Bone mineral density of lumbar vertebral end plates in the aging male sand rat spine

Study Design. Lumbar vertebral segments from young and old maie sand rats were assessed for quantitative determination of lumbar end plate bone mineral density. Objectives. To determine whether bone mineral density increases in the lumbar end plate with age in the male sand rat and to investigate its relationship to disc degeneration. Summary of the Background Data. Few basic science studies evaluated the end plate and disc degeneration. The sand rat provides an excellent economicai model in which disc degeneration is reliable and well characterized. Methods. none mineral density data on cranial and caudal lumbar end plates of young (mean age 6.8 months) and old (mean age 23.3 monthsi male sand rats were assessed for changes related to age, lumbar position, and radiologic features. Results. Mean bone mineral density was significantly greater in end plates in older compared to younger males (P ≤ 0.0018). Mean end plate bone mineral density within young animais was not significantly different in levels L5 to L7; in old animals, bone minerai density was significantly different (greater) progressing from L5 to L7 (P < 0.0001). in older animais, mean end plate bone mineral density for each disc showed a significant increase with lower lumbar sites (P = 0.0068). Mean end plate bone mineral density was significantly greater in animals with radiographic evidence of disc wedging (P = 0.006). End plate bone mineral density correlated positively with age. Conclusions. Results provide quantitative bone minerai density data on end plate sclerosis in male sand rats. Data reveal site specificities and show that in oid animals, end plate bone minerai density is greater than in young animals. Mean end plate bone mineral density was significantly greater at sites with radiographic disc wedging (P = 0.006). Data support the hypothesis that end plate sclerosis may play a role in disc degeneration.