Hamate Fracture

Other Names

• Hook of Hamate fracture
• Hamate avulsion fracture
• Hamulus Fracture
• Carpal Hamate Fracture
• Ulnar-Sided Carpal Fracture
• Hamate Bone Break
• Hookf of Hamate Stress Fracture

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Background

• This page refers to fractures of the hamate

History

• First published by Stark in 1975

Epidemiology

• Hamate fractures represent about 2% of all carpal fractures

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Introduction

Hook of hamate fracture

A 39-year-old mechanic presented with a 6-week history of activity-related ulnar sided wrist pain in his dominant right hand after punching injury. History, physical examination, and imaging were consistent with a hamate body fracture nonunion. The patient underwent open reduction internal fixation and went on to bony union and restoration of function.

Normal anatomy of the carpal bones. Diagram of the wrist (frontal view) shows the eight carpal bones and the three carpal arcs (Gilula arcs), which are shown as pink (arc I), blue (arc II), and red (arc III) lines. C (capitate), H (hamate), L (lunate), P (pisiform), S (scaphoid), Tm (trapezium), Td (trapezoid), Tr (triquetrum)

Wrist radiograph with carpal bones labeled, including the Hamate

General

• One of the less common carpal fractures which be classified into hook or body fractures
• Injury typically occurs during direct blunt trauma to the hook during swinging activities
• Patients have localized pain to the hypothenar eminence and reduced grip strength
• Often missed on radiographs, CT or MRI is needed for definitive diagnosis
• Treatment is conservative for nondisplaced fractures, surgical for displaced fractures

Mechanism

• Two primary mechanisms
  • Direct trauma to hook or body
  • Reptitive stress from gripping activities
• Traumatic Hook of hamate
  • Traditional mechanism involves direct blunt trauma from a racket, club, bat etc
  • Will make direct contact with hypothenar eminence during a swing
• Fatigue or stress fracture of hook of hamate
  • More recently the literature suggests repitive loading from flexor tendons may be more common mechanism
  • Deep flexor tendons apply cyclical tensile forces to the hook during gripping, creating fatigue stress that can lead to stress fractures
  • Compounded by vascular compromise from direct tendon pressure on local vessels, reducing blood flow and predisposing to both stress fracture and nonunion
• Hamate body fractures
  • Traumatic requiring high-energy axial loading along the fourth and fifth metacarpals
  • As an example, typically from punching with a clenched fist or falling on the hand

Anatomy of the Hamate

• General
  • A part of the distal carpal row and has a characteristic hook on its palmar surface
  • Articulates with lunate, 4th and 5th metacarpals, triquetrum, capitate
• Hook of hamate
  • Serves as an attachment point for Transverse Carpal Ligament
  • Makes up the medial border of Carpal Tunnel

Associated Conditions

• Ulnar Neuropathy
  • Fracture fragments can cause compression of the ulnar nerve, leading to ulnar nerve palsy
• Flexor Tendon Injuries
  • Flexor digitorum profundus tendons to the 4th, 5th digit lie directly adjacent to the hook of hamate and are at risk for wear or rupture
• Carpal Tunnel Syndrome
  • May develop as a delayed complication from fracture fragments or nonunion
• Scaphoid Fracture
  • Hook of hamate fractures are seen in 10.3% of scaphoid fractures

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Risk Factors

• Sports
  • Racket sports
  • Baseball
  • Golf
  • Hockey

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Differential Diagnosis

Carpal Bone Fractures

• Scaphoid Fracture
• Lunate Fracture
• Triquetrum Fracture
• Pisiform Fracture
• Trapezium Fracture
• Trapezoid Fracture
• Capitate Fracture
• Hamate Fracture

Differential Diagnosis Wrist Pain

• Fractures
  • Distal Radius Fracture
    • Bartons Fracture
    • Chauffers Fracture
    • Colles Fracture
    • Die-Punch Fracture
    • Radial Styloid Fracture
    • Smiths Fracture
  • Distal Ulna Fracture
  • Carpal Fractures
    • Scaphoid Fracture
    • Lunate Fracture
    • Triquetrum Fracture
    • Pisiform Fracture
    • Trapezium Fracture
    • Trapezoid Fracture
    • Capitate Fracture
    • Hamate Fracture
  • Essex Lopresti Fracture
• Dislocations
  • Wrist Dislocation (Radiocarpal and/or Ulnocarpal)
  • Carpometacarpal Joint Dislocation
  • Distal Radioulnar Joint Dislocation
  • Lunate Dislocation
  • Perilunate Dislocation
• Instability & Degenerative
  • Scapholunate Instability
  • Lunotriquetral Instability
  • Scaphoid Nonunion Advanced Collapse
  • Distal Radial Ulnar Joint Instability
  • Kienbocks Disease
  • Dorsal Wrist Impingement
  • Carpal Instability
• Tendinopathies & Ligaments
  • De Quervain's Tenosynovitis
  • Intersection Syndrome
  • TFCC Injury
  • Wrist Tendinopathies
  • Extensor Carpi Ulnaris Tendinopathy
• Neuropathies
  • Carpal Tunnel Syndrome
  • Pronator Teres Syndrome
  • Anterior Interosseus Nerve Syndrome
  • Posterior Interosseus Nerve Syndrome
  • Guyon Canal Syndrome
  • Wartenbergs Syndrome
• Pediatric Considerations
  • Distal Radial Epiphysitis (Gymnast's Wrist)
  • Torus Fracture
• Arthropathies
  • Wrist Osteoarthritis
  • Scaphotrapeziotrapezoidal Joint Arthritis (STT Arthritis)
  • Rheumatoid Arthritis
  • Gout
• Cartilage
  • Osteochondral Defect
• Vascular
  • Hypothenar Hammer Syndrome
• Other
  • Ganglion Cyst of Wrist
  • Ulnar Impingement Syndrome
  • Infectious Tenosynovitis

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Clinical Features

A, Provocation test leading to a high level of stress on the hamate hook. Pathognomonic for hamate injuries is increase of pain under flexion of digitorum IV and V against resistance in flexed and ulnar abducted wrist. B, No pain is triggered in extended and radial abducted position of the wrist with simultaneous flexion of the fingers against resistance.

History

• Patients may not endorse a clear mechanism or history of injury
  • Often there is a history of forceful swinging a grasped object (bat, racket, club, etc)
• Vague ulnar sided wrist pain at the base of the Hypothenar Muscles
• Pain is worse with gripping or direct palpation over hook of hamate
• Patients may report symptoms in Ulnar Nerve distribution

Physical Exam: Physical Exam Wrist

• Tenderness to palpation of the hamnate
• Pain with flexion of the 4th and 5th digit
• Grip strength may be weakened or asymmetric compared to the unafefcted hand
• Need to carefully evaluate the ulnar nerve

Special Tests

• Hook of hamate pull test: flex 4th and 5th digits and maintain it against examiner resistance

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Evaluation

Hamate fracture. (a) PA radiograph of the right wrist demonstrates an oblique fracture line (arrows) at the distal ulnar third of the hamate, with 0.5-mm separation of the ulnar fracture fragment. (b) A 45° oblique radiograph of the same wrist demonstrates the hamate fracture (arrow), with 2–3 mm of distal and dorsal displacement of the fracture fragment.

Hamate fracture. Axial (a), sagittal reformatted (b), and 3D (c) CT images show a nondisplaced fracture at the base of the hamate hook (arrow).

Radiographs

• Standard Radiographs Wrist
  • Initial imaging modality of choice
  • May need Carpal Tunnel View, Semisupinated Oblique View
  • Consider 1st webspace view
• Diagnostic accuracy
  • Sensitivity ranges from 54% to 72%
  • Even with additional views
• Specific radigoraphic signs
  • Ring Sign
  • Ghostly shadow, diffuse sclerosis
  • collectively demonstrate 85% sensitivity and 92% specificity

CT Scan

• Imaging modality of choice
  • Especially if negative radiographs and high clinical suspicion
  • Better at determining location, extend of fracture
• Diagnostic performance
  • Sensitivity: 100%
  • Specificity: 94%
  • Accuracy: 97%

MRI

• Equally effective as an alternative advanced imaging modality
• Particularly when concomitant soft tissue injuries are suspected
• Can detect occult carpal fractures and has the added advantage of evaluating soft tissue injuries
• Daignostic accuracy ranges from 85-100%

Ultrasound

• One case report succesfully identified a hook of hamate fracture
• There are no papers looking at diagnostic accuracy of hamate fractures

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Classification

Illustration of the Milch classification of hamate fractures

• Hook
• Body
  • Proximal pole
  • Medial tuberosity
  • Sagittal oblique
  • Dorsal coronal

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Management

Hamate body fracture in a 25-year-old hockey player. Plain radiograph (a) and sagittal CT (b) show displaced, intra-articular nature of the injury. Intra-operative view of articular surface restoration and dorsal plate is shown (c, d). X-rays demonstrate temporary K-wire stabilization of CMC joints (e). K-wires are removed 4 weeks after the procedure

Nonoperative

• Indications
  • Nondisplaced Hook of hamate
  • Nondisplaced Body of hamate
• Immobilization
  • Cast: Short Arm Cast 4-6 weeks

Operative

• Hook of hamate indications
  • Failure of nonoperative approach
  • Displaced
  • Chronic
  • Ulnar nerve compression
  • Symptomatic nonunion
• Body of hamate indications
  • Displaced
  • Carpometacarpal joint involvement
• Technique
  • Excision of hook of hamate
  • ORIF

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Rehabilitation/ Return to Play

Rehab

• Nonsurgical
  • Gradual progression includes gentle range of motion exercises
  • Followed by strengthening and sport-specific activities
• Following surgical excision
  • Begin sport-specific activities at 4-5 weeks

Rehab Program PDFs

• Hook of Hamate Fracture Rehab PDF
• Hamate Fractures Rehab Exercises PDF
• Hamate Fracture Patient Handout PDF

Return to Play

• Nonoperative
  • Return to play typically occurs at 8-12 weeks after radiographic and clinical healing is confirmed
• Surgical: excision
  • Athletes typically return to sport 4-7 weeks after excision
  • Professional baseball players in one series began hitting programs at an average of 4.6 weeks and returned to full baseball activities at 7.1 week
  • Median return to sport was 48 days (range 16-246 days) in another cohort of professional players
• Surgical: ORIF
  • Return to occupation at 4 months on average
  • Percutaneous fixation achieved union at a mean of 3 months, with return to original occupation at 3-6 months
  • Volar approach fixation demonstrated 100% union with return to work or hobbies at an average of 7 weeks

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Prognosis and Complications

Clinical presentation of the ulnar nerve injury. (A) Representative picture demonstrating the surgical incision in close proximity to the Guyon’s canal; (B) Flattening of the palmar arch of the hand due to a reduction of MCP joint flexion; (C) The occurrence of a positive Froment’s sign is evident as a bending of the distal tip of the thumb when attempting to pinch a piece of paper between the thumb and the index finger

Prognosis

• General
  • Generally excellent outcomes with approrpiate treatment
  • Complications occur in about 25% of cases
• Nonsurgical
  • Approximately 50% healing rate of waist and tip fractures due to poor vascularity
  • Nonunion rates are high
  • Subacute and incomplete fractures are also prone to fail nonoperative management
• Surgical
  • Prognosis is fairly favorable with preserved range of motion, grip strength
  • Grip strength may decrease after excision—reductions of 25%, 36%, and 47% in a cadaveric study
• Sports performance
  • Player utilization increased after surgery in professional baseball players, though hitting efficiency showed small numerical declines
  • No significant difference in return-to-sport rates exists between acute fractures (81%) and nonunion cases (76%).

Complications

• Nonunion
  • Occurs commonly in conservatively treated cases
• Malunion
• Carpometacarpal Arthritis
• Ulnar Nerve Injury
  • The most common complication
  • Occurs in approximately 25% of postoperative cases but typically resolving during rehabilitation
• Hypothenar Hammer Syndrome
• Flexor Digitorum Profundus tendon rupture
• Delayed return to play

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See Also

Internal

• Forearm Pain (Main)
• Wrist Pain (Main)
• Hand Pain (Main)
• Hand and Wrist Anatomy (Main)
• Physical Exam Wrist

External

• https://www.sportsmedreview.com/blog/diagnosing-hook-of-hamate-fractures/

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