Study Design. 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.
Summary of Background Data. 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).
Conclusion. 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.
Level of Evidence: 4
Facet joint capsule deformation during cervical flexion–extension was determined in arthrodesis patients and asymptomatic subjects. Facet joint capsule deformations vary among vertebral motion segments and capsule regions. Single-level anterior arthrodesis is associated with significantly less facet joint capsule deformation adjacent to the arthrodesis when the spine is in an extended orientation.
From the Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA.
Address correspondence and reprint requests to William J. Anderst, MS, Orthopaedic Research Laboratories, 3820 South Water St, Pittsburgh, PA 15203; E-mail: firstname.lastname@example.org
Acknowledgment date: September 12, 2013. First revision date: November 25, 2013. Second revision date: December 31, 2013. Acceptance date: January 6, 2014.
The manuscript submitted does not contain information about medical device(s)/drug(s).
NIH/NIAMS grant #1R03AR056265, a 21st century developmental grant from the Cervical Spine Research Society funds, was received to support this work.
No relevant financial activities outside the submitted work.