End Plate Disproportion and Degenerative Disc Disease: A Case-Control Study

STUDY DESIGN Case-control. PURPOSE To determine whether a disproportion between two neighboring vertebral end plates is associated with degenerative disc disease. OVERVIEW OF LITERATURE Recently, it has been suggested that disproportion of the end plates of two adjacent vertebrae may increase the risk of disc herniation. METHODS Magnetic resonance (MR) images (n=160) with evidence of grades I-II lumbar degenerative disc disease (modified Pfirrmann's classification) and normal MR images of the lumbar region (n=160) were reviewed. On midsagittal sections, the difference of anteroposterior diameter of upper and lower end plates neighboring a degenerated (in the case group) or normal (in the control group) intervertebral disc was calculated (difference of end plates [DEP]). RESULTS Mean DEP was significantly higher in the case group at the L5-S1 level (2.73±0.23 mm vs. 2.21±0.12 mm, p=0.03). Differences were not statistically significant at L1-L2 (1.31±0.13 mm in the cases vs. 1.28±0.08 mm in the controls, p=0.78), L2-L3 (1.45±0.12 mm in the cases vs. 1.37±0.08 mm in the controls, p=0.58), L3-L4 (1.52±0.13 mm in the cases vs. 1.49±0.10 mm in the controls, p=0.88), and L4-L5 (2.15±0.21 mm in the cases vs. 2.04±0.20 mm in the controls, p=0.31) levels. The difference at the L5-S1 level did not remain significant after adjusting for body mass index (BMI), which was significantly higher in the patients. CONCLUSIONS End plate disproportion may be a significant, BMI-dependent risk factor for lumbar degenerative disc disease.