Ingrowth of Blood Vessels in Disc Degeneration

Angiograms were made of twenty-two cadaveric lumbar spines to determine the presence of any new blood vessels between adjacent lumbar vertebrae and corresponding discs. The annulus and adjacent longitudinal ligaments were also analyzed histologically. A total of 105 intervertebral spaces were studied. It was found that the normal anastomosing arteries in the posterior longitudinal ligament were significantly obliterated with advancing degeneration of the disc (p < 0.001), whereas several tiny tortuous arteries ofien running between the osteophytic spurs were seen in the anterolateral aspects of the intervertebral spaces connecting the adjacent vertebrae. Histological examination of the anterolateral part of the annulus showed that the vascularity of the annulus increased significantly with degeneration of the disc (p < 0.001), and most of the arteries had a vertical orientation. Regression analysis showed that vascular changes occurred before degeneration of the disc at every lumbar level, suggesting that disturbances in the nutritional supply may precede degeneration. The correlation coefficient was 0.77 (95 per cent confidence limit, 0.52 to 0.90) for the increase in annular vascularity with an increase in the age of the individual at the time of death and 0.86 (95 per cent confidence limit, 0.69 to 0.94) for the increase in degeneration of the disc with an increase in age. I believe that the vascular ingrowth between adjacent vertebrae establishes new collateral pathways between the vertebrae and increases the local blood supply and that it does not. as has been previously supposedx. merely contribute to the healing of tears of the disc. Vascular connections between adjacent vertebrae are normally found within the anterior and posterior longitudinal ligaments of the spine. A few tiny periosteal arteries in the anterolateral aspect of the vertebrae anastomose with each other along the anterior longitudinal ligament. The larger posterior anastomotic arteries are *No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study. t16 Cranmore Road. Wellesley. Massachusetts 02181. as much as one millimeter in diameter and. unlike the arteries in the anterolateral aspect. are clearly visible on angiogram~'~" '~. The present study explores the relationship of arterial connections between adjacent vertebrae and degeneration of the intervening disc. Materials and Methods Angiograms were made of twenty-two cadaveric lumbar spines (from fourteen men and eight women) to evaluate the relationship of vascular connections between the adjacent vertebrae and degeneration of the disc. One hundred and five intervertebral spaces between the first lumbar and first sacral vertebrae were studied. Five spaces between the fifth lumbar and first sacral vertebrae were not included in the study because the intervertebral space had been disrupted during excision of the lumbar spine. Specimens from individuals who had evidence of scoliosis. major spinal deformities. previous spinal operations. or a history of death secondary to a traffic accident were excluded. No other selection criteria were used. The mean age of the individuals at the time of death was fifty-two years (range. twenty to seventy-three years). Preparation of the Specinzens for Arlgiograplly The cadavera were kept for two to six days at 4 degrees Celsius until twelve hours before the autopsy and aortography. at which time they were allowed to warm to room temperature. The aorta was transected cephalad to the diaphragm, and the anterior and lateral branches and the external iliac arteries were clamped. The internal iliac arteries were clamped beyond the origin of the iliolumbar arteries. The contrast medium consisted of liquid silicone rubber (Silikon Kautschuk RTV-Vergussmasse K: Wacker Chemie, Munich. Germany) made radiopaque with 20 per cent lead oxide and then mixed with 2 per cent solidifier (Haerter T Wacker Chemie). This material was injected into the aorta under 150 millimeters of mercury (20.00 kilopascals) of pressure to visualize the lumbar arteries and their branches. Pressure was maintained for two hours to allow the mixture to solidify. This technique of injection has been found to fill arteries as narrow as 0.1 millimeter in diameter. The technique of an26 THE J O U R X A L O F BONE A ~ D J O I N T S L ' R G E R Y INGROWTH O F BLOOD VESSELS I N DISC' 1~EC;ENERATION