Metacarpal #s Flashcards
Index/Mid/Ring/Little fingers
- hand can adjust to dorsal angulation in the metacarpal equal to its motion at the CMC joint, plus 10-15 degrees (in some pts)
- index & middle (immobile at their CMC joints): accomm only 10-15 degrees of dorsal angulation
- ring (normal= 20-30 degrees @ CMC): may accomm 40-45 degrees dorsal ang+
- little (normal= 30-50 degrees @ CMC): may accomm 50-70 degrees dorsal ang+
- finger metacarpals: may accomm 10-15 degrees lateral angulation & 3-4 mm of shortening
- rotational deformity, spiral & oblique #s: poorly tolerated!! (Just 10 degrees of malrotation may result in 2cm overlapping)
- shortening: surg indicated with 2-3 mm, 1mm of articulated surface step-off, >25% articular involvement, or any degree of malrotation.
Metacarpal head #s
Pathophys:
- rare
- usually result due to direct trauma/crush injury, typically comminuted
- occur distal to the attachment of collateral ligaments
- physical exam: tenderness/swelling over MCP joint, pain increased if axial compression applied along extended digit
- lacs over metacarpal heads: SIG!! Open # suspicion (esp human bite)
- Radiology: ball catchers view may assist
Management;
Closed:
- RICE
- immobilisation in SAFE position
- referral to surg for ALL
Open:
- emergent surg consult
- prophylactic coverage w cephalosporin OR highly contam+ penicillin w a Beta-lactimase inhibitor & an aminoglycoside
Complications:
- avascular necrosis, rotational mal alignment, interosseous miscule fibrosis, extensor tendon injury/fibrosis, chronic stiffness
- many may req late arthroplasty
Metacarpal neck #s
Pathophys:
- most common # of the hand
- MOI - direct impact = punch w closed fist
- Boxer’s #: # neck of lil’ finger metacarpal
- most have typical dorsal angulation
- inherently unstable: due to deforming muscle forces & freq comminution of volar cotex (difficult to maintain any reduction)
Management;
Ring/little fingers:
- 35 & 45 degrees of ang+ allowed
- any rotational malalignment should be corrected
- non-displaced #s without angulation deformity: RICE & gutter splint
- sig* angulation/deformity: may attempt reduction in ED, w haemothorax/nerve block, & apply traction (90-90 method), then gutter splint in position of function, then post reduction X-ray & post 1/52 for review
- closed reduction not achieved: surg req
Middle/index fingers:
- <15 degrees of ang* allowed
- any rotational malalignment should be corrected
- non-displaced #s without angulation deformity: RICE & gutter splint
- displaced/angulated: commonly req anatomic reduction & surgical fixation.
- ED; RICE, volar splint, & referral
Complications:
- if excessive angulation is not corrected; forced hyperextension of MCP & flexion of PIP when extending finger & pain upon tightly grasping objects
- extensor tendon injury
- collateral ligament damage
- nonunion is rare post closed #s
Metacarpal Shaft #s
Pathophys:
- 3 types; transverse, oblique or spiral, & comminuted
- transverse/comminuted: result from direct blow & commonly exhibit dorsal angulation
- spiral: indirect trauma/rotational torque to finger shaft
Management:
- rotational deformity & shortening are more likely & less angular deformity is acceptable
- index/middle: No angulation acceptable (acceptable reduction <10 degrees)
- ring/little: small amount may be compensated for (acceptable reduction <20 degrees)
- All: < 3mm of shortening & normal rotational alignment!!
- ED: RICE, gutter splint (inc wrist & entire metacarpal shaft - but Not MCP joint if proximal to the neck). Repeat X-ray & referral to hand surg
- surg fixation req: if manipulative reduction necessary, OR multiple displaced metacarpal #s, irreducible transverse #, displaced open #s.
Complications:
- similar to other metacarpal #s
- malrotation also: leading to painful grip, limited extensor function, and interosseous muscle fibrosis.
Metacarpal base #s
Pathophys:
- generally stable & occur infrequently
- direct blow over base of metacarpal or axial/torque force applied along the digit
- tenderness & swelling at base of affected metacarpal, significant rotational deformity may be evident
- # base ring/little fingers may involve injury to motor branch of ulnar nerve (paralysis of intrinsic hand muscles) & may be assoc* w carpal bone #
Management:
- ED: RICE, analgesia, immobilisation (bulky compressive dressing or volar splint) & referral to hand surg
Complications:
- extensor/flexor tendon damage & sig* rotational malalignment
- chronic CMC joint stiffness often assoc* w intra-articular # & may necessitate arthrodesis/arthroplasty
Thumb metacarpal #s
Pathophys:
- relatively uncommon due to high degree of mobility
- most #s involve the base
Extra-articular #s:
- more common than below & usually result from direct trauma/impaction
- 3 types; transverse, oblique & in paeds, epiphyseal
- localised pain & swelling
- thumb allows 20-30 degrees of angular deformity without functional impairment
- closed reduction req if >30 degrees, post reduction rad* & immob* in Spica cast for 4/52
- oblique #s may req surg fixation
Intra-articular;
- Bennett’s #: intra-art* # base of thumb metacarpal combined w dislocation/subluxation of the CMC joint
- complete disruption of the ligaments around the CMC
- usually axial force acting on a partially flexed metacarpal (closed fist Vs rigid object)
-ED: RICE, analgesia, closed anatomic reduction, immob* thumb spica splint, & hand surg referral
- if anatomic reduction fails Or # fragment >20% of articular surface - open reduction & internal fixation req
Rolando’s #:
- comminuted # of the base of the thumb metacarpal
- typically Y or T shaped comminution
- severity often very difficult to depict in radiographic studies
- MOI same as above, though carries much poorer prognosis
- ED: RICE, analgesia, thumb spica splint & referral to hand surg for open reduction
Complications:
- joint stiffness, degenerative arthritis, malunion
- nonunion is rare
- post-traumatic arthritis common & may req further surg intervention
