Subclassification and clinical treatment options of refractory atlantoaxial dislocation / 中华骨科杂志

Objective:To subdivide clinical classification of refractory atlantoaxial dislocation, and evaluate the reliability of new subdivide clinical classification of refractory atlantoaxial dislocation.Methods:From January 2010 to December 2018, 48 patients with refractory atlantoaxial dislocation were treated, including 19 males and 29 females, aged 16 to 65 years, with an average of 39.2±13.3 years. According to the changes of relative anatomical position of C 1 and C 2 under general anesthesia with heavy traction of 1/6 body weight, subdivide clinical classification of refractory atlantoaxial dislocation were proposed, and refractory atlantoaxial dislocation was divided into traction loosening type (atlantoaxial angle≥5°) and traction stabilization type (atlantoaxial angle<5°). The traction loosening type was directly reduced by posterior atlantoaxial screw-rod fixation and fusion without anterior or posterior soft tissue release. For traction stabilization type, transoral soft tissue release was performed first, and then transoral anterior reduction plate fixation and fusion or posterior atlantoaxial screw-rod fixation and fusion were performed. Atlantodental interval (ADI) and atlantoaxial angle (AAA) were measured and collected before and after surgery to evaluate atlantoaxial reduction. The space available for the spinal cord (SAC) were measured to evaluate spinal cord compression. Visual analogue score (VAS) was used to evaluate the neck pain levels, and Japanese Orthopaedic Association (JOA) scores was used to evaluate the neurological function. American Spinal Cord Injury Association impairment scale (AIS) was used to evaluate the degree of spinal cord injury. One week, 3, 6, 12 months postoperatively and the annual review of the X-ray and CT scan were checked, in order to evaluate the reduction, internal fixation and bone graft fusion. Results:Among all 48 cases, 22 cases were traction loosening type, of which posterior atlantoaxial screw-rod fixation and fusion were performed in 16 cases and occipitocervical fixation and fusion in 6 cases. 26 cases were traction stabilization type, and they all underwent anterior transoral release, and then, anterior TARP fixation and fusion were performed in 24 cases and posterior screw-rod fixation and fusion in the other 2 cases. X-ray, CT and MRI images and of all patients 1 week after surgery showed good atlantoaxial reduction and decompression of spinal cord. In each of the two types, there was one case lost to follow-up. For 46 cases in follow-up, the follow-up time ranged from 6 to 72 months, with an average of 38.0±17.2 months. Among 46 cases, 21 cases of traction loosening type showed that, ADI reduced from preoperative 9.9±2.2 mm to 2.3±0.9 mm at 3 months after surgery and 2.3±1.0 mm at the last follow-up, AAA increased from preoperative 57.9°±12.3° to 91.0°±2.2° at 3 months after surgery and 90.9°±2.2° at the last follow-up, SAC increased from preoperative 9.8±1.3 mm to 15.1±0.7 mm at 3 months after surgery and 14.9±0.7 mm at the last follow-up, VAS score reduced from preoperative 1.5±2.1 to 0.7±1.0 at 3 months after surgery and 0.3±0.6 at the last follow-up, and JOA score increased from preoperative 10.2±1.7 to 13.3±1.3 at 3 months after surgery and 14.9±1.5 at the last follow-up. Twenty-five cases of traction stabilization type presented that, ADI reduced from preoperative 9.7±2.0 mm to 2.1±1.4 mm at 3 months after surgery and 2.1±1.3 mm at the last follow-up, AAA increased from preoperative 55.8°±9.2° to 90.9°±1.4° at 3 months after surgery and 90.9°±1.3° at the last follow-up, SAC increased from preoperative 10.5±1.0 mm to 15.4±0.5 mm at 3 months after surgery and 14.8±2.8 mm at the last follow-up, VAS score reduced from preoperative 1.7±2.1 to 0.7±0.9 at 3 months after surgery and 0.3±0.5 at the last follow-up, and JOA score increased from preoperative 10.1±1.3 to 12.9±1.5 at 3 months after surgery and 14.4±1.3 at the last follow-up. In the traction loosening type, all the 10 grade D patients were improved to grade E at the last follow-up. In the 2 grade C patients of traction stabilization type before surgery, 1 patient was improved to grade E, 1 patient was improved to grade D, and all 11 patients with grade D were improved to grade E at the last follow-up. Bony fusion was obtained in all patients from 3 to 6 months, with an average of 4.4±1.5 months. During follow-up period, no looseness of internal fixation or redislocation happened.Conclusion:Refractory atlantoaxial dislocation can be divided into traction loosening type and traction stabilization type. For traction loosening type, satisfactory reduction can be achieved by using posterior atlantoaxial screw-rod system without soft tissue release. For traction stabilization type, anterior release is preferable, and then anterior TARP or posterior screw-rod can be used to achieve satisfactory reduction.

Transoral stepped atlantoaxial release theory for irreducible atlantoaxial dislocation / 中华骨科杂志

Objective:To investigate the clinical efficacy of different grade transoral atlantoaxial release for the treatment of irreducible atlantoaxial dislocation.Methods:From January 2010 to December 2019, 297 patients with irreducible atlantoaxial dislocation treated by different grade releases were retrospectively analyzed, including 132 males and 165 females, aged 42.3±12.14 years (range, 10-63 years). All cases were treated by different grade releases, Grade I (196, 66.0%), Grade II (54, 18.2%), Grade III (28, 9.4%) and Grade IV (19, 6.4%). The American Spinal Injury Association (ASIA) grade and Japanese Orthopedic Association (JOA) score were recorded as the clinical evaluation index. The clivus-canal angle (CCA) and cervico-medullary angle (CMA) were measured to evaluate the reduction. The surgery time, blood loss, duration of bony fusion and complications were also analyzed.Results:The follow-up time was 14.8±10.2 months (range, 9-36 months). The surgery time of Grade I-IV were 2.02±0.35 min, 3.00±0.36 min, 4.07±0.96 min and 5.24±0.83 min, respectively ( F=385.43, P<0.001), blood loss was 84.08±27.21 ml, 153.61±31.36 ml, 268.93±48.94 ml and 444.21±109.51 ml, respectively ( F=582.39, P<0.001). The preoperative ASIA motor score of Grade I-IV were 83.85±6.68, 84.06±5.47, 84.07±5.99 and 85.00±4.11, respectively. The last follow-up were 98.34±2.38, 98.67±1.79, 98.86±1.58 and 98.32±2.11, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative JOA score of Grade I-IV were 11.44±1.73, 11.59±1.72, 11.61±1.47 and 11.32±1.80, respectively. The last follow-up were 16.22±1.00, 16.28±1.02, 16.14±1.04 and 16.16±1.07, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CCA of Grade I-IV were 110.19°±8.76°, 112.48°±7.66°, 106.61°±6.54° and 109.05°±7.79°, respectively. The last follow-up were 140.22°±8.04°, 141.86°±7.04°, 142.35°±8.62° and 140.15°±6.49°, respectively, with statistically significant differences from preoperative ( P<0.05). The preoperative CMA of Grade I-IV were 113.48°±9.54°, 116.03°±8.38°, 109.55°±7.13°, and 112.46°±8.33°, respectively. The last follow-up were 144.28°±7.75°, 146.40°±6.98°, 145.81°±8.27° and 143.24°±6.36°, respectively, with statistically significant differences from preoperative ( P<0.05). Solid bony fusion was obtained except for 3 cases, the fusion time was 9.71±2.55 months (range 3-14 months). Altogether 33 complications occurred in all cases (11.1%), including 3 fusion failure, 3 cerebrospinal leak, 3 wound infection, 2 death (1 case caused by cerebrospinal leak), 11 pharyngeal discomfort, 4 postoperative pain surrounding iliac crest, and 8 malunion of iliac crest. Conclusion:Transoral stepped atlantoaxial release theory could provide guidelines for atlantoaxial dislocation treatment, and make the transoral release technique more effective and safer.

Comparison of Jefferson-fracture reduction plate and micro titanium plate in the transoral single-segment fixation of unstable atlas fractures / 中华创伤骨科杂志

Objective:To compare Jefferson-fracture reduction plate (JeRP) and micro titanium plate in the transoral single-segment fixation of unstable atlas fractures.Methods:From January 2008 to December 2020, 45 patients with unstable atlas fracture were treated by single-segment fixation through an oral approach with a JeRP or a micro titanium plate at Department of Orthopedic Surgery, General Hospital of Southern Theatre Command. They were 24 males and 21 females, aged from 15 to 67 years. By the Gehweiler classification, 11 atlas fractures were type Ⅰ and 34 type Ⅲ; by the American Spinal Injury Association (ASIA) classification, the spinal cord injury was grade D in 7 cases and grade E in 38 cases; by the Dickman classification, the atlas transverse ligament injury was type Ⅰ in 4 cases and type Ⅱ in 11 cases. Of the patients, 26 were treated by transoral single-segment fixation with a JeRP and 19 by transoral single-segment fixation with a micro titanium plate. The 2 groups were compared in terms of baseline data, operation time, blood loss, hospital stay, visual analog scale (VAS) for neck pain and atlas lateral mass displacement (LMD) before operation and at the last follow-up, and intraoperative and postoperative complications.Results:The 2 groups were comparable because there was no significant difference between them in the preoperative general data ( P>0.05). All patients were followed up for 12 to 55 months (mean, 21.8 months). Wound dehiscence or infection was observed in none of the patients after operation. About 12 months after operation, all fractures achieved bony union, neck pain basically disappeared, and neck movement had no obvious limitation. The hospital stay was (13.9±2.2) d for the JeRP group and (14.2±2.9) d for the micro titanium plate group, showing no significant difference between the 2 groups ( P>0.05). The operation time was (203.5±173.4) min and the blood loss (167.3±138.6) mL in the JeRP group, significantly more than those in the micro titanium plate group [(121.5±50.5) min and (98.4±57.2) mL] ( P<0.05). In the JeRP group, the preoperative LMD was (6.7±1.7) mm and the preoperative VAS score (6.8±1.0) points, significantly higher than the last follow-up values [(0.7±0.6) mm and (0.7±0.6) points] ( P<0.05). In the micro titanium plate group, the preoperative LMD was (6.6±1.5) mm and the preoperative VAS score (6.7±0.9) points, significantly higher than the last follow-up values [(0.9±0.6) mm and (0.8±0.7) points] ( P<0.05). However, there was no significant difference in the preoperative or the last follow-up comparison between the 2 groups ( P>0.05). Implant loosening was observed in one patient in the JeRP group while foreign body sensation in the throat was reported in one patient after operation in the micro titanium plate group. Conclusions:Both JeRP and micro titanium plate in the transoral single-segment fixation can lead to effective treatment of unstable atlas fractures. Compared with JeRP, the micro titanium plate can effectively shorten operation time and reduce blood loss due to its smaller size and lower incision.

Diagnosis and treatment of posterior atlantoaxial dislocation with odontoid retrolisthesis / 中华创伤骨科杂志

Objective:To report our experience in diagnosis and treatment of posterior atlantoaxial dislocation with odontoid retrolisthesis.Methods:A retrospective study was conducted of the 5 patients who had been treated from July 2012 to August 2018 at Department of Orthopaedics, General Hospital of Southern Theater Command for posterior atlantoaxial dislocation. They were 4 men and one woman, aged from 34 to 67 years (average, 47 years). All of them had a history of trauma. Of them, 4 were complicated with odontoid fracture and one with congenital free os odontoideum. Their posterior atlantoaxial dislocation ranged from 3 to 9 mm (average, 6 mm). By the American Spinal Injury Association (ASIA) grading system, their preoperative spinal injury was rated as grade B in one, as grade C in 3 cases and as grade D in one. All the 5 patients underwent skull traction at 10° flexion. Surgical trans-oralpharyngeal atlantoaxial reduction and internal fixation was performed for the one patient whose reduction had not been achieved by traction while posterior atlantoaxial screw-rod fixation or anterior odontoid screwing was conducted for the 4 patients whose reduction had been achieved by traction. The distance of posterior atlantoaxial dislocation was measured to evaluate their reduction and ASIA grade system was used to assess their spinal function after operation.Results:The postoperative distance of posterior atlantoaxial dislocation was 0 mm, showing a reduction rate of 100%. The 5 patients were followed up for 6 to 36 months (average, 15 months). By the ASIA grade system, the postoperative functional recovery of the spine was grade D in 4 cases and grade C in one. No implant loosening or breakage occurred.Conclusion:As a kind of high-energy hyperextension injury, posterior atlantoaxial dislocation is rare in clinic, but an appropriate treatment can be adopted to deal with its different clinical types to achieve good outcomes.

Biomechanical properties of a novel automatic anti-rotation posterior atlantoaxial internal fixation system: a finite element analysis / 中国组织工程研究

BACKGROUND: Atlantoaxial posterior approach is currently the main surgical treatment for atlantoaxial instability and/or dislocation, but the shape of rod in normal screw-rod device system is cylindrical. To obtain satisfactory reduction of atlantoaxis, the rod will be pre-bent obviously before fixation; however, the cylindrical rod will be rotated when tighten the nuts. Extra devices will be required to adjust and maintain the direction of the rod, thereafter, the surgical field will be blocked by the device, and spinal injury will occur once the devices are not held tightly. While the novel automatic anti-rotation rod has the function of anti-rotation during nut-tightening process, and also holds all the advantages of normal rod. Further research should be performed for the differences in biomechanical characteristics between two methods.OBJECTIVE: To investigate the biomechanical properties of the novel automatic anti-rotation rod for internal fixation system of atlantoaxial posterior approach based on three-dimensional finite-analysis model of upper cervical spine.METHODS: The three-dimensional finite element model of upper cervical spine with internal rod fixation system was developed. The biomechanical characteristics of the internal fixation system were analyzed. RESULTS AND CONCLUSION: The traditional and novel three-dimensional finite element model with realistic and geometric similarity contained 198330 elements, 964747 nodes and 246788 elements, 996069 nodes,correspondingly. There was no obvious stress concentration in both two systems, stress was concentrated mainly in the screw-bone and screw-rod interfaces. The stress values of the novel system were higher than those of the traditional system, but the maximum Von Misses Stress of two systems was lower than the yield (795-827 MPa ) and ultimate (860-896 MPa) strength of titanium alloys. These results show that the design of the novel automatic anti-rotation rod-screw fixation system has matched the biomechanical requirements for new internal fixation instruments, and is one safe, effective and practical device for atlantoaxial posterior procedure showing promising application prospect.

Posterior screw-rod fixation fusion for the treatment of atlantoaxial dislocation due to rheumatoid arthritis / 中华骨科杂志

Objective To investigate the clinical effect of posterior screw-rod fixation fusion for the treatment of atlantoaxial dislocation due to rheumatoid arthritis.Methods From January 2011 to December 2015,15 patients with atlantoaxial dislocation due to rheumatoid arthritis were treated,including 6 males and 9 females,aged 35 to 75 years (mean 55 years).All cases were evaluated about the difficulty of relocation by extension-flexion X-ray and treated with posterior screw-rod reduction,fixation and autogenous bone grafting under general anesthesia.Atlantodental interval (ADI) was measured and collected before and after surgery.Visual Analogue Scale/Score (VAS),American Spinal Cord Injury Association (ASIA) and Japanese Orthopaedic Association (JOA) scores were comprehensively used to evaluate the clinical effect.1 week,3,6,12 months postoperatively and the annual review of the X-ray and CT were checked,in order to evaluate the reduction,internal fixation and bone graft fusion.Results All patients were reducible dislocation and successfully performed the posterior screw-rod fixation fusion surgery.The patients were followed up for 3 to 24 months (average,15 months).Atlantoaxial solid bony fusion was obtained from 3 to 6 months.ADI reduced from preoperative 6.3±1.7 mm to postoperative 2.2±0.8 mm,VAS score reduced from preoperative 5.4±2.7 to postoperative 1.7±1.0,ASIA motor score improved from preoperative 82.3±15.6 to 95.3±4.5 at 6 months after the surgery,JOA score increased from preoperative 13.8±2.9 to 15.5±1.4 at 6 months after the surgery,and the statistical significance was revealed between preoperation and postoperation.Nine cases were in D grade of ASIA,3 cases improved from D to E grade after surgery,2 cases reached E grade in the other 6 cases after 6 months,2 cases recovered to E grade after 12 months and other 2 cases in D grade got uniformity after surgery.Well internal fixation and no redislocation were found on X-ray and CT during follow-up period.Conclusion Atlantoaxial dislocation because of rheumatoid arthritis was numerously reducible genre.Posterior screw-rod fixation and autogenous bone grafting can gain satisfying clinical efficacy.

Effects of Learning Environment on Learning and Memory and Microvessel Density in Hippocampus of Rats after Cerebral Infarction / 中国康复理论与实践

@# Objective To study the effects of learning environment on learning memory and microvessel density in hippocampus of rats after cerebral infarction. Methods 80 Sprague-Dawley rats were coagulated right middle cerebral arteries electrically, and randomly divided into learning envionment (LE) and standard environment (SE) groups. They were tested with Morris Water Maze 7 d and 28 d after operation. The microvessel density in hippocampus was measured with CD34 immunohistochemstry 1, 3, 7, 14 and 28 days after operation. Results The achievement of Morris Water Maze was significantly better in the LE group than in the SE group (P<0.001), while the microvessel density in the hippocampus was more since 7 days after operation (P<0.05). Conclusion The learning environment can promote the angiogenesis and improve the learning and memory function recovery.

Effects of Learning Environment on Learning and Memory and Microvessel Density in Hippocampus of Rats after Cerebral Infarc-tion / 中国康复理论与实践

Objective To study the effects of learning environment on learning memory and microvessel density in hippocampus of rats after cerebral infarction. Methods 80 Sprague-Dawley rats were coagulated right middle cerebral arteries electrically, and randomly divided into learning envionment (LE) and standard environment (SE) groups. They were tested with Morris Water Maze 7 d and 28 d after opera-tion. The microvessel density in hippocampus was measured with CD34 immunohistochemstry 1, 3, 7, 14 and 28 days after operation. Re-sults The achievement of Morris Water Maze was significantly better in the LE group than in the SE group (P<0.001), while the microvessel density in the hippocampus was more since 7 days after operation (P<0.05). Conclusion The learning environment can promote the angio-genesis and improve the learning and memory function recovery.

Application of transoral atlantoaxial reduction plate Ⅲ in treatment of complicated atlantoaxial dislocation / 中华创伤杂志

Objective To evaluate the biomechanical characteristics and the clinical advantage of transoral atlantoaxial reduction plate(TARP)Ⅲ.Methods Design of TARP-Ⅲ was based on TARP-Ⅱ.The screw hole in the axis was moved 1-2 mm upwards and inwards in a plate which turned a vertebral screw into a pedicle screw or an articular process screw.A polyaxial self-lock ring and polyaxial guiding drill were added to the crew hole of the plate.Finally,the withdrawal resist ence force of the three axis screws was tested and TARP-Ⅲ was used in 44 patients with complicated irreducible atlantoaxial dislocation.The axis was fixed with the pedicle screw or the articular process screw.Results The maximum withdrawal resist ence force of the anterior pedicle screw,the articular process screw and the vertebral screw in the axis was(593.1 ± 97.8)N,(469.9 ± 73.3)N and(395.2 ± 75.1)N respectively,with statistical difference between groups among three fixation methods(P ＜ 0.05).All 44 patients were followed up for 5-38 months(average 18 months),which showed complete anatomic reduction in 36 patients and appropriate anatomic reduction in eight,with basic correction of the angles between the brain stem and the spinal cord and sufficient decompression of the spinal cord.The decompression rate of the cervical spinal cord was average 88.2% according to the Yin evaluating method of cervical cord decompression.The improvement rate of spinal cord function was average 76.6% according to Japanese Orthopaedic Association(JOA)score.Conclusion With the design of polyaxial self-lock mechanism,TARP-Ⅲ with the pedicle screw or the articular process screw surpasses TARP-Ⅱ with vertebral screw in aspect of biomechanics.

Anatomic and clinical evaluation of the location relation between C1 pedicle and C_2 lateral mass / 中华骨科杂志

Objective To study the relevant position of atlas pedicle to axis lateral mass, set up a technique of C1 pedicle screw placement with the lateral mass of axis as an anatomic landmark, and evaluate the reliability of the present screw placement technique by clinical practice. Methods 50 paired atlas and axis specimens were used to measure the distance from the sagittal midline to the medial border, the midpoint (the middle point of the mediolateral border) and the lateral border of C1 pedicle and C2 lateral mass. Furthermore, the distance between the medial border of C1 pedicle and that of C2 lateral mass, the distance between the midpoint of C1 pedicle and that of C2 lateral mass and the distance between the lateral border of C1 pedicle and that of C2 lateral were calculated respectively. The technique of C1 pedicle screw fixation was established. Using the present landmark technique, C1 pedicle screws were placed in 6 patients of atlantoaxial instability, including 5 males and 1 female averaged 41 years old, with os odontoideum in 1, odontoid hypoplasia in 3, and old odontoid fractures in 2. Results The medial border, the midpoint and lateral border of C1 pedicle was averaged (1.37?0.51) mm, (1.60?0.61) mm and (2.15?0.60) mm medial to C2 lateral mass, respectively. The entry point of C1 pedicle screw in present technique was defined as the method of making a vertical line through the midpoint of C2 lateral mass, and the entry point was 3 mm under the cross point of the superior rim of C1 posterior arch with the vertical line. 12 C1 pedicle screws were placed exactly in all 6 patients, and no neural or vascular injury was observed. The postoperative radiographs and CT scans verified all of C1 screws with a good position. Conclusion There is a steady anatomic relation between C1 pedicle and C2 lateral mass, the C2 lateral mass could be as a convenient anatomic landmark to determine the location of C1 pedicle and the position of C1 pedicle screw entry point.