Atlantoaxial intra-articular cage fusion by posterior intermuscular approach for treating reducible atlantoaxial dislocation: a technique note with case series.

PURPOSE: To evaluate the clinical feasibility of atlantoaxial intra-articular cage (AIC) fusion via intermuscular approach for treating reducible atlantoaxial dislocation (AAD). METHODS: An analysis was conducted on the data of 10 patients who underwent C1-C2 segmental fixation and AIC fusion for AAD by unilateral intermuscular approach and contralateral open approach. Outcome assessments included Japanese Orthopaedic Association score (JOA) and Visual Analog Scale Score for Neck Pain (VASSNP). The duration of surgical exposure, screw insertion and cage insertion, and postoperative drainage volume were also compared between two approaches. Bone fusion was evaluated through computed tomography (CT) reconstruction. Postoperative paravertebral tissue edema was evaluated by paravertebral tissue cross-sectional area (CSA) and signal intensity on T2 weighted sequence of magnetic resonance imaging (MRI) at 3 days postoperatively. RESULTS: The intermuscular approach exhibited a longer exposure time but lower drainage postoperatively compared to the open approach (P < 0.05). After operation, JOA scores significant improved (P < 0.05), while VASSNP scores significantly decreased (P < 0.05). There was no significant difference in preoperative CSA between two approaches (P > 0.05). However, compared to the open approach, the intermuscular approach exhibited less CSA (P < 0.05) and lower T2 signal intensity on MRI postoperatively, indicating less invasive to the paravertebral tissues. CONCLUSIONS: AIC fusion by intermuscular approach is an effective and safe technique in the treatment of reducible AAD. Intermuscular approach could reduce the postoperative drainage volume and the extent of paravertebral tissue edema compared to open approach.

The Impact of Cervical Degeneration and Sagittal Balance on Retro-Odontoid Soft-Tissue Thickness.

OBJECTIVE: To investigate whether retro-odontoid soft-tissue thickness (ROSTT) is associated with cervical degeneration, cervical spine mobility, and sagittal balance of cervical spine. METHODS: The data of 151 patients who presented at our hospital with cervical spondylosis were reviewed. The ROSTT was measured using T1-weighted sagittal cervical magnetic resonance imaging findings. The assessment of the degree of cervical intervertebral disc degeneration (IVDD) was conducted using sagittal T2-weighted imaging. The T1 slope (T1S), C0-C2 angle, C1-C2 angle, C2-C7 angle, C1-C7 sagittal vertical axis and C2-C7 sagittal vertical axis were measured. The range of motion was assessed by measuring the flexion-extension radiographs. According to the ROSTT, those measuring less than 3 mm were classified as normal group and those measuring larger than 3 mm were classified as thickened group. RESULTS: The thickened group had larger cervical IVDD grade, age, C2-C7 angle, and T1S compared to the normal group (all P < 0.05). Additionally, the C0-C2 angle was significantly smaller in the thickened group than in the normal group (P < 0.05). ROSTT showed a negative correlation with C0-C2 angle (r = -0.181, P < 0.05), but positive correlations with both C2-C7 angle (r = 0.255, P < 0.05) and T1S (r = 0.240, P < 0.05). Furthermore, ROSTT was positively correlated with age (r = 0277, P < 0.05) and cervical IVDD grade (Spearman, r = 0.299, P < 0.05). CONCLUSIONS: Cervical sagittal balance and cervical degeneration have a significant impact on ROSTT. Patients with a higher T1S and severe cervical degeneration are more likely to result in greater ROSTT.

C1 Transposterior Arch Lateral Mass Screws Combined With C2 Pedicle Screw and Rod Fixation for Pediatric Atlantoaxial Subluxation: A Minimal 10-Year Follow-up Outcome Analysis.

BACKGROUND AND OBJECTIVES: Although the short-term outcomes of the 1-step reduction and fixation technique using C1 transposterior arch lateral mass screws combined with C2 pedicle screw and rod fixation system for the treatment of pediatric atlantoaxial subluxation (AAS) have been satisfactory, its long-term outcomes and impact on spinal development are not well studied. This study was intended to assess the long-term reliability of this technique for pediatric AAS. METHODS: A retrospective case series study was conducted to analyze the minimum 10-year follow-up outcomes from 7 pediatric patients with AAS who underwent atlantoaxial fusion using the aforementioned technique. Quality of life and cervical range of motion were both measured thoroughly. In addition, vertical growth within the fusion construct (C1-2), overall cervical alignment, and subaxial cervical spine degeneration were evaluated radiographically. RESULTS: The mean age of the 7 patients was 8.14 ± 2.41 (6-12) years at the time of surgery. The mean follow-up period was 11.00 ± 1.15 (10-13) years. No patients presented identifiable intervertebral disk degeneration or segmental instability in the subaxial cervical spine except for 1 patient who showed mild intervertebral disk degeneration. Vertical growth did continue within the atlantoaxial complex after surgery (11.90% ± 2.37%); however, there was a decrease in the percentage of vertical growth compared with the corresponding normal populations of the same age and sex. Moreover, there was a significant decrease in the range of cervical extension and rotation motion, and the overall cervical alignment straightened at the latest follow-up. CONCLUSION: The 1-step reduction and fixation technique is a relatively reliable surgical technique for pediatric AAS, which does not adversely affect the postoperative quality of life or the subaxial cervical degeneration. Nevertheless, certain limitations, such as decreased cervical range of motion and changes in cervical alignment, should be concerned.

Advanced glycation end products induce nucleus pulposus cell apoptosis by upregulating TXNIP via inhibiting glycolysis pathway in intervertebral disc degeneration.

Accumulation of advanced glycation end products (AGEs) causes apoptosis in human nucleus pulposus cells (NPCs), contributing to intervertebral disc degeneration (IVDD). The purpose of this study was to determine the roles of thioredoxin-interacting protein (TXNIP) in the mechanisms underlying AGE-induced apoptosis of NPCs. TXNIP was silenced or overexpressed in HNPCs exposed to AGEs. Glycolysis was assessed using extracellular acidification rate (ECAR), ATP level, GLUT1, and GLUT4 measurements. AGEs, TXNIP, GLUT1, and GLUT4 levels in IVDD patients were measured as well. In NPCs, AGEs reduced cell viability, induced apoptosis, inhibited glycolysis, and increased TXNIP expression. Silencing TXNIP compromised the effects of AGEs on cell viability, apoptosis, and glycolysis in NPCs. Furthermore, TXNIP overexpression resulted in decreased cell viability, increased apoptotic cells, and glycolysis suppression. Furthermore, co-treatment with a glycolysis inhibitor improved TXNIP silencing's suppressive effects on AGE-induced cell injury in NPCs. In IVDD patients with Pfirrmann Grades II-V, increasing trends in AGEs and TXNIP were observed, while decreasing trends in GLUT1 and GLUT4. AGE levels had positive correlations with TXNIP levels. Both AGE and TXNIP levels correlated negatively with GLUT1 and GLUT4. Our study indicates that TXNIP plays a role in mediating AGE-induced cell injury through suppressing glycolysis. The accumulation of AGEs, the upregulation of TXNIP, and the downregulation of GLUT1 and GLUT4 are all linked to the progression of IVDD.

Novel Radiographic Parameters for Posterior Atlantoaxial Dislocation Secondary to Os Odontoideum and Its Clinical Significance.

OBJECTIVE: To explore correlations of 3 novel radiographic parameters with myelopathy induced by posterior atlantoaxial dislocation (PAAD) secondary to os odontoideum (OO) and assess their reproducibility. METHODS: Of the 51 patients with OO with PAAD enrolled in this study, 28 developed PAAD-induced myelopathy (myelopathy group), and the other 23 patients had no myelopathy (control group). Neurologic function was evaluated by the neurologic function rating system and the Japanese Orthopaedic Association score system. Three novel radiographic parameters (OP [median sagittal diameter of the spinal canal from the posteroinferior edge of the ossicle to the anterosuperior edge of the spinous process of C2]/C4 SAC [space available for spinal cord] ratio, C1 posterior inclination angle, and posterior dislocation index) were measured by lateral cervical dynamic radiography. Their correlations with neurologic function were analyzed, and their reproducibility was assessed by the intraclass correlation coefficient (ICC). In addition, receiver operating characteristic curve analysis was performed. RESULTS: A significant correlation was observed between the OP/C4 SAC ratio and the neurologic function (P < 0.01), and between the C1 posterior inclination angle and the neurologic function (P < 0.01). Furthermore, their interobserver and intraobserver reliability was excellent (ICC ≥ 0.912). Receiver operating characteristic curve analysis showed that the optimal threshold value relating to myelopathy of the OP/C4 SAC ratio and C1 posterior inclination angle was 0.93 and 20°, respectively. CONCLUSIONS: The OP/C4 SAC ratio and the C1 posterior inclination angle seem to be 2 effective and objective radiographic parameters for relating myelopathy in patients with OO with PAAD. When the OP/C4 SAC ratio is <0.93 and/or the C1 posterior inclination angle is >20°, the risk of developing myelopathy should be highly suspected in patients with OO with PAAD.

Biocompatible Gallium Nanodots against Drug-Resistant Bacterial Pneumonia and Liver Abscess.

Resistant bacterial infection remains a severe public health threat, and conventional antibiotic drugs work poorly in effectively treating infectious diseases. Here, we developed gallium-based nanodots (Ga NDs), consisting of specific disruption of bacterial iron ability, to treat multidrug-resistant (MDR) Gram-negative bacteria-infected diseases. The Ga NDs significantly suppress the proliferation of two typical MDR bacteria strains (P. aeruginosa and ESBL E. coli) compared with clinically used antibacterial drugs, including penicillin and levofloxacin. Ga NDs could also disrupt the biofilms of these two bacterial strains. In P. aeruginosa infected pneumonia and ESBL E. coli infected acute liver abscess models, the Ga NDs enable substantial inhibition of bacterial growth and reduce the organs' inflammation that resulted in significant improvement of survival. Further, the Ga NDs demonstrated excellent biocompatibility and biosafety characteristics. Together, we believe that our gallium containing nanotherapeutics are expected to be developed into promising alternative therapies to combat drug-resistant bacterial infection.

Exosomes derived from Mouse Bone Marrow Mesenchymal Stem Cells Attenuate Nucleus Pulposus Cell Apoptosis via the miR-155- 5p/Trim32 Axis.

BACKGROUND: Lower back pain, shown to be strongly associated with IVDD, affects approximately 60%-80% of adults and has a considerable societal and economic impact. Evidence suggests that IVDD, caused by abnormal apoptosis of nucleus pulposus cells (NPCs), can be treated using MSC-derived exosomes. OBJECTIVE: This study aimed to evaluate the role of miR155-5p/Trim32 in intervertebral disc disease (IVDD) and elucidate the underlying molecular mechanisms. Deregulating miR-155 has been shown to promote Fas-mediated apoptosis in human IVDD. Evidence also suggests that tripartite motif (TRIM)-containing protein 32 (Trim32) is regulated by miR-155. However, the role of miR155-5p/Trim32 in IVDD remains unclear. METHODS: Cell viability was checked using CCK-8 kits, and flow cytometry was used to analyze cell cycle and apoptosis. Cell migration was measured with a Transwell assay, while a luciferase assay was adopted to study how miR-155-5p interacts with Trim32. The roles of Trim32 and miR-155-5p were studied by silencing or up-regulating them in NPCs, while qPCR and immunoblots were used to evaluate mRNA and protein changes, respectively. RESULTS: TNF-α treatment significantly inhibited cell viability but promoted Trim32 expression in primary mouse NPCs. Administration of bone marrow mesenchymal stem cells (BMSCs) attenuated primary NPC cell cycle arrest and apoptosis induced by TNFα. BMSCs-derived exosomes could be taken up by NPCs to inhibit TNF-α-induced cell cycle arrest and apoptosis through miR-155-5p. Examination of the underlying mechanism showed that miR-155-5p targeted Trim32. Moreover, Trim32 overexpression inhibited the effect of BMSCs-derived exosomes on primary mouse NPC cell apoptosis induced by TNF-α. CONCLUSION: Overall, these findings suggest that exosomes from BMSCs can suppress TNF-α-induced cell cycle arrest and apoptosis in primary mouse NPCs through the delivery of miR-155-5p by targeting Trim32. This study provides a promising therapeutic strategy for IVDD.

Posterior Reduction and Intra-Articular Cage Fusion With a C2 Nerve Root Preservation Technique for Treating Posterior Atlantoaxial Dislocation Secondary to Os Odontoideum.

BACKGROUND AND OBJECTIVES: Posterior C1-C2 interlaminae compression fusion with iliac bone graft may lead to donor site complications and recurrent C1 posterior dislocation for posterior atlantoaxial dislocation (AAD) secondary to os odontoideum. C1-C2 intra-articular fusion often needs C2 nerve ganglion transection to facilitate exposing and manipulating the facet joint, leading to bleeding from the venous plexus and suboccipital numbness or pain. Therefore, this study was conducted to evaluate the outcomes of posterior C1-C2 intra-articular fusion with a C2 nerve root preservation technique in the treatment of posterior AAD secondary to os odontoideum. METHODS: Data of the 11 patients who underwent C1-C2 posterior intra-articular fusion because of posterior AAD secondary to os odontoideum were retrospectively reviewed. Posterior reduction was performed using C1 transarch lateral mass screws and C2 pedicle screws. Intra-articular fusion was performed using a polyetheretherketone cage filled with autologous bone from the caudal edge of the C1 posterior arch and cranial edge of the C2 laminar. Outcomes were evaluated by using the Japanese Orthopaedics Association score, Neck Disability Index, and visual analog scale for neck pain. Bone fusion was evaluated by using computed tomography and 3-dimensional reconstruction. RESULTS: The average follow-up duration was 43.9 ± 9.5 months. All patients achieved good reduction and bone fusion, without transection of the C2 nerve roots. The mean bone fusion time was 4.3 ± 1.1 months. There was no complication related to the surgical approach and instrumentation. Function of the spinal cord manifested by the Japanese Orthopaedics Association score significantly improved ( P < .05). The Neck Disability Index score and visual analog scale for neck pain markedly decreased (all P < .05). CONCLUSION: Posterior reduction and intra-articular cage fusion with a C2 nerve root preservation technique was a promising treatment of posterior AAD secondary to os odontoideum.

The Relationship Between Cervical Sagittal Balance and Type of Atlantoaxial Dislocation Secondary to Os Odontoideum.

OBJECTIVE: To analyze the effect of cervical sagittal balance on the direction and type of atlantoaxial dislocation. METHODS: Data of 55 patients seen at our hospital for atlantoaxial instability/dislocation caused by os odontoideum were reviewed. Radiographic variables, including T1 slope (T1S), C1-C2 angle, C2-C7 angle, C1-C2 sagittal vertical axis (SVA), C2-C7 SVA, and atlanto-dens interval (ADI), were measured preoperatively. Patients were divided into three groups according to ADI: anterior atlantoaxial dislocation, atlantoaxial instability, and posterior atlantoaxial dislocation. Differences within and between groups in radiographic variables and relationships between the investigated variables were analyzed. RESULTS: ADI was strongly negatively associated with C1-C2 angle (r = -0.805, P < 0.05); whereas ADI had a medium-strength positive relationship with C2-C7 angle (r = 0.425, P < 0.05) and a medium-strength negative relationship with C2-C7 SVA (r = -0.411, P < 0.05). However, ADI was not significantly correlated with T1 slope (r = -0.092, P > 0.05). CONCLUSIONS: The type and direction of atlantoaxial dislocation is closely associated with cervical sagittal balance. C2-C7 SVA is an important factor in assessing the direction of atlantoaxial subluxation secondary to os odontoideum. ADI decreases with increasing C2-C7 SVA. The larger the C2-C7 SVA, the more likely the atlantoaxial dislocation is to be posterior.

Sagittal Reconstruction of the Atlantoaxial Lateral Mass Complex with an Intra-Articular Cage Fusion Technique for Degenerative Atlantoaxial Instability.

OBJECTIVE: To evaluate outcomes of sagittal reconstruction of the atlantoaxial lateral mass complex using a modified intra-articular cage fusion technique for treating degenerative atlantoaxial instability. METHODS: Data from 15 patients with degenerative atlantoaxial instability were retrospectively reviewed. All patients underwent posterior reduction and intra-articular fusion with a cage filled with local autologous bone. Atlantodental interval values on plain radiography in flexion before and after surgery were recorded. Bone fusion was evaluated on computed tomography reconstruction, and bone fusion time was recorded. Lateral atlantoaxial joint space height before and after surgery was measured on coronal computed tomography reconstruction. Japanese Orthopaedic Association score and visual analog scale score for neck pain before surgery and at final follow-up were compared. RESULTS: Mean follow-up time was 40.7 ± 13.4 months. All patients achieved good reduction and solid bone fusion at follow-up. Mean fusion time was 4.4 ± 1.1 months. Atlantodental interval decreased from 8.6 ± 1.5 mm preoperatively to 1.9 ± 0.5 mm at final follow-up (P < 0.05). Lateral atlantoaxial joint space height significantly improved from 1.7 ± 0.5 mm preoperatively to 4.7 ± 0.3 mm at final follow-up (P < 0.05). Japanese Orthopaedic Association score significantly improved from 14.9 ± 1.5 preoperatively to 16.7 ± 0.6 at final follow-up (P < 0.05). Visual analog scale score for neck pain markedly decreased from 4.5 ± 1.8 preoperatively to 0.5 ± 0.6 at final follow-up (P < 0.05). CONCLUSIONS: Posterior reduction and intra-articular cage fusion with a C2 nerve root preservation technique is effective in treatment of degenerative atlantoaxial instability. Satisfactory reconstruction of the sagittal alignment and the height of atlantoaxial complex can be achieved.

C2 Dome-Like Expansive Laminoplasty Versus C2 Open-Door Laminoplasty for Treating Multilevel Cervical Ossification of the Posterior Longitudinal Ligament Involving C2.

BACKGROUND: There are controversies over the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) involving C2. OBJECTIVE: To compare the outcomes of C2 dome-like expansive laminoplasty (C2DL) and C2 open-door laminoplasty (C2OL) for treating cervical OPLL involving C2. METHODS: The data of 36 patients undergoing C2OL and 40 patients treated with C2DL because of cervical OPLL involving C2 were retrospectively analyzed. The functional outcomes of the Japanese Orthopedic Association score, Neck Disability Index, 36-Item Short Form Health Survey score, and visual analog scale score for neck pain were compared between the 2 groups. The C2-C7 Cobb angle, cervical range of motion (ROM), and space available for the spinal cord at C2 were measured. RESULTS: At the final follow-up, the Japanese Orthopedic Association score, Neck Disability Index, and 36-Item Short Form Health Survey score significantly improved in both groups (all P < .05), but with no significant intergroup differences (all P > .05). The visual analog scale score for neck pain reduced significantly in both groups (P < .05), but the patients in the C2OL group experienced more severe neck axial pain (P < .05). The C2-C7 Cobb angle and cervical ROM reduced greatly in both groups (P < .05), but those in the C2OL group decreased more (P < .05). The spinal cord at C2 significantly improved in both groups (P < .05), with no significant intergroup differences (P > .05). CONCLUSION: C2DL was superior to C2OL in maintaining the cervical alignment and ROM and reducing neck axial pain for treating OPLL involving C2.

Comparison of Atlantoaxial Intra-Articular Fusion and Posterior Structural Bone Grafting Techniques for Treating Atlantoaxial Dislocation.

BACKGROUND: The structural bone grafting (SBG) technique provided high fusion rate and satisfied outcomes for treating atlantoaxial dislocation, but it is unclear whether the atlantoaxial intra-articular cage (AIC) technique can provide clinical results comparable with SBG technique. OBJECTIVE: To compare the outcomes of 2 bone graft techniques applied in posterior C1-C2 screw-rod fixation and fusion surgery for treating atlantoaxial dislocation. METHODS: The data from 55 patients with atlantoaxial dislocation were retrospectively reviewed. The SBG technique had been used in 29 patients and the AIC technique in 26 patients. The outcomes were evaluated using the Japanese Orthopedic Association scale score, Neck Disability Index, and visual analog scale score for neck pain and compared between the 2 groups. The donor site complications were also recorded in SBG group, and donor site pain was assessed using a visual analog scale. RESULTS: In the final follow-up, the bone fusion rate was 100% in both groups. No significant differences were found in the bone fusion time between the 2 groups ( P > .05). Postoperatively, the Japanese Orthopedic Association, Neck Disability Index, and visual analog scale score for neck pain indexes improved significantly within both SBG (all P < .05) and AIC groups (all P < .05). Nevertheless, there were no statistically significant differences between the 2 groups (all P > .05). CONCLUSION: The SBG and AIC techniques were both effective for achieving atlantoaxial arthrodesis, and the AIC technique is a perfect alternative to the SBG technique when the posterior arch of C1 is incompetent.

New Subtype of Atlantoaxial Rotatory Fixation (Type IIIa).

OBJECTIVE: Some atlantoaxial rotatory fixations (AARFs) cannot be classified according to the Fielding and Hawkins classification. This study aimed to introduce a new subtype of AARF (type IIIa AARF) with a C1 anterior displacement >5 mm, but with one lateral mass being displaced anteriorly and another posteriorly. METHODS: Data from 10 cases of AARF with anterior C1 displacement of >5 mm were retrospectively reviewed. The exclusion criteria were as follows: 1) type I, II, or IV AARF according to the Fielding and Hawkins classification; 2) cases caused by trauma, tumor, or infection; 3) AARF with os odontoideum or odontoid fracture; and 4）age ≥18 years. Imaging features were analyzed. The atlanto-dental interval was measured to evaluate C1 anterior displacement. RESULTS: Three cases that did not match type III AARF were classified under type IIIa AARF. They had the following common imaging features: 1) atlanto-dental interval of >5 mm, being similar to type III AARF; 2) one lateral mass of C1 displaced anteriorly and the other posteriorly (the most important feature distinguishing the type from type III AARF in which both C1 lateral masses displaced anteriorly); and 3) C1-C2 separation angle (mean 44.2 ± 2.9°) being larger than that in type III AARF. CONCLUSIONS: AARF with anterior C1 displacement of >5 mm, but with one lateral mass displaced anteriorly and the other posteriorly, was defined as type IIIa AARF. It should not be confused with type III AARF because these 2 types differ in biomechanics and imaging parameters.

Black-Phosphorus-Nanosheet-Reinforced Coating of Implants for Sequential Biofilm Ablation and Bone Fracture Healing Acceleration.

Incurable implant-related infection may cause catastrophic consequences due to the existence of a biofilm that resists the infiltration of host immune cells and antibiotics. Innovative approaches inspired by nanomedicine, e.g., engineering innovative multifunctional bionic coating systems on the surface of implants, are becoming increasingly attractive. Herein, 2D black phosphorus nanosheets (BPs) were loaded onto a hydroxyapatite (HA)-coated metal implant to construct a BPs@HA composite coating. With its photothermal conversion effect and in situ biomineralization, the BPs@HA coating shows excellent performances in ablating the bacterial biofilm and accelerating fracture healing, which were verified through both in vitro and in vivo studies. Moreover, differentially expressed genes of bone formation and bone mesenchymal stem cells (BMSCs) regulated by the BPs@HA coating were identified using absolute quantitative transcriptome sequencing followed by the screening of gene differential expressions. A functional enrichment analysis reveals that the expression of core markers related to BMSC differentiation and bone formation could be effectively regulated by BPs through a metabolism-related pathway. This work not only illustrates the great potential in clinical application of the BPs@HA composite coating to eliminate bacteria and accelerate bone fracture healing but also contributes to an understanding of the underlying molecular mechanism of osteogenesis physiological function regulation based on an analysis of absolute quantitative transcriptome sequencing.

One-Stage Anterior Retropharyngeal Release Followed by Posterior Open Reduction and Intra-Articular Cage Fusion for Treating Chronic Fixed Type III Atlantoaxial Rotatory Fixation.

OBJECTIVE: To verify the effectiveness of anterior retropharyngeal release followed by posterior open reduction using long arm reduction screws combined with intra-articular fusion with a cage filled with the local autologous bone for treating fixed Type III atlantoaxial rotatory fixation (AARF). METHODS: Data from 6 children with fixed AARF were retrospectively reviewed. All patients underwent anterior retropharyngeal release followed by posterior open reduction using long-arm reduction screws combined with intra-articular fusion with a cage filled with local autologous bone. Outcomes were measured using the atlantodental interval value, the Japanese Orthopedic Association score and visual analog scale for neck pain. Patient age, sex, operation time, blood loss, and bone fusion time were recorded. Complications related to the operation were also recorded. RESULTS: All patients achieved complete reduction and solid bone fusion at follow-up. The atlantodental interval dropped to 2.1 ± 0.5 mm after the operation from a preoperative score of 15.3 ± 3.1 mm (P < 0.05). Japanese Orthopedic Association score significantly improved from a preoperative score of 15.3 ± 0.5 to 17 ± 0 at the final follow-up (P < 0.05). Visual analog scale for neck pain markedly decreased from preoperative 4.5 ± 1.0 to 0.2 ± 0.4 at the final follow-up (P < 0.05). No complication related to the surgical approach or instrumentation was observed. CONCLUSIONS: One-stage anterior retropharyngeal release followed by posterior open reduction combined with intra-articular cage fusion is effective in treating chronic fixed type III AARF.

Open Reduction for Potentially Reducible Atlantoaxial Dislocation Secondary to Transverse Ligament Laxity in Patients with Rheumatoid Arthritis.

OBJECTIVE: Atlantoaxial dislocation (AAD) is classified into reducible AAD and irreducible AAD (IRAAD). Anterior or posterior releasing followed by occipitocervical/atlantoaxial fusion is often performed for IRAAD, but is technically demanding. This study aimed to evaluate the results of the posterior open reduction technique without releasing the atlantoaxial joint in the treatment of potentially reducible AAD (PRAAD) caused by transverse ligament laxity in patients with rheumatoid arthritis (RA). METHODS: Data from 38 RA patients who experienced PRAAD due to transverse ligament laxity were retrospectively reviewed. They all underwent posterior open reduction and fusion without releasing the atlantoaxial joint. Outcomes were evaluated by using atlantodental interval, modified Japanese Orthopedic Association scores, Nurick grade, Neck Disability Index, and visual analog scale score for neck pain. RESULTS: All the patients achieved solid bone fusion at follow-up. The mean atlantodental interval was reduced to 5.6 ± 0.7 mm and 2.1 ± 0.5 mm after traction and operation, respectively, from a preoperative score of 8.2 ± 0.6 mm (P < 0.05). Compared with the respective preoperative values, the mean modified Japanese Orthopedic Association score and Nurick grade were significantly increased at the final follow-up (both P < 0.05), whereas the Neck Disability Index and visual analog scale score for neck pain were significantly decreased (both P < 0.05). CONCLUSIONS: AAD with partial reduction after skeletal traction for 48 hours should be defined as PRAAD, not IRAAD. Open reduction with a C1-C2 pedicle screw-rod system can be safely and effectively applied in the treatment of PRAAD due to transverse ligament laxity in patients with RA.

Clinical and Radiographic Outcomes of Combined Posterior Transfacet Screw Fixation and Anterior Cervical Discectomy and Fusion Surgery for Unilateral Cervical Facet Fracture with Traumatic Disc Herniation: A Retrospective Cohort Study.

INTRODUCTION: Combined lateral mass screw-rod (LMSR) fixation and anterior cervical discectomy and fusion (ACDF) surgery is currently the most widely described and accepted procedure for subaxial cervical facet fracture with traumatic disc herniation. Recent biomechanical studies have demonstrated that the use of transfacet screw (TFS) can be considered as a simple alternative method to LMSR. However, to date, little is known about the feasibility and effectiveness of TFS in the combined approach. The aim of this study was to compare the clinical and radiographic results of TFS + ACDF surgery and LMSR + ACDF surgery, and to provide a less invasive alternative technique for spine surgeons. METHOD: We retrospectively reviewed patients with unilateral cervical facet fracture with traumatic disc herniation who had undergone TFS + ACDF (N = 36) or LMSR + ACDF (N = 34) with a minimum 2-year follow-up. Clinical assessments, which included American Spinal Injury Association impairment scale (AIS), visual analog scale for neck pain (VASSNP) score and patient satisfaction, were made before surgery and at follow-up. For the radiographic outcomes, the instability parameters of segmental kyphosis and sagittal translation were measured. RESULTS: The demographic characteristics of the two groups of patients were similar. In terms of clinical outcomes, both two groups were associated with significant improvements at the final follow-up. There were no significant between-group differences in VASSNP score or patient satisfaction (both P > 0.05). The LMSR + ACDF group suffered more blood loss and had longer operative time (mean 206.0 ml; mean 274.4 min, respectively) than in the TFS + ACDF group (mean 110.0 ml; mean 142.8 min, respectively) (P < 0.001 for both comparisons). For the radiographic results, the segmental kyphosis and sagittal translation were significantly corrected after surgery in both groups (P < 0.001 for both groups), and no significant differences were found between groups at the last follow-up (P > 0.05). CONCLUSION: In the absence of any self-evident clinical and radiographic benefits of one technique over the other (TFS + ACDF vs. LMSR + ACDF), we recommend combined TFS + ACDF surgery as a safe and less invasive alternative treatment for unilateral cervical facet fractures with traumatic disc herniation, as it was associated with a shorter duration of surgery and lower estimated blood loss than LMSR + ACDF surgery.

Cervical Myelopathy Due to Idiopathic Retro-odontoid Pseudotumor.

OBJECTIVE: A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial instability or rheumatoid arthritis. However, ROP in the absence of atlantoaxial instability or rheumatoid arthritis, which is termed idiopathic ROP (IROP), is a rare condition. The pathomechanisms and optimal treatment strategies for IROP remain controversial. The aim of the present study was to evaluate the radiographic and clinical characteristics of IROP patients and to assess the efficiency of atlantoaxial/occipitocervical fusion on IROP regression. METHODS: Data from 5 patients diagnosed with IROP were retrospectively reviewed. Posterior atlantoaxial or occipitocervical fixation and fusion were performed in 4 patients and C1 posterior arch resection alone in 1 patient. The patients' features, surgical procedures, and complications were recorded. The retro-odontoid soft tissue thickness was measured on preoperative and postoperative magnetic resonance imaging to evaluate IROP regression. RESULTS: The mean follow-up time was 37 months. ROP regression was achieved in patients who received atlantoaxial/occipitocervical fusion, but not for the patient with C1 posterior resection alone. There were no observed neurovascular complications associated with surgery. CONCLUSIONS: IROP was related to a restricted range of motion of the subaxial spine. Upper cervical fixation is an optional treatment that produces IROP regression over time. By contrast, direct removal of the IROP is unnecessary.

Anterior Canal Reconstruction and Fusion for Myelopathy Caused by Degenerative Cervical Kyphosis and Stenosis With or Without Ossification of the Posterior Longitudinal Ligament.

STUDY DESIGN: This was a retrospective study. OBJECTIVE: To introduce an anterior surgical technique for myelopathy caused by degenerative cervical kyphosis and stenosis (DCKS) with or without ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA: The optimal approach in the treatment of DCKS remains a controversy because each anterior or posterior route surgery has advantages and disadvantages. MATERIALS AND METHODS: In the period from June 2017 through June 2019, a consecutive cohort of adults diagnosed with DCKS underwent anterior canal reconstruction and fusion (ACRF). All patients underwent x-ray, computed tomography, and magnetic resonance imaging of the cervical spine. Radiologic assessment included kyphosis, canal area, canal reconstruction, OPLL, and spinal cord curvature and morphology. The Japanese Orthopaedic Association (JOA) scoring system was used to evaluate the neurological status. Surgery-related and implant-related complications were all recorded. Follow-up was carried out at 3, 6, 12, 24, and 36 months postoperation. RESULTS: Fourty-one patients were included in the study, of which 19 presented with OPLL. Postoperatively, the canal area were significantly greater at last follow-up compared with preoperation (208.4 vs. 123.2 mm2; P=0.001). There was significant kyphosis correction (-17.6 vs. 8.5 degrees, P=0.001) at last follow-up. Ninety-six segmental canal reconstruction were performed, 89 (92.7%) reached bone fusion at both grooves with a mean time of 7.9 months. On sagittal magnetic resonance imaging, 33 (80.5%) patients presented with lordosis in the spinal cord curvature, 8 (19.5%) with straight. The mean JOA score at last follow-up was significantly better than preoperation (15.0 vs. 9.3 points; P<0.01). One patient presented with cerebrospinal fluid leakage, 1 with screw displacement and 2 with dysphagia. CONCLUSION: ACRF, receiving good correction of kyphosis, amplified canal area, solid instrumented fusion and circumferential decompression, is an effective and safe surgical technique for cervical myelopathy caused by DCKS with or without OPLL. LEVEL OF EVIDENCE: Level III-a retrospective analysis.

Local delivery and controlled release of miR-34a loaded in hydroxyapatite/mesoporous organosilica nanoparticles composite-coated implant wire to accelerate bone fracture healing.

Immediate mechanical stability is a prerequisite for fracture healing. In addition to bringing immediate mechanical stability in fracture site, implants with bioactive coating can release active substance to accelerate bone-fracture healing. However, limited drug-loading capacity of established coatings weakens their biological functions, which urges the engineering of more effective coating biomaterials for accelerating fracture healing. Herein, mesoporous organosilica nanoparticles (MONs), as miR-34a delivers, are loaded onto hydroxyapatite (HA)-coated Kirschner wire to engineer a HA/MONs@miR-34a composite coating. The composite coating can effectively deliver miR-34a into osteoclasts, generate gene dose-dependent inhibiting effect on differentiation and resorptive activity of osteoclasts by regulating multiple downstream gene expression at the early stage of fracture healing, which additionally exhibits decent bone regeneration potentials as evidenced in rat tibial fracture model. In particular, differentially expressed genes regulated by miR-34a are identified using RNA-seq followed by bioinformatics analysis. Functional enrichment analysis reveals that genes with altered expression mainly distribute in mainly distribute in DNA replication and cell cycle, which are associated with the development of osteoclasts. This work not only demonstrates the high clinical translation potential of HA/MONs@miR-34a to accelerate fracture healing, but also reveals the underlying molecular mechanism of regulating physiological functions of osteoclasts based on analysis of singlecell RNA sequencing.