INTRODUCTION: This study uses a previously unstudied species of non‐human primates, the vervet (Chlorocebus aethiops). The purpose of this study is to establish whether natural disc degeneration occurs in this species and also to determine whether age and body mass are associated with higher rates of disc degeneration
METHODS: The vervet colony at Wake Forest University Primate Center (fully pedigreed) was studied. 38 females were chosen at random for this study. Lateral radiographs lumbar discs (L1‐S1) were graded on five variables: height loss, anterior osteophyte, annular calcification, endplate irregularity, and endplate sclerosis. An overall degeneration score (Composite Grade) was assigned based on the sum of each of the 5 individual degeneration scores. Regression analysis was performed to assess statistical association between the monkey's age (avg 10.8 years) or body mass (avg 5.03kg) with the parameters evaluated.
RESULTS: Fifteen animals (40.5%) were considered middle aged or older. Of 37 animals, 23 (62.2%) exhibited some form of degeneration. The Composite Grade was highest at L6‐7 (most degenerated). Univariate regression analysis indicated that age was significantly correlated with of the five variables and the Composite Grade (R2=0.62, P<0.001). Body mass was significantly correlated Composite Grade (R2=0.18, P=0.01). In the multivariate regression analysis, age was statistically associated with all of the individual variables and with Composite Grade (P<0.001), explaining 64% of the variability of the Composite Grade. However, body mass was not significantly associated with degeneration.
DISCUSSION: In the vervet females, natural lumbar disc degeneration occurs and is related to age, but not to body mass. The pattern of degeneration by age and level is similar to humans. As this vervet colony is pedigreed and genetically mapped, evaluation of the full colony with advanced imaging will allow powerful future genetic studies.