Study design: Laboratory biomechanical experiment.
Objective: To evaluate how different anterior cervical collar heights restrict full, active range of motion (ROM), and functional ROM during 15 activities of daily living.
Summary of background data: Hard cervical collars are commonly used in the clinical setting. Collar fit is presumed to affect immobilization, making neck height an important variable. No prior study has evaluated how different collar heights affect full, active and functional ROM.
Methods: A previously validated electrogoniometer device was employed to quantify both full, active, and functional ROM. For each of 10 subjects, these ROM measurements were repeated without a collar and with an adjustable, hard collar (Aspen Vista) at each of 6 collar neck height settings.
Results: For each increase in collar height, there was a corresponding decrease in mean full, active ROM of 3.7% (3°) in the sagittal plane (R2 = 0.91, P = 0.003), 3.9% (3°) in the coronal plane (R2 = 0.88, P = 0.005), and 2.8% (4°) in the rotational plane (R2 = 0.86, P = 0.006). For each increase in collar height, there was a corresponding decrease in mean functional ROM across all of the tested activities of daily living of 1.1% (1°) in the sagittal plane (R2 = 0.90, P = 0.004), 0.4% (0.4°) in the coronal plane (R2 = 0.86, P = 0.007), and 0.6% (0.5°) in the rotational plane (R2 = 0.81, P = 0.014). For each increase in collar height, there was a 1.7° increase in mean neck extension while in the neutral position (R2 = 0.99, P < 0.001).
Conclusion: This study suggests that greater cervical collar height for hard cervical collars will better restrict full, active, and functional cervical ROM. However, the change in functional ROM was only about one quarter to that of full active ROM and the clinical significance of this may be questioned. This must be balanced by the fact that this increased collar height forces the neck into greater extension which may not be the most clinical desired or functional position and may cause skin-related issues at the jaw or chest.