Fixation Strength of Caudal Pedicle Screws after Posterior Lumbar Interbody Fusion with the Modified Cortical Bone Trajectory Screw Method

Study Design Clinical case series. Purpose In the posterior lumbar interbody fusion (PLIF) procedure in our institute, the cephalad screw trajectory follows a mediolateral and caudocephalad directed path according to the original cortical bone trajectory (CBT) method. However, the starting point of the caudal screw is at the medial border of the pedicle on an articular surface of the superior articular process, and the trajectory takes a mediolateral path parallel to the cephalad endplate. The incidence of caudal screw loosening after PLIF with this modified CBT screw method was investigated, and significant risk factors for caudal screw loosening were evaluated. Overview of Literature A biomechanical study of this modified caudal screw trajectory using the finite element method reported about a 20% increase in uniaxial yield pullout load compared with the traditional trajectory. However, there has been no clinical study concerning the fixation strength of this modified caudal screw trajectory. Methods The subjects were 193 consecutive patients who underwent single-level PLIF with modified CBT screw fixation. Caudal screw loosening was checked in computed tomography at 6 months after surgery, and screw loosening was defined as a radiolucency of 1 mm or more at the bone-screw interface. Results The incidence of caudal screw loosening after lumbosacral PLIF (46.2%) was significantly higher than that after floating PLIF (6.0%). No significant differences in sex, brand of the instruments, and diameter and length of the caudal screw were evident between patients with and without caudal screw loosening. Patients with caudal screw loosening were significantly older at the time of surgery than patients without caudal screw loosening. Conclusions Fixation strength of the caudal screw after floating PLIF with this modified CBT screw technique was sufficiently acceptable. Fixation strength after the lumbosacral procedure was not.

[1]  N. Hosogane,et al.  Biomechanical evaluation of the fixation strength of lumbar pedicle screws using cortical bone trajectory: a finite element study. , 2015, Journal of neurosurgery. Spine.

[2]  A. Patwardhan,et al.  Effect of Physiological Loads on Cortical and Traditional Pedicle Screw Fixation , 2014, Spine.

[3]  T. Asazuma,et al.  Cortical bone trajectory for lumbosacral fixation: penetrating S-1 endplate screw technique: technical note. , 2014, Journal of neurosurgery. Spine.

[4]  K. Sairyo,et al.  Hybrid technique of cortical bone trajectory and pedicle screwing for minimally invasive spine reconstruction surgery: a technical note. , 2014, The journal of medical investigation : JMI.

[5]  Mohamed M. Mohi Eldin,et al.  Asian Spine Journal Asian Spine Journal Lumbar Transpedicular Implant Failure: a Clinical and Surgical Challenge and Its Radiological Assessment , 2022 .

[6]  N. Crawford,et al.  Biomechanics of Lumbar Cortical Screw–Rod Fixation Versus Pedicle Screw–Rod Fixation With and Without Interbody Support , 2013, Spine.

[7]  D. Kiel,et al.  QCT measures of bone strength at the thoracic and lumbar spine: The Framingham study , 2012, Journal of Bone and Mineral Research.

[8]  S. Kishida,et al.  Radiographic Evaluation of Monocortical Versus Tricortical Purchase Approaches in Lumbosacral Fixation With Sacral Pedicle Screws: A Prospective Study of Ninety Consecutive Patients , 2010, Spine.

[9]  C. Puttlitz,et al.  Cortical bone trajectory for lumbar pedicle screws. , 2009, The spine journal : official journal of the North American Spine Society.

[10]  B. Sandén,et al.  The significance of radiolucent zones surrounding pedicle screws. Definition of screw loosening in spinal instrumentation. , 2004, The Journal of bone and joint surgery. British volume.

[11]  K. Okuyama,et al.  Influence of bone mineral density on pedicle screw fixation: a study of pedicle screw fixation augmenting posterior lumbar interbody fusion in elderly patients. , 2001, The spine journal : official journal of the North American Spine Society.

[12]  K. Okuyama,et al.  Can insertional torque predict screw loosening and related failures? An in vivo study of pedicle screw fixation augmenting posterior lumbar interbody fusion. , 2000, Spine.

[13]  R. Yeasting,et al.  Internal Architecture of the Sacrum in the Elderly: An Anatomic and Radiographic Study , 2000, Spine.

[14]  K. Okuyama,et al.  Posterior lumbar interbody fusion: a retrospective study of complications after facet joint excision and pedicle screw fixation in 148 cases. , 1999, Acta orthopaedica Scandinavica.

[15]  L. Plank,et al.  Pedicle screw placement at the sacrum: anatomical characterization and limitations at S1. , 1999, Journal of spinal disorders.

[16]  J. Leong,et al.  Comparison of the Strengths of Lumbosacral Fixation Achieved With Techniques Using One and Two Triangulated Sacral Screws , 1998, Spine.

[17]  J. Hipp,et al.  The Internal Bony Architecture of the Sacrum , 1998, Spine.

[18]  D. Bradford,et al.  Sacral screw loads in lumbosacral fixation for spinal deformity. , 1993, Spine.

[19]  S. Esses,et al.  Complications associated with the technique of pedicle screw fixation. A selected survey of ABS members. , 1993, Spine.

[20]  S. Garfin,et al.  The effects of depth of penetration, screw orientation, and bone density on sacral screw fixation. , 1993, Spine.

[21]  S. Garfin,et al.  Screw Fixation in the Human Sacrum: An In Vitro Study of the Biomechanics of Fixation , 1992, Spine.

[22]  R. Winter,et al.  Fusion to the Sacrum for Nonparalytic Scoliosis in the Adult , 1986, Spine.