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.