LAUSR

STUDY DESIGN Biomechanical study. OBJECTIVE To demonstrate that robotic cervical traction can apply closed cervical traction as effectively as manual weight-and-pulley traction in extension spring and cadaveric models. SUMMARY OF BACKGROUND DATA Closed cervical traction is used to reduce subaxial cervical spine dislocation injuries and to distract the intervertebral space during cervical spine surgery. Weight-and-pulley cervical traction relies on cumbersome and imprecise technology without any safeguard to prevent over-traction or weights being pulled/released inadvertently. METHODS A prototype robotic traction device was designed and manufactured by the authors with real-time tensile force measurement,±1 lbs (5 N) force application accuracy, locking/non-backdriveable linear actuators with actuator position sensing, 200 lbs (900 N) maximum force capability, up to 20° of flexion/extension manipulation, <25 lbs (111 N) device weight, and compatibility with Gardner-Wells tongs or Mayfield head clamp. The device was tested using an extension spring model and an intact fresh cadaver specimen to assess applied and desired force over time and radiographic changes in the cervical spine as traction force increased. The cadaver was tested in manual traction and then robotic traction in 10-lbs (50 N) increments up to 80 lbs (355 N) to compare methods. RESULTS The prototype device met or exceeded all requirements. In extension spring testing, the device reached prescribed forces of both 25 lbs (111 N) and 80 lbs (355 N) accurately and maintained a desired weight. In cadaveric testing, radiographic outcomes were equivalent between the prototype and manual weight-and-pulley traction at 80 lbs (355 N; disc space measurements within ±10% for all levels), and the device reached the desired weight within±1 lbs (5 N) of accuracy at each weight interval. CONCLUSION This preliminary work demonstrates that motorized robotic cervical traction can safely and effectively apply controlled traction forces.