The Pauwel's classification ( I–III ) describes femoral neck fractures according to the angle of the fracture line. It only applies to subcapital fractures and reflects the instability of the fracture.
- I – the fracture line with the horizontal forms an angle of up to 30 ° , relatively stable wedged, abduction fractures (compressive forces prevail)
- II – the fracture line forms an angle of 30–50 ° with the horizontal , relatively stable (compression and shear forces in balance)
- III – the fracture line with the horizontal makes an angle above 50 ° , least stable, risk of avascular necrosis of the head (shearing forces prevail)