General Orthopedic Spine Pedicle Screw-Rod Fixation System Design Research And Clinical Application

ObjectiveDevelopment of the Chinese people for spinal pedicle screw-rod fixation system of orthopedic devices, and associated biomechanical testing and clinical application of research, evaluation of its effectiveness.MethodsThis study is divided into three parts: 1 General orthopedic spine pedicle screw-rod fixation system design and development: Spine at home and abroad of the characteristics of each instrument, absorbing the merits of various equipment to improve the deficiencies. Anatomical data by Chinese people in the design and manufacture the general orthopedic spine pedicle screw-rod fixation system. 2 bio-mechanics test:Design based on the actual application of the test methods and procedures, System fixed to the axial loading experiments, the overall bending equipment to reverse the experiment, a fixed rod holder from the flexible pull-out strength in the experiments, pull-out strength of pedicle screws from the comparison test, a fixed vertical rod bend and the finite element analysis, screw bending test and the overall fatigue experiments. According to test data of the pilot model of integrated mechanical analysis. 3 clinical application: Since October 2005 -2008 in January in the clinical application of GOSS of the treatment of spinal disorders 686 cases, follow-up to be a complete and up to 12 months 186 cases.ResultFirst, the biomechanical test results: 1 An axial load test: Afterburning points in the axial load, the load and strain relationship is linear. When the load reached at 600N, the strain point is still the linear strain changes, indicating that the overall structure of the model is still in steady state, showing that the high flexibility. 2 Reverse bending experiment: Specimen bending torque and the relative twist angle between the two ends of a linear relationship. Bending torque reached 300 N ? cm, the twist angle <6°, the overall structure of the sample without any signs of damage on the structure of the sample have a good ability to bending-twisting. 3 Fixed rod holder from the flexible pull-out strength in the experiment: Experiments showed that the minimum fixed bar pull-out strength, that is, a fixed rod holder in the flexibility of both the sliding load at the time of> 3300N; the greatest pull-out strength, that is, sliding friction are the most> 8500N. Experimental data shows that the use of flexible fixed screw-rod holder with high reliability. In addition, the loosening of the fixed rod to completely pull out there> 5000N mechanical gradient, showing that the holder a high degree of flexibility in the safety and high flexibility. Since the pedicle screw pull-out test: GSS biggest screw pull-out strength, compared with CCD Screw difference was significant (P <0.001) 4 Finite element analysis of test: Physiological spinal curvature in accordance with fixed pre-bending rod in the column force is more uniform stress distribution and deformation caused by the smaller, closer to the biological fixation. 5 screw bending experiment: the data from the testing, we can see that the inside of the lateral bending moment greater than about 2 times. When the external load is 40Kg, the maximum lateral bending moment M = 867.5N-cm, medial to turn away from the M =- 273.4N -cm. Lateral stress is greater than about 2 times the inner stress, maximum stress insideσ=- 145.6Mpa, lateral maximum stressσ= 487.0Mpa, the above-mentioned law of model structure and characteristics of test match, and a better viscosity materials elastic characteristics. 6 the overall fatigue test: data from the test, in the fatigue test, when the model of circulation for more than 10 million times, no model is any damage, model no loosening of the connection site. Second,Clinical application of the results: 186 cases of patients in this group have been a complete follow-up time from 12 to 30 months, an average of 13 months follow-up results of the disease are as follows: Cervical spinal stenosis and 14 cases of cervical spine instability, intraoperative and postoperative X-ray cervical spine lateral photo shows the location of the pedicle screw, and a fixed and reliable, non-loosening. Atlantoaxial instability, cervical spine fracture-dislocation: 16 patients, 18 pre-operative vertebral height compression 76.6%±12.3%, after 93.5%±14.3% (P <0.001), significantly reduce the restoration of vertebral height. Cervical fracture and dislocation of the 16 cases, vertebral height preoperative average 5.0±1.2mm, after an average of 8.8±2.1mm (P <0.001), 20 patients with spinal cord of patients with varying degrees of postoperative recovery. Thoracic and lumbar fracture and dislocation of 89 cases, thoracic and lumbar load force before and after the margin line and curve are recovered well. Postoperative follow-up of more than 9 months, bone union had been. No broken nails and kyphosis occur without a high degree of loss. Lumbar spinal stenosis and 15 cases of lumbar instability, spondylolisthesis two cases, follow-up results showed that: no fixed screw loosening signs of fracture and re-detachment. Patients with low back pain, lower limb pain were significantly eased, the vast majority of patients with the restoration of the original work and normal life. Nine cases of idiopathic scoliosis patients with a single curved thoracolumbar - bending lumbar average 58°(47°~ 75°), double the average in patients with the main bend 68°(56°~ 90°), respectively, after corrected to 10°(correction 83%) and 15°(correction 77%). A fixed level of equipment, the overall correct rate of curved bends in a single patient was 86%, in patients with double-bend for 82%. Postoperative compensatory proximal bending automatically corrected, a single correction to the main bend 17°(correction 47%). Double-bend correction to 20°, (corrected 66.7%).Ankylosing spondylitis six cases of multi-segment inverted V-osteotomy fixation devices orthopedic postoperative follow-up of the lordosis area of 46°±13°, height increased 10±5cm.Conclusions1 through biomechanical testing has shown general orthopedic spinal pedicle screw-rod fixation system with good stability, structure, process of its under load, stress and bending moment nails were linear law. Screw of the lateral stress and bending moment is greater than the inside on the inside of the smaller stress, can withstand greater stress and bending moment, in the variable load a certain fixed characteristics of visco-elastic. Met the requirements of the biological fixation. Reverse the overall test of no significant loosening in the overall high-intensity fatigue test more than 105 non-stamping destruction and loosening of the fixator reasonable structure, the overall stability of a good, fully met the requirements of spine biomechanics.2 Clinical results showed that the healing of spinal injury, intervertebral height, spinal sequence, the recovery of neural effects are good, the fixation system is simple, easy to grasp, a good reduction, fixed and reliable with few complications.