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Metacarpal Fractures

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Topic updated on 07/06/14 10:00am
Introduction
  • Metacarpal fractures
    • divided into fractures of metacarpal head, neck, shaft
    • treatment based on which metacarpal is involved and location of fracture
    • acceptable angulation varies by location
    • no degree of malrotation is acceptable
  • Epidemiology
    • incidence
      • metacarpal fractures account for 40% of all hand injuries
    • demographics
      • men aged 10-29 have highest incidence of metacrapal injuries
    • location
      • metacarpal neck is most common site of fracture
      • fifth metacarpal is most commonly injured
  • Mechanism of injury
    • direct blow to hand or rotational injury with axial load
    • high energy injuries (ie. automobile) may result in multiple fractures
  • Associated conditions
    • wounds may indicate open fractures or concomitant soft tissue injury
      • tendon laceration
      • neurovascular injury
    • compartment syndrome
      • closed injuries with multiple fractures or dislocations
      • crush injuries
Anatomy
  • Metacarpal anatomy
    • concave on palmar surface
    • 1st, 4th, and 5th digits form mobile borders
    • 2nd and 3rd digits form stiffer central pillar
      • index metacarpal is the most firmly fixed, while the thumb metacarpal articulates with the trapezium and acts independently from the others
    • three palmar and four dorsal interossei muscles arise from metacarpal shafts
  • Insertional anatomy
    • extensor carpi radialis longus/brevis
      • insert on the base of metacarpal II, III (respectively); assist with wrist extension and radial flexion of the wrist
    • extensor carpi ulnaris
      • inserts on the base of metacarpal V; extends and fixes wrist when digits are being flexed; assists with ulnar flexion of wrist
    • abductor pollicis longus
      • inserts on the trapezium and base of metacarpal I; abducts thumb in frontal plane; extends thumb at carpometacarpal joint
    • opponens pollicis
      • inserts on metacarpal I; flexes metacarpal I to oppose the thumb to the fingertips
    • opponens digiti minimi 
      • inserts on the medial surface of metacarpal V; Flexes metacarpal V at carpometacarpal joint when little finger is moved into opposition with tip of thumb; deepens palm of hand.
Presentation
  • Physical exam
    • inspect for open wounds and associated injuries
      • fight wounds over MCP joint are open until proven otherwise
      • extensor tendon can be lacerated and retracted
      • dorsal wounds over metacarpal fractures are almost always open fractures
    • deformity indicates location
      • deformity at metacarpal base may indicate CMC dislocation
      • shortening can be assessed by comparing contralateral hand
      • malrotation assessed by lining up fingernail in partial flexion and full flexion if possible, compare to contralateral side  
    • motor examination
      • typically no motor deficits unless open wounds present
      • check integrity of flexor/extensor tendons in presence of open wounds
    • neurovascular examination
      • dorsal wounds may affect dorsal sensory branch of radial/ulnar nerve
      • volar wounds can involve digital nerves
      • test for radial and ulnar border two-point descrimination on the injured digit before any regional/hematoma block or attempted reduction
Imaging
  • Radiographs
    • standard AP, oblique, and lateral films
    •  oblique radiographs
      • for evaluation of CMC joint and improved visualization of affected digit
        • 30°pronated lateral 
          • to see 4th and 5th CMC fx/dislocation 
        • 30°supinated view 
          • to see 2nd and 3rd CMC fx/dislocation
    • Brewerton view for metacarpal head fractures
    • Roberts view for thumb CMC joint
  • CT
    • indications
      • inconclusive radiographs of CMC fractures/dislocations
      • multiple CMC dislocations
      • complex metacarpal head fractures


General Treatment
  • Nonoperative
    • immobilization
      • indications
        • must be stable pattern
        • no rotational deformity
        • acceptable angulation & shortening (see table)
  Acceptable Shaft Angulation (degrees) Acceptable Shaft Shortening (mm) Acceptable neck Angulation
Index & Long Finger 10-20 2-5 10-15
Ring Finger 30 2-5 30-40
Little Finger 40 2-5 50-60
 
  • Operative
    • operative treatment 
      • general indications
        • intra-articular fxs
        • rotational malalignment of digit
        • significantly displaced fractures (see above criteria)
        • multiple metacarpal shaft fractures 
        • loss inherent stability from border digit during healing process
      • postoperative
        • early motion is critical
        • remove pins/ cast at ~ 4 weeks
Treatment - Metacarpal Head Fractures
  • Operative
    • ORIF
      • indications
        • no degree of articular displacement acceptable
        • majority requires surgical fixation  
    • external fixation
      • indications
        • severely comminuted fractures
    • MCP arthroplasty
      • indications
        • severely comminuted fractures
    • MCP fusion
      • indications
        • arthritis late disease
  • Techniques
    • ORIF
      • approach
        • dorsal incision
        • either centrally split extensor apparatus or release and repair sagittal band
      • fixation
        • hardware cannot protrude from joint surface
        • fix with multiple small screws in collateral recess, headless screws, or k-wires
        • ideal fixation should allow for early motion
  • Complications
    • stiffness
      • most common
      • prevented with early motion
Treatment - Metacarpal Shaft Fractures
  • Nonoperative
    • immobilization
      • indications
        • nondisplaced metacarpal neck fractures
        • acceptable angulation (see above table)
        • no malrotation
        • shortening (asthetic problem only)
      • immobilize MCP joints in 70-90 degrees of flexion
      • cast for 4 weeks
  • Operative
    • ORIF vs. CRPP
      • indications
        • open fractures
        • unnacceptable angulation (see above table)
        • any malrotation
        • multiple fractures
  • Techniques
    • closed reduction percutaneous pinning
      •  place retrograde through metacarpal base or antegrade through collateral recess
        • remove pins at 4 weeks
    • open reductions with lag screw
      • can use multiple lag screws for long spiral fractures
        • try to get at least two lag screws
    • open reduction with dorsal plating
      • works best for transverse fractures  
      • try to cover plate with periosteum to prevent tendon irritation
      • begin early motion to prevent tendon irritations
Treatment - Metacarpal Neck Fractures 
  • Nonoperative
    • reduction and casting
      • acceptable degrees of apex dorsal angulation (varies by study, see above table)
      • immobilize MCP joints in 70-90 degrees of flexion, leave PIP joints free
      • cast for 4 weeks
      • reduce using Jahss technique
        • 90 degrees MCP flexion, dorsal pressure through proximal phalanx while stabilizing metacarpal shaft
  • Operative
    • reduction and fixation
      • indications
        • unacceptable angulation (see above table)
        • open fractures
        • any malrotation
        • intraarticular fractures
  • Technique
    • CRPP with MCP's flexed
      • antegrade through metacarpal base
      • retrograde through collateral recess
    • ORIF
      • perform if cannot get reduction for CRPP
      • difficult to plate because limited bone for distal fixation

 

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Qbank (1 Questions)

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(OBQ11.18) A 25-year-old female is involved in a motorcycle collision and presents with the injuries seen in Figures A through D. What is the best option for definitive management of the injuries seen in Figure D? Topic Review Topic
FIGURES: A   B   C   D    

1. Open reduction and internal fixation
2. Closed reduction and casting
3. External fixation
4. Immediate therapy
5. Removable splint

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Cases

http://upload.orthobullets.com/cases/2042/akb_metcarp_1.jpg http://upload.orthobullets.com/cases/2042/akb_metacarp.jpg http://upload.orthobullets.com/cases/2042/akb_mc_post_fic.jpg
HPI - Underwent ORIF 5 months prior to presentation. Denies any issues except pain.
poll How would you treat this current patient?
10/14/2014
830 responses
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