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Bennett Fracture

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Other Names

  • 1st metacarpal fracture
  • Noncomminuted intra-articular fracture of the base of the proximal first metacarpal
  • Bennett’s fracture
  • Bennett fracture luxation
  • Bennett fracture-dislocation
  • Intra-articular two-part fracture of the base of the first metacarpal

Background

  • This page refers to the Bennett fracture, a two part intra-articular fracture of the base of the 1st metacarpal

History

  • Named after Edward Hallaran Bennett (1837-1907), a surgeon from Dublin, Ireland[1]

Epidemiology

  • 80% of fractures involve the base of the thumb (need citation)

Introduction

Illustraction of Rolando vs Bennett fracture[2]
PA and oblique view of Bennet fracture[3]

General

  • Most common fracture involving base of thumb
  • Comminuted, two part intra-articular fracture of base of 1st metacarpal
  • Considered unstable, require surgical fixation

Mechanism

  • Axial load to a partially flexed thumb
    • Resulting in forced abduction of the 1st metacarpal
    • Example would be a fist fight/ altercation
  • Fracture starts at ulnar base of thumb metacarpal
    • Palmar ulnar aspect of thumb is normally stabilized by strong ligaments
    • Disruption of the ulnar fragment destabilizes thumb
  • Volar fracture fragment remains attached to CMC by volar anterior oblique ligament
    • Anterior oblique ligament anchors volar lip of metacarpal to tubercle of the trapezium
    • Subsequent, small volar lip fragment remains attached to anterior oblique ligament which is attached to trapezium
  • Distal metacarpal fragment contains most of articular surface
    • Displaced proximally, radially, dorsally by pull of abductor pollicis longus
    • Displaced metacarpal is also rotated in supination by the pull of
    • Metacarpal head is also displaced into palm by pull of ADP

Pathoanatomy of the 1st Carpometacarpal Joint

Associated Pathology


Risk Factors

  • Unknown

Differential Diagnosis

Differential Diagnosis Finger And Hand Pain


Clinical Features

History

  • Patient should be able to describe some kind of trauma or injury
  • Pain at the base of thumb
  • Worse with movement

Physical Exam: Physical Examination Hand

  • Pain at base of thumb
  • Inspection: swelling, bruising
  • Deformity may or may not be present
  • Palpation: Tenderness at base of thumb
  • Decreased pinch grasp and grip strength

Evaluation

Intra-articular fracture and mild displacement of the base of the 1st metacarpal bone showing oblique fracture line extending into the articular surface[4]

Radiographs

  • Standard Radiographs Hand
    • Intra-articular, 2 piece fracture of the base of the 1st metacarpal
    • Dorsolaterally displaced
    • Small fragment of 1st metacarpal may continue to articulate with trapezium due to attachment ot anterior oblique ligament
    • Retraction of the 1st metacarpal shaft by APL
  • Robert's View: True AP of thumb

Ultrasound

  • 5% sensitivity and 98.3% specificity[5]
  • Water bath technique can help

CT

  • Useful to clarify complex fracture patterns

Classification

Gedda Classification[6]

  • Type 1: single ulnar fragment and subluxation of the metacarpal base
  • Type 2: an impaction fracture without subluxation of the first metacarpal
  • Type 3 an injury with a small ulnar avulsion fragment in association with metacarpal dislocation

Management

Closed reduction technique for Bennet fracture[2]
Pre and post op radiographs of a Bennett Fracture[7]

Acute Reduction

  • Longitudinal traction on the end of thumb
  • In addition to abduction and extension of metacarpal
  • Thumb is pronated to bring into opposition with non-displaced palmer fragment
  • Pressure at the thumb metacarpal base

Nonoperative

  • Indications
    • Can be considered in stable, non-displaced fractures
  • Immobilization: Thumb Spica Cast

Operative

  • Indications
    • Most are considered unstable and require surgical intervention
    • Unstable fracture patterns
    • Intra-articular displacement of >1 mm
  • Technique
    • ORIF

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/Work

  • Needs to be updated

Prognosis and Complications

Prognosis

  • Radiographic features which predict outcome
    • Location, displacement of the fracture
    • Extent of crush or impaction at the metacarpal
    • Presence or absence of shearing or impaction injury to radial side of articular surface of trapezium

Complications


See Also

Internal

External


References

  1. CULLINGWORTH, CJ. "JUNE 12, I897. ROYAL MEDICAL AND CHIRURGICAL SOCIETY."
  2. 2.0 2.1 Image courtesy of journal.aspetar.com
  3. Image courtesy of liftfl.com
  4. Case courtesy of Mohamed Mahmoud Elthokapy, Radiopaedia.org, rID: 91004
  5. Blaivas, Michael, et al. “Water bath evaluation technique for emergency ultrasound of painful superficial structures.” The American journal of emergency medicine 22.7 (2004): 589-593.
  6. GEDDA KO. Studies on Bennett's fracture; anatomy, roentgenology, and therapy. Acta Chir Scand Suppl. 1954;193:1-114
  7. Image courtesy of schreibermd.com
Created by:
John Kiel on 15 August 2019 23:01:58
Last edited:
13 June 2024 20:11:57
Categories:
Trauma | Osteology | Finger | Hand | Wrist | Fractures