The effect of starting point placement technique on thoracic transverse process strength: an ex vivo biomechanical study

<p>Abstract</p> <p>Background</p> <p>The use of thoracic pedicle screws in spinal deformity, trauma, and tumor reconstruction is becoming more common. Unsuccessful screw placement may require salvage techniques utilizing transverse process hooks. The effect of different starting point placement techniques on the strength of the transverse process has not previously been reported. The purpose of this paper is to determine the biomechanical properties of the thoracic transverse process following various pedicle screw starting point placement techniques.</p> <p>Methods</p> <p>Forty-seven fresh-frozen human cadaveric thoracic vertebrae from T2 to T9 were disarticulated and matched by bone mineral density (BMD) and transverse process (TP) cross-sectional area. Specimens were randomized to one of four groups: A, control, and three others based on thoracic pedicle screw placement technique; B, straightforward; C, funnel; and D, in-out-in. Initial cortical bone removal for pedicle screw placement was made using a burr at the location on the transverse process or transverse process-laminar junction as published in the original description of each technique. The transverse process was tested measuring load-to-failure simulating a hook in compression mode. Analysis of covariance and Pearson correlation coefficients were used to examine the data.</p> <p>Results</p> <p>Technique was a significant predictor of load-to-failure (<it>P </it>= 0.0007). The least squares mean (LS mean) load-to-failure of group A (control) was 377 N, group B (straightforward) 355 N, group C (funnel) 229 N, and group D (in-out-in) 301 N. Significant differences were noted between groups A and C, A and D, B and C, and C and D. BMD (0.925 g/cm²[range, 0.624-1.301 g/cm²]) was also a significant predictor of load-to-failure, for all specimens grouped together (<it>P </it>< 0.0001) and for each technique (<it>P <</it>0.05). Level and side tested were not found to significantly correlate with load-to-failure.</p> <p>Conclusions</p> <p>The residual coronal plane compressive strength of the thoracic transverse process is dependent upon the screw starting point placement technique. The funnel technique significantly weakens transverse processes as compared to the straightforward technique, which does not significantly weaken the transverse process. It is also dependent upon bone mineral density, and low failure loads even in some control specimens suggest limited usefulness of the transverse process for axial compression loading in the osteoporotic thoracic spine.</p

The Impact of Acute Brucellosis on Mean Platelet Volume and Red Blood Cell Distribution

Background: Brucellosis is an inflammatory disease which may infect any organs or systems in the body. Mean Platelet Volume (MPV) is one of the most frequently used surrogate markers of platelet function. It reveals the presence of disease activity in many inflammatory diseases. Red blood cell distribution width (RDW) is a parameter that measures variation in red blood cell size or red blood cell volume. Its predictive value approves inflammatory and infectious diseases. Objectives: The current study aimed to determine the assessment levels of red blood cell distribution in cases with acute brucellosis. Patients and Methods: The current study investigated whether MPV and RDW played any roles in acute brucellosis diagnosis. The study was conducted from 2008 to 2014 through prospective examination of the inflammatory markers found in adult patients with acute brucellosis. Results: The follow-up within the year after treatment was examined. The values of age, gender, leukocyte count, C-reactive protein, RDW and MPV were recorded. The study included 351 subjects, 250 of them in the acute brucellosis group and 101 in the control group. The mean MPV levels were 7.64 +/- 1.30 fL, and 7.67 +/- 1.29 fL in the acute brucellosis and control groups, respectively (P > 0.05). The mean CRP levels were 32.57 +/- 53.20 mg/dL, and 4.81 +/- 4.89 mg/dL in the acute brucellosis and control groups, respectively (P 0.05). Conclusions: While the CRP value was in patients with acute brucellosis in the current study, the MPV, RDW and leukocyte counts were within the normal range. CRP value remains the most valuable inflammatory marker in cases of acute brucellosis