CT Hounsfield units in cervical ossification of the posterior longitudinal ligament-A comparison with other forms of degenerative cervical myelopathy using propensity score matching.

backgroundBone mineral density (BMD) constitutes a critical determinant in evaluating instrumentation-related complications among spinal surgery candidates. Recent advancements in diagnostic imaging have established computed tomography (CT) Hounsfield Units (HU) as a reliable biomarker for assessing regional bone mineral density. Nevertheless, only a paucity of studies have explored the association between HU values and patients with cervical ossification of the posterior longitudinal ligament (OPLL). PURPOSE: (1) to conduct a quantitative comparison of bone mineral density between cervical OPLL and other forms of degenerative cervical myelopathy (DCM) cohorts by HU values, (2) to contrast the HU values of cervical OPLL among different types and analyze its correlation with DEXA-derived T-scores, (3) to probe into the risk factors for the development of OPLL. MATERIALS AND

methodsA total of 376 patients were enrolled, encompassing 168 cases of cervical OPLL and 208 cases of other forms of DCM. We conducted a comparative analysis of bone mineral density (BMD) through measurement of HU values across C1-C7 segments in patients with cervical OPLL versus other forms of DCM patients. Following 1:1 propensity score matching, HU values and T-scores of 124 paired patients were compared between, and the HU values of the four different type of OPLL patients were compared. Secondly, the segmental HU values among OPLL patients and its correlation with T-scores were identified. Lastly, we performed conditional logistic regression to identifythe risk factors for the development of OPLL.

resultsOverall, the cervical OPLL cohort showed higher segmental HU values and DEXA derived T-scores compared with other forms of DCM patients. Before performing a one-way analysis of variance (ANOVA), only C1 HU (P = 0.061)and C2 HU (P = 0.053༉showed no significant differences among the four different type groups. However, after conducting the ANCOVA test to control for the covariate age, only C5 HU (P = 0.005༉and global HU (P = 0.025༉showed significant differences. No statistically significant differences were observed among the HU values of C1-C5 (P > 0.05). Conversely, the HU values at C6 and C7 were remarkably lower when compared with those of C1-C5 (P < 0.0001). The correlation of HU values and T-scores showed a statistically significant positive weak to moderate correlation among all the comparisons (p < 0.0001). Conditional logistic regression analysis found that TC ( odds ratio [OR] 2.989, 95% CI 1.979-3.999), UA (OR 1.636, 95% CI 1.427-1.947), Calcium (OR 0.551, 95% CI 0.343-0.884) were significant risk factors for the development of OPLL.

conclusionsThe cervical OPLL patients showed significantly higher segmental HU values and DEXA derived T-scores when compared with the other forms of DCM. In different types of ossification, C5 HU values and global HU values exhibit significant differences. HU values at C6, C7 were significant lower in comparison to C1-C5. Additionally, the level of serum TC, UA and Calcium were significant risk factors for the development of OPLL. This study provides us with a new insight for understanding the bone density of OPLL patients.