Finite Element Analysis of a Novel Anterior Locking Plate for Thoracolumbar Burst Fracture.

PURPOSE: The finite element analysis method was used to explore the biomechanical stability of a novel locking plate for thoracolumbar burst fracture fusion fixation. METHODS: The thoracolumbar CT imaging data from a normal volunteer was imported into finite software to build a normal model and three different simulated surgical models (the traditional double-segment fixation model A, the novel double-segment fixation model B, and the novel single-segment fixation model C). An axial pressure (500 N) and a torque (10 Nm) were exerted on the end plate of T12 to simulate activity of the spine. We recorded the range of motion (ROM) and the maximum stress value of the simulated cages and internal fixations. RESULTS: Model A has a larger ROM in all directions than model B (flexion 5.63%, extension 38.21%, left rotation 46.51%, right rotation 39.76%, left bending 9.45%, and right bending 11.45%). Model C also has a larger ROM in all directions than model B (flexion 555.63%, extension 51.42%, left rotation 56.98%, right rotation 55.42%, left bending 65.67%, and right bending 59.47%). The maximum stress of the cage in model A is smaller than that in model B except for the extension direction (flexion 96.81%, left rotation 175.96%, right rotation 265.73%, left bending 73.73%, and right bending 171.28%). The maximum stress value of the internal fixation in model A is greater than that in model B when models move in flexion (20.23%), extension (117.43%), and left rotation (21.34%). CONCLUSION: The novel locking plate has a smaller structure and better performance in biomechanical stability, which may be more compatible with minimally invasive spinal tubular technology.

Patient and Perioperative Factors Influencing the Functional Outcomes and Mortality in Elderly Hip Fractures.

This study aimed to evaluate the functional outcomes and mortality following hip fracture surgery in elderly patients, and to identify the associated risk factors. Between January 2016 and December 2017, 480 consecutive patients were finally included for data analyses. The Harris score and Barthel index were used to evaluate the hip function and ability to perform activities of daily living (ADL). Univariate and multivariate logistics regression analyses were performed to determine the independent risk factors for mortality, poor hip function or poor ability to perform ADL. The mortality rate was 15.6% (75/480). In the survivors, poor outcome developed in 133 (32.8%) patients and poor ADL was in 72 (17.8%) patients. The independent factors that influenced mortality were advanced age (p = 0.033), male gender (0.031), living in rural area (p < 0.001), self-reported diabetes (p = 0.005), tumor (p = 0.024), preoperative delay >7 days (p = 0.020), postoperative drainage use (p = 0.034), WBC > 10 × 109/L (p = 0.005), reduced RBC (p = 0.011), PLT < 100 × 109/L (p < 0.001), ALB < 35 g/L (p < 0.001) and CK > 200 U/L (p = 0.003). The independent factors that influenced the hip function were male gender (p = 0.009), WBC > 10 × 109/L (p < 0.001), lower HBG (p = 0.005), and ALB < 35 g/L (p < 0.001). The independent factors that influenced the ability to perform ADL were diagnosis of trochanteric fracture (p = 0.048), preoperative delay > 7 days (p = 0.027), postoperative drainage use (p = 0.010), elevated WBC (p = 0.020), lower HGB (p < 0.001), PLT < 100 × 109/L (p = 0.002), and ALB < 35 g/L (p < 0.001). Although most of risk factors were not modifiable, they aid in patient individual risk evaluation, risk stratification, and counseling patients or relatives.