Segment-specific association between cervical pillar hyperplasia (CPH) and degenerative joint disease (DJD)

BACKGROUND Cervical pillar hyperplasia (CPH) is a recently described phenomenon of unknown etiology and clinical significance. Global assessment of pillar hyperplasia of the cervical spine as a unit has not shown a relationship with degenerative joint disease, but a more sensible explanation of the architectural influence of CPH on cervical spine biomechanics may be segment-specific. OBJECTIVE The objective of this study was to determine the level of association between degenerative joint disease (DJD) and cervical pillar hyperplasia (CPH) in an age- and gender-matched sample on a [cervical spine] by-level basis. RESEARCH METHODS Two-hundred and forty radiographs were collected from subjects ranging in age between 40 and 69 years. The two primary outcome measures used in the study were the segmental presence/absence of cervical pillar hyperplasia from C3 to C6, and segment-specific presence/absence of degenerative joint disease from C1 to C7. Contingency Coefficients, at the 5% level of significance, at each level, were used to determine the strength of the association between CPH and DJD. Odds Ratios (OR) with their 95% Confidence Intervals (95% CI) were also calculated at each level to assess the strength of the association. RESULTS Our study suggests that an approximately two-to-one odds, or a weak-to-moderate correlation, exists at C4 and C5 CPH and adjacent level degenerative disc disease (DDD); with the strongest (overall) associations demonstrated between C4 CPH and C4-5 DDD and between C5 CPH and C5-6 DDD. Age-stratified results demonstrated a similar pattern of association, even reaching the initially hypothesized OR >or= 5.0 (95% CI > 1.0) or "moderately-strong correlation of C >or= .4 (p <or= .05)" in some age categories, including the 40-44, 50-59, and 60-64 years of age subgroups; these ORs were as follows: OR = 5.5 (95% CI 1.39-21.59); OR = 6.7 (95% CI 1.65-27.34); and OR = 5.3 (95% CI 1.35-21.14), respectively. CONCLUSION Our results suggest that CPH has around two-to-one odds, that is, only a weak-to-moderate association with the presence of DJD (DDD component) at specific cervical spine levels; therefore, CPH may be but one of several factors that contributes (to a clinically important degree) to the development of DJD at specific levels in the cervical spine.