Biomechanical Comparison of Anterior Cervical Plating and Combined Anterior/Lateral Mass Plating

Introduction:

Some surgeons believe that unstable cervical burst fractures with posterior element involvement may be treated with an anterior plating procedure alone, while others believe that the posterior tension band must also be reconstructed. We compared the biomechanical stability of anterior vertebral body plating to combined anterior plating and posterior lateral mass plating.

Methods:

Four human cadaveric cervical spine specimens have been studied (six expected by February). A cervical burst fracture with involvement of the posterior elements was simulated by corpectomy and facet capsule disruption. Specimens were tested nondestructively in the intact condition, after 2–level anterior plating alone, and after anterior plus posterior plating. Specimens were torqued to induce flexion, extension, lateral bending, and axial rotation. Three–dimensional motion was recorded optoelectronically.

Results:

Angular range of motion (ROM) was reduced after injury and anterior plating alone to well within the normal ROM (9.5–15.5 degree compared to 2.4–3.3 degree unilateral motion). ROM was most effectively reduced in flexion and extension. ROM was further reduced to an average of 0.6 degree or less in any direction by adding lateral mass plates. As with anterior plating alone, ROM was reduced most in flexion and extension after combined plating.

Discussion/ Conclusion:

Although anterior plating alone reduced motion to within normal range, the reconstruction of the posterior tension band greatly further reduced motion. The application of these findings to clinical situations must be judiciously applied. However, the use of posterior instrumentation may help improve immediate postoperative stability and allow earlier and more vigorous rehabilitation.