The Research On Individualized Strategy Of Screw Insertion For Posterior Lumbar Internal Fixation And Its Clinical Efficacy

Objective: Through the preoperative imaging data of patients with lumbar disc herniation related to the structure and angle of measurement,and the location of the intraoperative anatomical landmarks.This research proposed and implemented a new strategy of individualized screw insertion for posterior lumbar internal fixation.Patients were followed up regularly to observe the clinical efficacy postoperatively with lumbar X-ray and CT scan to evaluate the safety assessment of screw insertion.Methods: There were 94 patients with lumbar disc herniation adopted posterior lumbar interbody fusion(PLIF)or transforaminal lumbar interbody fusion(TLIF)with the newly designed screw insertion technique from January 2013 to January 2014.During the surgery,the insertion point of the pedicle screw was at the outer edge of the superior facet joint,4 mm below the upper border of processus transversus.The direction of screw insertion was determined by the vertical line,which connected between the superior and inferior facet joints.The abduction angle is determined by the parallelogram rule.Postoperative radiograph and computed tomography(CT)were taken to evaluate the safety assessment of the screws and to make the relevant measurements.Oswestry Disability Index score,Japanese Orthopedic Association score,and Visual Analogue Scale were used respectively to evaluate the functional outcomes.Outcomes: All patients underwent the surgery smoothly and successfully without any serious complications were found.A total of 82 patients(39 males and 43 females,mean age 58.69±8.32)were followed-up with an average time of 46.05 months(36-60).The average operation time and amount of bleeding loss were 168.60±40.21 min and 469.32±187.33 ml,respectively.A number of 394 pedicle screws were inserted applied by the newly proposed screw insertion technique.There were significant differences between the JOA score,the ODI score and VAS score when doing preoperative and postoperative follow-up.The recovery rate calculated by the JOA score was 53.94%±19.20%.No nerve injury or other related manifestations were founded among all patients.There were 7 patients showed hypoesthesia of skin in the nerve root innervation area after surgery.5 of these patients had completed recovery at the last follow-up visit.The remaining 2 patients didn’t completely recover at the last follow-up visit,however,it was significantly symptom decreased compared with that before surgery.No fusion failure,screw loosening,breakage or shift was appeared.At the last follow-up visit,19 screws(4.82%)penetrated the cortex in I degree,2 screws(0.51%)had penetrated the cortex in II degree,and the remaining screws were placed in proper position according to the Lothar Wiesner’s classification.Conclusion: This research proposed and implemented a new surgical procedure for lumbar pedicle screw insertion,which effectively avoided the miss position of pedicle screw caused by individual differences,different body positions,anesthesia and other factors.This research has a series of novel and legible landmarks.The clinical applications have proved the safety and effectiveness of the individualized strategy of lumbar pedicle screw insertion technique.