ABSTRACT
Objective To compare biomechanical performance of four-part proximal humeral fractures fixed by novel locking plate or by AO-PHILOS plate. Methods The finite element fixation models of both the novel locking plate and AO-PHILOS plate for four-part proximal humeral fractures were established, respectively. The maximum Von Mises stress and displacement under 4 different functional positions of shoulder abduction in the two fixation models were compared by finite element analysis. Results The maximum displacement in shoulder abduction of 0°,30°,60°,90° were 6.644, 7.079, 5.850, 3.005 mm, respectively, in novel locking plate fixation model, and 6.293, 6.826, 5.774, 3.023 mm, respectively, in AO-PHILOS plate fixation model. Since the maximum displacements in both fracture fixation models were similar, it indicated that there was no significant difference in the stability for fixing proximal humeral fracture. The maximum Von Mises stress in shoulder abduction of 0°,30°,60°,90°were 1 033.0, 904.1, 888.1, 1 062.0 MPa in novel locking plate fixation model, while in AO-PHILOS plate fixation model, it showed 743.1, 692.4,486.4,393.5 MPa, respectively. During the process of shoulder abduction, the total stress in both fracture fixation models gradually decreased, but the new locking plate decreased in a larger range, showing an obvious stress dispersion. Conclusions Both the novel locking plate and AO-PHILOS plate can be used as internal fixation treatment for complex four-part proximal humeral fractures with no significant difference in stress distribution, and both showing a stable fixation effect. For fixing proximal humeral fractures with osteoporosis combined with the great and less tuberosity, the novel locking plate has an advantage over AO-PHILOS plate due to its unique anatomical wings and better fixing effect.
ABSTRACT
<p><b>BACKGROUND</b>The neurogenic bladder dysfunction caused by spinal cord injury is difficult to treat clinically. The aim of this research was to establish an artificial bladder reflex arc in rats through abdominal reflex pathway above the level of spinal cord injury, reinnervate the neurogenic bladder and restore bladder micturition.</p><p><b>METHODS</b>The outcome was achieved by intradural microanastomosis of the right T13 ventral root to S2 ventral root with autogenous nerve grafting, leaving the right T13 dorsal root intact. Long-term function of the reflex arc was assessed from nerve electrophysiological data and intravesical pressure tests during 8 months postoperation. Horseradish peroxidase (HRP) tracing was performed to observe the effectiveness of the artificial reflex.</p><p><b>RESULTS</b>Single stimulus (3 mA, 0.3 ms pulses, 20 Hz, 5-second duration) on the right T13 dorsal root resulted in evoked action potentials, raised intravesical pressures and bladder smooth muscle, compound action potential recorded from the right vesical plexus before and after the spinal cord transaction injury between L5 and S4 segmental in 12 Sprague-Dawley rats. There were HRP labelled cells in T13 ventral horn on the experimental side and in the intermediolateral nucleus on both sides of the L6-S4 segments after HRP injection. There was no HRP labelled cell in T13 ventral horn on the control side.</p><p><b>CONCLUSION</b>Using the surviving somatic reflex above the level of spinal cord injury to reconstruct the bladder autonomous reflex arc by intradural microanastomosis of ventral root with a segment of autologous nerve grafting is practical in rats and may have clinical applications for humans.</p>
Subject(s)
Animals , Male , Rats , Anastomosis, Surgical , Atropine , Pharmacology , Models, Theoretical , Rats, Sprague-Dawley , Reflex, Abdominal , Physiology , Trimethaphan , Pharmacology , Urinary Bladder, NeurogenicABSTRACT
<p><b>OBJECTIVE</b>To evaluate an alternative landmark for thoracic vertebral screw insertion using the nutrient artery entrance on the posterolateral wall of thoracic vertebral bodies, and to discuss its clinical significance.</p><p><b>METHODS</b>Twenty normal adult cadaver thoracic vertebral specimens were obtained randomly. Measurements included the number of nutrient artery entrance on left and right wall of thoracic vertebral bodies from T5 to T12, the diameter of the maximal nutrient artery entrance (d), the distance from nutrient artery entrance to the superior (A) or posterior (B) margin of the vertebral body, the distance between the posterior edge of the vertebral body and the nutrient artery entrance line (C) or the upper costal facet line (D). The length between left and right nutrient artery entrance (a) or costal facet (b) was measured too.</p><p><b>RESULTS</b>From T5 to T12, the nutrient artery entrance were all underneath the upper costal facet. There were no significant differences between left and right side of anatomic measurements of each vertebral body from T5 to T12. The distance of A increased from T5 to T12, and the diameter and distance of B were no significant differences from T5 to T12. There were significant differences between the value C and the value D from T5 to T10.</p><p><b>CONCLUSIONS</b>The anatomical position of the nutrient artery entrance is relatively settled, and it could be used as a new landmark for screw placement.</p>