Abstract：Objective To evaluate effect of percutaneous transvertebral fixation of thoracolumbar fractures using both monoaxial and polyaxial pedicle screws. Methods The study involved single-level thoracolumbar fracture patients without neurological deficits undergone minimally invasive percutaneous fixation with CD-Horizon Longitude system from January 2010 to December 2011. Three level vertebras were immobilized by six pedicle screws. They were randomized into two groups: control group fixed with polyaxial screws for the fractured vertebra as well as the upper and lower adjacent vertebras and study group fixed with monoaxial screws for the superior adjacent vertebra and polyaxial screws for the injured vertebra and inferior adjacent vertebra. General information, height of fracture vertebral body, Gardner segmental kyphotic deformity, GSKD) and local kyphosis angle were assessed and compared between groups after operation so as to estimate correction ability of kyphosis deformity. Visual analogue scale (VAS) and Oswestry disability index (ODI) were used to evaluate alteration of back pain and lower limb function. Incidence of screw breakage was also compared between groups. Results Totally, 30 patients were enrolled in the trial and received an average follow-up of 10.5 months (range, 6-18 months). Two groups were similar in general information (sex, age, fracture levels, and fracture types) and perioperative information (operation time, intraoperative blood loss, proportion of antalgic supplement and hospital stay). GSKD and local kyphosis angle were significantly higher in study group than in control group after operation ［(15.0±5.4)°vs (8.8±5.4)°, (16.0±6.5)°vs (9.0±5.5)° respectively, P＜0.01］. While, correction loss of GSKD and local kyphosis was similar between study and control groups ［(2.6±1.3)°vs (1.9±1.5)°, (3.7±2.1)° vs (2.7±2.2)° respectively,P＞0.05］. Correction of anterior vertebral body height and correction loss of posterior vertebral body height were superior in study group to control group ［(33.0±11.4)% vs (22.7±11.4)%, (1.2±1.2)% vs (2.5±2.1)% respectively, P＜0.05］. Correction loss of anterior vertebral body height and correction of posterior vertebral body height were similar between study and control groups ［(2.8±2.7)% vs (5.4±4.7)%, (5.0±4.8)% vs (3.1±2.9)% respectively, P＞0.05］. Besides, there were no significant differences of VAS and ODI between the two groups in the same period after operation. Conclusion Combined use of monoaxial and polyaxial pedicle screws in minimally invasive percutaneous fixation improves kyphosis deformity and correction ability of anterior height and decreases correction loss of posterior height of the fractured vertebral body.
WANG Xu-ke,LI Chang-qing,WANG Hong-wei et al. Percutaneous transvertebral fixation of thoracolumbar fractures with monoaxial and polyaxial pedicle screws[J]. CHINESE JOURNAL OF TRAUMA, 2013, 29(5): 431-437.
［1］Fogel GR, Reitman CA, Liu W, et al. Physical Characteristics of polyaxial- headed pedicle screws and biomechanical comparison of load with their failure. Spine, 2003, 28(5):470-473.
［3］Korovessis PG, Baikousis A, Stamatakis M. Use of the Texas Scottish Rite Hospital instrumentation in the treatment of thoracolumbar injuries. Spine, 1997, 22（8）:882-888.
［4］Magerl F, Aebi M, Gertzbein SD, et al. A comprehensive classification of thoracic and lumbar injuries. Eur Spine J, 1994， 3(4):184-201.
［5］Mathews HH, Long BH. Endoscopy assisted pereutaneous anterior interbody fusion with subcutaneous suprafascial internal fixation：evolution of technique and surgical considerations. Orthop Int Ed, 1995, 3(6):496-500.
［7］Foley KT, Gupta SK, Jusis JR, et al. Pereutaneous pedicle serew fixation of the lumbar spine. Neurosurg Focus, 2001, 10(4):E10.
［8］Stanford RE, Loefler AH, Stanford PM, et al. Multiaxial pedicle screw designs: static and dynamic mechanical testing. Spine, 2004, 29(4):367-375.
［9］Gelb D, Ludwig S, Karp JE, et al. Successful treatment of thoracolumbar fractures with short-segment pedicle instrumentation. J Spinal Disord Tech, 2010, 23(5):293-301.
［10］Shepard MF, Davies MR, Abayan A, et al. Effects of polyaxial pedicle screws on lumbar construct rigidity. J Spinal Disord Tech, 2002, 15(3):233-236.
［11］Goel VK, Lim TH, Gwon J, et al. Effects of rigidity of an internal fixation device. A comprehensive biomechanical investigation. Spine, 1991, 16 Suppl 3:S155-S161.
［12］Scifert JL, Sairyo K, Goel VK, et al. Stability analysis of an enhanced load sharing posterior fixation device and its equivalent conventional device in a calf spine model. Spine, 1999, 24(21):2206-2213.
［13］Lindsey C, Deviren V, Xu Z, et al. The effects of rod contouring on spinal construct fatigue strength. Spine, 2006, 31(15):1680-1687.
