STABILIZING PROPERTIES OF THE HALO APPARATUS

Citation
Sk. Mirza et al., STABILIZING PROPERTIES OF THE HALO APPARATUS, Spine (Philadelphia, Pa. 1976), 22(7), 1997, pp. 727-733
Citations number
14
Categorie Soggetti
Orthopedics,"Clinical Neurology
ISSN journal
03622436
Volume
22
Issue
7
Year of publication
1997
Pages
727 - 733
Database
ISI
SICI code
0362-2436(1997)22:7<727:SPOTHA>2.0.ZU;2-Z
Abstract
Study Design. A cadaveric cervical spine specimen fixed between a fibe rglass torso and a plastic skull was used as a model to determine the effect of halo structural parameters on motion at a lesion simulated a t C5-C6. In a second part, nine commercially available halo devices we re compared. of the halo apparatus to reducing motion in an injured ce rvical spine and to compare the stability offered by a sample of comme rcially available halo devices. Controversy exists concerning the abil ity of the halo apparatus to stabilize the injured cervical spine. Sum mary of Background Data. The halo apparatus has been shown to be the m ost effective nonsurgical method for stabilizing the fractured spine. Nonetheless, several clinical studies have demonstrated that unaccepta bly large motions can occur at the injured spinal segment stabilized w ith a halo apparatus. Methods. Each cadaveric cervical spine was mount ed onto a fiberglass torso and a rigid plastic skull was attached to t he base of the occiput. A posterior ligamentous lesion was created bet ween C5 and C6. The halo ring was fitted to the skull and a vest to th e torso. Loads were applied to the skull in flexion, extension, and la teral bending, and relative angulation between C5 and C6 was measured with electroinclinometers. In the first part, the effect of parameters such as vest tightness, vest-thorax friction, vest deformation, and c onnecting bar rigidity on spinal angulation were measured using one ve st. In the second part, the stability offered by each of nine commerci ally available halo devices was compared. Results. Increasing chest st rap tightness and decreasing vest deformation reduced angulation at th e spinal lesion. Once connecting bar joints were tightened to 25% of t heir recommended torque, increased tightening or adding additional bar s had no effect on rigidity. Although specific vests permitted signifi cantly greater motion in specific directions, no vest allowed greater angulation consistently in all loading planes. Conclusions. Increasing vest tightness, decreasing the deformability of the vest, and ensurin g a good fit can reduce motion in the fractured spine. Most commercial ly available halo vests provide similar mechanical stability to the in jured cervical spine.