Effects of cervical orthoses on neck biomechanical responses during transitioning from supine to upright

Our objectives were to use a hybrid cadaveric/surrogate model to evaluate the effects of the cervicothoracic orthosis and collar on head and neck biomechanical responses during transitioning from supine to upright.

The model consisted of an adult-male surrogate dummy with its artificial neck replaced by a human neck specimen (n=10). The model was transitioned from supine to upright using a rotation apparatus. A high-speed digital camera tracked motions of the head, vertebrae, cervicothoracic orthosis, pelvis, and rotation apparatus. Head load cell data were used to compute occipital condyle loads. Average peak spinal loads and motions were statistically compared (P<0.05) among experimental conditions (cervicothoracic orthosis: anterior strut locked and unlocked; collar; and unrestricted).

Loads at the occipital condyles consisted of anterior shear, compression, and extension moment. The most rigid device tested, cervicothoracic orthosis with anterior strut locked, significantly reduced axial compression neck force and increased anterior shear neck force and provided the greatest immobilization by significantly reducing spinal rotations as compared to other experimental conditions. Similar neck biomechanical responses were observed between the cervicothoracic orthosis, anterior strut unlocked, and collar.

The simple maneuver of supine-to-upright transitioning, commonly performed clinically, produced complex neck loads and motions including head protrusion which caused cervical spine snaking. Neck motions consisted of extension at the upper cervical spine and flexion at the subaxial cervical spinal levels. Of the devices tested, the cervicothoracic orthosis, with anterior strut locked, provided the greatest cervical spine immobilization thereby reducing the risk of potential secondary neck injuries.