We obtained intervertebral discs with cartilage endplates and underlying cancellous bone at operation from patients with degenerative disc disease and then used immunohistochemical techniques to localise the nerves and nerve endings in the specimens. We used antibodies for the ubiquitous neuronal protein gene product 9.5 (PGP 9.5). Immunoreactivity to neuropeptide Y was used to identify autonomic nerves and calcitonin gene-related peptide (CGRP) and substance P to identify sensory nerves. Blood vessels were identified by immunoreactivity with platelet-endothelial cell-adhesion molecule (CD31; PECAM).

In a control group with no known history of chronic back pain, nerve fibres immunoreactive to PGP 9.5 and neuropeptide Y were most closely related to blood vessels, with occasional substance P and CGRP immunoreactivity. In patients with severe back pain and markedly reduced disc height, proliferation of blood vessels and accompanying nerve fibres was observed in the endplate region and underlying vertebral bodies. Many of these nerves were immunoreactive to substance P or CGRP, and in addition, substance P- and CGRP-immunoreactive nociceptors were seen unrelated to blood vessels. Quantification by image analysis showed a marked increase in CGRP-containing sensory nerve fibres compared with normal control subjects.

We speculate that a chemotactic response to products of disc breakdown is responsible for the proliferation of vascularity and CGRP-containing sensory nerves found in the endplate region and vertebral body adjacent to degenerate discs. The neuropeptides substance P and CGRP have potent vasodilatory as well as pain-transmitting effects. The increase in sensory nerve endings suggests increase in blood flow, perhaps as an attempt to augment the nutrition of the degenerate disc. The increase in the density of sensory nerves, and the presence of endplate cartilage defects, strongly suggest that the endplates and vertebral bodies are sources of pain; this may explain the severe pain on movement experienced by some patients with degenerative disc disease.

1. Because of the importance of nutrition of the intervertebral disc in relation to its disorders, a detailed study has been made of the neighbouring vasculature of the vertebral body.

2. This has been made possible by an injection technique involving prevention of leakage by freezing with liquid nitrogen.

3. By this method capillary beds are found in the vertebral end-plate cartilage in the adult. A very fine subchondral post-capillary venous network has been demonstrated draining by short vertical tributaries to a much coarser horizontal collecting vein system connecting with the familiar basivertebral system.

4. This arrangement may be of special importance in the nutrition of the intervertebral disc.

1. Sixteen patients with articular cartilage erosions after slight injury have been described, as have the results of their treatment.

2. The clinical features of this rarely diagnosed condition are discussed. Attention is drawn to "articular crepitus" and "synovial crepitus" as useful physical signs in establishing the diagnosis.

3. A radiographic sign of localised subarticular osteoporosis is reported and discussed.

4. The surgical treatment used was either shaving of the affected area of cartilage or a combination of shaving with drilling of the subchondral bone plate.