Autologous rib grafts for craniocervical junction surgery in children: a clinical application.

OBJECTIVE: Autologous iliac bone is commonly used as a bone graft material to achieve solid fusion in craniocervical junction (CVJ) surgery. However, the developing iliac bone of children is less than ideal as a bone graft material. The matured rib bone of children presents a potential substitute material for iliac bone. The aim of this study was to evaluate the efficacy of autologous rib grafts for craniocervical junction surgery in children. METHODS: The outcomes of 10 children with abnormalities of the craniocervical junction who underwent craniocervical junction surgery between January 2020 and December 2022 were retrospectively reviewed. All patients underwent posterior fusion and internal fixation surgery with autologous rib grafts. Pre- and post-operative images were obtained and clinical follow-ups were conducted to evaluate neurological function, pain level, donor site complications, and bone fusion rates. RESULTS: All surgeries were successful. During the 8- to 24-month follow-up period, all patients achieved satisfactory clinical results. Computed tomography at 3-6 months confirmed successful bone fusion and regeneration of the rib defect in all patients with no neurological or donor site complications. CONCLUSION: Autologous rib bone is a safe and effective material for bone grafting in craniocervical junction fusion surgery for children that can reduce the risks of donor site complications and increase the amount of bone graft, thereby achieving a higher bone fusion rate.

Can a Nomogram Predict Survival After Treatment for an Ankylosing Spondylitis Cervical Fracture in a Patient With Neurologic Impairment? A National, Multicenter Study.

BACKGROUND: Ankylosing spondylitis-related cervical spine fracture with neurologic impairment (ASCF-NI) is a rare but often lethal injury. Factors independently associated with survival after treatment remain poorly defined, and identifying patients who are likely to survive the injury remains challenging. QUESTIONS/PURPOSES: (1) What factors are independently associated with survival after treatment among patients with ASCF-NI? (2) Can a nomogram be developed that is sufficiently simple for clinicians to use that can identify patients who are the most likely to survive after injury? METHODS: This retrospective study was conducted based on a multi-institutional group of patients admitted and treated at one of 29 tertiary hospitals in China between March 1, 2003, and July 31, 2019. A total of 363 patients with a mean age of 53 ± 12 years were eventually included, 343 of whom were male. According to the National Household Registration Management System, 17% (61 of 363) died within 5 years of injury. Patients were treated using nonsurgical treatment or surgery, including procedures using the anterior approach, posterior approach, or combined anterior and posterior approaches. Indications for surgery included three-column injury, unstable fracture displacement, neurologic impairment or continuous progress, and intervertebral disc incarceration. By contrast, patients generally received nonsurgical treatment when they had a relatively stable fracture or medical conditions that did not tolerate surgery. Demographic, clinical, and treatment data were collected. The primary study goal was to identify which factors are independently associated with death within 5 years of injury, and the secondary goal was the development of a clinically applicable nomogram. We developed a multivariable Cox hazards regression model, and independent risk factors were defined by backward stepwise selection with the Akaike information criterion. We used these factors to create a nomogram using a multivariate Cox proportional hazards regression analysis. RESULTS: After controlling for potentially confounding variables, we found the following factors were independently associated with a lower likelihood of survival after injury: lower fracture site, more-severe peri-injury complications, poorer American Spinal Injury Association (ASIA) Impairment Scale, and treatment methods. We found that a C5 to C7 or T1 fracture (ref: C1 to C4 and 5; hazard ratio 1.7 [95% confidence interval 0.9 to 3.5]; p = 0.12), moderate peri-injury complications (ref: absence of or mild complications; HR 6.0 [95% CI 2.3 to 16.0]; p < 0.001), severe peri-injury complications (ref: absence of or mild complications; HR 30.0 [95% CI 11.5 to 78.3]; p < 0.001), ASIA Grade A (ref: ASIA Grade D; HR 2.8 [95% CI 1.1 to 7.0]; p = 0.03), anterior approach (ref: nonsurgical treatment; HR 0.5 [95% CI 0.2 to 1.0]; p = 0.04), posterior approach (ref: nonsurgical treatment; HR 0.4 [95% CI 0.2 to 0.8]; p = 0.006), and combined anterior and posterior approach (ref: nonsurgical treatment; HR 0.4 [95% CI 0.2 to 0.9]; p = 0.02) were associated with survival. Based on these factors, a nomogram was developed to predict the survival of patients with ASCF-NI after treatment. Tests revealed that the developed nomogram had good performance (C statistic of 0.91). CONCLUSION: The nomogram developed in this study will allow us to classify patients with different mortality risk levels into groups. This, coupled with the factors we identified, was independently associated with survival, and can be used to guide more appropriate treatment and care strategies for patients with ASCF-NI. LEVEL OF EVIDENCE: Level III, therapeutic study.

Calcium phosphate cement promotes the stability of osteoporotic lumbar pedicle screw by enhancer-injecters with different number of holes.

BACKGROUNDS: This study aimed to compare whether Calcium phosphate cement (CPC) promotes the stability of osteoporotic lumbar pedicle screw by enhancer-injecters with different number of holes. METHODS: Through a self-designed bone cement injection device, the pedicle screw canal was strengthened with calcium phosphate bone cement, and divided into 4-hole group, 6-hole group, 8-hole group, straight pore group and the control group. The screw was inserted into the mechanical test module, the Maximum insertion torque and Maximum axial pull-out strength were recorded, and the distribution of calcium phosphate bone cement was analyzed by CT and X-ray. The data results were analyzed using SPSS19.0 statistical software package. RESULTS: The distribution of bone cement in different reinforcement groups was different and showed regularity. The bone cement in the 4-hole group was roughly located in the head 1/3 of the screw, the 6-hole group was located in the middle 1/3 of the screw, and the 8-hole group was located in the caudal 1/3 of the screw. Compared with the control group, the maximum axial pull-out force of screws in the lateral hole and full screw tunnel reinforcement group was significantly increased. There was no significant difference between the 4-hole, 6-hole and straight pore groups. There was no difference in the screw-in torque between the reinforcement groups, and they all increased significantly compared with the control group, and the difference was statistically significant. After the screw was pulled out, the interface between the bone cement and the polyurethane material was fractured, and a tight package was formed with the screw. CONCLUSIONS: Enhancer syringes with different hole numbers combined with CPC bone cement injection can significantly increase the maximum screw pull-out force. The 8-hole group has a smaller pull-out force and is relatively prone to leakage of reinforcing material, which lacks safety in use. The local reinforcement of 4-hole and 6-hole sheath can play a similar role to that of total nail tunnel reinforcement.

Treating Pediatric Irreducible Atlantoaxial Rotatory Fixation (IAARF) by Unlocking Facet Joint Through Transoral Approach and Fixing With Slim-TARP Plate (15 Cases Series).

BACKGROUND: Irreducible atlantoaxial rotatory fixation (IAARF) often requires surgical treatment. Transoral unlocking the facet joints is a key measure for the treatment of IAARF. We investigate a novel method for treating pediatric IAARF by unlocking facet joint through transoral appraoch and fixed with slim-tarp plate in same stage with same approach. OBJECTIVE: The objective of this study is to investigate the method and efficacy of a unique transoral approach to unlock facet joints and fixation with slim-shaped transoral anterior reduction plate (slim-TARP) plate in the treatment of IAARF. METHODS: Fifteen patients diagnosed with AARF were transferred to our hospital. After 1 week of bidirectional cervical cranial traction, they were diagnosed with irreducible AARF that, and then underwent transoral release and fixation with slim-TARP plate procedures. Postoperative computed tomography and magnetic resonance were used to evaluate the reduction effect, bone fusion, and fusion time. Japanese orthopaedic association scores were used to compare the recovery of spinal cord function in patients before and after surgery. Complications such as wound infection, neurovascular injury, and loosening of internal fixation were evaluated too. RESULTS: All 15 patients underwent transoral unlocking facet joint and fixation with slim-TARP procedures smoothly. The operation time were 129.2±11.9 minutes, blood loose were 83±23 mL. There were no neurological injury, wound infections, verified or suspected vertebral artery injury, etc. All patients were followed up for a mean of 17.8±6.6 months (range: 12 to 36 mo). Bony fusion was achieved in all patients. Mean fusion time was 3.6±1.2 months (range: 3 to 6 mo). Complete correction of torticollis was achieved in all 15 cases. Preoperative symptoms of neck pain and limitation of neck movement were effectively alleviated at 3 months after surgery. The 3 patients with preoperative neurological deficits had significant relief after surgery, and their latest follow-up results showed that their Japanese orthopaedic association scores increased from 13.0±1.0 to 16.3±0.6. CONCLUSIONS: Transoral release and fixation with slim-TARP plate by transoral approach is a feasible and safe method for treating pediatric irreducible atlantoaxial rotatory fixation.

Treatment of irreducible atlantoaxial dislocation by bony deformity osteotomy, remodeling, releasing, and plate fixating through transoral approach.

OBJECTIVE: Investigate a novel method for treating irreducible atlantoaxial dislocation (IAAD) or with basilar invagination (BI) by bony deformity osteotomy, remodeling, releasing, and plate fixating through transoral approach. METHOD: From March 2015 to December 2019, 213 consecutive patients diagnosed as IAAD/BI were treated with transoral bony deformity remodeling and releasing combined with plate fixation. The main clinical symptoms include neck pain, headache, numbness of the limbs, weakness, unstable walking, inflexible hand-held objects, and sphincter dysfunction. The bony factors that impact reduction were divided into as follows: type A1 (sloping of upper facet joint in C2), type A2 (osteophyte in lateral mass joints between C1 and C2), type A3 (ball-and-socket deformity of lateral mass joint), type A4 (vertical interlocking between lateral mass joints of C1-C2), type A5 (regional bone fusion in lateral mass joints), type B1 (bony factor hindering reduction between the atlas-dens gap), type B2 (uncinate odontoid deformity), and type B3 (hypertrophic odontoid deformity). All of them were treated with bony deformity osteotomy, remodeling, and releasing techs. RESULT: The operation time was 144 [Formula: see text] 25 min with blood loss of 102 [Formula: see text] 35 ml. The average pre-operative ADI improved from 7.5 [Formula: see text] 3.2 mm pre-surgery to 2.5 [Formula: see text] 1.5 mm post-surgery (p < 0.05). The average VDI improved from 12.3 [Formula: see text] 4.8 mm pre-surgery to 3.3 [Formula: see text] 2.1 mm post-surgery (p < 0.05). The average pre-operative CMA improved from 115 [Formula: see text] 25° pre-surgery to 158 [Formula: see text] 21° post-surgery (p < 0.05); the pre-operative CAA changed from 101 [Formula: see text] 28° pre-surgery to 141 [Formula: see text] 10° post-surgery. After the operation, the clinic symptoms improved, and the JOA score improved from 9.3 [Formula: see text] 2.8 pre-operatively to 13.8 [Formula: see text] 2.5 in the sixth months of follow-up. CONCLUSION: In addition to soft tissue factors, bony obstruction was another important factor impeding atlantoaxial reduction. Transoral bony deformity osteotomy, remodeling, releasing combined with plate fixating was effective in treating IAAD/BI with bony obstruction factors.

Research on pharyngeal bacterial flora in transoral atlantoaxial operation and the postoperative follow-up study.

OBJECTIVES: To study the changes of bacterial flora after a series of preoperative oral disinfection and the postoperative recovery of nerve function of patients with craniovertebral junction disorders who were treated with transoral approach operations. METHODS: This research analyzed 20 cases collected from October 2009 to May 2010. All these patients were with CVJ disorders, including 8 males and 12 females, aged 2 to 66 (38.1 on average), and they were all treated with transoral approach operations. The mucosa samples of the posterior pharyngeal wall were sent for bacteria culture. These samples were collected by sterile cotton swabs at four crucial points, including 3 days before operation/before gargling, 3 days after continuous gargling/after anesthesia intubation on the day of operation, after intraoperative cleaning and washing of the mouth, and after intraoperative iodophor immersion. The microflora was stained by means of smear and further counted after an investigation by microscope. The neural function of patients was evaluated by the ASIA classification and the JOA scores. All patients but two with posterior stabilization performed respectively underwent transoral atlantoaxial reduction plate (TARP) fixation consecutively in the same sitting. A regular reexamination of cervical vertebra with lateral and open mouth X-ray, CT and MRI was conducted after operation to evaluate the reduction of atlantoaxial dislocation, internal fixation position, bone graft fusion, inflammatory lesions and tumor recurrence. RESULTS: This bacteriological research showed that the mucosa of the posterior pharyngeal wall of all the patients was in a sterile state after a series of oral preoperative preparations and intraoperative iodophor disinfection, which was considered as type I incision. The bacterial culture results of the mucosa samples of the posterior pharyngeal wall collected at different time points showed significant differences (χ2 = 42.762, P = 0.000). All the patients had improvement in ASIA, and their neural functions were improved to different levels after operation. There was a significant difference in JOA scores before and after operation (t = 8.677, P = 0.000). Postoperative imaging examination showed that the atlantoaxial screw position was good and firm, and the CVJ disorders were treated appropriately. CONCLUSION: It is safe and effective to cut the posterior pharyngeal muscle layer and implant internal fixation by means of transoral approach.

A novel bone cement injector augments Chinese osteoporotic lumbar pedicle screw channel: a biomechanical investigation.

BACKGROUND: The study aimed to (1) create a series of pedicle injectors with different number of holes on the sheath especially for the Chinese elderly patients and (2) further investigate the effects of the injectors on the augmentation of pedicle screw among osteoporotic lumbar pedicle channel. METHODS: This study used the biomechanical test module of polyurethane (Pacific Research Laboratory Corp, USA) to simulate the mechanical properties of human osteoporotic cancellous bone. The bone cement injectors were invented based on anatomical parameters of lumbar pedicle in Chinese elderly patients. Mechanical test experiments were performed on the bone cement injectors according to the three groups, namely, a local augmentation group, a full-length augmentation group, and a control group. The local augmentation group included three subgroups including 4-hole group, 6-hole group, and 8-hole group. All holes were laterally placed. The full-length augmentation group was a straight-hole injector. The control group was defined that pedicle screws were inserted without any cement augmentation. Six screws were inserted in each group and the maximum insertion torque was recorded. After 24 h of injecting acrylic bone cement, routine X-ray and CT examinations were performed to evaluate the distribution of bone cement. The axial pull-out force of screws was tested with the help of the material testing system 858 (MTS-858) mechanical tester. RESULTS: The bone cement injectors were consisted of the sheaths and the steel rods and the sheaths had different number of lateral holes. The control group had the lowest maximum insertion torque as compared with the 4-hole, 6-hole, 8-hole, and straight pore groups (P < 0.01), but the differences between the 4-hole, 6-hole, 8-hole, and straight pore groups were no statistical significance. The control group had the lowest maximum axial pull-out force as compared with the other four groups (P < 0.01). Subgroup analysis showed the 8-hole group (161.35 ± 27.17 N) had the lower maximum axial pull-out force as compared with the 4-hole group (217.29 ± 49.68 N), 6-hole group (228.39 ± 57.83 N), and straight pore group (237.55 ± 35.96 N) (P < 0.01). Bone cement was mainly distributed in 1/3 of the distal end of the screw among the 4-hole group, in the middle 1/3 and distal end of the screw among the 6-hole group, in the proximal 1/3 of the screw among the 8-hole group, and along the long axis of the whole screw body in the straight pore group. It might indicate that the 8-hole and straight-hole groups were more vulnerable to spinal canal cement leakage. After pullout, bone cement was also closely connected with the screw without any looseness or fragmentation. CONCLUSIONS: The bone cement injectors with different number of holes can be used to augment the pedicle screw channel. The pedicle screw augmented by the 4-hole or 6-hole sheath may have similar effects to the straight pore injector. However, the 8-hole injector may result in relatively lower pull-out strength and the straight pore injector has the risks of cement leakage as well as cement solidarization near the screw head.

The associations of CYP19A1 rs700518 polymorphism with bone mineral density and risk of osteoporosis: a meta-analysis.

Osteoporosis is now a worldwide public health problem that seriously endangers human health, but its causes have not yet been fully clarified. Recently, increasing evidence suggested that polymorphisms in CYP19A1 gene were associated with osteoporosis risk and bone mineral density (BMD), but results remained conflicting. We herein performed a meta-analysis based on evidence currently available from the literature to make a more precise estimation of these relationships. The PubMed, Embase, Cochrane library, CNKI (China National Knowledge Infrastructure), and Wan Fang databases were searched for eligible studies. Odds ratio (OR), mean difference (MD), and 95% confidence interval (CI) were applied to assess the strength of these relationships. A total of 8 studies involving 2632 subjects were included in our meta-analysis. We observed that the AG genotype of CYP19A1 rs700518 was significantly associated with lower BMD values of lumbar spine and femoral neck (AG vs. GG: p = .001 and.01, respectively). However, this polymorphism had no obvious impacts on osteoporosis risk according to current available data. In conclusion, the present meta-analysis showed that CYP19A1 rs700518 polymorphism may be a potential candidate biomarker for osteoporosis screening, early diagnosis, and treatment, which will help improve individualized therapy of osteoporosis patients in clinics.

Surgical Failure and Revision Strategy for Atlantoaxial Dislocation: A retrospective study of 109 Cases.

STUDY DESIGN: Retrospective study. OBJECTIVE: To classify surgical failures following atlantoaxial dislocation, present strategies for revisions and evaluate the clinical results of revision surgery. SUMMARY OF BACKGROUND DATA: With the increase in atlantoaxial dislocation surgery, the number of surgical failures has gradually risen. However, current reports on atlantoaxial surgical revision are limited in scope. There remains a lack of summary regarding the causes of surgical failure, a detailed classification system, and no proposed strategy for revision surgery. METHODS: 109 cases of failed surgery following atlantoaxial dislocation were classified according to the reduction immediately after surgery and the fusion status before revision. The reduction, decompression, fusion status and outcomes following revision surgery were evaluated by X-ray, CT, MRI and JOA score. The data were analyzed statistically with a paired-samples t test and multivaraible logistic regression analysis. RESULTS: The 109 patients were classified into three categories of failure: non-reduction with non-fusion (NR-NF, 73 cases), non-reduction with fusion (NR-F, 19 cases), and reduction with non-fusion (R-NF, 17 cases). Sixty-four patients underwent anterior revision, 21 posterior revision, and 24 anteroposterior revision. Postoperative complications were the primary cause of early revisions. After revision, complete decompression was achieved in all cases, anatomical reduction in 89 cases, significant improvement of JOA score in 77 cases, and fusion achieved in 86 cases. Twelve cases experienced surgical complications and 3 underwent a second revision. CONCLUSIONS: We found that NR-NF was the most common type of failure following surgery for atlantoaxial dislocation. Revision strategies can be guided according to our descriptive classification of failure, and revision surgery should focus on achieving adequate reduction, appropriate fixation and reliable fusion to optimize post-surgical outcomes.

The use of a novel reduction plate in transoral anterior C1-ring osteosynthesis for unstable atlas fractures.

Background: Transoral anterior C1-ring osteosynthesis has been reported as an effective treatment for unstable atlas fracture, which aims to preserve important C1-C2 motion. However, previous studies have shown that the anterior fixation plates used in this technique were not suitable for the anterior anatomy of the atlas and lacked an intraoperative reduction mechanism. Objective: This study aims to evaluate the clinical effects of a novel reduction plate used in transoral anterior C1-ring osteosynthesis for unstable atlas fractures. Methods: 30 patients with unstable atlas fractures treated by this technique from June 2011 to June 2016 were included in this study. The patients' clinical data and radiographs were reviewed, and the reduction of the fracture, internal fixation placement, and bone fusion were assessed using pre- and postoperative images. The patients' neurological function, rotatory range of motion, and pain levels were evaluated clinically during follow-up. Results: All 30 surgeries were successfully performed, and the average follow-up duration was 23.5 ± 9.5 months (range 9-48 months). One patient suffered atlantoaxial instability during the follow-up and was treated with posterior atlantoaxial fusion. The remaining 29 patients had satisfactory clinical outcomes, with ideal fracture reduction, good screw and plate placement, well-preserved range of motion, neck pain alleviation and solid bone fusion. There were no vascular or neurological complications during the operation or follow-up. Conclusions: The use of this novel reduction plate in transoral anterior C1-ring osteosynthesis is a safe and effective surgical option in the treatment of unstable atlas fractures. This technique offers an immediate intraoperative reduction mechanism, which provides satisfactory fracture reduction, bone fusion, and preservation of C1-C2 motion.

A study of low elastic modulus expandable pedicle screws in osteoporotic sheep.

STUDY DESIGN: Low elastic modulus expandable pedicle screw (L-EPS) was inserted into osteoporotic sheep. Biomechanical tests, micro-CT analysis and histologic observation were performed. OBJECTIVE: To find out whether the L-EPS can further improve fixation strength compared to the expandable pedicle screws (EPS) in osteoporotic sheep spine. The screw-bone interface is also detected by micro-computed tomography (CT) and histologic techniques. SUMMARY OF BACKGROUND DATA: There are some studies on EPS in vivo; however, no earlier study has focused on the elastic modulus of EPS, especially in osteoporosis. METHODS: Twelve months after ovariectomy, bilateral pedicles of lumbar vertebrae (L1 to L5) of 4 female sheep were fixed with EPSs. The L-EPS and EPS were randomly placed into each pedicle and then were expanded. Six months later, the sheep were sacrificed and biomechanical tests, micro-CT analysis, and histologic observation were conducted on the isolated specimen vertebrae. RESULTS: Twelve months after ovariectomy, animal model of osteoporosis was established successfully. The axial pull-out strength in L-EPS group was significantly enhanced compared with that in the EPS group (P < 0.05). Micro-CT reconstruction and analysis showed that there was more bone around the L-EPS group compared with those in EPS group (P < 0.05), meanwhile the more homogeneous bone formation distribution around the screws was found in the L-EPS group. Histologic observation showed that newly formed bone extended along the expandable fissures and grew into the center of EPS; meanwhile, the more direct contact and the less fibrous tissue on the screw-bone interface were observed in the L-EPS group. CONCLUSIONS: The L-EPS can further improve the biomechanical fixation strength of EPS in the osteoporotic sheep. The screw elastic matching with surrounding bone is helpful to distribute stress uniformly, relieve the stress shielding effect, and strengthen the screw-bone interface. Although the experience with the L-EPS is very limited and preliminary, results to date indicate that it is of value in treating patients with osteoporosis and warrants further study.

A novel surgical management for pediatric patients with irreducible atlantoaxial dislocation: Transoral intraarticular cage distraction and fusion with C-JAWS staple fixation.

Background: Currently, irreducible atlantoaxial dislocation (IAAD) can be treated by a single transoral approach in one stage to reduce surgical injuries to patients. However, the widely used fixation devices are not suitable for pediatric patients because of larger profile of devices. Objective: The purpose of this study is to report the preliminary clinical outcomes of a novel surgical technique by transoral intraarticular cage distraction and fusion with C-JAWS staple fixation for pediatric patients with IAAD. Methods: From June 2011 to June 2014, eight pediatric patients with IAAD were enrolled and treated by this technique in our department. Patients' clinical data were retrospectively analyzed, including neurological status, clinical symptoms, reduction, bone fusion, and complications. Results: The surgeries were successfully performed in all patients without injuries to spinal cord, nerve and blood vessel. Clinical symptomatic relief was presented on all 8 patients (100%). Satisfactory reduction was indicated by significant decrease of atlanto-dental interval postoperatively (P < 0.05). The remarkable improvement of postoperative neurological function has been proved by significant increase of Japanese Orthopaedic Association score (P < 0.05). The average follow-up duration was 19.4 ± 5.8 months (range 12-30 months). Bone fusion was achieved in all 8 cases. No complications were documented after operation and during follow-up. Conclusions: Transoral intraarticular cage distraction and fusion with C-JAWS staple fixation is an effective treatment for pediatric patients with IAAD, which can achieve satisfactory reduction, fixation and bone fusion.

Instantaneous death risk, conditional survival and optimal surgery timing in cervical fracture patients with ankylosing spondylitis: A national multicentre retrospective study.

Background: The mortality rate in patients with ankylosing spondylitis (AS) and cervical fracture is relatively high. Objectives: This study aimed to investigate the instantaneous death risk and conditional survival (CS) in patients with AS and cervical fracture. We also studied the relationship between surgical timing and the incidence of complications. Methods: This national multicentre retrospective study included 459 patients with AS and cervical fractures between 2003 and 2019. The hazard function was used to determine the risk of instantaneous death. The five-year CS was calculated to show the dynamic changes in prognosis. Results: The instantaneous death risk was relatively high in the first 6 months and gradually decreased over time in patients with AS and cervical fracture. For patients who did not undergo surgery, the instantaneous risk of death was relatively high in the first 15 months and gradually decreased over time. For patients with American Spinal Injury Association impairment scale (ASIA) A and B, the 5-year CS was 55.3% at baseline, and improved steadily to 88.4% at 2 years. Odds ratios (ORs) for pneumonia, electrolyte disturbance, respiratory insufficiency, and phlebothrombosis decreased as the surgery timing increased. Conclusion: Deaths occurred mainly in the first 6 months after injury and gradually decreased over time. Our study highlights the need for continued surveillance and care in patients with AS with cervical fractures and provides useful survival estimates for both surgeons and patients. We also observed that early surgery can significantly increase functional recovery, and decrease the incidence of complications and rehospitalisation.

Augmentation of pedicle screw stability with calcium sulfate cement in osteoporotic sheep: biomechanical and screw-bone interfacial evaluation.

STUDY DESIGN: Augmentation of pedicle screws with calcium sulfate cement (CSC) was performed in osteoporotic sheep. Biomechanical tests, micro-computed tomography (CT) analysis, and histological observation were performed. OBJECTIVE: To investigate the long-term biomechanical performance of pedicle screws augmented with CSC in vivo and evaluated the screw-bone interfacial bonding with micro-CT and histological techniques. SUMMARY OF BACKGROUND DATA: There is little information on the long-term biomechanical performance and screw-bone interfacial bonding of pedicle screws augmented with CSC in osteoporosis in vivo. METHODS: Twelve months after ovariectomy, bilateral pedicles of lumbar vertebrae (L1 to L5) of 6 female sheep were fixed with pedicle screws. One pedicle of each vertebral body was treated with a screw augmented with CSC (CSC group) and the contralateral pedicle was treated with a screw without any augmentation (control group). Three months later, the sheep were killed and biomechanical tests, micro-CT analysis, and histological observation were conducted on the isolated specimen vertebrae. RESULTS: Twelve months after ovariectomy, animal model of osteoporosis was established successfully. Both the axial and vertical stabilities of the pedicle screws in CSC group were significantly enhanced compared with those in the control group (P<0.05). Micro-CT reconstruction and analysis showed that there were more bone trabeculae around the screws in CSC group compared with those in control group (P<0.05), and the bone trabeculae were significantly denser than those in control group (P<0.05). Histological observation showed that CSC was completely degradated and bone trabeculae around the screws in CSC group were more and denser than that in the control group. Bone trabeculae held the screws tightly without any interspaces between screw and bone, which formed strong bonding between bone and screw. CONCLUSIONS: CSC can significantly improve screw-bone interfacial bonding and strengthen the long-term stability of pedicle screws in osteoporotic sheep. Augmentation with CSC may be a potentially useful method to increase the stability of pedicle screws in patients with osteoporosis.

Expandable pedicle screw trajectory in cadaveric lumbar vertebra: an evaluation using microcomputed tomography.

STUDY DESIGN: An in-vitro cadaver-based measurement using microcomputed tomography. OBJECTIVES: To evaluate the safety of removal of expandable pedicle screws (EPSs) in human vertebral bodies after a long (6 mo) insertion time. SUMMARY OF BACKGROUND DATA: Transpedicular fixation is commonly used for posterior fixation of the spine. Osteoporotic patients are in high risk of internal fixation failure. EPS is an available device for increasing transpedical fixation in the osteoporotic spine. However, it is unclear that how much the diameter of the expanding screw tip increases in the human vertebral body, and no reports have assessed the potential for fracture of the pedicle when the EPS is removed. Therefore, the safety of removal of EPS needs to be evaluated. METHODS: In this study, 6.50 mm EPSs were inserted into cadaveric lumbar vertebrae. The maximum diameters of expansion, the maximum diameters of the EPS trajectories, and the diameters of the EPS trajectories in the pedicles were measured using microcomputed tomography imaging and 3-dimensional reconstruction. Regions of interest of the same size adjacent to the EPS in the pedicle and in the vertebral body were reconstructed and analyzed using the same thresholds (1000). Bone volume divided by total volume (BV/TV) in these regions of interest was determined. RESULTS: The maximum diameter of expansion of the EPSs in the vertebral body was 7.63 mm, a 17.38% increase from the original diameter. The maximum diameter of the EPS trajectory and the diameter of the EPS trajectory in the pedicle were 7.56 mm and 7.09 mm, respectively, increases of 16.31% and 9.08%. The differences were statistically significant (P < 0.05). In the pedicle, there was a negative correlation between the diameter of the EPS trajectory and the BV/TV along the EPS trajectory (r = -0.88; P = 0.002). In the vertebral body, a negative correlation occurred between the maximum expansion diameter of the EPS and vertebral BV/TV (r = -0.85; P = 0.004). CONCLUSIONS: The EPS could be reliably removed after expansion without fracturing the pedicle. Furthermore, the BV/TV had an important influence on the degree of expansion of EPS and whether or not pedicle fracture occurs.

A new method of partial screw augmentation in sheep vertebrae in vitro: biomechanical and interfacial evaluation.

STUDY DESIGN: Partial screw augmentation was carried out by the injection of polymethylmethacrylate (PMMA) through the novel tap into the bone tissue in sheep vertebrae in vitro. Biomechanical tests and microcomputerized tomography analysis were done. OBJECTIVE: To evaluate the stability of the screw and the interface between the bone and the screw in partial screw augmentation. SUMMARY OF BACKGROUND DATA: Augmentation of the pedicle screw with PMMA improves screw stability significantly. However, it results in the full envelopment of the screw by PMMA and the formation of a full "screw-PMMA-bone" interface, which may increase the difficulties in screw removal. Therefore, it is urgent to develop a novel method to augment screw fixation, which avoids full wrapping of PMMA around the screw and facilitates screw removal. We designed a novel tap with an inner hollow and the multiple lateral apertures. METHODS: A total of 78 fresh adult sheep lumbar vertebrae were randomly divided into 3 groups. No screw augmentation was performed in the control group. The pilot hole was filled with PMMA in the full screw augmentation group, whereas PMMA was injected through the tap into the bone tissue in the partial screw augmentation group. Pedicle screws were ultimately inserted into all the holes. Axial pullout tests, cyclic bending tests, and microcomputerized tomography analysis were carried out 24 hours after screw fixation. RESULTS: Both partial screw augmentation and full screw augmentation caused significant increase in pedicle screw stability compared with the control group in both the axial pullout tests and the cyclic bending resistance tests. Partial screw augmentation resulted in the formation of a partial "screw-bone" interface and a partial screw-PMMA-bone interface, which seems like 3 anchors or roots extending and fixing in the bone tissue in a cross section of the interface. It was obviously different from the complete screw-PMMA-bone interface with a complete PMMA mantle around the screw in the full screw augmentation group. CONCLUSIONS: Our proof-of-concept study showed that partial screw augmentation could enhance pedicle screw fixation strength, avoided the full surrounding of the PMMA around the screw, and generated a partial screw-PMMA-bone and a partial screw-bone interface. Partial screw augmentation may be a potential method to augment pedicle screw stability.

Biomechanical comparison of different techniques in primary spinal surgery in osteoporotic cadaveric lumbar vertebrae: expansive pedicle screw versus polymethylmethacrylate-augmented pedicle screw.

INTRODUCTION: Transpedicular fixation can be challenging in the osteoporotic spine. Expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw (PMMA-PS) were both used to increase screw stability. However, there are a little or no biomechanical comparisons of EPS and PMMA-PS, especially in primary spinal surgery in osteoporotic vertebrae. The purpose of this study was to compare the stability of EPS and PMMA-PS in primary spinal surgery. MATERIALS AND METHODS: Fifteen osteoporotic vertebrae were randomly divided into three groups. The conventional pedicle screw (CPS) was inserted in CPS group, the pilot hole was filled with PMMA followed by CPS insertion in PMMA-PS group, and EPS was inserted in EPS group. Twenty-four hours later, X-ray and CT examination and biomechanical tests were performed to all vertebrae. RESULTS: In PMMA-PS group, PMMA existed in bone tissue around the CPS in both vertebral body and pedicle of vertebral arch, and PMMA surrounding the screw formed a spindle-shaped structure in vertebral body. In EPS group, anterior part of EPS presented an obvious expansion in vertebral body and formed a clawlike structure. Screw stabilities in PMMA-PS and EPS groups were significantly enhanced compared with those in CPS group (P < 0.05). However, there was no significant difference between PMMA-PS and EPS groups (P > 0.05). CONCLUSION: Expansive pedicle screw can markedly enhance screw stability with a similar effect to the traditional method of screw augmentation with PMMA in primary surgery in osteoporotic vertebrae. In addition, EPS can overcome pedicle fracture, leakage and compression caused by lager screw and augmentation with PMMA. We propose that EPS is an effective, safe and easy method and has a great application potential in augmentation of screw stability in osteoporosis in clinic.

Biomechanical and histological evaluation of an expandable pedicle screw in osteoporotic spine in sheep.

Transpedicular fixation can be challenging in the osteoporotic spine as reduced bone mineral density compromises the mechanical stability of the pedicle screw. Here, we sought to investigate the biomechanical and histological properties of stabilization of expandable pedicle screw (EPS) in the osteoporotic spine in sheep. EPSs and standard pedicle screws, SINO screws, were inserted on the vertebral bodies in four female ovariectomized sheep. Pull-out and cyclic bending resistance test were performed to compare the holding strength of these pedicle screws. High-resolution micro-computed tomography (CT) was performed for three-dimensional image reconstruction. We found that the EPSs provided a 59.6% increase in the pull-out strength over the SINO screws. Moreover, the EPSs withstood a greater number of cycles or load with less displacement before loosening. Micro-CT image reconstruction showed that the tissue mineral density, bone volume fraction, bone surface/bone volume ratio, trabecular thickness, and trabecular separation were significantly better in the expandable portion of the EPSs than those in the anterior portion of the SINO screws (P < 0.05). Furthermore, the trabecular architecture in the screw-bone interface was denser in the expandable portion of the EPS than that in the anterior portion of the SINO screw. Histologically, newly formed bone tissues grew into the center of EPS and were in close contact with the EPS. Our results show that the EPS demonstrates improved biomechanical and histological properties over the standard screw in the osteoporotic spine. The EPS may be of value in treating patients with osteoporosis and warrants further clinical studies.

[Treatment of tuberculosis in craniovertebral junction].

OBJECTIVE: To investigate the method of treating tuberculosis in the craniovertebral junction and its effectiveness. METHODS: The clinical data of 18 patients with tuberculosis in the craniovertebral junction between July 2010 and January 2019 was analyzed retrospectively. There were 14 males and 4 females, aged 21 months to 75 years (median, 35 years). The disease duration ranged from 2 weeks to 60 months (median, 4 months), and the affected segment was C 0-C 3. Preoperative visual analogue scale (VAS) score was 6.7±1.5 and the Japanese Orthopaedic Association (JOA) score was 16.1±1.8. The American Spinal Cord Injury Association (ASIA) grading system was applied to classify their neurological functions, according to which there were 6 cases of grade D and 12 cases of grade E. Among 18 patients, 4 patients underwent conservative treatment, 1 patient removed tuberculosis via transoral approach, 1 patient removed tuberculosis via posterior cervical approach, and 12 patients removed tuberculosis via transoral approach immediately after posterior cervical (atlantoaxial or occipitalcervical) fusion and internal fixation. The VAS score, ASIA grading, and JOA score were applied to evaluate effectiveness. X-ray film, CT, and MRI were taken after treatment to evaluate the tubercular recurrence, cervical stability, and bone healing. RESULTS: All the patients were followed up 3 to 42 months (median, 12 months). At 3 months after treatment, the VAS score was 1.7±1.0, showing significant difference when compared with preoperative score ( t=15.000, P=0.000); and the JOA score was 16.7±1.0, showing no significant difference when compared with preoperative score ( t=1.317, P=0.205). According to ASIA grading, 6 patients with grade D before treatment had upgraded to grade E after treatment, while the remaining patients with grade E had no change in grading. The imaging examinations showed the good stability of the cervical spine. All patients had complete tuberculosis resection and no recurrence, and the patients who underwent internal fixation via posterior cervical approach achieved atlantoaxial or occipitalcervical bone fusion. CONCLUSION: On the premise of regular chemotherapy, if there is no huge abscess causing dysphagia or dyspnea, atlantoaxial instability, and neurological symptoms, patients can undergo conservative treatment. If not, however, the transoral approach can be used to completely remove the tuberculosis lesion in the craniovertebral junction. One-stage debridement via transoral approach combined with posterior cervical fusion and internal fixation can achieve satisfactory effectiveness.

[An application of posterior cervical and transoral approaches to treating primary malignant osseous tumors in craniovertebral junction].

OBJECTIVE: To investigate the surgical method for primary malignant osseous tumors in the craniovertebral junction (CVJ) and its effectiveness. METHODS: The clinical data of 7 patients with primary malignant osseous spinal tumors in CVJ, which collected between September 2010 and April 2019, were retrospectively analyzed. There were 5 males and 2 females, aged 23 to 75 years (median, 56 years). All patients were diagnosed as chordoma in 4 cases, plasmacytoma in 2 cases, and fibrosarcoma in 1 case. The disease duration ranged from 0.7 to 36.0 months, with an average of 12.2 months. Lesion location: 1 case of C 0, 1, 3 cases of C 2, 1 case of C 1, 2, 1 case of C 2, 3, and 1 case of C 0-2. Preoperative visual analogue scale (VAS) score was 6.7±2.1, the Japanese Orthopaedic Association (JOA) score was 15.6±2.4. According to American Society of Spinal Cord Injury (ASIA) grading system, there was 1 case of grade C, 1 case of grade D, and 5 cases of grade E. According to Enneking stage of spinal malignant tumor, there was 1 case of stage ⅠB, 2 cases of stage ⅡB, and 4 cases of stage Ⅲ. According to Weinstein-Boriani-Biagini (WBB) stage, there was 1 case of 5-8/A-D, 1 case of 4-9/A-D, 1 case of 6-7/B-D, 1 case of 6-7/A-D, 2 cases of 1-12/A-D, and 1 case of 3-10/A-D. All these patients were treated with tumor extended resection, bone graft fusion, and internal fixation via posterior cervical approach, as well as tumor (stage Ⅰ or stage Ⅱ) boundary resection via transoral or submandibular approach. Meanwhile, anterior reconstructive fusion was procedured with bone grafting Cage needed to place the internal fixation. RESULTS: The operation time was 307-695 minutes (mean, 489.57 minutes), and the intraoperative blood loss was 400-2 000 mL (mean, 1 107.14 mL). There was no intraoperative injury in vertebral artery and spinal cord or any related postoperative complications, including incision infection, intracranial infection, and pulmonary infection. All the patients were followed up 3-57 months (mean, 21 months). Postoperative X-ray film and CT showed that the internal fixation screw was firm and in a satisfactory position, and the bone graft was fused at 3-6 months after operation. Symptoms such as neck pain, limb numbness, and fatigue relieved to different degrees after operation. At 3 months after operation, the VAS score improved to 1.7±0.8 ( t=7.638, P=0.000); while the JOA score improved to 16.1±1.5, but no significant difference was found when compared with preoperative score ( t=1.549, P=0.172). According to ASIA grading system, 1 patient with grade C had upgraded to grade D after operation, while the remaining patients had no change. There were 4 cases of recurrence after operation, in which those patients were with high malignancy of tumors before the first surgery. Their tumors also affected a wide range of slope or surrounding soft tissues and could not be completely removed. Among the 4 cases, 1 patient underwent transoral tumor removal operation again, while the other 3 cases gave up further treatment. There was no recurrence among the remaining 3 cases. CONCLUSION: Primary malignant osseous tumors in the CVJ can be completely exercised via means of trabsoral or submandibular approach. Meanwhile the anterior reconstruction can be achieved by placing special Cage specimen. These two methods together with postoperative adjuvant treatments such as radiotherapy and chemotherapy can improve the survival time of patients and reduce tumor recurrence.