Study design: The amount of motion allowed by various cervical orthoses was compared with the amount of unrestricted neck motion in vivo.
Objectives: To determine how much mechanical stability commonly used cervical orthoses provide to the wearer.
Summary of background data: Few studies have compared quantitatively the restriction of motion from cervical orthoses that are commonly prescribed for patients. No studies have used methods allowing measurement of all three rotations throughout the range of motion in passive and active tests. Previous studies may have overstated the amount of restriction provided resulting from the methods used.
Methods: Five subjects were tested for cervical range of motion in flexion-extension, axial, rotation, and lateral bending. Each was tested with no collar, with soft collar, with Philadelphia collar, with Philadelphia collar with thoracic extension, and with sterno-occipital mandibular immobilizer brace. Each test was conducted passively and actively. Measurements were taken with the CA-6000 Spine Motion Analyzer, a highly accurate and precise computerized linkage system that simultaneously records all three rotations in real time.
Results: All orthoses restricted motion to some extent. Generally, the collars ranked (from least restrictive to most restrictive): soft, Philadelphia, Philadelphia with extension, and sterno-occipital mandibular immobilizer brace. However, the differences were not usually large, and the collars did not restrict motion as much as previously reported. No collar restricted the motion of any of the subjects to less than 19 degrees of flexion-extension, 46 degrees of axial rotation, or 45 degrees of lateral bending, and most subjects demonstrated significantly more motion.
Conclusions: Although cervical orthoses can be helpful for other reasons, they do not provide a high level of mechanical restriction of motion. Additionally, the restriction they do provide can vary widely between people. Prescribing physicians should consider the relative merits of the various orthoses before deciding whether they will meet a patient's needs. The differences between the collars tested may not be enough to justify one of the more expensive or less comfortable collars.