Anatomical projection of the cervical uncinate process in ventral, ventrolateral, and posterior decompressive surgery

Abstract

<jats:p content-type="fine-print"><jats:italic>Object.</jats:italic> The cervical uncinate processes (UPs), their variations, and the relationships between the neurovascular structures and surrounding bone were investigated in this anatomical study. The object of this study was to highlight the important surgery-related considerations associated with ventral, ventrolateral, and posterior decompressive surgery.</jats:p> <jats:p content-type="fine-print"><jats:italic>Methods.</jats:italic> Forty-nine adult C3–7 dry bone samples were used, and 10 measurements were obtained for each vertebra. The anterior measurements involved the cervical uncinate process (UP): height, width, length, distance between its tip and vertebral foramina, interuncinate process distance, sagittal angle with the superior margin of the vertebral body (VB), VB anteroposterior diameter, and VB width. Posterior measurements involved the vertical distance between the superior border of the lamina at the lamina—facet joint and the tip of the UP, as well as the horizontal distance between the medial-most border of the superior facet and the tip of the UP. All symmetrical structures were measured bilaterally. There were no statistically significant differences between right- and left-sided measurements in this series.</jats:p> <jats:p content-type="fine-print">The height of the UP increased gradually at each segmental level between C-3 and C-7. The width of the UP did not change with segmental level (5.0 mm at C-3 compared with 5.3 mm at C-7). On average, the length of the UP was relatively constant. The distance from the tip of the UP to vertebral foramina averaged 1 mm at the C2–3 level and 1.5 mm at the C5–6 level. Interuncinate distance and VB width gradually increased and were highly variable, which appeared to be related with osteophyte formation. There was a slight gradual increase from C-3 to lower segments, and it paralleled with the midline anteroposterior diameter of the same VB. The angle between the UP and the superior margin of the VB exhibited great variety. The posterior measurements decreased gradually from C-3 to C-7.</jats:p> <jats:p content-type="fine-print"><jats:italic>Conclusions.</jats:italic> Based on the data obtained in this study, a surgeon is provided with a three-dimensional orientation as well as anatomical knowledge. This knowledge also allows for a more effective neurovascular decompression by minimizing the surgery-related complications.</jats:p>

Morphometric evaluation of the uncinate process and its importance in surgical approaches to the cervical spine: a cadaveric study

“…(2,25) The UP is an important bone landmark that becomes larger and flatter as individuals get older, losing its sharp and bony characteristics. (8) In the present study, we found that in both direct cadaveric and CT measurements, the height of the UP increased from C3 to C7 (i.e. C3: 5.8 ± 1.0 mm, C7: 6.6 ± 0.5 mm vs. C3: 5.9 ± 1.2 mm, C7: 6.9 ± 0.6 mm).…”

“…Researchers have shown that excessive decompression of the UP increases the risk of cervical instability. (8) Thus, in order for the surgery to be minimally invasive and to achieve sufficient decompression, surgeons should be aware of the morphology and morphometry of the UP; (9,10) it borders the lateral line of the intervertebral disc. Tubbs et al (3) did not regard uncovertebral joints as synovial joints; the UP was regarded as a product of the formation of fibrocartilage and new bone due to reactive osteogenesis and degeneration, i.e.…”

“…(2,5) To treat these pathologies, uncoforaminectomy, decompressive surgery or osteophyte resection may be necessary. (2,6,8) However, foraminotomy and uncovertebral joint resection procedures may also cause vertebral artery injury, (11)(12)(13)(14)(15)(16) possibly leading to ischaemic neurological pathologies. (17,18) Vertebral artery injury usually occurs following the use of a high-speed drill for lateral decompression, aggressive discectomy or decompression of bony tissues.…”

“…The vertebral artery or spinal nerve root injury is a very serious complication of surgeries performed with an anterior cervical approach. (5,8,23) For patients who have spondylolisthesis, the distance between the UP and the medial border of the transverse foramen is narrower than that of a healthy person. (2,23) In a study conducted by Russo et al, (24) the distances between the medial border of the vertebral artery and the UP were as follows: C2-3 level left: 3.2 ± 1.0 mm, right: 3.5 ± 0.6 mm; C3-4 level left: 1.3 ± 0.6 mm, right: 1.1 ± 0.4 mm; C4-5 level left: 1.7 ± 0.9 mm, right: 1.6 ± 1.0 mm; C5-6 level left: 1.2 ± 0.8 mm, right: 1.1 ± 1.2 mm).…”

“…Although several studies have been conducted on the UP based on the analysis of dry bone materials, (7)(8)(9) to the best of our knowledge, none used direct cadaveric measurements to evaluate the UP. The present study aimed to assess the anatomy of the UP and vertebral body via direct measurement of cadavers and angiographic computed tomography (CT).…”