Study design: A study of spine biomechanics in a cadaver model.
Objective: To quantify motion in multiple axes created by transfer methods from stretcher to operating table in the prone position in a cervical global instability model.
Summary of the background data: Patients with an unstable cervical spine remain at high risk for further secondary injury until their spine is adequately surgically stabilized. Previous studies have revealed that collars have significant, but limited benefit in preventing cervical motion when manually transferring patients. The literature proposes multiple methods of patient transfer, although no one method has been universally adopted. To date, no study has effectively evaluated the relationship between spine motion and various patient transfer methods to an operating room table for prone positioning.
Methods: A global instability was surgically created at C5-6 in 4 fresh cadavers with no history of spine pathology. All cadavers were tested both with and without a rigid cervical collar in the intact and unstable state. Three headrest permutations were evaluated Mayfield (SM USA Inc), Prone View (Dupaco, Oceanside, CA), and Foam Pillow (OSI, Union City, CA). A trained group of medical staff performed each of 2 transfer methods: the "manual" and the "Jackson table" transfer. The manual technique entailed performing a standard rotation of the supine patient on a stretcher to the prone position on the operating room table with in-line manual cervical stabilization. The "Jackson" technique involved sliding the supine patient to the Jackson table (OSI, Union City, CA) with manual in-line cervical stabilization, securing them to the table, then initiating the table's lock and turn mechanism and rotating them into a prone position. An electromagnetic tracking device captured angular motion between the C5 and C6 vertebral segments. Repeated measures statistical analysis was performed to evaluate the following conditions: collar use (2 levels), headrest (3 levels), and turning technique (2 levels).
Results: For all measures, there was significantly more cervical spine motion during manual prone positioning compared with using the Jackson table. The use of a collar provided a slight reduction in motion in all the planes of movement; however, this was only significantly different from the no collar condition in axial rotation. Differences in gross motion between the headrest type were observed in lateral bending (Foam Pillow<Prone View, P=0.045), medial lateral translation (Foam Pillow<Mayfield, P=0.032), and anterior posterior translation (Prone View<Mayfield, P=0.030).
Conclusions: The data suggest that the manual transfer technique produces 2 to 3 times more cervical spine angular motion than the Jackson table method of transfer. The use of a collar provides significant benefit in limiting spine motion that is only observed in axial rotation. Choice of headrest does have a significant effect on the amount of motion allowed during turning, with the Foam Pillow and Prone View generally providing more effective stabilization compared with the Mayfield.