The retrospective analysis of 131 patients suffering from a fracture of the ring of the axis is reported. The injury was classified into three types according to radiological displacement and stability. Associated injuries and neurological deficit are discussed and a theory of pathogenesis presented. Guidelines for the management of each type of fracture are proposed.

1. Osmium tetroxide and nitrogen mustard were injected into normal adult rabbit joints. Within one week widespread chondrocyte necrosis had occurred as evidenced by electron microscopic examination and radioactive proline uptake autoradiography.

2. Initially, the cartilage matrix was intact but three to seven months later the cartilage surface began to disintegrate.

3. These studies indicate that osmium tetroxide and nitrogen mustard are unsuitable agents for chemical synovectomy.

4. They also indicate that there may be a long latent period between cartilage cell death and cartilage destruction, and that the evaluation of any agent for chemical synovectomy must take this into consideration.