http://upload.orthobullets.com/topic/6035/images/33_moved.JPG
http://upload.orthobullets.com/topic/6035/images/hamate_golf.jpg
http://upload.orthobullets.com/topic/6035/images/hamate_baseball.jpg
http://upload.orthobullets.com/topic/6035/images/carpals.jpg
http://upload.orthobullets.com/topic/6035/images/hamate_lat.jpg
http://upload.orthobullets.com/topic/6035/images/hamate_anatomy.jpg
Introduction
  • Epidemiology
    • incidence
      • 2% of carpal fractures
    • risk factors 
      • often seen in
        • golf
        • baseball
        • hockey
  • Pathophysiology
    • typically caused by a direct blow
      • grounding a golf club
      • checking a baseball bat
  • Associated conditions
    • bipartite hamate
      • will have smooth cortical surfaces
Anatomy
  • Hamate
    • one of carpal bones, distal and radial to the pisiform
    • articulates with
      • fourth and fifth metacarpals
      • capitate
      • triquetrum
    • hook of hamate
      • forms part of Guyon's canal, which is formed by
        • roof - superficial palmar carpal ligament
        • floor - deep flexor retinaculum, hypothenar muscles
        • ulnar border - pisiform and pisohamate ligament
        • radial border - hook of hamate
      • one of the palpable attachments of the flexor retinaculum
      • deep branch of ulnar nerve lies under the hook
Presentation
  • Symptoms
    • hypothenar pain
    • pain with activities requiring tight grip
  • Physical examination
    • provocative maneuvers
      • tender to palpation over the hook of hamate  
      • hook of hamate pull test:
        • hand held in ulnar deviation as patient flexes DIP joints of the ulnar 2 digits, the flexor tendons act as a deforming force on the fracture site, positive test elicits pain
    • motion and strength
      • decreased grip strength
    • neurovascular exam
      • chronic cases
        • parasthesia in ring and small finger
        • motor weakness in intrinsics
Imaging
  • Radiographs 
    • recommended views
      • AP and carpal tunnel view
    • findings
      • fracture best seen on carpal tunnel view 
  • CT
    • indications 
      • establish diagnosis if radiographs are negative    
Treatment
  • Nonoperative
    • immobilization 6 weeks
      • indications
        • acute hook of hamate fractures
        • body of hamate fx (rare)
  • Operative
    • excision of hamate fracture fragment
      • indications
        • chronic hook of hamate fxs with non-union
    • ORIF
      • indications
        • ORIF is possible but has little benefit
Complications
  • Non-union
  • Scar sensitivity
  • Iatrogenic injury to ulnar nerve
  • Closed rupture of the flexor tendons to the small finger 
 

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Questions (4)

(OBQ11.130) A 24-year-old racquetball player presents after accidentally striking his racket against the wall during a match two months ago. He is tender to palpation over the hypothenar mass, and his pain is aggrevated by grasping. A radiograph and CT scan of his wrist are shown in Figures A and B. Which of the following treatment methods has been definitively shown in the literature to have a favorable outcome, and a high chance to return to pre-injury activities in patients with this injury? Review Topic

QID:3553
FIGURES:
1

Activity restriction and continued monitoring

3%

(52/1544)

2

Open reduction and internal fixation

3%

(45/1544)

3

Casting for 6 weeks, followed by physical therapy

6%

(91/1544)

4

Corticosteroid injection and immediate return to play

0%

(5/1544)

5

Surgical excision

87%

(1346/1544)

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

The patients history and imaging are consistent with a subacute hook of the hamate fracture. This is demonstrated by the carpal tunnel view radiograph in Figure A, and confirmed by the CT scan of the wrist in Figure B. CT scan of the wrist is usually indicated to definitively diagnose these fractures. Current literature supports the most favorable results and ability to return to pre-injury activities with excision of the fracture fragment. There is little available literature reporting the results of open reduction and internal fixation of these fractures.

Rettig et al review traumatic wrist injuries in athletes. With regards to treatment of hook of the hamate fractures, they state that ORIF and excision are the two viable treatment options in athletes. Of these, the literature supports fragment excision, which has an average return to sport time of 7-10 weeks.

Welling et al determined which wrist fractures are not diagnosed with initial radiography, using CT as a gold standard and identified specific fracture patterns. In their series, they found that only 40% of hamate fractures were diagnosed on plain radiography, suggesting that CT should be considered after a negative radiographic finding if clinically warranted.


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(OBQ08.23) A professional baseball player develops acute hand pain after fouling off a pitch. He is tender over the hypothenar eminence and has paresthesias in the ring and small fingers. Which radiographic view is most likely to reveal the pathology? Review Topic

QID:409
1

PA wrist

1%

(30/2012)

2

AP wrist in ulnar deviation

4%

(80/2012)

3

Lateral wrist

4%

(89/2012)

4

Carpal tunnel

89%

(1798/2012)

5

Scaphoid

0%

(10/2012)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Plain radiographs usually do not reveal the fracture; carpal tunnel and supinated oblique views should be obtained. Diagnosis is confirmed by CT scan and bone scan.

Fractures of the body of the hamate may occur from trauma and may occur in combination with fractures of the base of the fourth and fifth metacarpals. Fractures of the hook of the hamate are more common in athletes. The incidence of hook of the hamate fractures is 2% to 4% of all carpal fractures. The mechanism of injury is thought to be caused by abutment of the hook on an object or by a shearing force applied by the flexor tendon of the small and ring fingers. The injury usually occurs in athletes who participate in baseball, golf, and racquet sports because of the position of the implement in the hand.

Rettig reviewed hand injuries in athletes. He noted that hamate hook fractures occur in a watershed area that may explain the high incidence of nonunion post fractures. Hook of the hamate fracture must be suspected in athletes participating in racquet sports, golf, or baseball who are seen with ulnar wrist pain. Examination reveals tenderness over the hook of the hamate, which lies on a line between the pisiform and second metacarpal head. Treatment of hook of the hamate fractures in athletes varies from casting to open reduction and internal fixation to excision.

Bishop and Beckenbaugh reported 21 cases of this fracture: 17 were treated by excision, 3 underwent ORIF, and 1 had casting. Although two of three fractures that were treated with ORIF healed, many authors recommend excision, which has an average return to sport of 6 to 10 weeks.

Illustration A shows a representative carpal tunnel view, with the bony anatomy labeled.

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(SBQ07.40) A 44-year-old man presents with ulnar-sided right wrist pain and mild constant tingling in the fourth and fifth digits after injuring his wrist while playing golf. Although pain and function have improved with conservative treatment 6 months following the injury, he still reports difficulty with his golf game. Which of the following should initially be obtained in this patient to aide in the diagnosis? Review Topic

QID:1425
1

Bone scan of the wrist and hand

1%

(9/1334)

2

EMG study of the affected extremity

15%

(199/1334)

3

Carpal tunnel view radiograph

75%

(1002/1334)

4

CT scan of the distal forearm and wrist

4%

(50/1334)

5

Contrast enhanced magnetic resonance angiogram

5%

(65/1334)

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

This patients clinical presentation is most consistent with a chronic hook of the hamate fracture, which should initially be evaluated with a carpal tunnel view radiograph. Hook of the hamate fractures typically are associated with pain localized to the hypothenar eminence, and chronic cases can be associated with neuropathy of the ulnar nerve. Excision of the hook through the fracture site usually yields satisfactory results in the presence of chronic injuries.

Parker et al treated five patients with six hook of the hamate fractures over an eight year period. All patients ultimately underwent hook resection and returned to their previous level of activity in 6 to 8 weeks after surgery without loss of function. Based on their case series, they concluded that the entire hook should be resected to the base of the hamate as the primary form of treatment in hook of the hamate fractures.

Illustration A: Patient positioning for carpal tunnel radiograph-wrist is extended 70 degrees, and beam is angled 25-30 deg to the long axis of the hand(arrow).

Illustration B: Carpal tunnel view radiograph demonstrates a fracture at the base of the hook of the hamate(black arrow) and normal pisotriquetral joint space.

Incorrect Answers:
1-Bone scans are not typically indicated in the diganostic setting of acute or chronic hook of the hamate fractures.
2-Imaging should be obtained to rule out bony injury prior to obtaining an EMG study.
4-CT scans can used to confirm the diagnosis of a hook of the hamate fracture after obtaining a carpal tunnel view radiograph.
5-Contrast enhanged MRA of the wrist is typically used to diagnose hypothenar hammer syndrome or other vascular abnormalities.

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(OBQ04.21) A 24-year-old professional baseball outfielder reports persistent pain in the hypothenar region when batting for the past year. His CT scan is shown in Figure A. What is the recommended treatment? Review Topic

QID:132
FIGURES:
1

pisiform excision

2%

(23/930)

2

hook of hamate excision

91%

(844/930)

3

carpal tunnel release

0%

(2/930)

4

decompression of Guyon's canal

0%

(2/930)

5

open reduction and internal fixation

5%

(49/930)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

The history is typical of a hook of the hamate fracture, which is confirmed on the CT image. A carpal tunnel view radiograph of this injury is shown in Illustration A. It commonly occurs in baseball players and golfers. Physical exam findings include point tenderness at the hamate, ulnar nerve paresthesias (hemorrhage within Guyon's canal), and pain with axial load of ring and little fingers. For cases seen late, with few exceptions, the recommended treatment has been excision of the hook fragment. Marchessault provides a review of diagnoses and treatment for carpal fractures. They discuss the treatment of these injuries, indicating that acute, nondisplaced fractures may be placed in a cast, and excised if nonunion develops. The authors go on to say that certain investigators recommend excision of asymptomatic nonunions to minimize the risk for flexor tendon rupture.

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