, the diagnosis is suggested by pain and tenderness with direct palpation of the pisiform.

Trapezial fractures

Trapezial fractures usually result from a direct blow to the dorsum of the hand or from a fall on a radially deviated closed fist. Patients usually complain of a painful and weak pinch. On clinical examination, point tenderness is present on direct palpation of the trapezium.

One study (N = 166) found the trapezium to be one of the most frequently fractured bones in patients with acute wrist trauma, accounting for 20.4% of fractures. [8 The scaphoid was the clinically suspected fractured bone at initial assessment in the majority of patients with trapezium fractures.

Hamate fractures

The mechanism of hamate injury usually involves direct trauma to the volar aspect of the hand. It is not an uncommon injury in athletes who sustain a direct blow against the hamate while gripping the handle of a tennis racquet, golf club, or baseball bat. The end of the handle strikes the hamate during an unorthodox swing, resulting in a fracture.

Pain elicited with the gripping of objects is a common complaint. On clinical examination, tenderness is localized to either the volar or dorsal ulnar aspect of the wrist. [9]

Capitate fractures

Because of the protected position of the capitate, isolated fractures of this structure are rare. Capitate injury usually involves a direct axial load transmitted down the shaft of the third metacarpal with the wrist in dorsiflexion and slight radial deviation.

Tenderness is demonstrated with direct palpation immediately proximal to the base of the third metacarpal.

Etiology

Carpal injury is usually a result of direct or indirect trauma. In general, mechanisms that cause carpal fractures are injuries of moderately high energy. If the diagnosis is not established early or if a displaced fracture displacement is not recognized, disability may result.

Epidemiology

Upper-extremity fractures are among the most common fractures of the skeletal system. [10Carpal bone fractures account for 18% of hand fractures. Of the carpal elements, bones in the proximal row are the most frequently fractured.

Scaphoid fracture is by far the most common carpal bone fracture, representing 60-70% of fractures in the carpal group and 10% of all hand fractures. [1112Triquetral fracture is the second most common, accounting for 14% of wrist injuries. The incidence of isolated fractures of any of the remaining carpal bones is comparatively low, in the range of 0.2-5%. [13]

Prognosis

Carpal fractures can be among the most challenging orthopedic injuries to evaluate. Because no single treatment modality ensures an acceptable result for all carpal fractures, the treating physician must possess the knowledge and skill necessary to achieve an acceptable anatomic outcome. If diagnosed promptly and treated appropriately, the vast majority of these fractures will heal. [1415Early establishment of anatomic alignment provides the best opportunity for the later recovery of wrist motion and function.

CLINICAL PRESENTATION

History and Physical Examination

A complete history should be obtained from each patient being evaluated for a potential wrist injury. A thorough physical examination and an extensive radiographic evaluation should be complemented by basic knowledge of wrist anatomy and common fracture patterns. This vastly improves the accuracy of the diagnosis and thereby directs the treatment of carpal fractures. [16171819]

Once the diagnosis is established, the cardinal objective is to obtain and maintain normal anatomic alignment, because nonanatomic positioning may lead to functionally disabling results. Thereafter, treatment revolves around protective immobilization followed by thorough rehabilitation of the injured hand. These established principles provide clinical guidelines for the management of carpal injuries, and they are critical steps to a successful outcome in the treatment of carpal fractures.



Imaging Studies

Standard radiographs, including the anteroposterior (AP), lateral, and oblique views, are usually sufficient to diagnose carpal fractures. [20 If such fractures are not adequately depicted with standard radiographs, additional imaging studies, including bone scanning, computed tomography (CT), and magnetic resonance imaging (MRI), may help confirm them. [212223 A retrospective study of pediatric carpal fractures by Eckert et al suggested that MRI may be the imaging method of choice for children with persistent symptoms. [24]

Nondisplaced scaphoid fracture. Nondisplaced scaphoid fracture.
Scaphoid fracture with minimal displacement. Scaphoid fracture with minimal displacement.


Approach Considerations

The accepted indications for surgical intervention in the treatment of carpal fractures include the following:

  • Presence of an unstable or displaced fracture
  • Open fracture
  • Failure of nonoperative treatment with established nonunion

Treatment of carpal fractures has no absolute contraindications. The key to treatment is to obtain and maintain anatomic alignment with the most appropriate method.

Operative fracture repair has traditionally revolved around the use metal implants, including pins, plates, and screws. In most cases, this hardware is later removed, sometimes with an open procedure.

The future of bone fixation may involve resorbable prosthetic implants. Most bioabsorbable implants are made of polymers that degrade slowly over time, eliminating the need for a second retrieval operation. Bioresorbable materials with mechanical properties comparable to those of traditional pins, plates, and screws are being investigated. These may perhaps provide an alternative approach to carpal fracture fixation.

Surgical Therapy

Before selecting the appropriate fixation method, the treating physician must carefully consider the patient's age and occupation and the nature of the injury. Furthermore, it is imperative to obtain written informed consent. This means that the patient understands the complexity of the injury and the estimated time required for healing.

The operative risks and potential complications, including nonunion, risk of infection, and the need to later remove hardware (if indicated), should also be discussed. Thorough patient education cannot be overemphasized, because it is critical to the success of treatment.

With the upper extremity anesthetized, the arm is prepared and draped in the standard fashion. A pneumatic tourniquet on the upper arm is inflated to maintain a bloodless operative field.

Depending on the nature and location of the fracture, a volar or dorsal approach may be used to expose the injury. Reduction may be achieved by using Kirschner wires (K-wires) as joysticks. Fixation may proceed with either K-wires or a bone screw. Bone grafting may be considered for injuries with extensive comminution. Intraoperative fluoroscopy is used to determine the effectiveness of the reduction.

After the wound is closed, a protective cast is then applied for immobilization.

Scaphoid fractures

Scaphoid fractures are classified as fractures of the proximal pole, wrist, distal one third, or distal tubercle. They are then further categorized as stable or unstable. Stable fractures are nondisplaced and have minimal comminution, whereas unstable fractures are displaced and have considerable comminution. A standard series of radiographs, including those in the anteroposterior (AP), lateral, and oblique views, are necessary to evaluate a scaphoid fracture (see Workup). [25]

A stable scaphoid fracture is usually treated with cast immobilization. [26On average, a period of 12 weeks is required for union of the scaphoid to occur. If radiographic evidence of scaphoid nonunion persists after 4 months of immobilization, operative intervention may be indicated. [27]

Should a strong clinical suspicion be present, even in the presence of apparently normal radiographic findings, a possible scaphoid fracture should be diagnosed on the basis of the history and clinical findings. When a scaphoid fracture is suspected without radiographic confirmation, treatment consists of cast immobilization for 2-3 weeks followed by repeat radiographic examination. If plain radiographic findings are equivocal after 2 weeks, the scaphoid can be evaluated with comuted tomography (CT).

An unstable scaphoid fracture and scaphoid nonunion should be treated surgically with open reduction and internal fixation (ORIF; see the image below).

Open reduction and internal fixation of displaced Open reduction and internal fixation of displaced scaphoid fracture.

The scaphoid is approached volarly through a longitudinal incision beginning several centimeters proximal to the flexion crease of the wrist. The incision is made along the tendon sheath of the flexor carpi radialis (FCR). It is then curved radially toward the trapezium. The sheath of the FCR is opened, and the tendon is retracted radially. The radioscaphocapitate ligament is identified and divided sharply in such a way that it can later be repaired. The scaphoid is located deep to this ligament.

With the fracture exposed, the appropriate procedure should be chosen. Repair may involve K-wire fixation, screw fixation, bone grafting, or a combination of these techniques. [282930]

After fixation is achieved, it should be confirmed intraoperatively with fluoroscopy to ensure full reduction. Postoperative immobilization is then provided for 6-12 weeks with application of a thumb spica cast.

Lunate fractures

Lunate fracture patterns are classified into the following four stages on the basis of radiographic findings:

  • Stage I demonstrates no significant radiographic changes
  • Stage II is characterized by the presence of some degree of bone fragmentation without evidence of collapse
  • Stage III shows fragmentation and collapse
  • Stage IV demonstrates evidence of fragmentation, collapse, and arthritis

Treatment of lunate fractures varies according to the stage of the disease. Most treatment options revolve around stress reduction, revascularization, or replacement of the lunate. Salvage procedures are reserved for advanced disease.

Treatment options for stage I include no treatment or immobilization. The remaining stages are surgically treated with a variety of techniques. In stages II and III, the treatment options are surgical and include stress reduction, revascularization, and lunate replacement. Stage IV is also treated surgically with salvage procedures, such as scaphocapitate arthrodesis, total wrist arthrodesis, or proximal row carpectomy.

Triquetral fractures

Triquetral fractures are radiologically separated into two main types, as follows:

  • Peripheral chip fractures
  • Body fractures

Standard AP, lateral, and oblique radiographs are usually sufficient for their diagnosis.

Triquetral chip fractures are treated symptomatically with 2-3 weeks of immobilization if discomfort becomes significant. Once symptoms resolve or become less significant, range-of-motion (ROM) exercises can be initiated. Fractures of the body of the triquetrum require more significant attention. If the fracture is minimally displaced, it should be treated with cast immobilization for 4-6 weeks, with ROM exercises beginning after cast removal.

Displaced triquetral chip fractures that fail to unite after conservative immobilization are rarely symptomatic enough to warrant surgical excision. On the contrary, displaced fractures involving the body of the triquetrum should be surgically treated with either closed reduction and percutaneous pinning or ORIF. [31]

Pisiform fractures

The pisiform fracture patterns commonly include the following:

  • Transverse body fractures
  • Comminuted fractures
  • Avulsion fractures

Standard radiographs, including AP, lateral, and oblique views, are usually sufficient for diagnosis. Pisiform fractures are almost universally treated conservatively with cast immobilization for 6 weeks. ROM exercises should be initiated after cast removal.

Trapezial fractures

Trapezial fractures involve either the body or the trapezial ridge. Fractures of the body are either comminuted or vertical in orientation. Trapezial ridge fractures have been separated into two types, as follows:

  • Type I fractures occur through the base of the trapezial ridge
  • Type II fractures involve the tip of the trapezial ridge

Standard radiographs, including carpal tunnel views, may help in making the diagnosis.

Nondisplaced trapezial body fractures are treated conservatively with the application of a thumb spica cast for 6 weeks. Displaced trapezial body fractures require surgical attention. Both type I and type II trapezial ridge fractures are treated conservatively with closed reduction in a thumb spica cast for 6 weeks. Displaced trapezial fractures are approached volarly. Trapezial body fractures are treated with ORIF by using K-wire fixation. If symptoms persist despite conservative treatment, small type II fractures involving the trapezial ridge may be excised.

Capitate fractures

Capitate fractures are classified into the following two categories:

  • A fracture pattern known as scaphocapitate syndrome, consisting of a scaphoid wrist fracture and a proximal capitate fracture
  • An isolated capitate fracture

Plain radiography is usually sufficient to make the diagnosis. Isolated capitate fractures may be difficult to diagnose with standard plain radiography, and CT is often required to establish the diagnosis.

Nondisplaced capitate fractures should be treated with closed reduction and immobilization. Displaced capitate fractures require ORIF. The capitate is usually approached dorsally. Alignment is typically achieved and maintained by using K-wire or screw fixation. If comminution is extensive, bone grafting may be performed concomitantly.

Hamate fractures

Fractures involving the hamate are separated into the following two categories:

  • Hamate hook fractures
  • Hamate body fractures

AP, lateral, and oblique radiographs usually depict the fracture. Carpal tunnel views are useful in diagnosing hamate hook fractures, but CT may provide the most definitive findings.

Nondisplaced hamate hook fractures (see the image below) and nondisplaced hamate body fractures are both treated conservatively and immobilized with a cast for 6 weeks. ROM exercises are started when the cast is removed.

Nondisplaced fracture of the hook of the hamate. Nondisplaced fracture of the hook of the hamate.

Displaced hamate hook fractures and displaced hamate body fractures are treated surgically with ORIF. Hamate hook fractures are approached volarly. Hook fractures are surgically reduced, and alignment is maintained with K-wire fixation. In contrast, hamate body fractures are approached dorsally. Typically, K-wire fixation is used to maintain alignment.

Postoperative immobilization is maintained for 8 weeks for hamate hook fractures, whereas hamate body fractures may heal after 6 weeks of immobilization.

Postoperative Care

Various postoperative management strategies exist. Bone healing after internal fixation may take 6-12 weeks or, in a few cases, longer. Postoperative cast immobilization is maintained until healing is confirmed radiographically or clinically. K-wires can be removed after radiographs show evidence of bony union. Wrist arthroscopy has been employed as a means of assessing scaphoid union in cases where clinical examination, radiography, and CT do not provide sufficient information. [32]

Mobilization is initiated once the fixation is deemed stable. Thereafter, ROM and strengthening exercises can be initiated with the supervision and guidance of a physical therapist.

Complications

Nonunion is the most common complication after scaphoid fracture treatment, and it may occur in as many as 5-10% of cases despite proper treatment. Factors predictive of this complication include smoking, longer time elapsed since the fracture, and avascular necrosis (AVN) of the proximal fragment. [33Over several years or longer, patients with nonunion may then experience pain, instability, and eventual collapse that leads to intercarpal or radiocarpal arthritis. Observation alone has no role in the treatment of scaphoid nonunion, and all cases should be corrected surgically. [3435]

Most pisiform fractures heal with conservative measures. However, chronic pain at the pisotriquetral joint may persist as a result of degenerative changes in the joint. Pisotriquetral arthrosis is suspected when pain symptoms persist after a period of immobilization. Pisiform excision is the accepted treatment for this condition.

The incidence of nonunion is higher with fractures involving the tip of the trapezial ridge than with fractures of the base of the trapezial ridge. The accepted treatment for painful nonunion of either type is excision, which is generally well tolerated.

Nonunion of the hamate hook is a potential complication after operative reduction and fixation. Excision is the accepted treatment for symptomatic hamate hook nonunion.


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