Intrafacet Spacer Placement as a Mobility-Sparing Bailout Option in Atlantoaxial Fusion Construct Salvage.

Background: Salvage revisions of atlantoaxial (AA) joint complex posterior segmental instrumented fusion constructs require careful individualized planning to prevent occipital extension. In this case report, we describe the use of bilateral intrafacet spacer placement as a mobility-sparing bailout option for the revision surgery. Case Report: A 64-year-old male with a history of diffuse idiopathic skeletal hyperostosis, extremely limited baseline cervical mobility, and prior AA posterior segmental instrumented fusion presented with increasing pain at his 6-month follow-up. Imaging showed fusion and hardware failures and dynamic instability. To prevent occipitocervical fixation, AA intra-articular fusion via a DTRAX spinal system (Providence Medical Technology, Inc) was used as an adjunct to a navigated C1 lateral mass and C2 pars screw posterior segmental instrumented fusion construct. The patient had an uneventful postoperative course and was discharged with resolution of symptoms. Three-month postoperative follow-up confirmed persistent resolution of symptoms and absence of complaints, along with successful arthrodesis on imaging. Conclusion: AA posterior segmental instrumented fusion revision is technically challenging, particularly when partial preservation of craniovertebral junction mobility is required. Bilateral intra-articular cages may be used as an adjunct to hardware revision in construct salvage when sturdy arthrodesis is desired without occipital extension and may represent a major potential strength of intra-articular cages.

Lateral atlanto-axial joint access using the C2 pedicle.

BACKGROUND: Neck pain and headaches can arise from the lateral atlanto-axial joint (LAA joint). This pain can be diagnosed with intra-articular injections of local anesthetic. A widely used technique for access to the lateral atlanto-axial joint uses a posterior approach, but this approach can be hazardous because of the proximity of the vertebral artery, the dural sac, and the C2 spinal nerve and dorsal root ganglion. OBJECTIVE: The objective was to describe and test a new technique for accessing the LAA joint that avoids structures that lie behind the joint. INTERVENTIONS: The new technique was described, and tested for tolerance in 10 patients with unilateral suboccipital pain, and tenderness over the LAA joint, along with evidence of LAA joint arthropathy on SPECT CT. The technique requires inserting a needle along a trajectory tangential to the dorsal surface of the C2 lamina. It involves obtaining a declined view of the C2 lamina and C2 pedicle. CONCLUSIONS: In all cases, the C2 pedicle was easily identified and allowed the needle to pass asymptomatically underneath the neurovascular structures behind the joint. The tactile response of the lamina of C2 provided important feedback regarding needle depth caudal to the LAA joint.

Unexpected postoperative atlantoaxial rotatory subluxation after excision of melanocytic nevi of the head and neck in older children: two case reports and literature review.

Postoperative atlantoaxial rotatory subluxation (AARS) is a rare complication that develops almost exclusively in children following oropharyngeal and otologic surgeries, proposing that oropharyngeal inflammatory responses and excessive head rotation are responsible factors. However, there have been no reports of AARS after excision of a nevus on the head and neck. Here, we present two cases of AARS following limited head rotation during simple nevus excision. Patient 1, a 9-year-old girl, complained of neck pain and limited range of motion after excision of the nevus on the neck. After 2 months, computed tomography and magnetic resonance imaging finally revealed AARS with a ruptured transverse atlantal ligament. A month of halo traction was required for the treatment. Patient 2, an 11-year-old girl, presented with immediate pain and limited neck extension after tissue expander insertion under the upper chest and excision of the nevus on her left cheek. The diagnosis was promptly made using cervical spine radiography. A cervical collar was applied for 1 month. Both patients recovered without any complications after treatment. This report highlights the importance of suspicion for AARS after surgery regardless of surgical duration or amount of head rotation.

Clinical characteristics of upper cervical spine injuries in children: a retrospective case series.

OBJECTIVE: Pediatric cervical spine injuries (CSI) can be devastating, and children < 8 years are particularly at risk for upper CSI given unique anatomical differences. Diagnosis of these injuries can be delayed due to variable clinical presentations and a paucity of existing literature. The authors aimed to characterize the spectrum of pediatric upper CSI. METHODS: This was a retrospective, single-center case series of trauma patients aged < 16 years who were assessed at a level I pediatric trauma center and diagnosed with upper CSI between 2000 and 2020. Patients were included if they had evidence of bony or ligamentous injury from the occiput to C2 on imaging or autopsy. Data were obtained from manual chart review and analyzed using descriptive statistics. RESULTS: In total, 502 patients were screened and 202 met inclusion criteria. Of these, 31 (15%) had atlanto-occipital (AO) joint distractions, 10 (5%) had atlanto-axial (AA) joint distractions, 31 (15%) had fractures of C1-2, and 130 (64%) had ligamentous injury without joint distraction. Of the patients with AO injury, 15 patients had complete dislocation. They presented as hemodynamically unstable with signs of herniation and 14 died (93%). In contrast, 16 had incomplete dislocation (subluxation). They usually had stable presentations and survived with good outcomes. Of the patients with AA injury, 2 had complete dislocation, presented with arrest and signs of herniation, and died. In contrast, 8 patients with subluxation mostly presented as clinically stable and all survived with little residual disability. The most common fractures of C1 were linear fractures of the lateral masses and of the anterior and posterior arches. The most common fractures of C2 were synchondrosis, hangman, and odontoid fractures. Overall, these patients had excellent outcomes. Ligamentous injuries frequently accompanied other brain or spine injuries. When these injuries were isolated, patients recovered well. CONCLUSIONS: Among upper CSI, AO and AA joint injuries emerged as particularly severe with high mortality rates. Both could be divided into complete dislocations or incomplete subluxations, with clear clinical differences and the former presenting with much more severe injuries. Lateral cervical spine radiography should be considered during resuscitation of unstable trauma patients to assess for these CSI subtypes. Fractures and ligamentous injuries were clinically heterogeneous, with presentations and outcomes depending on severity and associated injuries.

Posterior-only approach for treatment of irreducible traumatic Atlanto-axial dislocation, secondary to type-II odontoid fracture; report of a missed case, its management and review of literature.

INTRODUCTION AND IMPORTANCE: Odontoid fracture (OF) is among the most common and challenging cervical spine fractures in regards to the treatment and surgical approach. Atlanto-axial dislocation (AAD) is considered a significant complication after failed non-surgical treatment of OF. Traditionally, it requires anterior odontoidectomy followed by posterior C1-C2 reduction and fusion. In latest studies, Atlanto-axial joint (AAJ) remodeling in a posterior-only approach has got attention. CASE PRESENTATION: We herein present a 30-year-old man with missed type-II OF, presenting with irreducible anterior AAD and progressive neurological deficit. Old non-united OF with dorsal callous formation, compressing spinal cord, was detected. The patient underwent correction of the deformity and reduction of the fracture utilizing the posterior-only approach. AAJ remodeling, callous release and C1-C2 fusion was performed in standard prone position, under fluoroscopic guide and intraoperative electrophysiological monitoring. The patient had uneventful surgery and postoperative course and was neurologically intact with appropriate alignment in 6-month follow-up. CLINICAL DISCUSSION: The irreducible AAD following type-II OF could be successfully treated with posterior-only approach (C1-C2 fusion). CONCLUSION: Type-II OF is considered unstable requiring surgical management. Close follow-up and appropriate patient education is mandatory in non-surgical treatment. Irreducible AAD has been managed with anterior odontoid resection and posterior fusion. Several complications of anterior surgery, makes posterior-only approach a noticeable choice.

Long-term efficacy of self-designed posterior atlas polyaxial screw-plate in the treatment of unstable atlas fracture / 中华创伤杂志

Objective:To investigate the long-term efficacy of self-designed posterior atlas polyaxial screw-plate in the treatment of unstable atlas fracture.Methods:A retrospective case series study was conducted to analyze the clinical data of 20 patients with unstable atlas fracture who were admitted to Affiliated Honghui Hospital of Xi′an Jiaotong University from January 2011 to April 2013, including 14 males and 6 females, aged 23-60 years [(42.7±8.6)years]. All the patients were treated with internal fixation using self-designed posterior atlas polyaxial screw-plate. The operation time and intraoperative bleeding volume were recorded. The fracture reduction was evaluated by CT scan at 3 days after surgery. The bone healing was observed by X-ray (anterior-posterior and lateral views of the cervical spine) and CT scan at 9 months after surgery. The delayed spinal cord injuries were evaluated by Frankel grade at 1 and 2 years after surgery and at the last follow-up. The Visual Analogue Scale (VAS) before surgery, at 3 months, 1 year, 2 years after surgery and at the last follow-up were compared. The axial rotation, flexion and extension range of the cervical spine at 3 months, 1 year, 2 years after surgery and at the last follow-up were compared. Intraoperative and postoperative complications were observed.Results:All the patients were followed up for 121-148 months [(135.0±6.8)months]. The operation duration was 68-122 minutes [(86.0±14.1)minutes], with the intraoperative blood loss of 90-400 ml [(120.0±67.9)ml]. The CT scan of the cervical spine at 3 days after surgery showed all satisfactory fracture reduction. Satisfactory bone reunion was observed at 9 months after surgery. All patients were scaled as Frankel grade E at 1 year, 2 years and at the last follow-up after surgery, with no delayed spinal cord injuries observed. The VAS scores of the cervical spine at 3 months, 1 year, 2 years after surgery and at the last follow-up were 2.0(1.3, 3.0)points, 1.0(1.0, 1.8)points, 1.0(0.3, 1.0)points and 1.0(0.3, 1.0)points, which were significantly lower than that before surgery [7.0(6.0, 7.8)points] ( P<0.05), with significantly lower scores at 1-, 2-year after surgeny and at the last follow-up than at 3 months after surgery ( P<0.05). There were no significant differences among the other time points ( P>0.05). The axial rotation ranges of the cervical spine were (103.0±8.3)°, (128.3± 11.4)° and (129.8±13.6)° at 1 year, 2 years after surgery and at the last follow-up respectively, which were significantly higher than that at 3 months after surgery [(85.3±7.0)°] ( P<0.05); It was further improved at 2 years after surgery and at the last follow-up compared with that at 1 year after surgery ( P<0.05), with no significant difference at the last follow-up compared with that at 2 years after surgery ( P>0.05). The flexion and extension range of the cervical spine at 1 year, 2 years after surgery and at the last follow-up were (65.5±4.8)°, (78.3±6.5)° and (79.3±6.9)° respectively, which were significantly higher than that at 3 months after surgery [(54.3±4.4)°] ( P<0.05); It was further improved at 2 years after surgery and at the last follow-up compared with that at 1 year after surgery ( P<0.05), with no significant difference between the last follow-up and 2 years after surgery ( P>0.05). No intraoperative injuries such as arteriovenous injury were observed. No incision infection or dehiscence occurred after surgery, with no complications caused by long-term bed rest such as lung or urinary tract infection, pressure sore formation or deep vein thrombosis occurred. No loosening or breakage of the screw and atlas plate was observed at the long-term follow-up. One patient had mild cervical pain, snap during rotation, and limited range of motion at the last follow-up. Conclusion:Self-designed posterior atlas polyaxial screw-plate has merits including small surgical wounds, satisfactory reduction, solid fixation, obvious pain relief, effective preservation of the previous cervical motion, few complications, and satisfactory long-term efficacy in the treatment of unstable atlas fracture.

Traumatic C2-C3 subluxation with atlanto-axial dislocation managed by posterior approach - A rare case report.

INTRODUCTION AND IMPORTANCE: Traumatic subluxation of C2-C3 with Atlanto-Axial dislocation is very rare and uncommon condition. Only a very few case reported. What constitutes appropriate management in cases of traumatic C2-C3 subluxation with Atlato-axial dislocation is still controversial due to the infrequency of this injury. We managed a patient who had traumatic C2-C3 subluxation with Atlanto-axial dislocation following a history of trauma through posterior approach successfully. CASE DESCRIPTION: A 45-year male day laborer presented with neck pain with progressive neurological deficit after two episodes of fall with heavy object within 1 year. Imaging revealed complete dislocation of C2 over C3 with Atlanto-Axial Dislocation. The patient was approached for posterior fixation with attempt to reduction per-operatively with skeletal traction and C1, C2, C3 joint distraction. After distraction of the joint, we achieved to do reduction of the C2-C3 and Atlanto-Axial joint. We did C1 lateral mass, C2 pedical and C3, C4 lateral mass screw and put a spacer in between C1-C2 facet joint. The patient was improved immediately after the operation. One year follow up shows, he was completely well. One year follow up shows in radiography proper alignment with fusion between C1, C2 and C3. CLINICAL DISCUSSION: Traumatic subluxation of the C2 vertebra is due to fractures of the lamina, articular facets, pedicles, or pars interarticularis and was first described by Bouvier in1843. To the best of our knowledge there has been 3/4 cases reported till now with traumatic C2-C3 subluxation with AAD. In three similar cases before ours, one was reported to be reduced after 3 weeks of bidirectional cervical traction and another two cases were managed by open reduction and stabilization. We managed this rare case surgically successfully through posterior approach with good outcome. CONCLUSION: Our management through posterior approach between C1 to C4 shows very good outcome with proper fusion. But it needs proper understanding the anatomy and mechanism of reduction by careful reading the image. Its needs more case description and management to establish a standard treatment for this type of disease.

Reference values of four measures of craniocervical stability using upright dynamic magnetic resonance imaging.

PURPOSE: To establish reference ranges for four most commonly used diagnostic measures of craniocervical instability (CCI) in three cervical sagittal positions. This necessitated development of a reliable measurement protocol using upright, dynamic MRI (udMRI), to determine differences in the extent of motion between positions, and whether age and sex correlate with these measures. MATERIALS AND METHODS: Deidentified udMRIs of 50 adults, referred for reasons other than CCI, were captured at three positions (maximal flexion, maximal extension and neutral). Images were analyzed, providing measures of basion-axial interval, basion-axial angle, basion-dens interval (BDI) and the Grabb-Oakes line (GOL) for all three positions (12 measures per participant). All measures were independently recorded by a radiologist and neurosurgeon to determine their reliability. Descriptive statistics, correlations, paired and independent t-tests were used. Mean (± 2 SD) identified the reference range for all four measures at each craniocervical position. RESULTS: The revised measurement protocol produced inter-rater reliability indices of 0.69-0.97 (moderate-excellent). Fifty adults' (50% male; mean age 41.2 years (± 9.7)) reference ranges for all twelve measures were reported. Except for the BDI and GOL when moving between neutral and full flexion, significant extents of movement were identified between the three craniocervical positions for all four measures (p ≤ 0.005). Only a minor effect of age was found. CONCLUSIONS: This is the first study to provide a rigorous standardized protocol for four diagnostic measures of CCI. Reference ranges are established at mid and ends of sagittal cervical range corresponding to where exacerbations of signs and symptoms are commonly reported.

Efficacy evaluation of cluster nursing in robot-assisted surgery for the treatment of reducible atlantoaxial dislocation / 中华创伤杂志

Objective:To explore the effect of cluster nursing in robot-assisted surgery for the treatment of reducible atlantoaxial dislocation.Methods:A retrospective cohort study was conducted to analyze the clinical data of 41 patients with reducible atlantoaxial dislocation treated by robot-assisted surgery in Honghui Hospital affiliated to Xi′an Jiaotong University from January 2019 to December 2021, including 28 males and 13 females; aged 18-79 years [(45.2±10.3)years]. Ninteen patients received cluster nursing (cluster nursing group), with operating room nursing team set up on the basis of routine nursing and performed cluster nursing in line with evidence-based medicine. Twenty-two patients received routine nursing (routine nursing group). The operation time, intraoperative blood loss, frequency of intraoperative C-arm fluoroscopy, time of drainage tube placement and chief surgeon′s satisfaction for nursing were compared between the two groups. The degree of pain was evaluated by pain numerical score (NRS) at 12 hours, 24 hours, 48 hours, 72 hours, 1 month and 3 months after operation and at the last follow-up. The neck disability index (NDI) was assessed at 1 day before operation, 1 month after operation, 3 months after operation and at the last follow-up. The complications were observed.Results:All patients were followed up for 12-18 months [(16.7±3.7)months]. The operation time, intraoperative blood loss, frequency of C-arm fluoroscopy and time of drainage tube placement in cluster nursing group were (82.9±10.4)minutes, (105.9±11.8)ml, (3.8±0.6)times and (1.5±0.4)days, while those in routine nursing group were (125.7±12.8)minutes, (208.4±13.8)ml, (9.7±2.3)times and (3.6±0.6)days, respectively (all P<0.01). The chief surgeon′s satisfaction for nursing was 94.7% (18/19) in cluster nursing group and was 68.2% (15/22) in routine nursing group ( P<0.05). The NRS in cluster nursing group was (6.2±0.4)points, (6.0±0.7)points, (4.9±1.1)points, (2.7±0.5)points, (1.9±0.4)points, (1.8±0.4)points and (1.5±0.3)points at 12 hours, 24 hours, 48 hours, 72 hours, 1 month and 3 months after operation and at the last follow-up, while it was (7.6±0.6)points, (6.8±1.2)points, (5.8±1.5)points, (4.2±0.8)points, (3.4±0.7)points, (2.6±0.5)points and (2.2±0.5)points in routine nursing group ( P<0.05 or 0.01). There was no significant difference in the NDI between the two groups at 1 day before operation, but the NDI in cluster nursing group was 20.6±4.5, 14.6±2.8 and 10.7±2.5 at 1 month and 3 months after operation and at the last follow-up, while it was 26.9±4.1, 18.7±3.3 and 13.7±1.7 in routine nursing group (all P<0.01). There was no hematoma, infection or implant-related complications in both groups .Conclusion:For robot-assisted surgery in the treatment of reducible atlantoaxial dislocation, cluster nursing is associated with shortened operation time and time of drainage tube placement, decreased intraoperative blood loss and frequency of intraoperative fluoroscopy, increased chief surgeon′s satisfaction for nursing, reduced pain and accelerated functional recovery.

Research progress of Chiari malformation type I and atlantoaxial instability / 中华骨科杂志

Chiari malformation (CM) is a group of congenital cerebellar tonsillar hernia malformations involving the craniocervical junction. Chiari malformation type I (CMI) is the most common in clinic, however its pathogenesis is still unclear, and there is no consensus on the surgical treatment standard of CMI. At present, the most widely accepted is the theory of posterior fossa incompatibility, so doctors at home and abroad use posterior fossa decompression (PFD) and posterior fossa compression with duraplasty (PFDD) as the gold standard for surgical treatment, and have their own experience and technical improvement. However, the volume of the posterior cranial fossa in some patients is no different from that in healthy people, and about 30% of the patients with CMI have poor results after posterior cranial fossa decompression. As a result, this operation cannot treat all patients with CMI. In recent years, with the development of imaging, the progress of diagnostic technology and the deepening of understanding of CM, some studies have shown that CMI may be related to atlantoaxial instability, and proposed that CMI is the secondary factor of atlantoaxial instability, and atlantoaxial fusion is the standard of surgical treatment, which has caused great controversy in academic circles. Different clinical research results of scholars support or oppose this theory: some studies have shown that the clinical symptom relief rate of patients with CMI treated with atlantoaxial fusion is 96.9%; another study showed that 70% of patients with CMI underwent atlantoaxial fusion had improved neurological function, but the overall postoperative effect was not satisfactory. In short, CMI is related to many diseases and its clinical manifestations are complex. Therefore, individualized management and treatment should be carried out in combination with the clinical manifestations and auxiliary examination results of patients.

Axial instrument strategy for atlantoaxial dislocation with complex artery variation / 中华骨科杂志

Objective:To evaluate the axial instrument strategy for atlantoaxial dislocation with complex vertebral artery variation.Methods:A total of 55 patients with atlantoaxial dislocation who underwent surgical treatment from January 2019 to December 2021 were retrospectively analyzed, including 14 males and 41 females, aged 54.0±12.8 years (range, 22-78 years). Among these patients, 10 patients with unilateral vertebral artery high ride with contralateral vertebral artery occlusion, 30 patients with bilateral vertebral artery high ride with single dominant vertebral artery, 15 patients with bilateral vertebral artery high ride. All patients underwent posterior reduction and internal fixation. Visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score were used to evaluate the postoperative efficacy.Results:All patients completed the surgery successfully with a follow-up time of 14.6±5.5 months (range, 6-24 months). C 2 pedicle screw fixation was performed on the non-dominant side of unilateral vertebral artery high ride and the non-dominant side of bilateral vertebral artery high ride with one dominant vertebral artery (40 vertebraes). The dominant side of unilateral high vertebral artery and bilateral high vertebral artery with one dominant vertebral artery was fixed with C 2 medial "in-out-in" screw (10 vertebraes), C 2 isthmus screw (21 vertebraes), C 2 without screw (9 vertebraes) only extended the fixed segment. For bilateral vertebral artery high ride patients, one side was used C 2 "in-out-in" pedicle screws (right 10 vertebraes, left 5 vertebraes), and the other side was fixed with C 2 medial "in-out-in" screw (8 vertebraes), C 2 isthmus screw (5 vertebraes), C 2 without screw only extended the fixed segment (2 vertebraes). The JOA scores were 8.5±1.8, 13.9±1.3, and 14.4±1.1 preoperatively, 6 months postoperatively, and at the final follow-up, respectively, with statistically significant differences ( F=279.40, P<0.001). JOA at 6 months postoperatively and at the final follow-up was greater than preoperatively, and the differences were statistically significant ( P<0.05), whereas the differences in JOA scores at 6 months postoperatively and at the final follow-up was not statistically significant ( P>0.05). Preoperative, 6 months postoperatively and final follow-up cervical VAS scores were 3.7±1.9, 2.1±0.9 and 1.6±1.0, respectively, with statistically significant differences ( F=39.53, P<0.001). The cervical VAS at 6 months postoperatively and at the last follow-up was less than that before surgery, and the differences were statistically significant ( P<0.05). Cervical VAS scores at 6 months postoperatively were greater than at the last follow-up, with a statistically significant difference ( P<0.05). Conclusion:For patients with atlantoaxial dislocation with complex vertebral artery variation, C 2 lateral "in-out-in" screw, C 2 medial "in-out-in" screw, isthmus screw fixation or C 2 without screw only extended the fixed segment can obtain good clinical efficacy.

3D-printed navigation template-assisted and freehand posterior cervical screw fixation of atlantoaxial fracture: a comparison of efficacies / 中华创伤杂志

Objective:To compare the efficacies of 3D-printed navigation template assisted and freehand posterior cervical screw fixation of atlantoaxial fractures.Methods:A retrospective cohort study was used to analyze the clinical data of 22 patients with atlantoaxial fractures admitted to Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology from September 2018 to December 2020. There were 13 males and 9 females, with age range of 26-68 years [(50.7±11.9)years]. All the patients underwent posterior atlantoaxial pedicle screw internal fixation and fusion, among whom 11 patients admitted from November 2019 to December 2020 were assisted with 3D printed navigation templates for the placement of pedicle screws (assisted group) and 11 patients admitted from September 2018 to October 2019 used the traditional way of placing pedicle screws (freehand group). A total of 88 pedicle screws were implanted, with 44 pedicle screws in each group. The operation time, intraoperative blood loss, and intraoperative fluoroscopy frequency were compared between the two groups. The visual analogue score (VAS) and Japanese Orthopedic Society (JOA) score were also compared before operation, at 3 days, 3 months, 6 months postoperatively and at the last follow-up. The accuracy of pedicle screw placement was evaluated according to the Kawaguchi classification, and complications were observed.Results:All the patients were followed up for 24-30 months [(26.4±1.8)months]. The assisted group showed the operation time of (87.3±19.5)minutes and the intraoperative fluoroscopy frequency of (6.4±1.4)times, decreased compared with the freehand group [(115.5±23.0)minutes, (10.3±1.7)times] [(all P<0.01). However, no significant difference was observed in the intraoperative blood loss between the two groups ( P>0.05). Both groups demonstrated comparable VAS and JOA score before operation, at 3 days, 3 months, 6 months postoperatively and at the last follow-up (all P>0.05). Furthermore, the assisted group exhibited a significantly higher accuracy of pedicle screw placement [95.5% (42/44)] compared with the freehand group [79.5% (35/44)] ( P<0.05). Notably, there were no intraoperative vertebral artery injury, spinal cord injury, or cerebrospinal fluid leakage in either group, or internal fixation loosening, fracture, nonunion in either group after operation. Conclusion:Compared with freehand posterior cervical screw placement, 3D-printed navigation template-assisted posterior cervical pedicle screw fixation of atlantoaxial fracture can shorten the operation time, reduce the intraoperative fluoroscopy frequency, and improve the accuracy of screw placement.

O-arm navigation system-assisted upper cervical pedicle screw internal fixation for traumatic atlantoaxial instability / 中华创伤杂志

Objective:To explore the efficacy of O-arm navigation system-assisted upper cervical pedicle screw internal fixation in the treatment of traumatic atlantoaxial instability.Methods:A retrospective cohort study was conducted to analyze the clinical data of 61 patients with atlantoaxial instability admitted to Affiliated Honghui Hospital of Xi′an Jiaotong University from January 2021 to June 2022, including 34 males and 27 females, aged 20-77 years [(50.2±13.1)years]. A total of 38 patients were treated with unarmed screw placement (unarmed group), and 23 with O-arm navigation system-assisted screw placement (navigation group). The unarmed group was divided into experienced group ( n=20) and unexperienced group ( n=18) based on the surgeons′ experience (whether they had 20 years or longer experience of spinal surgery and performed more than 100 atlantoaxial surgeries independently). The screw placement and surgical time of each group was recorded. The cervical CT scan was conducted at 7 days after surgery to evaluate the satisfaction rate of pedicle screw placement and cortical penetration rate according to Neo grading criteria. The cervical nerve function of the patients before, at 7 days after surgery and at the last follow-up was evaluated using the Japanese Orthopedic Association (JOA) score and the Neck Disability Index (NDI). The occurrence of complications was observed. Results:All patients were followed up for 9-25 months [(16.3±4.2)months]. There were no statistically significant differences in the screw placement and surgical time between the navigation group and the unarmed group (all P>0.05). The screw placement time of the navigation group was (41.0±7.8)minutes, longer than that of the experienced group [(23.6±6.8)minutes] ( P<0.01) and shorter than that of the unexperienced group [(50.1±10.1)minutes] ( P<0.05). The surgical time of the navigation group was (101.9±9.9)minutes, which was longer than that of the experienced group [(67.6±8.3)minutes] ( P<0.01) and shorter than that of the unexperienced group [(126.1±16.4)minutes] ( P<0.01). The satisfaction rate of pedicle screw placement and cortical penetration rate of the navigation group were 98.9% and 4.3%, respectively, which were better than those of the unarmed group (94.1% and 17.8%), the experienced group (96.2% and 13.8%), and the unexperienced group (91.7% and 22.2%) ( P<0.05 or 0.01). There was no statistically significant difference in JOA score or NDI before, at 7 days after surgery or at the last follow-up between the navigation group and the unarmed group, and no difference between the navigation group and the experienced group or the unexperienced group (all P>0.05). No complications such as spinal cord nervous or vascular injuries were observed during surgery in the navigation group or the unarmed group. Conclusions:Compared with the unarmed screw placement, O-arm navigation system-assisted upper cervical pedicle screw internal fixation shows no significant difference in screw placement time, surgical time, and postoperative neurological function status in the treatment of traumatic atlantoaxial instability, but has a higher accuracy in screw placement. Compared with the experienced surgeons′ unarmed screw placement, the technique also has higher screw placement accuracy but longer screw placement time and surgical time. Whereas in comparison with unexperienced surgeons′ unarmed screw placement, the technique can not only significantly improve its screw placement accuracy, while shortening screw placement time and surgical time so as to improve the surgical safety.

Posterior atlantoaxial non-fusion fixation versus anterior cervical odontoid screw fixation in treatment of odontoid fracture of Anderson-D'Alonzo type Ⅱ / 中华创伤骨科杂志

Objective:To compare the curative effects of posterior atlantoaxial non-fusion fixation and anterior cervical odontoid screw fixation in the treatment of odontoid fracture of Anderson-D'Alonzo type Ⅱ.Methods:A retrospective study was conducted to analyze the clinical data of 21 patients with odontoid type II fracture who had been treated at Department of Spine Surgery, The Central Hospital of Luohe from January, 2015 to January, 2020. The patients were divided into a posterior group subjected to posterior atlantoaxial non-fusion fixation and an anterior group subjected to anterior cervical odontoid screw fixation. In the posterior group of 12 patients, there were 7 males and 5 females with an age of (42.2±11.8) years. In the anterior group of 9 patients, there were 5 males and 4 females with an age of (40.0±9.1) years. The 2 groups were compared in terms of operation time, bleeding volume, intraoperative fluoroscopy, fusion time, cervical rotation and neck dysfunction index (NDI).Results:The differences in the preoperative general information were not statistically significant between the 2 groups, indicating comparability ( P>0.05). The implants were successfully inserted in all patients. Intraoperative fracture reduction was satisfactory and no arteriovenous or spinal cord injuries occurred. The mean follow-up time was (24.5±11.3) months. The operation time [(108.5±15.9) min] and bleeding volume [(48.3±12.2) mL] in the anterior group were significantly less than those in the posterior group [(153.9±34.2) min and (275.8±56.0) mL], and the intraoperative fluoroscopy [(13.0±2.1) times] in the anterior group was significantly higher than that in the posterior group [(7.2±1.4) times] ( P<0.05). There was no statistically significant difference in fracture healing time between the 2 groups ( P>0.05). There was no statistically significant difference either in total cervical rotation or NDI between the 2 groups at the last follow-up ( P>0.05). Conclusions:Posterior atlantoaxial non-fusion fixation can preserve the range of rotation of the cervical spine and reduce the dysfunction of the cervical spine. The anterior screw fixation may result in shorter operation time and less intraoperative bleeding, but more intraoperative X-ray fluoroscopy. Therefore, the 2 internal fixation methods should be adopted on the basis of each individual in the treatment of odontoid type Ⅱ fracture to achieve good curative results.

Preliminary application of self-designed posterior reduction forceps for atlantoaxial dislocation in treatment of irreducible atlantoaxial dislocation / 中华创伤骨科杂志

Objective:To evaluate the preliminary clinical application of our self-designed posterior reduction forceps for atlantoaxial dislocation in the reduction and fixation of irreducible atlantoaxial dislocation with simple posterior screw-rod system.Methods:Our posterior reduction forceps was self-designed and developed to assist simple posterior screw-rod system in the treatment of irreducible atlantoaxial dislocation based on the posterior atlantoaxial screw-rod system. A retrospective study was conducted to analyze the clinical data of 5 patients with irreducible atlantoaxial dislocation who had been treated from January 2021 to October 2022 at Department of Spine Surgery, General Hospital of Southern Theatre Command of PLA with our self-designed posterior reduction forceps. There were 2 males and 3 females, aged 53, 62, 45, 32 and 48 years, respectively. Diagnosis: 1 case of free odontoid process combined with atlantoaxial dislocation, 2 cases of atlantoaxial dislocation, and 2 cases of old odontoid process fracture combined with atlantoaxial dislocation. Respectively, their preoperative Japanese Orthopaedic Association (JOA) scores were 9, 11, 12, 13 and 10 points and their atlanto-dental intervals (ADI) 9.8, 7.4, 6.6, 6.4 and 8.5 mm. Postoperatively, atlantoaxial reduction and spinal cord compression were evaluated by X-ray, CT, and MRI examinations, and internal fixation, atlanto-axial sequence, and bone graft fusion by X-ray and CT examinations. One week after surgery, the JOA scores were used to evaluate the patients' neurological function and the ADI was measured to evaluate the atlantoaxial reduction.Results:The surgery was successfully performed in the 5 patients, with no intraoperative complications like neurovascular injuries to the spinal cord. The postoperative atlantoaxial reduction was satisfactory, the position of internal fixation was good, the compression to the spinal cord was relieved, and the clinical symptoms were significantly improved. At 1 week after surgery, respectively, the JOA score: 13, 14, 14, 15 and 13; the ADI: 2.6, 2.1, 1.8, 1.5 and 2.2 mm; the follow-up time: 3, 6, 12, 9 and 6 months; the bone fusion time: 3, 3, 6, 6 and 3 months. Follow-ups revealed no loosening or fracture of internal fixation, good atlanto-axial sequence, and no recurrence of dislocation.Conclusion:Our self-designed posterior reduction forceps for atlantoaxial dislocation can assist the simple posterior screw-rod system to treat irreducible atlantoaxial dislocation, leading to good preliminary clinical outcomes.

Biomechanical evaluation of four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs

Purpose: This study compared, through biomechanical evaluation under ventral flexion load, four surgical techniques for ventral stabilization of the atlantoaxial joint in dogs. Methods: In total, 28 identical atlantoaxial joint models were created by digital printing from computed tomography images of a dog, and the specimens were divided into four groups of seven. In each group, a different technique for ventral stabilization of the atlantoaxial joint was performed: transarticular lag screws, polyaxial screws, multiple screws and bone cement (polymethylmethacrylate­PMMA), and atlantoaxial plate. After the stabilization technique, biomechanical evaluation was performed under ventral flexion load, both with a predefined constant load and with a gradually increasing load until stabilization failure. Results: All specimens, regardless of stabilization technique, were able to support the predefined load without failing. However, the PMMA method provided significant more rigidity (p ≤ 0.05) and also best resisted the gradual increase in load, supporting a significantly higher maximum force (p ≤ 0.05). There was no statistical difference in flexural strength between the transarticular lag screws and plate groups. The polyaxial screws method was significantly less resistant to loading (p ≤ 0.05) than the other groups. Conclusions: The PMMA technique had biomechanical advantages in ventral atlantoaxial stabilization over the other evaluated methods.

Dual-Energy Computed Tomography Collagen Density Mapping of the Cranio-Cervical Ligaments-A Retrospective Feasibility Study.

The objectives of this study were to investigate the mean collagen content of the atlanto-axial joint (AAJ) ligaments in a cohort without inflammatory disease and to analyze clinical confounders such as age, sex, and presence of ligamentous calcifications. A total of 153 patients who underwent dual-energy computed tomography (DECT) due to various reasons (e.g., suspected cancer or infection) were included in this retrospective study. Reconstruction of collagen density maps from the DECT dataset was performed. Region of interest (ROI) analysis was performed to assess densities in the following regions: ligamentum transversum atlantis (LTA), ligamenta alaria, fasciculi longitudinales, ligamentum nuchae, and retro-odontoid soft tissue (RDS). Osteoarthritis (OA) and the presence of calcifications were assessed by two experienced readers blinded to clinical data. Subgroup comparisons were performed using unpaired t-tests. The correlation of collagen density and clinical factors was investigated using Pearson's correlation coefficient. Mean LTA collagen density was 141.7 (SD 35.7). Ligamentous calcifications were rare (14.4 %). OA of the AAJ was common (91.5 %). LTA collagen density was not associated with age (Pearson's r of 0.109; p = 0.180) and was not significantly higher in patients with OA (p = 0.070). No correlations between RDS thickness, collagen density or calcifications were found. Our results show collagen density mapping of the cranio-cervical joint ligaments to be feasible; collagen densities are not significantly associated with age, sex, AAJ degeneration, or asymptomatic ligamentous calcification.

Fijación con tornillos transarticulares C1-2 combinada con técnica de Gallie en luxación atloaxoidea / C1-2 transarticular screw fixation combined with Gallie technique in atloaxial dislocation

RESUMEN Introducción: existen múltiples técnicas quirúrgicas para tratar la inestabilidad del complejo atlantoaxial. La fijación con tornillos transarticulares C1-2 (técnica de Magerl) ha mostrado altos índices de fusión, y puede ser combinada con los sistemas de alambrado descritos inicialmente, para garantizar mayor estabilidad al constructo. Presentación de caso: masculino, 62 años, que luego de una caída de dos metros, es traído a la institución con dolor cervical y con imposibilidad para mover las extremidades. Al examen neurológico, presentaba un grado B en la American Spinal Injury Classiffication Scale. Se diagnostica fractura odontoidea conminuta y luxación atloaxoidea. Se le aplica tracción cervical con lo que se logra la alineación vertebral. Se planifica tratamiento quirúrgico mediante técnica de Magerl. Ante trayectoria subóptima del tornillo inicial, se combina con fusión atloaxoidea posterior, mediante técnica de Gallie. Se mantuvo inmovilización externa durante dos semanas. Al egreso hospitalario, el paciente logra la deambulación, aunque con disparesia braquial con predominio distal. En estudios radiológicos evolutivos, no se observa fallo del sistema de instrumentación. Conclusiones: en este caso la utilización de la técnica de Gallie, ante la malposición de uno de los tornillos transarticulares C1-2, permitió conservar la estabilidad del constructo.

ABSTRACT Introduction: Multiple surgical techniques exist to treat instability of the atlantoaxial complex. Transarticular C1-2 screw fixation (Magerl's technique) has shown high fusion rates, and can be combined with the initially described wiring systems to guarantee greater stability to the construct. Case presentation: male, 62 years old, who after a two-meter fall, was brought to the institution reporting cervical pain and inability to move the limbs. On neurological examination, he had a grade B on the American Spinal Injury Classiffication Scale. A comminuted odontoid fracture and atloaxial dislocation were diagnosed. Cervical traction was applied and vertebral alignment was achieved. Surgical treatment was planned using Magerl's technique. Given the suboptimal trajectory of the initial screw, it was combined with posterior atloaxoid fusion, using Gallie technique. External immobilization was maintained for two weeks. At hospital discharge, the patient achieved ambulation, maintaining brachial dysparesis with distal predominance. In evolutionary radiological studies, no failure of the instrumentation system was observed. Conclusions: In our case, the use of the Gallie technique, in view of the malposition of one of the C1-2 transarticular screws, allowed preserving the stability of the construct.

Normal Range of Movement During Rotation Stress Testing for the Alar Ligaments: An Observational Study.

OBJECTIVE: The purpose of this study was to determine the normal range of rotation occurring during rotation stress testing for alar ligament integrity and to ascertain whether rotation range on testing is affected by an individual's age. METHOD: In this observational study, 88 people aged 18 to 86 years old with no current neck problems or known risk factors for craniocervical instability underwent rotation stress testing for the alar ligaments. The test was performed in each direction in neutral, flexion, and extension, with the participant both sitting and supine. Rotation range was recorded using an electromagnetic movement tracking system. Range was assessed overall and then compared by 10-year age groups using analysis of variance. Reliability of measurements was assessed by intraclass correlation coefficient(2,1) and standard error of measurement. RESULTS: Mean angles of upper cervical rotation ranged between 10.91° (standard deviation 3.38°) to 16.12° (standard deviation 5.13°). Overall measured rotation ranged from 1.37° to 33.22°. Participants in older age groups generally displayed reduced rotation; however, the reduction was less than 4°. Reliability of rotation measurements was good to excellent, with the intraclass correlation coefficient ranging from 0.80 to 0.99. CONCLUSIONS: Normal range of rotation measured during stress testing for the alar ligament varied widely but did not exceed 33o. All values measured in this study fell below recommendations for ligament integrity. Age-related change was not clinically significant in the interpretation of this test in this asymptomatic population.

Morphological and Morphometric Analysis of Superior Articular Facet of Atlas Vertebra.

INTRODUCTION: The first cervical vertebra, also referred to as the atlas, forms a vital part of the craniovertebral junction (CVJ). The anatomy of the atlas is essential to understand the basis for CVJ anomalies and their surgical correction. The present study was undertaken to provide accurate morphometry and describe the morphological variations of the superior articular facet (SAF) of the atlas.  Methods: In this observational, cross-sectional study, the length and width of the SAF of 150 atlas were measured using a digital caliper. The variations in the morphology of the SAF in the same bones were also recorded. Z-test was applied to find the statistically significant difference between the measurements of the SAF of the atlas on the right and left sides. p-value ≤ 0.05 was considered statistically significant. RESULTS: The width of the SAF of the atlas was found to be significantly (p < 0.001) greater on the left side (8.76 mm to 14.84 mm) compared to the right (7.67 mm to 14.83 mm). The mean length of the SAF was 21.1 mm and 21.9 mm on the left and right sides, respectively. Morphologically, four variations of superior articular facets were noted: oval, bilobed, kidney, and dumbbell shaped. The most common variation was an oval-shaped facet with a prevalence of 66.7% on the left side and 57.3% on the right. The least common variation was the bilobed facet, with a prevalence of 4% on the left side and 8.7% on the right. CONCLUSION: The width of the SAF of the atlas was statistically significant on the left side. Morphologically, four types of variations were observed in the shape of the SAF. Knowledge of the morphological and morphometric variations of the SAF can be of help during surgical approaches at the CVJ.