[Objective]To investigate the clinical effects of the internal fixation for fracture and dislocation of cervical spine with pedicle screws.[Method]Forty-one cases suffered from cervical fracture and dislocation were treated with Axis system.The patients all took X-ray,CT and MRI examinations before operations.Personal manipulation of every pedicle screw was attained according to the imaging measurement.[Result]All of the patients were followed up for six to twelve months postoperatively.One hundred and ninty-six of total 218 screws (90%) were in correct positon and 22 were incorrect.One nerve root injury and one doubtful blood vessel injury happened.Complete reduction and fracture union were obtained in 38 cases while inadequacy reduction and nerve root irritation existed in 3 cases,one of which suffered anterior approach operation on account of degeneration.Recovery didn't happen in the 6cases with complete spine injury.Ninteen cases with inadequacy spine injury recovered apparently even near normal level.[Conclusion]Cervical pedicle screw technique was identified to be safe and feasible for cervical fracture and dislocation.The key factors for a successful operation contain selection of patients,familiarity of the cervical anatomy,standard skill of manipulation and individuality of screw placement.

Objective The purpose was to compare the biomechanical characteristics of new percutaneous guide wire and conventional wire in cadaveric spines,and to evaluate the new percutaneous guide wire's efficacy and safety in a clinical trial.Methods Compared the push-out and penetration forces of the new percutaneous guide wire and conventional wire in fresh cadaveric lumbar spines from L1 to L5.And analyzed the related complications of new percutaneous guide wire by clinical experiment.Results Push-out forces caused the spiral part of the new percutaneous guide wire to bend or spread,so as to resist the anterior migration of the guide wire.The mean push-out forces of the new percutaneous guide wire and conventional wire were (15.5-+ 1.9) N and (5.7 ± 0.8) N respectively (P ＜ 0.01),and the mean penetration forces were (69.1 ±4.2) N and (37.1 ±4.8) N respectively (P ＜0.01).There was no wire breakage or anterior-wall penetration in the clinical trial of 222 new percutaneous guide wire.Conclusion The mean push-out and penetration forces of the new percutaneous guide wire were approximately 2 to 3 times greater than those of conventional wire.The new percutaneous guide wire effectively prevented guide-wire anterior migration and penetration of the anterior vertebral-body wall.The new percutaneous guide wire device could effectively improve the safety of percutaneous pedicle screw insertion procedures for patient with osteoporosis.

Objective To discuss the short-term clinical effect of K-Rod pedicle dynamic fixation system for multiple segmental lumbar degeneration. Methods From January 2010 to October 2012,28 patients with multiple segmental lumbar degeneration who were accepted K-Rod pedicle dynamic fixation system were retrospectively reviewed. The short-term clinical effect were based on Oswestry disability index score,visual analogous scale ( VAS) ,improvement rate of low back pain,postoperative lumbar hyperextension, hyperbend X-ray film lumbar ROM value ( lumbar flexion mobility) ,average operation time, intraoperative blood loss. Results All of 28 cases were achieved 12 ~24 months follow-up,the difference of Oswestry disability index score and visual analogous scale ( VAS) between 12 months postoperatively and preoperatively were statistically significant,the improvement rate of low back pain was (87. 0 ± 2. 0)%,the average operation time was (99. 6 ± 16. 2) minutes,the average blood loss was (70. 5 ± 31. 5)mL,the average length of stay(ALOS) was (11. 2 ± 2. 6) days after sur-gery. Conclusion K-Rod pedicle dynamic fixation system in the treatment of multiple segmental lumbar degeneration can obtain satisfactory short-term clinical effect.

Objective To discuss the clinical effect and the notes of atlas lateral mass screws combined with posterior epistropheus ped-icle screws for the treatment of atlantoaxial joint instability. Methods In our hospital from January 2006 to January 2011,48 cases of atlan-toaxial joint instability accepted operation of the atlas lateral mass screws combined with epistropheus pedicle screws were analyzed. Results All patients with follow-up time 12~24 months,an average of 17 months,were achieved primary healing and atlanto-axial intervertebral osse-ous healing. Besides postoperative neck pillow area pain improved and nerve function get a degree of recovery,there was no inner fixed damage cases. Complications of operation include venous plexus hemorrhage was in 2 cases,cervical occipital pain and numbness increase in 3 cases,cere-brospinal fluid leak in 2 cases,vertebral artery extrusion occlusion after cerebral ischemic symptoms in 1 case. Conclusion Combination of atlas lateral mass screws and posterior epistropheus pedicle screws technique is one of the effective means of treatment of atlantoaxial joint instabili-ty and can obtain satisfactory clinical effect. Standard operation performance is the key to reduce or even eliminate surgical complications.

Objective To discuss the clinical characteristics and treatment methods of lumbar disc herniation in adolescent and to in-crease the awareness of lumbar disc herniation among orthopedists.Methods Retrospectively reviewed the clinical data of 201 adolescent pa-tients(aged 20 years or less)with lumbar disc herniation who were admitted in General Hospital of Shenyang Military Area Command from January 2001 to December 2010.Analyzed the clinical characteristics and treatment methods,and compared the VAS score and ODI score be-fore operation,one week after operation and at the last follow up.Meanwhile,the complications were observed and compared.Results Among the 201 patients,187 patients(93.0%)presented with low back pain with or without radiating pain,20 patients(10.0%)presented with leg pain for the first symptom.There were only 97 patients(48.3%)were diagnosed with lumbar disc herniation for their first diagnosis in other hospital.Totally 70 patients(34.8%)had a history of trauma before the onset.The most common segments were L4 /L5 (101 cases,50.2%) and L5 /S1 (70 cases,34.8%).There were 140 patients treated by microendoscopy discectomy(MED),25 patients treated by percutaneous endoscopic lumbar discectomy(PELD),and 36 patients treated by open lumbar discectomy(OLD).All the patients were followed up for more than 12 months with averagely followed up for(22.9 ±11.7)months.There was significant improvement one week after operation and at the last follow up compared with the preoperative VAS score and ODI score,and the differences were statistically significant(P <0.05).The rate of postoperative complications was 3.6%,4.0%,8.3% in patients with MED,PELD and OLD respectively.Conclusion Diagnosis of LDH in adolescent is usually delayed.Increase the awareness of lumbar disc herniation could help orthopedists to get a exact medical history,per-form a directed physical examination,and order appropriate imaging studies.Minimally invasive surgery is an effective method to treat lumbar disc herniation in adolescent.

Objective Currently there is little study on the K-Rod pedicle fixation system in the treatment of far lateral lum-ber disc hernaition with multiple segment degeneration.The study was to compare the short-term efficay of K-Rod pedicle dynamic fixa-tion system and lumbar fusion for far lateral lumber disc herniation with multiple segment degeneration. Methods Retrospective a-nalysis were made on 56 patients with lumbar intervertebral disc herniation with multiple segment degeneration who received operation in General Hospital of Shenyang Military Region from January 2010 to October 2012.They were divided into K-Rod group (combined treatment of lumbar fusion and adjacent degenerative segment unfusion) and traditional fusion group according to different treatments. 28 patients in K-Rod group were treated with K-Rod pedicle dynamic fixation system and 28 cases in traditional fusion group were trea-ted with traditional lumbar fusion and internal fixation.Comparative analysis were made on the indexes before and after operation be-tween two groups, including Oswestry disability index, visual analogous scale (VAS) ,improvement rate of low back pain, postopera-tive lumbar spine X-ray, operation time, intraoperative blood loss and postoperative average length of stay. Results 12 to 24 months follow-up were achieved on 56 cases.The Oswestry function score and visual analog scale for both groups were improved significantly at 12 months after operation, and the difference was of statistical significance (P<0.05).Oswestry function scores and vis-ual analog scales between two groups were of no significant difference either before operation or after operation (P>0.05), while the average operation time ([119.6 ±14.2] min vs [155.5 ±17.5]min), the average blood loss ([235.5 ±32.5] mL vs [367.5 ±29. 5] mL), the average length of stay (ALOS) ([10.5 ±2.2] vs [14.2 ±2.6]d) between K-Rod group and traditional fusion group were of significant difference(P<0.05). Conclusion In the treatment of far lateral lumber disc hernaition with multiple segment degeneration, the K-Rod pedicle dynamic fixation system atrributes to less intraoperative blood loss, shorter operation time and little postoperative effect on lumbar spine mobility.

Objective To expore the difference between magnetic resonance image ( MRI) expression of spinal tuberculosis and brku-cellare spondylitis. Methods Retrospectively analyzed the clinical data of 10 patients with tuberculous spondylitis and 12 patients with bru-cellar spondylitis from Jan. 2012 to Oct. 2013. All the patients were scanned by MRI, and the expression difference of MRI were compared. Results The vertebral body of spinal tuberculosis was destroyed severely, and it often accompanied by the kyphosis and multiple-level para-vertebral abscess, and even adjacent organs tuberculosis. The vertebral body of brucellar spondylitis was destroyed lightly,and the abscess is often limited. Conclusion We can distinguish spinal tuberculosis and brucellar spondylitis by the typical difference of the expression of MRI.

Objective The aim of this study was to provide methods for predicting ideal trajectory and position of C1 lateral mass screw (C1 LMS)from plain radiographs.Methods A total of 40 consecutive subjects (with 79 screws)who had undergone C1 LMS placement were enrolled.To evaluate the C1 LMS position,the positions of screw head and tips on anteroposterior radiographs,screw length,and height on lateral radiograph were graded as 0°,Ⅰ°,and Ⅱ°,respectively.On the postoperative computed tomography images,the lateral mass (LM) perforation,screw-thread engagement percent(%),bicortical fixation,extruded screw length,and violation of adjacent joints were analyzed. Results Screws with tip located medial to LM(tip 0)showed LMperforation in all cases.Polyaxial head located within the LM(head 0)or crossing the lateral margin of the LM(head Ⅰ)showed no LMperforation.Screw-thread engagement percent was the highest with head Ⅰ-tip Ⅰ (medial half of LM)position (97.6%),followed by head 0-tip Ⅰ (90.5%)and head Ⅰ-tip Ⅱ (lateral half of LM)(86.4%). Screws longer than the posterior half of C1 anterior arch (AA)showed bicortical fixation in all cases with mean extruded screw length of 1.9 mm.Adjacent joint was not violated in 98%,with the screw height below half of C1 AA.Conclusion On an anteroposterior radiograph, a C1 LMS with the screw head located on the lateral margin of the LMand with the screw tip in the medial half of the LMresulted in the safest and longest trajectory.On lateral radiograph,a screw tip that is placed within the anterior-inferior quadrant of the C1 AA results in safe bicorti-cal fixation without injury to the adjacent structures.These plain radiographic findings may be helpful bothpostoperatively and intraoperatively for assessing the trajectory and length of the screw.

Objective To evaluate the clinical and radiological outcomes of skip-level anterior cervical discectomy and fusion(ACDF) for the treatment of two-level noncontiguous cervical spondylotic myelopathy(CSM).Methods There were 34 patients with two-level noncontiguous CSM underwent skip-level ACDF in our department from January 2014 to December 2016.The clinical outcome including surgery time, intraoperative blood loss,Japanese Orthopaedic Association(JOA) scores,Neck dysfunction index(NDI),the improvement rate of JOA,segment lordosis,fusion rate and Odom's criteria were evaluted.Results The surgery time was from 92 minutes to 125 minutes,mean operative time 103.28 minutes;the intraoperative blood loss was 50 to 150 mL,with average blood loss of 90 mL.The cervical spine lateral radiographs showed that the cervical physiological curvature had restored.The patients were followed up for average 6 months.The fusion rate of was 94.1％ at the lastest follow-up.No cages subside,implant failure or migration and infection occured.The JOA and NDI scores at the latest follow-up were(14.21±0.732) and (3.26±1.14),respectively,the JOA scores improvement rates was 58.62％.The segmental lordosis before surgery was(10.75±1.132)°,the one after surgery was(15.61±1.312)°,the difference was significant(P<0.05).The Odom's criteria at the lastest follow-up showed that excellent in 21 patients,good in 9 patients and fair in 4 patients,with excellent and good rate of 88.2％.Conclusion Skip-level ACDF can achieve good clinical and radiological outcomes including a high fusion rate and well maintainence of spinal curvature and intervertebral height for patients with two-level noncontiguous CSM.

BACKGROUND: The characteristics of cervical anatomy and pedicle screw, operational specification, and individual screw implantation are the key factors of a successful implantation treatment.OBJECTIVE: This study was designed to investigate the cervical pedicle screw and host response as well as the recovery of spinal nerve functions during the surgery and follow-up period of cervical spine fracture-dislocation.DESIGN: A case analysis.SETTING: Department of Orthopaedics, General Hospital of Shenyang Military Area Command of Chinese PLA, Shenyang, Lianning Province, China.PARTICIPANTS: A total of 41 patients with cervical spine fracture-dislocation, who have complete follow-up data, were admitted to the Department of Orthopaedics, General Hospital of Shenyang Military Area Command of Chinese PLA between February 2002 and February 2006. Of the included patients, 18 were complicated by spinal cord injury (according to Frankel classification system, 6 were graded as A, 1 as B, 4 as C, and 7 as D.METHODS: Forty-one patients with cervical spine fracture-dislocation were treated by implanting a screw through the cervical pedicle and fixing it. Prior to surgery, all patients were subjected to X-ray, CT and MRI examinations. According to measurements, each cervical pedicle screw was individually implanted. The entire surgery was accomplished by Xiang Liang-bi, chief physician, whose qualification corresponds to the responsibilities.MAIN OUTCOME MEASURES: Material and host response during and after screw implantation as well as in the follow-up period. Recovery of spinal nerve function after screw implantation.RESULTS: All patients were followed up for 6-12 months and all incisions were healed primarily. Material and host response during the process of screw implantation: A total of 218 screws were implanted. After initial implantation, 12 screws were loosened, and such a phenomenon disappeared in 11 screws by adjusting inserting point and inserting direction or/and increasing screw diameter or length. The remaining 1 screw was stabilized by increasing the fixed segments. After drilling, poles of 10 screws bled much and treated by hemostasis. C1-2 venous plexus hemorrhage was caused in 3 patients and stopped by compression, and Apofix internal fixation was used in 1 of 3 patients due to unclear surgical visual field. Material and host response after surgery and during the follow-up: A total of 218 screws were inserted. Of the 218 screws, 196 were in correct position, and 22 were deviated to different degrees. Deviation of 1 screw caused injury to nerve root and that of another screw led to injury to blood vessel. Thirty-eight patients acquired satisfactory reduction and bone union. Three patients presented with symptoms of nerve root irritation due to incomplete reduction in the old fracture-dislocation. Among the 3 patients, 1 was subjected to anterior approach due to screw removed, and neither injury to vertebral artery, spinal cord, and nerve root nor internal fixation destroy was found in any other patients. Recovery of spinal nerve function after implantation: Among the 18 patients complicated with spinal cord injury, 6 patients, who were assessed as grade A spinal cord injury, did not exhibit improvement in spinal cord function, while the remaining 12 presented with 1 or 2 grades of improvement.CONCLUSION: There is a lower probability for biocompatibility reaction, and spinal nerve function recovers better after implantation of cervical pedicle screw. So implantation of a cervical pedicle screw system is an effective and relatively safe method for treatment of cervical spine fracture-dislocation.