Traditional one-above and one-below four-screw posterior short-segment instrumentation is used for unstable thoracolumbar burst fractures. However, this method has a high rate of implant failure and early loss of reduction. The purpose of this study was to use finite element (FE) analysis to determine the effect of treating thoracolumbar burst fractures by short-segment pedicle screw fixation using a combination of two additional pedicle screws and vertebroplasty at the level of the fracture. An intact T11-L1 spine FE model was created from the computed tomography images of a male subject. Four fixation models with posterior fusion devices (pedicle screws, rods, cross-link) were established to simulate an unstable thoracolumbar fracture with different fusion surgeries: short-segment fixation with: 1) a link (S-L); 2) intermediate bilateral screws (S-I); 3) a link and calcium sulfate cement (S-L-C); 4) intermediate bilateral screws and calcium sulfate cement (S-I-C). Different loading conditions (flexion, extension, lateral bending, and axial rotation) were applied on the models and analyzed with a FE package. The range of motion (ROM), and the maximum value and distribution of the implant stress, and the stress in the facet joint, were compared between the intact and fixation models. The ROM in flexion, extension, axial rotation, and lateral bending was the smallest in the S-I-C model, followed by the S-I, S-L-C, and S-L models. Maximum von Mises stress values were larger under lateral bending and axial rotation loadings than under flexion and extension loading. High stress was concentrated at the crosslink and rod junctions. Maximal von Mises stress on the superior vertebral body for all loading conditions was larger than that on the inferior vertebral body. The maximal von Mises stress of the pedicle screws during all states of motion were 265.3 MPa in S-L fixation, 192.9 MPa in S-I fixation, 258.4 MPa in S-L-C fixation, and 162.3 MPa in S-I-C fixation. Short-segment fixation with two intermediate pedicle screws together with calcium sulfate cement at the fractured vertebrae may provide a stiffer construct and less von Mises stress of the pedicle screws and rods as compared to other types of short-segment fixation.

A retrospective clinical and radiographic study was performed. To compare 2 grafting materials of anterior augmentation for thoracolumbar burst fractures: transpedicular cancellous bone (TPCB) grafting and transpedicular calcium sulfate grafting and to decide whether calcium sulfate cement can replace autogenous cancellous bone applied in anterior vertebral body augmentation after posterior short-segment instrumentation. Additional TPCB grafting was developed as an alternative to prevent early implant failure. However, the results are inconsistent and donor-site complications are a major concern. Calcium sulfate has been offered as a bone substitute for treating patients with metaphysis fractures or bone defect, but the results of application in spinal surgeries are uncertain. Fifty-one patients with a single-level thoracolumbar burst fracture for treatment with short-segment pedicle screw fixation were enrolled in the study. Fractures in group 1 patients were reinforced with TPCB (n = 31), and fractures in group 2 patients were augmented with transpedicular calcium sulfate cement (TPCSC; n = 20). All patients were followed-up at least 2 years after surgery. Radiographic parameters and clinical outcomes were compared between the 2 groups. The 2 groups were similar in age, sex, fracture levels, preoperative neurologic status distribution, and the associated injuries. The TPCB group had a longer period of follow-up (52.7 +/- 4.9 vs. 28.6 +/- 3.5 months, P < 0.001). Blood loss and operation time were less in the TPCSC group (247.5 +/- 164.2 vs. 600.0 +/- 403.1 mL, P = 0.001 and 161.7 +/- 28.5 vs. 227.2 +/- 43.6 minutes, P < 0.001). Radiographic parameters and clinical outcomes were similar in both groups. The TPCSC group had no surgical complication, but the TPCB group revealed 2 cases with wound infection after surgery. The failure rate, defined as an increase of 10 degrees or more in loss of correction or implant failure, was also not significantly different (TPCB = 9.6% and TPCSC = 15%; P = 0.565). All patients with partial neurologic deficits initially improved at the final follow-up. Additional TPCB grafting after posterior short-segment instrumentation remains a reliable surgical method for correcting and maintaining sagittal alignment and vertebral body height in thoracolumbar burst fractures. Calcium sulfate cement also proved to be an effective bone substitute used in spinal surgeries for patients with thoracolumbar burst fractures.

Infection after vertebroplasty (VP) is a rare but serious complication. Previous literatures showed most pathogens for infection after VP were bacteria; tuberculosis (TB) induced infection after VP was extremely rare. We reported our treatment experiences of cases with infectious spondylitis after VP, and compared the differences between developed pyogenic and TB spondylitis. From January 2001 to December 2015, 5749 patients had undergone VP at our department were reviewed retrospectively. The causative organisms were obtained from tissue culture of revision surgery. Parameters including type of surgery, the interval between VP and revision surgery, neurologic status, and visual analog scale (VAS) of back pain were recorded. Laboratory data at the time of VP and revision surgery were collected. Charlson comorbidity index (CCI), preoperative bacteremia, urinary tract infection (UTI), pulmonary TB history were also analyzed. Eighteen patients were confirmed with developed infectious spondylitis after VP (0.32%, 18/5749). Two were male and 16 were female. The median age at VP was 73.4 years. Nine patients were TB and the other nine patients were pyogenic. The interval between VP and revision surgery ranged from 7 to 1140 days (mean 123.2 days). The most common type of revision surgery was anterior combined with posterior surgery. Seven patients developed neurologic deficit before revision surgery. Three patients died within 6 months after revision surgery, with a mortality of 16.7%. Finally, VAS of back pain was improved from 7.4 to 3.1. Seven patients could walk normally, the other 8 patients had some degree of disability. Both pyogenic and TB group had similar age, sex, and CCI distribution. The interval between VP and revision surgery was shorter in the patients with pyogenic organisms (75.9 vs 170.6 days). At revision surgery, WBC and CRP were prominently elevated in the pyogenic group. Five in the pyogenic group had UTI and bacteremia; five in TB group had a history of lung TB. Infection spondylitis after VP required major surgery for salvage with a relevant part of residual disability. Before VP, any bacteremia/UTI or history of pulmonary TB should be reviewed rigorously; any elevation of infection parameters should be scrutinized strictly.