In vivo cervical facet joint capsule deformation during flexion-extension.
METHODS
Nonrandomized controlled cohort.


OBJECTIVE
To characterize subaxial cervical facet joint kinematics and facet joint capsule (FJC) deformation during in vivo, dynamic flexion-extension. To assess the effect of single-level anterior arthrodesis on adjacent segment FJC deformation.


BACKGROUND
The cervical facet joint has been identified as the most common source of neck pain, and it is thought to play a role in chronic neck pain related to whiplash injury. Our current knowledge of cervical facet joint kinematics is based on cadaveric mechanical testing.


METHODS
Fourteen asymptomatic controls and 9 C5-C6 arthrodesis patients performed full range of motion flexion-extension while biplane radiographs were collected at 30 Hz. A volumetric model-based tracking process determined 3-dimensional vertebral position with submillimeter accuracy. FJC fibers were modeled and grouped into anterior, lateral, posterior-lateral, posterior, and posterior-medial regions. FJC fiber deformations (total, shear, and compression-distraction) relative to the static position were determined for each cervical motion segment (C2-C3 through C6-C7) during flexion-extension.


RESULTS
No significant differences in the rate of fiber deformation in flexion were identified among motion segments (P = 0.159); however, significant differences were observed among fiber regions (P < 0.001). Significant differences in the rate of fiber deformation in extension were identified among motion segments (P < 0.001) and among fiber regions (P = 0.001). The rate of FJC deformation in extension adjacent to the arthrodesis was 45% less than that in corresponding motion segments in control subjects (P = 0.001).


CONCLUSIONS
In control subjects, FJC deformations are significantly different among vertebral levels and capsule regions when vertebrae are in an extended orientation. In a flexed orientation, FJC deformations are different only among capsule regions. Single-level anterior arthrodesis is associated with significantly less FJC deformation adjacent to the arthrodesis when the spine is in an extended orientation.


METHODS
4.
From the Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA.
William J
WJ
Anderst
William F
WF
Donaldson
Joon Y
JY
Lee
James D
JD
Kang
D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D017746:Joint Capsule / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D016059:Range of Motion, Articular; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D013123:Spinal Fusion; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D021801:Zygapophyseal Joint / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery