Biomechanical Experiments On Unilateral Percutaneous Pedicle Screw

Background:Lumbar degeneration, spondylolisthesis, spine fracture, spine tumor is orthopedic common diseases, using pedicle internal fixation to restore the stability of the spine is an effective method for treatment of these diseases. Over the past few decades, pedicle screw technique has been widely used in the treatment of spinal disorders, but extensive dissection of the muscle tissue, fascia and ligament in the common pedicle screw fixation cause postoperative symptoms such as chronic low back pain, muscle atrophy, decreased muscle strength. percutaneous pedicle screw fixation is percutaneous surgical technique. percutaneous pedicle screw technique can reduce the influence of the soft tissue around the spine,Recently there are many reports on the cases of unilateral pedicle screw fixation. compared with bilateral fixation, unilateral fixation reduced the soft tissue injury,the risk of surgery, bleeding and medical expenses. but no matter domestic or foreign, there is no biomechanical study of unilateral pedicle screw fixation has been reported at present. We build some models of the percutaneous pedicle screw fixation for biomechanical research, In order to provide experimental basis for unilateral percutaneous pedicle screw internal fixation technique be applied in clinical.Objective:Evaluate the biomechanical properties of unilateral percutaneous pedicle screw fixation, In order to provide experimental basis for unilateral percutaneous pedicle screw internal fixation technique be applied in clinical. Methods:We Choose 40 male Boer hybrid goats L3- L6 specimens which resemble in size,and without exception Under the X-ray. Get rid of the surrounding soft tissue and protect the ligaments. Specimens randomly divided into 4 groups, each group has 10. define group A in unilateral percutaneous pedicle screw fixation(fixed on the right side of pedicle), The right side of the B group was fixed with percutaneous pedicle screw, and the left side with common pedicle screw, define group C in bilateral percutaneous pedicle screw fixation, Define group D in bilateral common pedicle screw fixation. Fix the specimen under universal mechanical testing machine.Record the stress-strain curve of forward bends, flexion, Left and right lateral flexion and compression status, and Calculating elastic modulus. Recording strain value at 2.5 N * m torque in torsional experiment. analyze the data. Results:On the forward bends, flexion, Left and right lateral flexion and compression test, the difference among the 4 groups has no statistical significance(P > 0.05). In the left rotates, group A was significantly difference when compared with group B,C and D(P < 0.05), but no significant difference was found among group B C and D(P > 0.05). In the right rotates, group A was significantly difference when compared with group B,C and D(P < 0.05), there was no significant difference among group B,C and D(P > 0.05).Conclusion:Unilateral percutaneous pedicle screw internal fixation group has similar property with bilateral internal fixation groups on stretch and compression.But on rotates,unilateral percutaneous pedicle screw internal fixation group is week than bilateral internal fixation groups. Unilateral percutaneous pedicle screw internal fixation applied to the clinical need to be careful.