Mastication causing segmental spinal motion in common cervical orthoses.
METHODS
In vivo fluoroscopic quantification of segmental cervical spinal motion in asymptomatic volunteers during mastication.


OBJECTIVE
To quantify the degree of segmental cervical spine motion in patients during mastication and while wearing several commonly used cervical orthoses.


BACKGROUND
Cervical orthoses are routinely used to stabilize the cervical spine after trauma or cervical fusion and are, in some cases, prescribed to be worn at all times, including during eating.


METHODS
Seven volunteers with an average age of 31 years (range, 26-42 years) had 5 seconds of continuous lateral cervical fluoroscopic imaging while they chewed gum without any cervical orthosis (control) and while wearing a soft collar turned forward then backward, a Philadelphia collar, a Miami J collar, or a two-poster brace. Still images were created from the fluoroscopy video, which allowed for quantification of the amount of segmental motion.


RESULTS
All cervical collars produced statistically greater motion at occiput-C1 and C1-C2 when compared with no collar. The motion was greatest at the occiput-C1 junction and decreased to the C4 level. No motion was detected in any subject in any brace below C4. The two-poster brace produced the most segmental motion at occiput-C1 (6.3 degrees +/- 2.0 degrees) compared with the soft collar turned backwards (1.9 degrees +/- 1.9 degrees). No subject had any segmental motion below C2 in the soft collar. No segmental spinal motion was observed without a cervical brace.


CONCLUSIONS
To limit upper cervical spine segmental motion during mastication, for patients with unstable cervical spines, we propose a two-poster brace with removal of the mandibular component to allow for free mandibular action. For stable spines, we propose a soft collar turned backwards. Patients should be educated with this information.
Division of Spine Surgery, Department of Orthopaedics, Hospital of the University of Pennsylvania and the University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. kingsleychin@hotmail.com
Kingsley R
KR
Chin
Joshua D
JD
Auerbach
Samuel B
SB
Adams
Jeffrey F
JF
Sodl
K Daniel
KD
Riew
D000328:Adult; D002574:Cervical Vertebrae / Q000502:physiology*; D004867:Equipment Design; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007593:Joint Instability; D008297:Male; D008409:Mastication / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D009989:Orthotic Devices / Q000145:classification; D016059:Range of Motion, Articular / Q000502:physiology*