Assessing the efficacy of cervical orthoses in restricting spinal motion has historically proved challenging due to a poor understanding of spinal kinematics and the difficulty in accurately measuring spinal motion. This study is the first to use an 8 camera optoelectronic, passive marker, motion analysis system with a novel marker protocol to compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars. Restriction of cervical spine motion was assessed for physiological and functional range of motion (ROM).

Nineteen healthy volunteers (12 female, 7 male) were fitted with collars by an approved physiotherapist. ProReflex (Qualisys, Sweden) infra-red cameras were used to track the movement of retro-reflective marker clusters attached to the head and trunk. 3-D kinematic data was collected from uncollared and collared subjects during forward flexion, extension, lateral bending and axial rotation for physiological ROM and during five activities of daily living (ADLs). ROM in the three clinical planes was analysed using the Qualisys Track Manager (Qualisys, Sweden) 6 Degree of Freedom calculation to determine head orientation relative to the trunk.

For physiological ROM, the Aspen and Philadelphia were more effective at restricting flexion/extension than the Vista (p<0.001), Miami-J (p<0.001 and p<0.01) and Miami-J Advanced (p<0.01 and p<0.05). The Aspen was more effective at restricting rotation compared to the Vista (p<0.001) and Miami-J (p<0.05). The Vista was least effective at restricting lateral bending (p<0.001). Through functional ROM, the Vista was less effective than the Aspen (p<0.001) and other collars (p<0.01) at restricting flexion/extension. The Aspen and Miami-J Advanced were more effective at restricting rotation than the Vista (p<0.01 and p<0.05) and Miami-J (p<0.05). All the collars were comparable when restricting lateral bending.

The Aspen is superior to, and the Aspen Vista inferior to, the other collars at restricting cervical spine motion through physiological ROM. Functional ROM observed during ADLs are less than those observed through physiological ROM. The Aspen Vista is inferior to the other collars at restricting motion through functional ROM. The Aspen collar again performs well, particularly at restricting rotation, but is otherwise comparable to the other collars at restricting motion through functional ranges.