http://upload.orthobullets.com/topic/6037/images/multiple mc fractures.jpg
http://upload.orthobullets.com/topic/6037/images/metacarpal rotation.jpg
http://upload.orthobullets.com/topic/6037/images/mtthq2.jpg
http://upload.orthobullets.com/topic/6037/images/46_metacarpal-head-screw_11al.jpg
http://upload.orthobullets.com/topic/6037/images/mc shaft fx.jpg
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 metacarpal 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 discrimination 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 (aesthetic problem only)
      • immobilize MCP joints in 70-90 degrees of flexion
      • cast for 4 weeks
  • Operative
    • ORIF vs. CRPP
      • indications
        • open fractures
        • unacceptable angulation (see above table)
        • any malrotation
        • multiple fractures
  • Techniques
    • closed reduction percutaneous pinning
      •  place antegrade through metacarpal base or retrograde 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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Questions (1)

(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? Review Topic

QID:3441
FIGURES:
1

Open reduction and internal fixation

91%

(1442/1593)

2

Closed reduction and casting

5%

(83/1593)

3

External fixation

2%

(31/1593)

4

Immediate therapy

0%

(1/1593)

5

Removable splint

2%

(26/1593)

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

The patient presents with mutliple injuries including a subtalar dislocation (Figure A), femoral shaft fracture (Figure B), tibia shaft fracture (Figure C) and multiple metacarpal shaft fractures (Figure D). Multiple metacarpal shaft fractures are best managed with open reduction and internal fixation as non-operative management is associated with loss of motion, asynchronous grasp and decreased grip strength.

Souer and Mudgal retrospectively reviewed their experience treating patients with multiple metacarpal fractures utilizing hand-specific implants. They argue that rigid internal fixation of multiple metacarpal fractures allows for early mobilisation and tendon excursion, and found excellent results in 18 of 19 patients with a 230 degree total arc of motion.

Kawamura and Chung review fixation options for treating unstable oblique phalangeal and metacarpal fractures. They found low complication rates regarding tendon adhesion and stiffness with published studies examing dorsal plating of oblique metacarpal fractures as the extensor tendons are less adherent to bone at the level of the metacarpal.

Incorrect Answers:
Answer 2. Closed reduction and casting would lead to stiffness due to immobilization
Answer 3. External fixation would bind the extensor mechanism and would not allow for early motion
Answer 4. Immediate therapy, although beneficial, would be difficult to accomplish without rigid fixation
Answer 5. Removeable splinting would not facilitate early motion and and would likely lead to loss of metacarpal length and deformity as the stabilizing effect of the adjacent metacarpals is lost with multiple fractures


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