Abstract
1. Epiphysial tilt commonly precedes slipping.
2. This tilt is due to a diminished or arrested growth from compression of the back of the epiphysial plate.
3. The stresses on the upper end of the femur are such that the upper femoral epiphysial plate is peculiarly liable to compression.
4. A primary abnormality of the cartilage of the epiphysial plate renders it susceptible to the effect of compression.
5. Because this abnormality is diffuse, deformities due to a similar pathology may be found elsewhere, notably in the spine.