The practice of using traction—applying tensile forces to the long axis of the spine—to treat patients with spinal-mediated pain has been advocated for centuries. Modern support for traction stemmed largely from the British physician James Cyriax, who in the 1940s recommended using traction to treat patients with suspected disc lesions.1 Practitioners from Cyriax's time to those who use more recent treatment approaches, including those developed by Australian physiotherapist Geoffrey Maitland, also proposed traction to be of value in treating patients with spinal disorders.2,3 The rationale for this intervention in patient care may have evolved, but the fundamental concept of its usage has remained remarkably consistent over the years.
In the current evidence-guided era, the use of traction has been more closely examined for effectiveness in patient care. Many practitioners continue to cite traction as an essential clinical modality, often based on patterns observed in patient care experiences, although objective evidence of its value remains limited. In this chapter, the physiological and biomechanical effects of spinal traction will be described along with the clinical trials employing this modality. Additionally, the conventional traction methods often used by clinicians along with variations on traditional uses will be covered from a practical perspective.
BIOMECHANICAL AND PHYSIOLOGICAL EFFECTS OF TRACTION
Among the purported effects of traction is increasing the space between the vertebrae. The theorized value of intervertebral separation is for normalizing morphology—more specifically the disc's position and increasing the dimensions of the intervertebral foramen containing the spinal nerve root. Imaging studies in vivo and with cadaveric specimens have investigated the theoretical effects of traction on the cervical spine motion segment.
One study using fresh cadaveric human specimens4 and another using live subjects5 yielded nearly identical results. The dimensions of the intervertebral foramina were measured with computed tomography (CT) and radiography, respectively. In both studies, traction with the cervical spine in a neutral position significantly increased foraminal size. Combined cervical flexion and traction did not increase foraminal size greater than either flexion or traction alone. Other studies have documented a decrease in pressure within the intervertebral foramen6 and an increase in the dimensions7 of the intervertebral foramen with flexion of the cervical spine; these findings likely serve as the basis for including flexion when applying cervical traction.
In live humans, cervical intervertebral disc spaces were observed to increase with traction of almost 30 pounds while positioned in neutral and in flexion. Similar changes in the intervertebral disc spaces were not observed when traction was administered in extension of the cervical spine. Separation of the zygapophyseal joints was achieved only with traction in extension. In this study, however, the investigators reported that traction in this position was intolerable for many subjects, thereby limiting its clinical utility.7