- See:
-
Metacarpal Neck Frx
-
Metacarpal Shaft Frx
- Discussion:
- metacarpal neck frx involving little finger;
- only collateral ligaments, remain attached to the proximal phalanx, & therefore metacarpal head is freed from any proximal stabilizing influence;
- metacarpal head tilts volarly causing joint to lie in hyperextension & collateral ligaments become slack;
- if joint is allowed to remain in hyperextension, collateral ligaments will shorten, leading to limited MCP flexion;
- little finger CMC articulation allows flexion extension arc of 20-30 deg in addition to a rotatory motion facilitating little finger opposition to thumb;
- ring metacarpal provides 10-15 deg of mobility;
-
diff dx:
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transverse metacarpl shaft frx this frx may be ammenable to a 4 holed plate;
-
frx of metacarpal head;
- infrequent variant of boxer's frx;
- in this injury, impact is recieved directlly on metacarpal head, producing frx thru joint surface;
- requires operative fixation;
- Radiographs:
- true lateral radiograph is necessary with these fractures in order to measure the angle of displacement of the distal fragment;
- normal metacarpal neck angle is about 15 deg & therefore a measured angle on film of 30 deg actually = 15 deg;
- when displaced, angulate with dorsal angulation at frx line & distal metacarpal head displaces palmarward;
- Non Operative Treatment:
- clawing results from the palmar displacement of the metacarpal head & resulting imbalance of extrinsic tendons;
- may have cosmetic deformity, but good function;
-
methods of reduction:
- because collateral ligaments are the only remaining attachment to metacarpal head, collaterals must be placed in a tightened position to control distal fragment and achieve reduction;
- MP joint is flexed 90 deg to produce tightening of MP collateral ligaments;
- flexed metacarpal is directed dorsally, which effects reduction of metacarpal head by correction of volar angulation;
-
accetable reduction:
- on lateral view if angulation > 30-40 deg, a functional deficit (pseudoclawing) may result - consider percutaneous pin fixation.
- in the report by Ali et al (JHS Vol 24-A. July 1999), 30 deg of angulation resulted in loss of 22% of finger ROM;
- on AP view, little or no anglation should be accepted, since this indicates mal-rotation of the digit;
- references:
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Biomechanical effects of angulated boxer's fractures.
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Fractures of the fifth metacarpal neck: is reduction or immobilisation necessary?
-
casting technique:
- no matter what casting technique is used, it is essential to "buddy tape" the little and ring fingers (with an intervening layer of cast padding) in order to control fracture malrotation;
- Operative Treatment:
Year Book:
Functional Treatment of Metacarpal Fractures: 100 Randomized Cases With or Without Fixation.
Immediate mobilization of fractures of the neck of the fifth metacarpal.
Fractures of the metacarpal neck of the little finger.
[
Osteosynthesis using perpendicular pins in the treatment of fractures and malunions of the neck of the 5th metacarpal bone.]
Conservative treatment of boxer's fracture: a retrospective analysis.
Intra-articular fractures at the base of the fifth metacarpal. A clinical and radiographical study of 64 cases.
Biomechanical effects of angulated boxer's fractures.
Immediate mobilization gives good results in boxer's fractures with volar angulation up to 70 degrees: a prospective randomized trial comparing immediate mobilization with cast immobilization.
