Three types: Extra-articular, Intra-articular, Sesamoid Bone

1. Extra-articular Fracture

- Transverse

- Oblique

- Epiphyseal plate fracture (children)

Mechanism = Direct Blow

2. Intra-articular Base Fracture

- Bennett Fracture: fracture with subluxation or dislocation of the metacarpal joint

- Rolando Fracture: comminuted T or Y fracture involving joint surface

Mechanism = axial force directed against partially flexed metacarpal

Bennet Fracture (above)

Ronaldo Fracture (above)

3. Sesamoid Bone Fracture

- 3 sesamoids in thumb: two at MCP joint, one at IP joint

Mechanism = MCP Hyperextension

References:

Manthey, David E., and Kim Askew.. "Hand." Simon’s Emergency Orthopedics, 7eEd. Scott C. Sherman. New York, NY: McGraw-Hill, 2014.