Optimizing Lumbar Pedicle Screw Trajectory Utilizing a 3D-Printed Drill Guide to Ensure Placement of Pedicle Screws Into Higher Density Bone May Improve Pedicle Screw Pullout Resistance.

Background: Lower preoperative Hounsfield Unit (HU) values of vertebral body are associated with pedicle screw (PS) loosening after implantation with traditional trans-pedicular trajectory. However, the relationship between trajectory HU value and PS fixation quality remains unknown. This study aimed to investigate if 3-dimensionally (3D)-printed guider directed accurate implantation of pedicle screw could increase the anti-pulling properties of screws.

Hypertrophy and Fibrosis of the Ligamentum Flavum in Lumbar Spinal Stenosis is Associated With Increased Expression of LPA and LPAR1.

Study Design: Histologic, immunohistochemical (IHC), and enzyme-linked immunosorbent assay analysis of the human ligamentum flavum (LF).

Objective: The purpose of this study was to determine the level of expression of lysophosphatidic acid (LPA) in the LF from lumbar spinal stenosis (LSS) patients and to analyze the relationship among LPA, LPA receptors (LPARs), and LF hypertrophy.

Summary Of Background Data: LF hypertrophy and fibrosis are important causes of LSS.

Effect of a New Annular Incision on Biomechanical Properties of the Intervertebral Disc.

Objective: To compare the biomechanical properties of a novel annular incision technique, an oblique incision made approximately 60° to the spinal column, with the traditional transverse and longitudinal annular slit incision in an ex vivo sheep lumbar spine model.

Methods: Sixteen sheep lumbar spines were used for the current ex vivo biomechanical comparative study. Functional spine unit (FSU) specimens composed of two vertebrae and one disc in the middle was cut from the whole lumbar spine.

Beta1 integrin inhibits apoptosis induced by cyclic stretch in annulus fibrosus cells via ERK1/2 MAPK pathway.

Low back pain is associated with intervertebral disc degeneration (IVDD) due to cellular loss through apoptosis. Mechanical factors play an important role in maintaining the survival of the annulus fibrosus (AF) cells and the deposition of extracellular matrix. However, the mechanisms that excessive mechanical forces lead to AF cell apoptosis are not clear.

Quantitative T2 mapping to characterize the process of intervertebral disc degeneration in a rabbit model.

Background: To investigate the potential of T2 mapping for characterizing the process of intervertebral disc degeneration (IDD) in a rabbit model.

Methods: Thirty-five rabbits underwent an annular stab to the L4/5 discs (L5/6 discs served as internal normal controls). Degenerative changes were graded according to the modified Thompson classification and quantified in T2 respectively at pre-operation, 1, 3, 6, 12 and 24 weeks postoperatively.

Unilateral versus bilateral instrumented transforaminal lumbar interbody fusion in two-level degenerative lumbar disorders: a prospective randomised study.

Purpose: The aim of this study was to analyse the clinical and radiological outcomes of unilateral versus bilateral instrumented TLIF in two-level degenerative lumbar disorders.

Methods: A prospective randomised clinical study was performed from January 2008 to May 2011. Sixty-eight consecutive patients with severe low back pain and radicular pain were divided randomly into the unilateral (n = 33) or bilateral (n = 35) pedicle screw fixation group based on a random number list.

[Using perfusion bioreactor for mesenchymal stem cell proliferation in large tricalcium phosphate scaffold].

Objective: To investigate the feasibility of using perfusion culture bioreactor for bone mesenchymal stem cell proliferation in large scale beta-tricalcium phosphate (beta-TCP) scaffold.

Methods: In the dynamic perfusion culture group, the porous beta-TCP cylindrical scaffolds combined with the sheep mesenchymal stem cells were continuously perfused with the complete alpha-MEM medium by a peristaltic pump for 1, 2 and 4 weeks. While in the static culture group, the hybrid constructs were immersed in the medium without perfusion for 2 and 4 weeks.