This injury is the final stage of the continuum of carpal ligamentous injuries first explained by Mayfield, Johnson and Kilcoyne in 1980. Progressive hyperextension of the wrist will result in a predicted pattern of injury. The four stages are as follows:

1. Scapholunate dissocation

2. Perilunate dislocation

3. Perilunate and triquetral dislocation

4. Lunate dislocation

     The lunate dislocation is the most severe stage.