Posterior Reduction Research Articles

Novel MRI Signs in Atlantodental Space Predict Reduction Degree of Atlantoaxial Dislocation.

The type of atlantodental space tissue in patients with atlantoaxial dislocation (AAD) can help doctors understand the possibility of reduction before surgery. However, relevant research on this topic is lacking. This study aimed to summarize cases of AAD, classified based on the atlantodental space using magnetic resonance imaging (MRI), and preliminarily explore its impact on the degree of reduction. Preoperative T2-weighted MRIs and dynamic digital radiographs of patients who underwent posterior reduction and fixation surgery for congenital AAD between September 2012 and February 2023 were collected. The patients were classified into flexible and inflexible tissue sign groups based on T2-weighted imaging. Patients with an atlantodental interval < 3 mm on extension digital radiography were considered radiographically reducible. Three radiologists read and recorded the MRI results using standard protocols. Kappa and Fleiss kappa values were used to evaluate intra- and inter-observer agreements for MRI signs and dynamic digital radiography findings. Multivariate logistic regression and receiver operating characteristic curves were used to analyze the relationships between imaging parameters and the reduction degree. In total, 118 patients with AAD were included in the analysis. Inter-observer agreement among the three readers was higher for MRI than for dynamic digital radiography (0.816 vs. 0.668). The intra-observer consistency for MRI signs was also better than that of dynamic digital radiography. Both the flexible tissue sign and radiographically reducible groups showed a higher rate of satisfactory reduction. However, only the flexible tissue sign showed positive results in the multivariate regression. The receiver operating characteristic curve for MRI signs as a predictor of satisfactory reduction yielded an area under the curve of 0.776 (95% confidence interval, 0.667-0.875, p < 0.0001). Novel MRI signs of the atlantodental space exhibited high inter- and intra-observer agreement. Patients with flexible tissue signs were more likely to achieve satisfactory reduction after direct posterior surgery.

Posterior Reduction and Temporary Fixation Through Intermuscular Approach for Odontoid Fracture.

Posterior reduction and temporary fixation (PRTF) through open approach can effectively avoid the loss of C1-C2 motion caused by posterior atlantoaxial fusion in the treatment of odontoid fracture. PRTF through intermuscular approach can preserve the integrity of the paravertebral muscle. However, its contribution to the preservation of C1-C2 rotation remains unassessed in the context of fresh odontoid fractures. The data of 31 patients with odontoid fractures who underwent PRTF through intermuscular approach were retrospectively reviewed. Operation time, intraoperative blood loss, the time of ambulation and surgery-related complications were recorded. After fracture healing, the instrumentation was removed. The Japanese Orthopedic Association score, Visual Analog Scale score for neck pain, and patient satisfaction were recorded. The range of motion in rotation of C1-C2 was calculated 1 month after removing the instrumentation. Fracture healing was observed in all patients, and the instrumentation was removed. After removing the instrumentation, the range of motion of C1-C2 in rotation was returned to 35.6° ± 4.8°. Patient satisfaction was improved (P < .05). There was no significant difference in Japanese Orthopedic Association scores and Visual Analog Scale score for neck pain between 2 values before and after removing the instrumentation (P > .05). No osteoarthritis was observed at the C1-C2 lateral mass joints. There were no perioperative complications. PRTF through intermuscular approach can be used as a salvage treatment of an odontoid fracture with an intact transverse ligament in cases of failure of, or contraindication to, anterior screw fixation. This minimally invasive technique can effectively preserve the rotational function of the atlantoaxial complex.

Posterior Release, Reduction, and Intra-Articular Fusion for Irreducible Type III Atlantoaxial Rotary Fixation.

For irreducible atlantoaxial rotary fixation (AARF), anterior or posterior release was often needed before posterior reduction and fusion. Anterior atlantoaxial joint release has potential complications such as retropharyngeal abscess, persistent hoarseness, and infection. This study aims to assess the efficacy of posterior release, reduction, and intra-articular fusion without resecting the C2 nerve root on irreducible type III AARF. The data of 9 pediatric patients diagnosed with AARF who underwent posterior atlantoaxial release, reduction, and intra-articular fusion without resecting the C2 nerve root were retrospectively reviewed. Japanese Orthopaedic Association scores and Visual Analog Scale for Neck Pain were used to assess outcomes. The preoperative and follow-up assessments of atlantodens interval (ADI) were documented to evaluate the reduction of atlantoaxial joint. The patient demographics, surgery time, blood loss, bone fusion time, follow-up period, and surgery-related complications were meticulously documented. The mean follow-up duration was 35.1 ± 11.5 months. Complete reduction was achieved in 8 patients, while one patient did not achieve complete reduction. The ADI decreased significantly from 8.7 ± 2.2 mm before surgery to 2.1 ± 1.3 mm at the final follow-up. All patients demonstrated successful bone fusion, with an average fusion period of 3.7 ± 1.3 months. The Visual Analog Scale for Neck Pain at the final follow-up exhibited a significant decrease compared with preoperative values (P < .05), while no significant difference was observed in Japanese Orthopaedic Association scores. There were no complications related to surgery. Posterior atlantoaxial release, reduction, and intra-articular fusion with a C2 nerve root preservation technique is effective in the treatment of irreducible type III AARF.

How are global university rankings adjusted for erroneous science, fraud and misconduct? Posterior reduction or adjustment in rankings in response to retractions and invalidation of scientific findings

Global university rankings (GURs), such as the Times Higher Education World University Ranking (THE WUR), Quacquarelli Symonds University World Rankings (QS UWR) and the Academic Ranking of World Universities (ARWU) are positively incremental, that is, they do not reflect any level of penalisation in response to unscholarly activity, especially in the field of research and publication. In the light of an increasing trend in fraud, such as the use of paper mills and authorship-for-sale schemes, this letter proposes that GURs need to be reduced, or penalised, in response to cases of misconduct and instances of retractions. In the absence of a transparent corrective system, GURs will be further criticised for being unfair, biased and not reflective of an evolving and unstable academic publishing ecosystem.

Clinical effect and prognosis of transoral or endoscope-assisted transoral release for irreducible atlantoaxial dislocation: A retrospective cohort study

BackgroundThe clinical applications of endoscope-assisted transoral release for irreducible atlantoaxial dislocations are limited. This study aimed to investigate the clinical effect and prognostic factors of traditional and endoscope-assisted transoral release, as well as posterior reduction and fixation, in treating irreducible atlantoaxial dislocations. Materials and methodsWe conducted a retrospective study on 59 patients with irreducible atlantoaxial dislocation who underwent either traditional or endoscope-assisted transoral release, posterior fixation, and fusion between January 2018 and January 2023. Various data, including surgical time, blood loss, drainage volume, oral intake, hospital stay, complications, and neurological status (assessed by the Japanese Orthopedic Association [JOA] score and Oswestry Disability Index [ODI]), were recorded. Imaging parameters such as the atlantodontoid interval (ADI), space available for the cord (SAC), and cervicomedullary angle (CMA) were analyzed and compared. In addition, the correlation between ODI, JOA and patient age, course of disease, preoperative ADI, SAC and CMA were analyzed. ResultsNo significant differences were observed in age, sex, BMI, preoperative ADI, preoperative SAC, or preoperative CMA. All patients achieved excellent reduction with no significant differences between the two groups. Patients in the endoscopic group experienced significantly reduced blood loss, earlier oral intake, and shorter hospital stays compared to those in the open group (P < 0.05). The ODI and JOA scores improved significantly in both groups at 1, 6, 12, 18, and 24 months postoperatively (P < 0.05). Postoperative ADI, SAC, and CMA values in both groups were significantly better than preoperative values (P < 0.001). The patient age, course of disease and the preoperative ADI were negatively correlated with the postoperative ODI and the JOA improvement ratio (P < 0.01), and the preoperative SAC and preoperative CMA had positive correlations with the postoperative ODI and the JOA improvement ratio (P < 0.01) at 6, 12 and 24 months postoperatively. ConclusionPatient age, course of disease, preoperative ADI, SAC and CMA are correlated with the operative prognosis of irreducible atlantoaxial dislocation. The endoscope-assisted transoral approach, compared to the traditional transoral approach, is minimally invasive, resulting in less operative blood loss, earlier oral intake and a shorter length of hospital stay, which could be offered as an alternative for irreducible atlantoaxial dislocation.

The development of posterior reduction forceps for atlantoaxial dislocation and its preliminary application in irreducible atlantoaxial dislocation

ObjectiveTo develop posterior reduction forceps for atlantoaxial dislocation and evaluate the preliminary clinical application of this forceps in assisting simple posterior screw-rod system reduction and fixation in the treatment of irreducible atlantoaxial dislocation.MethodsBased on the posterior atlantoaxial screw-rod system, posterior reduction forceps was developed to assist simple posterior screw-rod system for the treatment of irreducible atlantoaxial dislocation. From January 2021 to October 2022, 10 cases with irreducible atlantoaxial dislocation were treated with this technique. The Japanese Orthopaedic Association (JOA) score was applied before and after surgery to evaluate the neurological status of the patient, and the Atlanto-dental interval (ADI) was measured before and after surgery to evaluate the atlantoaxial reduction. X-ray and CT were performed to evaluate internal fixation, atlantoaxial sequence and bone graft fusion during regular follow-up. MRI was performed to evaluate the status of atlantoaxial reduction and spinal cord compression after surgery.ResultsAll 10 patients were successfully operated, and there were no complications such as spinal nerve and vascular injury. Postoperative clinical symptoms were significantly relieved in all patients, and postoperative JOA score and ADI were significantly improved compared with those before surgery (P < 0.05).ConclusionsThe developed posterior reduction forceps for atlantoaxial dislocation can assist the simple posterior screw-rod system in the treatment of irreducible atlantoaxial dislocation to avoid the release in anterior or posterior approach and reduce the difficulty of surgery. The preliminary results of this technique are satisfactory and it has a good application prospect.

A novel classification and management scheme for craniocervical junction disorders with ventral neural element compression.

Craniocervical junction (CCJ) pathologies with ventral neural element compression are poorly understood, and appropriate management requires accurate understanding, description, and a more uniform nomenclature. The aim of this study was to evaluate patients to identify anatomical clusters and better classify CCJ disorders with ventral compression and guide treatment. A retrospective review of adult and pediatric patients with ventral CCJ compression from 2008 to 2022 at a single center was performed. The incidence of anatomical abnormalities and compressive etiologies was assessed. Surgical approach, radiographic data, and outcomes were recorded. Association rules analysis (ARA) was used to assess variable clustering. Among 51 patients, the main causes of compression were either purely bony (retroflexed dens [n = 18]; basilar invagination [BI; n = 13]) or soft tissue (degenerative pannus [n = 16]; inflammatory pannus [n = 2]). The primary cluster in ARA was a retroflexed dens, platybasia, and Chiari malformation (CM), and the secondary cluster was BI, C1-2 subluxation, and reducibility. These, along with degenerative pannus, formed the three major classes. In assessing the optimal treatment strategy, reducibility was evaluated. Of the BI cases, 12 of the 13 patients had anterolisthesis of C1 that was potentially reducible, compared with 2 of the 18 patients with a retroflexed dens (both with concomitant BI), and no pannus cases. The mean C1-2 facet angle was significantly higher in BI at 32.4°, compared with -2.3° in retroflexed dens and 8.1° in degenerative pannus (p < 0.05). Endonasal decompression with posterior fixation was performed in 48 (94.0%) of the 51 patients, whereas posterior reduction/fixation alone was performed in 3 patients (6.0%). Of 16 reducible cases, open posterior reduction alone was successful in 3 (60.0%) of 5 cases, with all successes containing isolated BI. Reduction was not attempted if vertebral anatomy was unfavorable (n = 9) or the C1 lateral mass was absent (n = 5). The mean follow-up was 28 months. Symptoms improved in 88.9% of patients and were stable in the remaining 11.1%. Tracheostomy and percutaneous G-tube placement occurred in 7.8% and 11.8% of patients, respectively. Reoperation for an endonasal CSF leak repair or posterior cervical wound revision both occurred in 3.9% of patients. In classifying, one cluster caused decreased posterior fossa volume due to an anatomical triad of retroflexed dens, platybasia, and CM. The second cluster caused pannus formation due to degenerative hypertrophy. For both, endonasal decompression with posterior fixation was ideal. The third group contained C1 anterolisthesis characterized by a steep C1-2 facet angle causing reducible BI. Posterior reduction/fixation is the first-line treatment when anatomically feasible or endonasal decompression with in situ posterior fixation when anatomical constraints exist.

Facet-occiput slope angle: A novel predictor of cage placement feasibility during surgery in basilar invagination patients

Background and aimDirect posterior reduction and manipulation of the C1-2 joints, accompanied by placement of spacers, is the state-of-the-art technique for treating basilar invagination (BI) and atlantoaxial dislocation (AAD). The hindrance of occiput to reaching up to the true atlantoaxial facets (AAF) during the surgery remains challenging for cage placement. The aim of this study was to explore an objective and precise method of measuring the effect of the hindrance of occiput to reaching up to the true AAF and cage placement during surgery. MethodWe collected the clinico-imaging data of 58 patients with BI and AAD (Group A) who underwent surgery in our hospital, and 78 control cohorts (Group B) were retrieved retrospectively. We measured facet-occiput slope angle (FOSA) in midsagittal CT. Patients were positioned prone for surgery based on preoperative flexion O–C2a, and access to the true AAF was observed intraoperatively. The cut-off value of FOSA for the feasibility of cage placement in BI and AAD patients was appointed when access to the true AAF was impossible due to the hindrance of occiput during surgery. ResultsThe cut-off value of FOSA for the feasibility of cage placement was 34o with an area under the curve AUC of 0.800 (95 % CI: 0.672–0.928, P < 0.001) and the Youden index of 0.607. In patients with FOSA >34o, reaching up to the true AAF and 3D-printed cage placement was impossible. FOSA was negative in Group A and positive in Group B, significantly larger in females compared to males in both groups and significantly larger postoperatively in Group A. ConclusionFOSA can objectively measure the feasibility of cage placement when the patient is positioned prone per preoperative flexion O–C2a. A FOSA >34o is contraindication for cage placement.

Myelopathy resulting from degenerative atlantoaxial subluxation.

To present the clinical features and treatment strategy of degenerative atlantoaxial subluxation (DAAS). Patients with DAAS treated in our institution from 2003 to 2020 were retrospectively reviewed. We utilized the Japanese Orthopedic Association (JOA) scale to evaluate the neurologic status and distance of Ranawat et al. (DOR) to measure vertical migration. We recruited 40 patients with > 2years of follow-up and an average age of 62.3 ± 7.7years. All the patients had myelopathy; only one patient had moderate trauma before exacerbation of symptoms, and the duration of symptoms was 34 ± 36months. The most frequent radiological features were vertical migration of C1 (100%), sclerosis (100%), and narrowing of the atlantoaxial lateral mass articulations (100%). Two patients underwent transoral release combined with posterior reduction and fusion, and 38 patients underwent posterior reduction and fusion with C1 lateral mass screws-C2 pedicle screws and plate systems only. Forty cases (100%) achieved a solid atlantoaxial fusion, and 38 cases (95%) achieved anatomic atlantoaxial reduction. The JOA score increased from 9.3 ± 2.6 to 14.8 ± 2.1 (P < 0.01). DOR increased from 14.5 ± 2.5 to 17.8 ± 2.2mm at the final follow-up (P < 0.01). Loosening of the locking caps was detected in one case, bony fusion was achieved, and harvest-site pain was reported in five patients. DAAS differs from other types of AAS and presents with anterior subluxation combined with vertical subluxation arising from degenerative changes in the atlantoaxial joints. We recommend anatomic reduction as an optimal strategy for DAAS.

The Arthroscopic Three-Point Fixation for Anterior Cruciate Ligament Avulsion Fracture: Surgical Technique

Several arthroscopic repairs and fixation for tibial intercondylar eminence fracture have been developed for restoring anterior cruciate ligament function. Repairing the avulsion fragment with multiple-point fixation provides some benefits over a single-point fixation. It provides multidirectional force control, especially on the posterior part of the fragment, and produces area of compression. We propose a 3-point fixation technique for providing proper reduction and compression in large fragment anterior cruciate ligament avulsion fracture. This includes using hybrid intra-articular and tunnel pull-out suture fixation to provide good posterior reduction and fixation. The number of tunnels is decreased by using a suture anchor.

A Review of Spinal Twine Injury and Its Management

There is no universal agreement on the best procedure for treating lower cervical dislocation because anterior reduction and interbody fusion fixation have not been directly compared to posterior reduction and short-segmental pedicle screw fixation. This study compares the long-term effects of severe cervical dislocation with spinal cord injury treated using an anterior versus a posterior method. A total of 149 patients (follow-up rate of 84.1%) could be followed for more than 10 years. 67 patients had posterior reduction and short-segmental pedicle screw fixation, while 92 patients underwent anterior reduction and interbody fusion and fixation. Surgical or post-operative problems as well as the Japanese Orthopaedic Association (JOA) scores, the Neck Disability Index (NDI), the American Spinal Injury Association grading (ASIA), Odom's criteria, cervical kyphosis, and operating parameters were assessed. 10 to 17 years were spent monitoring the patients. At the follow-up, there was no discernible difference between the two groups' primary JOA scores, NDI scores, or ASIA scores. The posterior method was linked to a larger loss of alignment at the last follow-up and by two years (P = 0.012 and P 0.001, respectively).

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

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. 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. 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). 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.

Baziler İnvajinasyonun Cerrahi Tedavisi: Farklı Cerrahi Yaklaşımların Klinik ve Radyografik Sonuçların Karşılaştırılması

Aim: Previous studies have outlined various surgical approaches to treatment of basilar invagination, but none have compared multiple different treatment options using objective clinical and radiological criteria. &#x0D; Material and Methods: We retrospectively reviewed the records of 30 patients with basilar invagination treated by five different surgical approaches. The surgical outcomes were evaluated and compared using objective clinical (Ranawat score) and radiological parameters (Chamberlain distance, atlantodental interval, and craniovertebral angle). &#x0D; Results: Our results show a statistically significant improvement in the Ranawat score for patients undergoing 1) anterior decompression with posterior stabilization, 2) posterior decompression with posterior stabilization, and 3) the Goel procedure (posterior decompression, posterior reduction, cage distraction, and posterior stabilization). Of these, the Goel procedure produced the most significant improvement in functional and radiographic outcomes. Neither group without posterior stabilization (posterior decompression alone or endoscopic transnasal odontoidectomy alone) had a significant improvement in Ranawat score or radiographic outcomes. &#x0D; Conclusion: For surgical management of basilar invagination, a combination of posterior decompression, posterior reduction, cage distraction, and posterior stabilization yielded the best clinical and radiological outcome. There is a risk of craniocervical instability and kyphosis and recurrence of stenosis in patients treated surgically without posterior stabilization. Therefore, when deciding on bacillary invagination surgery without posterior stabilization, it should be carefully considered.

Improvement of vertebral body fracture reduction utilizing a posterior reduction tool: a single-center experience

BackgroundExtensive research regarding instabilities and prevention of kyphotic malalignment in the thoracolumbar spine exists. Keystones of this treatment are posterior instrumentation and anterior vertebral height restoration. Anterior column reduction via a single-stage procedure seems to be advantageous regarding complication, blood loss, and OR-time. Mechanical elevation of the anterior cortex of the vertebra may prevent the necessity of additional anterior stabilization or vertebral body replacement. The purpose of this study was to examine (1) if increased bony reduction in the anterior vertebral cortex could be achieved by utilization of an additional reduction tool, (2) if postoperative loss of vertebral height could be reduced, and (3) if anterior column reduction is related to clinical outcome.MethodsFrom one level I trauma center, 173 patients underwent posterior stabilization for fractures of the thoracolumbar region between 2015 and 2020. Reduction in the vertebral body was performed via intraoperative lordotic positioning or by utilization of an additional reduction tool (Nforce, Medtronic). The reduction tool was mounted onto the pedicle screws and removed after tightening of the locking screws. To assess bony reduction, the sagittal index (SI) and vertebral kyphosis angle (VKA) were measured on X-rays and CT images at different time points ((1) preoperative, (2) postoperative, (3) ≥ 3 months postoperative). Clinical outcome was assessed utilizing the Ostwestry Disability Index (ODI).ResultsBisegmental stabilization of AO/OTA type A3/A4 vertebral fractures was performed in 77 patients. Thereof, reduction was performed in 44 patients (females 34%) via intraoperative positioning alone (control group), whereas 33 patients (females 33%) underwent additional reduction utilizing a mechanical reduction tool (instrumentation group). Mean age was 41 ± 13 years in the instrumentation group (IG) and 52 ± 12 years in the control group (CG) (p < 0.001). No differences in terms of gender and comorbidities were found between the two groups. Preoperatively, the sagittal index (SI) was 0.69 in IG compared to 0.74 in CG (p = 0.039), resulting in a vertebral kyphosis angle (VKA) of 15.0° vs. 11.7° (p = 0.004). Intraoperatively, a significantly greater correction of the kyphotic deformity was achieved in the IG (p < 0.001), resulting in a compensation of the initially more severe kyphotic malalignment. The SI was corrected by 0.20–0.88 postoperatively, resulting in an improvement of the VKA by 8.7°–6.3°. In the CG, the SI could be corrected by 0.12–0.86 and the VKA by 5.1°–6.6°. The amount of correction was influenced by the initial deformity (p < 0.001). Postoperatively, both groups showed a loss of correction, resulting in a gain of 0.08 for the SI and 4.1° in IG and 0.03 and 2.0°, respectively. The best results were observed in younger patients with initially severe kyphotic deformity. Considering various influencing factors, clinical outcome determined by the ODI showed no significant differences between both groups.ConclusionUtilization of the investigated reduction tool during posterior stabilization of vertebral body fractures in a suitable collective of young patients with good bone quality and severe fracture deformity may lead to better reduction in the ventral column of the fractured vertebral body and angle correction. Therefore, additional anterior stabilization or vertebral body replacement may be prevented.

Correlation Among Syrinx Resolution, Cervical Sagittal Realignment, and Surgical Outcome After Posterior Reduction for Basilar Invagination, Atlantoaxial Dislocation, and Syringomyelia.

The correlation among syrinx resolution, occipitoaxial sagittal alignment, and surgical outcome in long-term follow-up seems to have not been clarified. To further explore the relationship between the syrinx resolution and occipitoaxial realignment after posterior reduction and fixation in basilar invagination (BI)-atlantoaxial dislocation (AAD) patients with syringomyelia. A continuous series of 32 patients with BI-AAD and syringomyelia who received direct posterior reduction met the inclusion criteria of this study. Their clinical and imaging data were analyzed retrospectively. Before surgery and at the last follow-up, we used the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI) to assess the neurological status, respectively. The Pearson correlation coefficient and multiple stepwise regression analysis were used to explore the relevant factors that may affect surgical outcomes. There were significant differences in atlantodental interval, clivus-axial angle, occiput-C2 angle (Oc-C2A), cervicomedullary angle (CMA), subarachnoid space (SAS) at the foramen magnum (FM), syrinx size, NDI, and JOA score after surgery compared with those before surgery. ΔCMA and the resolution rate of syrinx/cord as relevant factors were correlated with the recovery rate of JOA (R 2 = 0.578, P < .001) and NDI (R 2 = 0.369, P < .01). What's more, ΔSAS/FMD (SAS/FM diameter) and ΔOc-C2A were positively correlated with the resolution rate of syrinx/cord (R 2 = 0.643, P < .001). With medulla decompression and occipital-cervical sagittal realignment after posterior reduction and fusion for BI-AAD patients with syringomyelia, the structural remodeling of the craniovertebral junction and occipitoaxial realignment could contribute to syringomyelia resolution.

C1-2 Fusion in Atlantoaxial Dislocation and Basilar Invagination with and without Chiari Malformation: Clinical/Radiological and Craniometric Results

Patients with Chiari malformation (CM) associated with atlantoaxial dislocation (AAD) and basilar invagination (BI) may present with a small posterior cranial fossa, but data on the volumetric analysis are lacking. Additionally, whether additional foramen magnum decompression (FMD) is needed together with atlantoaxial fusion remains controversial. This study evaluated the volumetric alterations of the posterior cranial fossa in these patients and analyzed the radiological and clinical outcomes after posterior C1-C2 reduction and fixation plus C1 posterior arch resection. Thirty-two adult CM patients with AAD and BI (CM-AAD/BI group) and 21 AAD and BI patients without CM (AAD/BI-only group) who received posterior atlantoaxial fusion plus C1 posterior arch resection were retrospectively studied. The clinical and radiological outcomes and volumetric measurements of the posterior cranial fossa were evaluated. The majority of CM-AAD/BI patients (94%) improved clinically and radiologically at 12mo postoperatively, and none required additional FMD. Morphological analysis revealed a significant reduction in the bony posterior cranial fossa volumes of the CM-AAD/BI group (P<0.01) and the AAD/BI-only group (P<0.01) relative to those of the CM group. No significant differences were observed between the CM-AAD/BI and AAD/BI groups. Compared with patients with simple CM, patients with AAD/BI with or without CM demonstrated a considerably and equally reduced bony posterior cranial fossa volume. No additional FMD is needed in the treatment of CM-AAD/BI patients after posterior reduction and fusion plus C1 posterior arch resection.

Humeral Head Three-Part Posterior Fracture-Dislocation Reduced through a Posterior Approach and Fixed with Blocked Threaded Wires: A Consecutive Case Series.

Background and Objectives: Posterior fracture dislocations are rare. There is currently no uniformity regarding treatment. Therefore, outcomes are difficult to compare. We evaluated clinical and radiological outcomes of patients with humeral head posterior fracture dislocation treated with an open posterior reduction and then fixed with a biomechanically validated configuration of blocked threaded wires. Materials and Methods: 11 consecutive patients with humeral head three-part posterior fracture dislocation were treated by reduction through a posterior approach and fixed with blocked threaded wires. All patients were clinically and radiographically evaluated after a mean follow-up of 50 months. Results: The mean irCS was 86.1% (range: 70.5-95.3%). No significant difference was found between irCS at 6 and 12 months postoperatively and the final follow-up. Six patients noted their pain intensity as 0/10, three as 1/10, and two as 2/10. The postoperative reduction was considered as excellent in eight patients (Bahr's criteria) and good in the remaining three; at the final follow-up, reduction was excellent and good in seven and four patients, respectively. The mean neck-shaft angles at FU 0 and at the final FU were 137° and 132°, respectively. No signs of avascular necrosis, non-union, and arthritis progression were seen. No recurrence of dislocation or posterior instability symptoms were reported. Conclusions: We believe that our very satisfactory results stem from: (1) the manual reduction of the dislocation through a vertical posterior surgical approach, which does not produce further osteocartilaginous damage of the humeral head; (2) no multiple perforations of the humeral head are performed; (3) the threaded wires have a smaller diameter than the screws, therefore they preserve the bone tissue of the humeral head; (4) deperiostization or further detachment of soft tissues are not expected; (5) the adopted and validated system is stable and limits translation, torsion, and the collapse of the humeral head.

Case Report-Traumatic L5-S1 Instability: Are Upright Radiographs Potentially Dangerous?

Traumatic lumbosacral instability is a rare but potentially devastating injury. These injuries are frequently associated with neurologic injury and often result in long-term disability. Despite their severity, radiographic findings can be subtle, and multiple reports exist in which these injuries were not recognized on initial imaging. Transverse process fractures, high-energy mechanisms, and other injury features have been suggested as indications for advanced imaging, which has a high degree of sensitivity in detecting unstable injuries. A 21-year-old man presented to our level I trauma center after being ejected in a rollover motor vehicle collision. He sustained multiple injuries, including multiple lumbar transverse process fractures and a unilateral superior articular facet fracture of S1. Initial supine computed tomography (CT) images showed no displacement of the fracture and no listhesis or instability. Subsequent upright imaging in a brace, however, demonstrated significant displacement of the fracture with dislocation of the contralateral L5-S1 facet joint and significant anterolisthesis. The patient underwent open posterior reduction and stabilization of L4-S1 followed by L5-S1 anterior lumbar interbody fusion. The patient demonstrated excellent alignment on postoperative imaging. At 3 months postoperatively, he had returned to work, was ambulating without assistance, and reported minimal back discomfort and no lower extremity pain, numbness, or weakness. This case serves as a warning that supine CT imaging alone may not be sufficient to rule out unstable lumbar spine injuries, such as traumatic L5-S1 instability, and that upright radiographs in these potentially unstable injuries may represent a hazard to patients. Fractures involving the pedicle, pars, or facet joints as well as multiple transverse process fractures and/or a high-energy mechanism of injury should all raise suspicion of instability and warrant additional imaging. This article provides guidance on approaching treatment for patients with potential traumatic lumbosacral instability.

A novel less invasive endoscopic-assisted procedure for complete reduction of low-and high-grade isthmic spondylolisthesis performed by anterior and posterior combined approach.

The optimal surgical management of low- and high-grade isthmic spondylolisthesis (LGS and HGS -IS) is debated as well as whether reduction is needed especially for high-grade spondylolisthesis. Both anterior and posterior techniques can be associated with mechanical disadvantages as hardware failure with loss of reduction and L5 injury. We purpose a novel endoscopic-assisted technique (Sled technique, ST) to achieve a complete reduction in two surgical steps: first anteriorly through a retroperitoneal approach to obtain the greatest part of correction and then posteriorly to complete reduction in the same operation. ST efficacy and complications rate were evaluated through a retrospective functional and radiological analysis. Thirty-one patients, 12 male (38.7%) and 19 female (61.3%), average age: 45.4years with single level IS underwent olisthesis reduction by ST. Twenty-three IS involved L5 (74.2%), 7 L4 (22.5%) and 1 L3 (3.3%). No intraoperative complications were recorded. One patient required repositioning of a pedicle screw. A significant improvement of functional and radiological parameters (L4-S1 and L5-S1 lordosis) outcomes was recorded (p < 0.001). ST provides a complete reduction in the slippage in LGS and HGS. The huge anterior release as well as the partial reduction in the slippage by the endoscopic-assisted anterior procedure, because of the cage is acting as a "guide rail", facilitate the final posterior reduction, always complete in our series, minimizing mechanical stresses and neurological risks. gov Identifier: NCT03644407.

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

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. 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. 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). 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.