The Ability of External Immobilizers to Restrict Movement of the Cervical Spine: a Systematic Review

Purpose: To review the ability of various types of external immobilizers to restrict cervical spine movement.

Methods: With a systematical review of original scientific articles, data on range of motion, type of used external immobilization device and risk of bias were extracted. The described external immobilization devices were grouped and the mean restriction percentage and standard deviation were calculated. Finally, each device was classified based on its ability to restrict movement of the cervical spine, according to five levels of immobilization: poor (MIL <20 %), fair (MIL 20-40 %), moderate (MIL 40-60 %), substantial (MIL 60-80 %), and nearly complete (MIL ≥80 %).

Results: The ability to reduce the range of motion by soft collars was poor in all directions. The ability of cervico-high thoracic devices was moderate for flexion/extension but poor for lateral bending and rotation. The ability of cervico-low thoracic devices to restrict flexion/extension and rotation was moderate, while their ability to restrict lateral bending was poor. All cranio-thoracic devices for non-ambulatory patients restricted cervical spine movement substantial in all directions. The ability of vests with non-invasive skull fixation was substantial in all directions. No studies with healthy adults were identified with respect to cranial traction and halo vests with skull pins and their ability to restrict cervical movement.

Conclusions: Soft collars have a poor ability to reduce mobility of the cervical spine. Cervico-high thoracic devices primarily reduce flexion and extension, but they reduce lateral bending and rotation to a lesser degree. Cervico-low thoracic devices restrict lateral bending to the same extent as cervico-high thoracic devices, but are considerably more effective at restricting flexion, extension, and rotation. Finally, cranio-thoracic devices nearly fully restrict movement of the cervical spine.