Effects of Spinal Immobilization and Spinal Motion Restriction on Head-Neck Kinematics during Ambulance Transport

<p><b>Objective:</b> To determine the influence of ambulance motion on head-neck (H-N) kinematics and to compare the effectiveness of two spinal precaution (SP) protocols: spinal immobilization (SI) and spinal motion reduction (SMR). <b>Methods:</b> Eighteen healthy volunteers (7 females) underwent a series of standardized ambulance transport tasks, across various speeds, under the two SP protocols in a balanced order (<i>n</i> = 12 drivers, <i>n</i> = 7 ambulances). Inertial measurement units were placed on participants’ heads and sternums, with another affixed to the stretcher mattress frame. Outcome measures included H-N displacement and acceleration. <b>Results:</b> Ambulance accelerations varied across driving tasks (2.5–9.5 m/s<sup>2</sup>) and speeds (3.0–6.2 m/s<sup>2</sup>) and resulted in a wide range of H-N displacements (7.2–22.6 deg) and H-N accelerations (1.4–10.9 m/s<sup>2</sup>). Relative to SMR, SI resulted in reduced H-N motion during turning, accelerating, and speed bumps (1.9–10.7 deg; 0.4–2.6 m/s<sup>2</sup>), but increased H-N accelerations during abrupt starts/stops and some higher speed tasks (0.4–2.5 m/s<sup>2</sup>). Ambulance acceleration was moderately correlated to H-N acceleration (r = 0.68) and displacement (r = 0.42). <b>Conclusion:</b> H-N motion was somewhat coupled to ambulance acceleration and varied across a wide range, regardless of SP approach. In general, SI resulted in a modest reduction in H-N displacement and acceleration, with some exceptions. The results inform clinical decisions on SP practice during prehospital transport and demonstrate a novel approach to quantifying H-N motion in prehospital care. <b>Key words</b>: ambulance; backboard; cervical collar; emergency care; spine injury</p>