Morphometric Analysis of the Uncinate Process as a Landmark for Anterior Controllable Antedisplacement and Fusion Surgery: A Study of Radiologic Anatomy.

OBJECTIVE: This study used the uncinate process (UP) base as the landmark to measure the various distances of the interested anatomic structures to improve the practicality of anterior controllable antedisplacement and fusion (ACAF) for ossification of the posterior longitudinal ligament (OPLL).

METHODS: Computed tomographic (CT) scan data of 20 OPLL patients were studied. We investigated the base distance of the UP, transverse foramen (TF) to UP base, pedicle to UP base, posterior to anterior UP, maximal width of OPLL, and width of the vertebrae-OPLL complex (VOC).

RESULTS: Base distance of the UP shows an increasing trend from C3 to C7. The average base distance of the UP ranges from 14.6 mm at C3 to 22.7 mm at C7. The TF to UP distance ranges from 4.6 to 7.2 mm. The pedicle to UP distance is significantly shorter than upper levels at C7 and C6. The posterior to anterior UP ranges from -3.7 to -5.7 mm with an increasing trend from C3 to C7. The maximal width of OPLL is 13.2 mm on average. The mean width of the VOC in the ACAF cases is 16.8 mm on average.

CONCLUSIONS: The results show that the UP can serve as a landmark for the location of longitudinal osteotomies in ACAF. However, preoperative measurement of CT images should be conducted for an individual dependent surgical planning of ACAF.