The displacement, velocity and frequency profile of the frontal plane motion produced by the cervical lateral glide treatment technique
Introduction
A neurophysiological basis for manual therapy is emerging. Investigations of the effect of the cervical lateral glide treatment technique on human nociceptive and sympathetic nervous system function has contributed to an understanding of the initial clinical and neurophysiological effects of manual therapy [1], [2], [3]. These studies have shown it to produce a coordinated hypoalgesia and sympathoexcitation that parallels the effects elicited from stimulation produced analgesia of the rat dorsal/dorsolateral periaqueductal gray (DPAG) region [4], [5] This has lead to the speculation that the DPAG may be activated by manual therapy treatment techniques [3], [6]. In stark contrast to the evolving knowledge base of the neurophysiological effects of the lateral cervical glide treatment technique is the lack of information about its initial biomechanical effects. Other manual therapy treatment techniques have been studied in terms of the frequency of oscillation, displacements (linear and angular), velocity, acceleration, and forces experienced by the treated and adjacent vertebra and their related soft tissues [7], [8], [9], [10]. In studies of manual therapy techniques that are categorised as passive mobilisation procedures, of which the cervical lateral glide technique is one, the frequency of oscillation imparted to the tissues and the displacements experienced by these tissues have been shown to determine the characteristics of the induced physiological effect.
The characteristics of the linear and angular displacements of the spinal tissues produced by manual therapy treatment techniques of the cervical spine have not been determined. However, the displacements produced by the posteroanterior glide technique applied to the lumbar spine have been elucidated. A significant finding in the lumbar spine was that a central posteroanterior glide applied to the L3 spinous process by a machine, produced significant linear and angular displacements not only at L3 but also at the thoracolumbar, low and mid-thoracic spine, rib cage and pelvis [10], [11], [12], [13]. Evaluation of the cervical lateral glide treatment technique requires a different approach to that used in studies of the central posteroanterior technique applied at the lumbar spine in which a mechanical device simulated the treatment technique. Mechanical simulation, although desirable for the control of variability in the application of the treatment technique, has not been developed for the cervical lateral glide treatment technique.
The study reported herein investigated the frontal plane motion that was produced by the lateral glide treatment technique applied manually to what was determined as the fifth cervical vertebra. The frequency, displacement and peak velocity of the markers overlying the occiput, and selected cervical spine and thoracic regions down to the fifth thoracic vertebra were described. The hypothesis which was primarily assessed in this study was that the lateral glide treatment technique would influence a broad region (Occiput to T5) while having its greatest effect (i.e., greatest linear and angular displacement as well as velocity) locally at the spinal region to which it was applied (C5) and that the engendered motion would be one of predominantly lateral displacement rather than lateral flexion (i.e., angular displacement). The consistency of the frequency, displacement and velocity that was produced by the technique was also determined.
Section snippets
Methods
Four female and four male subjects, with an average age of 31.9 yr (range: 19.2–40.0 yr) participated in the study. Seven subjects were right hand dominant, based on their self report. All volunteers underwent an interview and physical examination to evaluate the state of their neuro-musculoskeletal systems. Those included in the study cohort were healthy, asymptomatic at the time of the study, and had no history of significant symptomatology of the neck, thoracic spine and both upper limbs.
Data analysis
The images which were stored on disk were analysed in two stages: the first using ExpertVision (Santa Rosa, California, USA) software and then a customised program. Firstly the centroids of the reflective markers were determined and then ordered in time. These data were submitted to a program that applied a fourth order Butterworth digital filter (cutoff 5 Hz) and then calculated the dependent measures for each cycle of head movement. Thus approximately 30 cycles were analysed for each
Linear motion
The absolute transverse displacement (Fig. 3) engendered by the technique was greatest at the occiput (mean; 95%CI value: 7.910; 6.506–9.224 cm) and least at the T5 marker (less than 0.106; 0.072–0.140 cm). The C5 marker moved significantly less than the occiput by approximately 1 cm (Table 1). Absolute displacement at C5 was twice as much as that which occurred at T1 and substantially greater than the displacement which occurred at T3 (0.805; 0.273–1.337 cm) and T5. There was no influence of
Discussion
The lateral glide treatment technique applied to what was determined to be the fifth cervical vertebra influenced not only the cervical spine but also the upper to mid-thoracic spine. This result was demonstrated by the absolute displacement that occurred at the occiput, C5, T1 and T3. The fifth thoracic marker moved very little (0.1 cm) indicating that the lateral glide treatment technique exerted little influence below this level. The effect of the cervical lateral glide treatment technique,
Conclusion
The lateral glide treatment technique applied to the region of the fifth cervical vertebra produced greatest relative displacement and highest peak velocities in the lower cervical spine. The upper thoracic spine (T1/T3) was also substantially affected by the technique whereas the region around the third and fifth thoracic vertebrae demonstrated least motion.
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