Bilateral C1-C2 transarticular screw and C1 laminar hook fixation and bone graft fusion for reducible atlantoaxial dislocation: a seven-year analysis of outcome

Early Outcomes of Bone Autografting in the Bilateral Atlantoaxial Joints Applied in Posterior Fusion Surgery

OBJECTIVE

Cable-dragged reduction and cantilever beam internal fixation can provide promising results in the treatment of atlantoaxial dislocation or instability. However, bilateral atlantoaxial joints bone autografting has not been conducted in this technique. We aim to evaluate the safety and effectiveness of bilateral atlantoaxial joints bone autografting in posterior cable-dragged reduction and cantilever-beam internal fixation.

METHODS

In this retrospective study, we included 14 patients with a minimum 24-month follow-up from December 2019 to September 2020. The granular bone harvested from the iliac crest was packed into the bilateral atlantoaxial joints of 14 patients in posterior cable-dragged reduction and cantilever-beam internal fixation. X-ray imaging and cervical computed tomography (CT) were performed during follow-up. The time required for bone fusion was recorded. The clinical outcomes were evaluated using the JOA scores, NDI, and VAS scores. Mann-Whitney U test, the chi-squared test, or the Fisher exact test were used to compare the two groups regarding patient characteristics, clinical outcomes, bone fusion rates, and cervical sagittal alignment.

RESULTS

The operations were successfully performed in all patients without any intraoperative complications. The mean operation time was (169.64 ± 20.91) minutes, and the intraoperative blood loss was (130.71 ± 33.62) mL. All patients received satisfactory reductions and firm bony fusion at the final follow-up. The fusion rates were 64.29% in the atlantoaxial joints and 21.43% in post bone graft area at 3 months postoperatively, and a significant difference was observed (p = 0.022). Besides, the cervical sagittal alignment in all patients was well maintained in the last follow-up compared to preoperatively. Importantly, a complete bony fusion in the atlantoaxial joints was observed in all patients. Moreover, the JOA, NDI, and VAS scores had improved significantly at the last follow-up.

CONCLUSION

Bone autografting of the bilateral atlantoaxial joints is a safe and effective technique to increase bone fusion rates, shorten bone fusion time, and reduce complication rates when the cable-dragged reduction and cantilever beam internal fixation approach is used. Therefore, it is a cost-effective surgical procedure for treating patients with atlantoaxial dislocation or instability.

Comparison of three methods for measuring C0-1 angles and C0-2 angles

BACKGROUND

The mutual compensatory relationship between the upper cervical sagittal alignment and the lower cervical sagittal alignment has been repeatedly reported. However, the evaluation of the upper cervical sagittal parameters are varied in previous studies. This retrospective study was performed to compare three methods for measuring the upper cervical sagittal parameters.

METHODS

A total of 263 individuals with standing neutral lateral cervical radiographs were included in this study. The Frankfort horizontal line (FHL), foramen magnum line (FML), and McGregor line (ML) were separately used as the reference lines for measuring the C0-1 angle and C0-2 angle. Intraclass correlation (ICC) values were used to compare the consistency and repeatability of the three methods. Pearson's correlation analysis was used to analyze the correlation between the sagittal parameters of the upper and lower cervical spine.

RESULTS

The interobserver and intraobserver ICC values obtained from using the ML to measure the C0-1 angle and C0-2 angle were both higher than those obtained from using the FML or FHL. The C0-1 angle and C0-2 angle measured by the three methods were negatively correlated with the C2-7 angle. The upper sagittal parameters measured by the FHL were the most correlated with the C2-7 angle. The correlation between the C0-1 angle measured by the three methods and the C0-2 angle measured with the FHL or ML and the C2-7 angle increased with aging.

CONCLUSION

Use of the ML to measure the C0-1 angle and C0-2 angle has higher reliability. Use of the FHL to measure the sagittal alignment of the upper cervical spine is more suitable for evaluating the compensation mechanism between the upper and the lower cervical spine.

Supplementation of Screw-Rod C1-C2 Fixation With Posterior Arch Femoral Head Allograft Strut

BACKGROUND

Numerous C1-C2 fixation techniques exist for the treatment of atlantoaxial instability. Limitations of screw-rod and sublaminar wiring techniques include C2 nerve root sacrifice and dural injury, respectively. We present a novel technique that utilizes a femoral head allograft cut with a keyhole that rests posteriorly on the arches of C1 and C2 and straddles the C2 spinous process, secured by sutures.

OBJECTIVE

To offer increased fusion across C1-C2 without the passage of sublaminar wiring or interarticular arthrodesis.

METHODS

A total of 6 patients with atlantoaxial instability underwent C1-C2 fixation using our method from 2015 to 2016. After placement of a C1-C2 screw/rod construct, a cadaveric frozen femoral head allograft was cut into a half-dome with a keyhole and placed over the already decorticated dorsal C1 arch and C2 spinous process. Notches were created in the graft and sutures were placed in the notches and around the rods to secure it firmly in place.

RESULTS

The femoral head's shape allowed for creation of a graft that provides excellent surface area for fusion across C1-C2. There were no intraoperative complications, including dural tears. Postoperatively, no patients had sensorimotor deficits, pain, or occipital neuralgia. 5 patients demonstrated clinical resolution of symptoms by 3 mo and radiographic (computed tomography) evidence of fusion at 1 yr. One patient had good follow-up at 1 mo but died due to complications of Alzheimer disease.

CONCLUSION

The posterior arch femoral head allograft strut technique with securing sutures is a viable option for supplementing screw-rod fixation in the treatment of complex atlantoaxial instability.

Comparison of Two Bone Grafting Techniques Applied During Posterior C1-C2 Screw-Rod Fixation and Fusion for Treating Reducible Atlantoaxial Dislocation

BACKGROUND

Several bone grafting techniques for posterior atlantoaxial arthrodesis have been reported. The techniques of placing a cancellous morselized bone graft (MBG) on decorticated surfaces of the atlantoaxial complex and securing a structural iliac bone graft (SBG) between C1 and C2 have been used widely. The aim of the present study was to compare the outcomes of these 2 bone grafting techniques for atlantoaxial arthrodesis.

METHODS

The data from 64 patients with reducible atlantoaxial dislocation treated using posterior C1-C2 screw-rod fixation and fusion were retrospectively reviewed. The MBG technique had been used in 32 patients and the SBG technique in 32 patients. The time required for bone fusion was recorded. The outcomes were evaluated using the Japanese Orthopaedic Association scale score, Neck Disability Index, visual analog scale (VAS) score for neck pain, patient satisfaction, and neck stiffness and compared between the 2 groups. The donor site complications were also compared, and donor site pain was assessed using a VAS.

RESULTS

At the final follow-up, the bone fusion rate was 100% in both groups. No significant differences were found in the bone fusion time or donor site pain between the 2 groups (P > 0.05). Postoperatively, The Japanese Orthopaedic Association scale scores, Neck Disability Index, and VAS score for neck pain had improved significantly within both groups (P < 0.05), with no statistically significant differences between the 2 groups (P > 0.05). Additionally, no differences were found between the 2 groups in patient satisfaction and neck stiffness postoperatively (P > 0.05).

CONCLUSIONS

The MBG and SBG techniques were both effective for atlantoaxial arthrodesis, with the advantages of reducing the potential risk of catastrophic bleeding of the epidural venous plexus and C2 nerve root injury.

Three-point atlantoaxial fixation with C1-C2 transarticular screws and C1 lateral mass screws

BACKGROUND

Based on established posterior atlantoaxial fixation techniques, we present a novel technique that uses a polyaxial screw rod system and utilizes a combination of C1 lateral mass and C1-C2 transarticular screws.

METHODS

We conducted a retrospective review of six men and four women (mean age: 57, range: 20-86). Indication for atlantoaxial fixation was type II odontoid fractures or pseudarthrosis after odontoid fracture (n = 7), rheumatoid arthritis (n = 2) and os odontoideum (n = 1).

RESULTS

The mean follow-up time was 48 months (range: 24-72). There were no intraoperative complications such as vertebral artery, nerve root or spinal cord injury. Post-operative imaging showed no screw malposition. During follow-up, no patient had screw loosening, screw fracture or bone absorption around the screws. Clinically, patient neck pain improved in all cases.

CONCLUSIONS

C1 lateral mass and C1-C2 transarticular polyaxial screw rod fixation is a novel and potentially effective surgical technique for achieving immediate rigid immobilization of the C1-C2 motion segment. However, further biomechanical studies should be performed to prove our clinical results.

Miniplate-Augmented Interlaminar Fusion in C1-C2 Screwing

OBJECTIVE

The interlaminar fusion combination involving C1-C2 screwing fixation is one of the most effective techniques for atlantoaxial dislocation or subluxation, and the bone graft is usually stabilized by wiring constructs. However, some adverse events were reported during the insertion of sublaminar wiring, such as accidentally damaging the spinal cord or dura. Thus we used the miniplate to stabilize the harvest bone graft on the C1-C2 laminar, which led to a shorter operation time and prevented spinal canal violation. This study investigated the safety and efficacy of the novel surgical technique, namely miniplate-augmented interlaminar fusion.

METHODS

We retrospectively reviewed 43 patients who underwent posterior atlantoaxial fusion with the miniplate-augmented iliac crest autograft at our institute. Complications related to surgery were recorded and calculated. After operation, patients were followed up through routine radiography to examine whether the fusion of the atlantoaxial segment was achieved. Success of fusion was defined as follows: 1) the presence of bone bridging between the bone graft and both the atlas and axis; and 2) the absence of movement of the atlantoaxial spinous process on flexion-extension radiography, which meant that the variation of length measured in 2 views, respectively, was <1 mm. The first time when radiography showed successful fusion after surgery was termed as fusion time and was recorded individually. In addition, overall fusion rates and mean fusion times were analyzed.

RESULTS

Of 43 patients, long-term follow-up data were available for 31 patients, whereas the remaining 12 patients had dropped out (mean follow-up duration, 24.91 months; range, 6-72 months). Among 31 patients, 22 (70.96%) were women and 9 (29.03%) were men. The mean age was 63.33 years. Regarding the etiology, atlantoaxial dislocations or subluxations were caused due to degeneration, rheumatoid arthritis, odontoid fracture, trauma, and os odontoideum in 14 (45%), 3 (10%), 5 (16%), 8 (26%), and 1 (3%) patient(s), respectively. Successful fusion was achieved in 30 (96.77%) patients, with a mean fusion time of 6.23 months, whereas only 1 (3.23%) patient did not meet the fusion criteria. No complications related to the miniplate occurred. We noted vertebral artery rupture not requiring blood transfusion in 1 patient, aspiration pneumonia in 1 patient, urinary tract infection in 1 patient, anemia requiring transfusion in 1 patient, and leg dysesthesia in 1 patient. No neurologic deficit was found.

CONCLUSIONS

Miniplate-augmented interlaminar fusion with C1-C2 screwing resulted in excellent fusion rates with a considerably low probability of complications. Hence this novel technique for bone graft fixation with atlantoaxial screwing has a good efficacy and safety and can serve as an alternative for bone graft fixation during C1-C2 fusion.

Posterior atlantoaxial fusion: a comprehensive review of surgical techniques and relevant vascular anomalies

Posterior atlantoaxial fusion is an important surgical technique frequently used to treat various pathologies involving the cervical 1-2 joint. Since the beginning of the 20th century, various fusion techniques have been developed with improved safety profile, higher fusion rates, and superior clinical outcome. Despite the advancement of technology and surgical techniques, posterior C1-2 fusion is still a technically challenging procedure given the complex bony and neurovascular anatomy in the craniovertebral junction (CVJ). In addition, vascular anomalies in this region are not uncommon and can lead to devastating neurovascular complications if unrecognized. Thus, it is important for spine surgeons to be familiar with various posterior atlantoaxial fusion techniques along with a thorough knowledge of various vascular anomalies in the CVJ. Intimate knowledge of the various surgical techniques in combination with an appreciation for anatomical variances, allows the surgeon develop a customized surgical plan tailored to each patient's particular pathology and individual anatomy. In this article, we aim to provide a comprehensive review of existing posterior C1-2 fusion techniques along with a review of common vascular anomalies in the CVJ.

Comparison of Two Posterior Three-Point Fixation Techniques for Treating Reducible Atlantoaxial Dislocation

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To compare the outcomes of C1-C2 transarticular screw combined with C1 laminar hook (TAS+C1H) and C1-C2 transarticular screw combined with modified Gallie technique (TAS+G) for treating reducible atlantoaxial dislocation (AAD).

SUMMARY OF BACKGROUND DATA

Both TAS+C1H and TAS+G fixation were 3-point fixation techniques for AAD. TAS+C1H technique was comparable to TAS+G technique in biomechanics. However, it is unknown whether it can achieve same outcomes as TAS+G technique.

METHODS

Data of the 63 patients who underwent TAS+C1H or TAS+G fixation and fusion because of AAD were retrospectively reviewed. Bone fusion time was recorded. The outcomes evaluated by visual analog scale score for neck pain (VASSNP), Nurick scale, neck stiffness (none/mild/severe), patient satisfaction, and Neck Disability Index (NDI) were compared between two groups.

RESULTS

At the final follow-up, bone graft fusion rates were 100% in both groups (P > 0.05). Nurick scales were significantly improved in both groups (P < 0.05), but with no significant differences between groups (P > 0.05). There were no significant differences between two groups in VASSNP, neck stiffness, patient satisfaction, or NDI (all P > 0.05). There were no complications related to the surgical approach and instrumentation in either group.

CONCLUSION

Both TAS+C1H and TAS+G fixation were effective in the treatment of reducible AAD. TAS+C1H was safer than TAS+G because it could potentially reduce the risk of spinal cord and venous plexus injury associated with sublaminar cables.

LEVEL OF EVIDENCE

3.

Type II Odontoid Fracture: a case series highlighting the treatment strategies

BACKGROUND

A type II odontoid fracture, if unstable, can cause spinal cord damage. In this case, it is essential to choose the correct treatment-but the issues of what the correct treatment is and which of the different surgical options is best are quite controversial. In this paper we present strategies for treatment of type II odontoid fracture.

MATERIALS AND METHODS

Thirty consecutive cases of type II odontoid fracture were treated at the Division of Neurosurgery at Villa Sofia Hospital in Palermo (23 cases) and at the Neurosurgical Clinic, University Hospital of Palermo (seven cases), from January 2011 to August 2016. Four patients were treated with external immobilization. Twenty-six patients underwent a surgical procedure.

RESULTS

There was no mortality related to the surgical procedure. One patient had a pre- and postoperative neurological deficit, and remained tetraparetic. Follow-up radiological studies in the surgically treated group showed bone union in 21 patients and stable fibrous union in one.

CONCLUSION

In our and other authors' experience, when the direction of the fracture line is down and forward, external immobilization can be sufficient for healing. Anterior odontoid screw fixation can be considered the treatment of choice for unstable odontoid fractures (with a horizontal, down and back, or comminuted fracture line) without dislocation or with dislocation less than 7 mm.When the odontoid fracture is associated with a Jefferson fracture or dislocation greater than 7 mm, stabilization of C1-C2 may be necessary. In this case, placement of screws in the dens and in the joints through a single approach represents the most valid technique.In the case of an inveterate fracture of the dens with severe C1-C2 dislocation, the surgical operation that offers the best prospects is posterior stabilization, utilizing the Guo technique.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Comparison of Outcomes Between C1-C2 Screw-Hook Fixation and C1-C2 Screw-Rod Fixation for Treating Reducible Atlantoaxial Dislocation

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

To compare the outcomes of C1-C2 transarticular screw with C1 laminar hook (TAS + C1H) fixation and C1 trans-arch lateral mass screw with C2 pedicle screw (C1TLMS + C2PS) fixation in the treatment of reducible atlantoaxial dislocation (AAD).

SUMMARY OF BACKGROUND DATA

TAS + C1H is comparable to TAS with posterior wiring techniques and superior to C1 lateral mass screw combined with C2 pedicle screw (C1LMS + C2PS) in biomechanics. There were, however, few studies analyzing the differences in outcomes between TAS + C1H technique and modified C1LMS + C2PS technique (C1TLMS + C2PS) for treating AAD.

METHODS

Data of 30 patients with reducible AAD treated by TAS + C1H fixation and another 30 cases treated by C1TLMS + C2PS fixation were retrospectively analyzed. Bone fusion time was recorded. The outcomes evaluated by American Spinal Injury Association impairment scale, visual analog scale score for neck pain, neck stiffness (none/mild/severe), patient satisfaction, and Neck Disability Index (NDI) were compared between two groups.

RESULTS

There were no complications related to the surgical approach and instrumentation in either group. At the final follow-up, bone graft fusion rates were 100% in both the TAS + C1H fixation group and the C1TLMS + C2PS fixation group (P > 0.05). The neurological status evaluated by American Spinal Injury Association impairment scale were greatly improved in both screw-hook group (P < 0.001) and screw-rod group (P < 0.001), but with no significant differences between groups (P > 0.05). There were no significant differences between two groups in visual analog scale score for neck pain, neck stiffness, patient satisfaction, or Neck Disability Index (all P > 0.05).

CONCLUSION

C1TLMS + C2PS fixation was comparable to TAS + C1H fixation in fusion rate and functional outcomes for treating reducible AAD. To reduce the risk of vertebral artery injury, computed tomography scan, and reconstruction should be done to analyze vertebral artery course and C1-C2 anatomic structures before operation.

LEVEL OF EVIDENCE

3.

Biomechanical Evaluation of a Novel Integrated C1 Laminar Hook Combined with C1-C2 Transarticular Screws for Atlantoaxial Fusion: An In Vitro Human Cadaveric Study

OBJECTIVE

To evaluate the acute stability of a novel integrated C1 laminar hook (H) combined with a C1-C2 transarticular screw (TAS) with established techniques.

METHODS

A novel integrated C1 laminar hook was tested. Seven human cadaveric cervical spines (C0-C3) were used. The range of motion (ROM) of C1-C2 during flexion-extension, lateral bending, and axial rotation were recorded. The specimens were tested under the following conditions: intact, destabilized (using a type II odontoid fracture model), and destabilized but with internal fixation. The following screw systems were used: bilateral C1-C2 TAS combined with the Gallie (G) technique (TAS+G), C1-C2 TAS combined with a novel integrated C1 laminar hook (TAS+H), C1 lateral mass screw and C2 pedicle screws (C2PS+C1LMS), and novel integrated C1 laminar hook combined with C2 pedicle screws (C2PS+H). The TASs were always inserted after the C2PSs. The C2PS+C1LMS and C2PS+H tests were performed alternatively, as were the TAS+G and TAS+H tests.

RESULTS

All fixation constructs greatly improved acute atlantoaxial stability, with no significant difference among TAS+H, TAS+G, and C2PS+C1LMS (all P > 0.05). C2PS+H showed the greatest C1-C2 ROM in axial rotation, significantly different from TAS+G, C2PS+C1LMS, and TAS+H fixation models (all P < 0.05). However, there were no significant differences between C2PS+H and the other 3 models in flexion-extension and lateral bending (all P > 0.05).

CONCLUSIONS

The TAS+H technique can achieve acute stability comparable to that with the TAS+G technique for treating C1-C2 instability. The C2PS+H is a promising alternative, although it provides less stability in axial rotation than TAS+G, TAS+H, or C2PS+C1LMS.

Posterior atlantoaxial fixation: a review of all techniques

BACKGROUND CONTEXT

Posterior atlantoaxial fixation is an effective treatment for atlantoaxial instability. Great advancements on posterior atlantoaxial fixation techniques have been made in the past decades. However, there is no article reviewing all the posterior atlantoaxial fixation techniques yet.

PURPOSE

The aim was to review the evolution and advancements of posterior atlantoaxial fixation.

STUDY DESIGN

This was a literature review.

METHODS

The application of all posterior fixation techniques in atlantoaxial stabilization, including wiring techniques, interlaminar clamp fixation, transarticular fixation, screw-plate systems, screw-rod systems, and hook-screw systems, are reviewed and discussed. Recent advancements on the novel technique of atlantoaxial fixation are described. The combination of the C1 and C2 screws in screw-rod systems are described in detail.

RESULTS

All fixation techniques are useful. The screw-rod system appears to be the most popular approach. However, many novel or modified fixation methods have been introduced in recent years.

CONCLUSIONS

Great advancements on posterior atlantoaxial fixation techniques have been made in the past decades. The wiring technique and interlaminar clamps technique have fallen out of favor because of the development of newer and superior fixation techniques. The C1-C2 transarticular screw technique may remain the gold standard for atlantoaxial fusion, whereas screw-rod systems, especially the C1 pedicle screw combined with C2 pedicle/pars screw fixation, have become the most popular fixation techniques. Hook-screw systems are alternatives for atlantoaxial fixation.

The efficacy of pedicle screw instrument in treatment of irreducible atlantoaxial dislocation

OBJECTIVE

To explore the effect of pedicle screw instrument in treatment of irreducible atlantoaxial dislocation.

PATIENTS AND METHOD

From June 2003 to February 2009, 14 cases of atlas dislocation with upper cervical cord compression were enrolled and anterior transoral soft tissue release combined with posterior reduction and pedicle screw fixation were performed. CT, MRI and radiograph were used preoperatively, and screw placement and bone graft were administered in all cases intraoperatively. Cervical collars were used for 3 months.

RESULTS

Screws were successfully placed in atlas in all cases. The average follow-up period was 18 months. Bone fusion was observed in all cases without the following complications: neurologic symptoms, internal fixation failure and redislocation. Neurological recovery was observed in all 14 cases.

CONCLUSIONS

Pedicle screw instrument has the following advantages in atlas and axis injury treatment: direct screw placement, short-segment fusion, intraoperative reduction and high fusion rate, which should be a better surgical method for the treatment of atlantoaxial dislocation.