Subtrochanteric Fracture
A subtrochanteric fracture occurs in the proximal femoral region extending from the inferior border of the lesser trochanter to approximately 5 cm distally.
These fractures experience very high mechanical stresses and powerful deforming muscle forces.
The typical deformity is:
Proximal fragment
- Flexed by iliopsoas
- Abducted by gluteus medius and minimus
- Externally rotated by short external rotators
Distal fragment
- Adducted by adductor muscles
- Shortened proximally
This explains why subtrochanteric reduction is often more difficult than passage of the nail itself.
Seinsheimer classification
Type I
- Nondisplaced
- Less than 2 mm displacement
Type II
Two part fracture.
IIA
- Transverse two part fracture
IIB
- Spiral fracture
- Lesser trochanter remains with proximal fragment
IIC
- Spiral fracture
- Lesser trochanter remains with distal fragment
Type III
Three part fracture.
IIIA
- Lesser trochanter is a separate third fragment
IIIB
- Third fragment is a butterfly fragment
Type IV
- Four or more major fragments
- Comminuted fracture
Type V
- Subtrochanteric fracture extending proximally into the intertrochanteric region.
Russell Taylor classification
This system describes involvement of the piriformis fossa and lesser trochanter.
Type IA
- Piriformis fossa intact
- Lesser trochanter intact
Type IB
- Piriformis fossa intact
- Lesser trochanter involved
Type IIA
- Piriformis fossa involved
- Lesser trochanter intact
Type IIB
- Both piriformis fossa and lesser trochanter involved.
Modern cephalomedullary implants have reduced the treatment relevance of the Russell Taylor system because trochanteric entry nails can be used despite many proximal fracture extensions.
