Uncinate Process Area as a New Sensitive Morphological Parameter to Predict Cervical Neural Foraminal Stenosis.

Background: Hypertrophy of the uncovertebral joint has been considered as a major cause of cervical neural foraminal stenosis (CNFS). The cross-sectional area of the uncinate process is a key morphologic parameter in the identification of uncovertebral joint hypertrophy. To evaluate the connection between CNFS and the uncinate process, we devised a new morphological parameter, the uncinate process area (UPA).

Objective: We hypothesized that the UPA is an important morphologic parameter in the diagnosis of CNFS.

Study Design: Retrospective observational study.

Setting: The single center study in Incheon, Republic of Korea.

Methods: UPA data were collected from 146 patients with CNFS and 197 control subjects who underwent neck computed tomography (CT) as part of a routine medical examination. Neck CT images were obtained from all subjects. The whole cross-sectional area of the bone margin of the uncinate process was measured at the C5-6 intervertebral disc level on CT scans using a picture archiving and communications system.

Results: The average UPA was 15.52 mm-squared in the control group and 29.97 mm-squared in the CNFS group. The CNFS group displayed significantly greater UPA levels (P < 0.001). Regarding the validity of the UPA as a predictor of CNFS, the receiver operating characteristic curve analysis revealed an optimal cut-off point for the UPA of 21.15 mm-squared, with 91.8% sensitivity, 93.4% specificity, and an area under the curve of 0.972 (95% CI,0.956-0.989) in the CNFS group.

Limitations: Anatomically, the UP is located on the superior lateral surfaces of the C3-7 cervical vertebral bodies. However, we focused on the C5-6 uncovertebral joint level, because many previous studies revealed C6 UP has the greatest height among UP and C5-6 uncovertebral joint hypertrophy is a primary cause of CNFS.

Conclusions: The newly devised UPA is a sensitive parameter for assessing CNFS. A hypertrophied UPA is associated with an increased risk of CNFS. We think that this result will be helpful for diagnostic radiology in evaluating patients with CNFS.Institutional Review Board (IRB) approval number: IS16RISI0002KEY WORDS: Uncinate process area, cervical neural foraminal stenosis, Uncovertebral joint hypertrophy, optimal cut-off point, cross- sectional area.