Hamate Fracture 

Updated: Aug 06, 2018
Author: Amy Powell, MD; Chief Editor: Sherwin SW Ho, MD 

Overview

Background

Although hamate fractures are increasing in incidence secondary to the popularity of sports activities involving racquets, bats, and clubs, these injuries remain relatively rare. Estimates suggest hamate fractures constitute 2% of all carpal fractures. The hamate bone is a roughly triangular-shaped bone composed of both a body and a hook (see images below). Hamate fractures are thus classified as type I fractures involving the hook and type II fractures involving the body. Type I fractures are more common than type II fractures.[1, 2]

Posterior (dorsal) view of the wrist. Posterior (dorsal) view of the wrist.
Anterior palmar view. Anterior palmar view.

For excellent patient education resources, visit eMedicineHealth's First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles Wrist Injury and Broken Hand.

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Epidemiology

Frequency

United States

Hamate fractures account for 2% of all carpal fractures.[3] Of the 2%, one third are hamate hook fractures due to repetitive swinging by golfers.

Functional Anatomy

The hamate is a triangular bone located in the distal carpal row farthest to the ulnar side (see the images below). The hamate is bordered proximally by the pisiform and the lunate in the proximal carpal row, radially by the capitate, and distally by the bases of the fourth and fifth metacarpals.

Posterior (dorsal) view of the wrist. Posterior (dorsal) view of the wrist.
Anterior palmar view. Anterior palmar view.

A roughly circular projection or hook on the volar surface of the hamate is the inferolateral border of the Guyon canal. The roof (superficial) of the canal is formed by the palmar carpal ligament, and the floor (deep) is formed by the flexor retinaculum. The canal carries the ulnar artery and nerve, and, for this reason, hook fractures should suggest a high probability of ulnar artery and nerve damage.[4] In addition, the hamate hook has a dual blood supply, with vessels entering from both the ulnar tip and radial base. These vessels often have a poor anastomosis, which clinically can result in nonunion due to insufficient blood supply.

Sport-Specific Biomechanics

Type I fractures involving the hook of the hamate are the most common and can occur via several different mechanisms.[1, 2, 5, 6, 7, 8] First, repeated microtrauma to the hook during sports involving swinging clubs, bats, or racquets can result in a hook stress fracture. These usually occur in the nondominant hand and account for approximately one third of hamate fractures. Second, direct trauma can be applied during sports when the butt of the club rests on the hamate and the force of the swing is then transmitted directly to the bone. In addition, indirect trauma can be applied to the hook through its muscular and ligamentous attachments. This can occur either when falling on a hyperextended wrist or during power grips.

Type II fractures involving the body of the hamate are less common than type I fractures and always require direct force.[5] Most commonly, these fractures occur with a punch-press injury or dorsopalmar compression of the wrist between heavy weights.[3]

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Presentation

History

Hamate hook fractures are usually seen in individuals who participate in sports involving a racquet, bat, or club or in individuals who have a history of falling on an outstretched hand.[1, 2, 5, 6, 7, 8] Because most patients with this injury seek medical advice only after persistent symptoms, they often present weeks to months after the initial injury. Most report palmar pain aggravated by grasp, pain with dorsoulnar deviation, and pain with flexion of the fourth and fifth digits.

In the case of a hamate body fracture or direct trauma, persons may present immediately. Fractures involving the body of the hamate are typically associated with high-energy, direct-force trauma or crushing injuries. External evidence of these forces is evident in these individuals.

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Physical

Physical examination findings are usually nonspecific and may even be absent. If symptoms are present, physical examination typically reveals discrete point tenderness with palpation over the hook of the hamate, diminished grip strength, and, secondary to the proximity of hamate fractures to the ulnar nerve, paresthesia may be present in the fourth and fifth fingers.

Resisted distal interphalangeal flexion of the fourth and fifth fingers with the wrist in ulnar deviation causes pain over the fractured hook, whereas testing in radial deviation does not. In the case of more severe injury, brief examination for neurologic and vascular competency, accompanied by basic radiographs, are all that is appropriate in an emergency department setting. More detailed exploration and radiographic studies should be performed later, while the patient is under anesthesia.

Causes

Hamate fractures are generally associated with sports activities that use a racquet, bat, or club. For a more complete discussion of the causes and mechanisms of hamate fractures, see Sport-Specific Biomechanics.

 

DDx

Diagnostic Considerations

Consider the following when evaluating hamate fractures:

  • Tears to any of the ligaments surrounding the hamate (eg, palmar carpal ligament, flexor retinaculum, pisohamate ligament, palmar carpometacarpal ligament, dorsal carpometacarpal ligament)

  • Injury to the ulnar flexor profundus tendon, such as rupture or tenosynovitis

 

Workup

Laboratory Studies

See the list below:

  • Laboratory studies are not necessary for the diagnosis of hamate fractures.

Imaging Studies

See the list below:

  • Radiographs: Fractures to the hamate may not be readily evident on radiographic images (see the images below).[9, 10] For this reason, multiple views of the wrist, including a carpal tunnel view, supination oblique view (hook of hamate view), and flexion and extension films, should be ordered. Even when appropriate radiographs are obtained, some studies demonstrate 72% sensitivity and 88% specificity for detecting hamate fractures.[10]

    Anteroposterior view of the wrist. Anteroposterior view of the wrist.
    Lateral view of the wrist. Lateral view of the wrist.
    Oblique view of the wrist. Oblique view of the wrist.
  • Computed tomography (CT) scan: In cases in which clinical findings suggest a fracture but the radiographic evidence is questionable, a CT scan should be ordered (see the images below).[9] CT scanning is considered the criterion standard, with sensitivity and specificity approaching 100%. In addition, this imaging modality determines the degree of fracture displacement, which aids in therapeutic decision making.

    Computed tomography scan of the wrist. Computed tomography scan of the wrist.
    Lateral computed tomography scan of the wrist. Lateral computed tomography scan of the wrist.
    Reconstruction of the hamate fracture. Reconstruction of the hamate fracture.
  • Magnetic resonance imaging (MRI): This study can be performed instead of CT scanning if the patient lacks neurologic and/or vascular competency in order to better view soft-tissue structures. Sensitivity and specificity approach 100% for diagnosing fractures.

 

Treatment

Acute Phase

Medical Issues/Complications

Complications include ulnar nerve compression at the level of the Guyon canal. The hook of the hamate is the distal lateral border of the Guyon canal and is close to the motor branch of the ulnar nerve and ulnar artery as they pass through the canal. The ulnar nerve then turns around the hook of the hamate and travels deep to innervate the intrinsic musculature. When surgical treatment is indicated, care must be taken to prevent damage to the motor branch of the ulnar nerve. Additionally, rupture of the small- and ring-finger flexor tendons may occur if injured by the irregular fracture edges.

Surgical Intervention

In the past, hamate hook fractures were treated conservatively with lower arm cast immobilization for 6 weeks, provided the fracture was diagnosed within 1 week of the injury.[11] Retrospective analyses have demonstrated nonunion rates greater than 50% and as high as 80-90% with conservative treatment. These nonunions are likely multifactorial, involving poor blood supply, delayed diagnosis, and fragment displacement with continuous movement of the fourth and fifth digits while casted. Therefore, all hamate hook fractures should be referred to a hand surgeon for possible surgical intervention.

Two types of surgeries are commonly performed for hamate hook fractures.[5, 11] One involves excision of the hook itself. The other is an open reduction and internal fixation (ORIF) procedure. Of the 2 procedures, the former (excision of the hook) is considered the criterion standard.[12]

Complications that may arise from hook excision include decreased grip strength secondary to removal of the attachment for the transverse carpal ligament, pisohamate ligament, and flexor and opponens digiti minimi muscles. Because of this concern, 2 retrospective studies compared grip strength in patients who underwent excision versus those who underwent ORIF.[5, 11] Both studies failed to show any statistically significant difference in grip strength up to 3 years post procedure.

Hamate body fractures are commonly associated with dislocation of the fourth and fifth fingers.[13, 14, 15, 16] Shearing forces from the metacarpals can cause either a dorsal cortical hamate fracture or a coronal body fracture.[17, 18, 19, 20] These fractures can be reapproximated by reduction of the carpometacarpal joint; however, they usually require internal fixation because of the high incidence of instability in these injuries.[21]

Consultations

Consultation with an orthopedist or hand surgeon is recommended for all patients with hamate fractures secondary to the high risk of nonunion with conservative treatment (see Surgical Intervention). If an ulnar nerve injury is suspected, an electrodiagnostic evaluation should be performed by a physiatrist or neurologist with electrodiagnostic expertise before surgical exploration and treatment in order to determine the degree of axonal injury.

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Other Treatment

Data are emerging that suggest ultrasound is useful in promoting fracture healing. Fujioka et al published a case report of a hamate nonunion in an 18-year-old woman treated with low-intensity ultrasound that was performed 20 min/d for 4.5 months.[22] During her ultrasound treatments, the patient was allowed routine activities and was not immobilized. CT scanning confirmed union of her fracture.

The role ultrasound will play in the future remains unclear; however, it will likely be limited because this imaging modality is both more time consuming and requires longer activity limitations than current treatments.[23, 24]

Recovery Phase

Rehabilitation Program

Physical Therapy

Recovery from injury occurs in 4 stages (ie, wound healing, recovery of motion, recovery of strength and power, and recovery of endurance). Although these divisions are arbitrary, they provide a progressive sequence for management and a target for physical therapy. Early motion, instituted before collagen cross-linking and scarring occur, favors functional recovery. Collagen has more elasticity in the earlier stages of formation; and this elasticity decreases with time and immobilization.

The goals of physical therapy are tailored to the desires of the patient and the demands of his or her occupation or lifestyle. In all phases of recovery, special attention is directed to any development of edema. Fibrin contained in the exudate has the potential to evolve into scar tissue and limit function. For this reason, recommend elevation, compression, and motion in order to mobilize excess fluid from around the wound until maximum medical recovery is achieved.

The ability to begin physical therapy and increase the intensity of exercises varies according to the initial treatment of the hamate fracture. Conservative treatment requires immobilization with casting for 6 weeks, followed by an additional 4-6 weeks of physical therapy. If the injury is treated surgically with hook excision, the patient can start physical therapy immediately, without limitations, and can return to full activity within 6-8 weeks. If the injury is treated surgically with ORIF, the patient requires casting for 2 weeks, followed by an additional 4 weeks of physical therapy without placing strain on the affected wrist, before progressing to full activity in 6-8 weeks (see Return to Play).[25]

Maintenance Phase

Rehabilitation Program

Physical Therapy

The maintenance phase is the final phase of the rehabilitation process. The goals for therapy are focused on specific functional activities, whether related to work or sports, to enable the patient to safely return to his or her premorbid level of functioning. In addition to working on specific strengthening activities with a physical therapist, the patient should also be independently engaging in a home exercise program for continued range-of-motion therapy and strengthening of the wrist and hand if optimum mobility and strength has not been attained.

 

Medication

Medication Summary

Pain control following surgery is the most common medication concern. Usually, 5-7 days of a low-strength narcotic analgesic, followed by over-the-counter (OTC) nonsteroidal anti-inflammatory drugs (NSAIDs), is sufficient to control pain in most patients. Sufficient amounts of pain medication should be used in the early phases of physical therapy to allow maximum movement with minimal discomfort. Pain control encourages the patient to continue in the program and speeds recovery of the wrist.

Antibiotic coverage has proven to have little value in the full spectrum of hand injuries; however, its use in open fractures is of definite value.[26, 27] Although only a short course, 1-5 days of cephalosporin therapy must be administered. The speed of administration is of primary concern. Continued therapy more than 48 hours after definitive wound closure has been achieved is not necessary. No antibiotic therapy can compensate for a lack of adequate debridement.[28]

Analgesics

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma.

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Hydrocodone/Acetaminophen (Lortab, Vicodin, Norcet),

Indicated for moderate to severe pain.

Nonsteroidal anti-inflammatory drugs

Class Summary

Although most NSAIDs are used primarily for their anti-inflammatory effects, they are effective analgesics and are useful for mild to moderate pain.

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Ibuprofen (Motrin, Ibuprin)

DOC for mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Antibiotics

Class Summary

Antibiotic therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.

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Cefazolin sodium (Ancef, Kefzol, Zolicef)

First-generation cephalosporin. Bactericidal, binds to bacterial membranes, and inhibits cell wall synthesis. Has a half-life of 1.4-1.8 h, which is increased in the presence of renal dysfunction. Excreted primarily unchanged in urine.

 

Follow-up

Return to Play

Return to full activity depends on the patient's activity level and desires. Return to full activity is also dependent on the initial fracture treatment (see Physical Therapy). Typically, if treated conservatively, simple fractures of the hamate are unified within 6-8 weeks of injury.

Patient participation in full-contact sports, such as football, usually requires bracing or protection for the wrist until full musculature and flexibility have returned. This improvement should be achieved within 12 weeks with a diligent physical therapy program. In contrast, if the injury is treated surgically with either ORIF or excision, return to play occurs much sooner. Although no evidence-based guidelines have been developed, the general consensus is that return to play takes 6-8 weeks after either surgery, but this is very individualized and often depends on the level of the athlete.

A study by Guss et al that included data from 18 Major League Baseball players with hook of hamate fractures reported no significant change in Wins Above Replacement or isolated power when preinjury and postinjury performance were compared and also reported no significant decline in performance the first season and second season after injury was found.[29]

Complications

The most frequent complication is nonunion.[4, 30, 31] This can follow conservative treatment in more than 50% of patients. Often, these patients present with continued palmar pain, especially with grip. Conventional radiographs can miss this diagnosis in 30-50% of patients. Therefore if the clinical suspicion is high and radiographic findings are negative, CT scanning should be performed. The treatment of nonunion involves either excision of the hamate hook or ORIF (see Surgical Intervention).

In cases in which internal fixation has been tried and has failed, excision of the fragment is the recommended treatment. These fragments may be small, and full range of motion is often preserved. Pathologic fractures due to cyst formation in the hamate may also occur. These types of fractures are treated best with bone packing, using tissue from the iliac crest, and external fixation. In addition, there has been one case report that described avascular necrosis occurring in the hamate hook.[31]

Prevention

Having good strength and flexibility of both the wrist flexors and extensors can aid in the prevention of some wrist injuries. If participating in sports activities in which diving or falling is not an uncommon occurrence (eg, rollerblading, skiing, ice skating), a protective wrist guard may be recommended to prevent injury to the wrist and hand. Athletes who golf may have increased risk for fracturing the hook of the hamate secondary to repetitive wrist extension. One good method of prevention in this population is to ensure that a proper length of club is always used.

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Prognosis

The prognosis of hamate fractures depends on the degree of injury encountered and the patient's effort in the physical therapy program. In a retrospective review of 29 cases, the patient's functional recovery was indirectly related to the degree of soft-tissue damage at the time of the injury (an increase in soft-tissue damage results in a decrease in functional recovery).[5] For most isolated hamate fractures treated soon after the injury, the prognosis is excellent.

Education

Patient education is an important part of the rehabilitation program for patients recovering from hamate fractures. Patients need to have a good understanding of the healing process and must adhere to recommendations provided by their physician and physical therapist to recover full strength and functional abilities.