Surface Landmarks do not Correspond to Exact Levels of the Cervical Spine: References According to the Sex, Age and Height

Abstract

ObjectiveA general orientation along the cervical spine could be estimated by external landmarks, and it was useful, quick and less exposable to radiation, but, sometimes it gave reference confusion of target cervical level. The authors reviewed the corresponding between the neck external landmarks and cervical levels.MethodsTotally 1,031 cervical lateral radiographs of different patients were reviewed in single university hospital. Its compositions were 534 of males and 497 females; 86 of second decades (10-19 years-old), 169 of third decades, 159 of fourth decades, 209 of fifth decades, 275 of sixth decades, and 133 of more than seventh decades (>60 years-old). Reference external landmarks (mandible, hyoid bone, thyroid cartilage, and cricothyroid membrane) with compounding factors were reviewed.ResultsThe reference levels of cervical landmarks were C2.13 with mandible angle, C3.54 with hyoid bone, C5.12 with thyroid cartilage, and C6.01 with cricothyroid membrane. The reference levels of cervical landmarks were differently observed by sex, age, and somatometric measurement (height) accordingly mandible angle from C1 to C3, hyoid bone from disc level of C2 and C3 to C5, thyroid cartilage from disc level of C3 and C4 to C7, and cricothyroid membrane from C4 to disc level of C7 and T1.ConclusionSurface landmarks only provide general reference points, but not correspond to exact levels of the cervical spine. Intraoperative fluoroscopy ensures a more precise placement to the targeted cervical level.

Anatomic considerations of the anterior upper cervical spine during decompression and instrumentation: a cadaveric based study

“…5, 6). These surface landmarks only provide general reference points, they do not correlate with the exact levels of the cervical spine [10]. The exact cervical spine level and midline location of the plate and screw trajectories is assessed fluoroscopically, with true lateral cervical views.…”

A reassessment of cervical surface anatomy via CT scan in an adult population

“…It is worth noting that because of the wide range of variation, surface landmarks only provide general reference points, sometimes causing confusion about the target cervical level. Intraoperative fluoroscopy ensures a more precise placement to the targeted cervical level (Oh et al, ).…”

Intrinsic Vertebral Markers for Spinal Level Localization in Anterior Cervical Spine Surgery: A Preliminary Report

“…The use of surface landmarks, such as the mandibular angle, hyoid bone, thyroid cartilage, first cricoid ring, and C6 carotid tubercle, as general reference points for SLL has been reported in the literature; however, these landmarks do not correspond to the exact cervical spine levels [91026]. Although these landmarks can facilitate skin incision placement, definitive SLL cannot be based on these landmarks alone.…”

“…Except for the C6 tubercle, positions of all these surface landmarks are likely to change with respect to shifts in the vertebral body positions caused by head and neck movements [10]. Despite various reports on these landmarks, observations vary significantly depending on the patients' age, sex, and somatometric measurements [91026]. However, none of these factors affect intrinsic markers, which are located directly on the vertebral body.…”