Utility of O-arm navigation for atlantoaxial fusion with Bow Hunter’s syndrome

Background: In spinal instrumentation surgery, safe and accurate placement of implants such as lateral mass screws and pedicle screws should be a top priority. In particular, C2 stabilization can be challenging due to the complex anatomy of the upper cervical spine. Here, we present a case of Bow Hunter’s syndrome (BHS) successfully treated by an O-arm-navigated atlantoaxial fusion. Case Description: A 53-year-old male presented with a 10-year history of repeated episodes of transient loss of consciousness following neck rotation to the right. Although the unenhanced magnetic resonance imaging showed no pathological findings, the MR angiogram with dynamic digital subtraction angiography revealed a dominant left vertebral artery (VA) and hypoplasia of the right VA. The latter study further demonstrated significant flow reduction in the left VA at the C1-C2 level when the head was rotated toward the right. With these findings of BHS, a C1-C2 decompression/posterior fusion using the Goel-Harms technique with O-arm navigation was performed. The postoperative cervical X-rays showed adequate decompression/fixation, and symptoms resolved without sequelae. Conclusion: C1-C2 posterior decompression/fusion effectively treats BHS, and is more safely/effectively performed utilizing O-arm navigation for C1-C2 screw placement.

Atlantoaxial Stabilization by Posterior C1 and C2 Screw-Rod Fixation for Various Pathologies: Case Series and Comprehensive Review of Literature

We retrospectively analyzed atlantoaxial dislocation (AAD) of various pathologies, namely, rheumatoid arthritis (RA), os odontoideum, and trauma. Various techniques were discussed in relation to C1-C2 stabilization. The study aims to share our clinical experience in a series of six cases of C1-C2 instability that underwent posterior C1-C2 fusion, with free hand technique and limited fluoroscopy. The clinicoradiological presentation for each patient is described. We reviewed different literatures related to our case vividly and focused on the basic neuroanatomy involved in the atlantoaxial joint. All patients of AAD had evidence of severe canal compromise and chronic compressive spinal cord changes. In our study, the patients age ranged from 28 to 52 years. The study included four males and two females. Out of six patients of AAD, three had history of trauma, two had os odontoideum, and one had chronic inflammatory condition (RA). From our case series, we concluded that the Goel–Harms technique is the most versatile and surgeon friendly technique for C1-C2 fixation. Early recognition and surgical intervention of atlantoaxial joint instability is essential to prevent catastrophic neurological complications.

Managing the Anomalous Vertebral Artery in C1–C2 Stabilization for Congenital Atlantoaxial Instability

Objectives This study aimed to demonstrate the technique of handling the anomalous vertebral artery in congenital atlantoaxial instability. The vertebral artery course can be variable in congenital atlantoaxial instability, especially if there is assimilation of atlas. The surgical technique to stabilize the atlantoaxial joint should ensure the patency and safety of the vertebral artery and prevents devastating stroke. Computed tomography (CT) angiography of the vertebral artery is mandatory in planning the surgical strategies. The vertebral artery can be injured during dissection of soft tissues between atlas and axis and can be compromised during distraction and instrumentation. The vertebral artery needs to be mobilized based on the tortuosity in the course during instrumentation and prevents compression of the artery against bony structures or screw heads. The vertebral artery has to be identified earlier in the course of dissection and should protect it. It is also imperative to choose the surgical approach that can be performed under vision using operative microscope rather than adapting blind procedures like transarticular screw. Here, in our present case, we demonstrate the technique of mobilizing the vertebral artery which was coursing medially preventing the access for the instrumentation and perform stabilization of atlantoaxial joint using Goel–Harms technique, and prevent its compression after placement of screw by deroofing the bony ridges of axis (Figs. 1 and 2). We also emphasize the various technical nuances during the stabilization with distraction of joint space of atlas and axis.The link to the video can be found at: https://youtu.be/pgURpF_jACc.

Clinicoradiological outcomes of Goel and Harms fixation for atlantoaxial instability: An institutional experience

Background: Few studies have reported on the long-term outcomes of Goel and Harms C1-C2 fusions in the Asian population. Methods: This was a retrospective analysis of 53 patients undergoing Goel and Harms fixation (2010 –2018). Clinical outcomes were assessed utilizing the neck disability index (NDI), Japanese Orthopedic Association (JOA) score, and visual analog scale (VAS). Outcomes were then correlated with fusion rates (using dynamic X-rays), atlanto-dens interval (ADI), and space available for cord (SAC) data. Results: The study’s 53 patients averaged 49.98 years of age and included 42 males and 11 females. The mean preoperative versus postoperative scores on multiple outcome measures showed NDI 31.62 ± 11.05 versus decreased to 8.68 ± 3.76 post, mean JOA score (e.g., in 41 patients with myelopathy) improved from 13.20 ± 3.96 to 15.2 ± 2.17, and the mean VAS decreased from 4.85 ± 1.03 to 1.02 ± 0.87 and showed restoration of the ADI (1.96 ± 0.35 mm) and SAC (20.42 ± 0.35 mm). A 98.13% rate of C1-C2 fusion was achieved at 12 postoperative months. Conclusion: Goel and Harms technique for C1-C2 fusion resulted in both good clinical and radiological outcomes.

Biomechanical evaluation of two alternative techniques to the Goel-Harms technique for atlantoaxial fixation: C1 lateral mass–C2 bicortical translaminar screw fixation and C1 lateral mass–C2/3 transarticular screw fixation

OBJECTIVEThe authors conducted a study to investigate the biomechanical feasibility and stability of C1 lateral mass–C2 bicortical translaminar screw (C1LM-C2TL) fixation, C1 lateral mass–C2/3 transarticular screw (C1LM-C2/3TA) fixation, and C1LM-C2/3TA fixation with transverse cross-links (C1LM-C2/3TACL) as alternative techniques to the Goel-Harms technique (C1 lateral mass–C2 pedicle screw [C1LM-C2PS] fixation) for atlantoaxial fixation.METHODSEight human cadaveric cervical spines (occiput–C7) were tested using an industrial robot. Pure moments that were a maximum of 1.5 Nm were applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). The specimens were first tested in the intact state and followed by destabilization (a type II odontoid fracture) and fixation as follows: C1LM-C2PS, C1LM-C2TL, C1LM-C2/3TA, and C1LM-C2/3TACL. For each condition, the authors evaluated the range of motion and neutral zone across C1 and C2 in all directions.RESULTSCompared with the intact spine, each instrumented spine significantly increased in stability at the C1–2 segment. C1LM-C2TL fixation demonstrated similar stability in FE and LB and greater stability in AR than C1LM-C2PS fixation. C1LM-C2/3TA fixation was equivalent in LB and superior in FE to those of C1LM-C2PS and C1LM-C2TL fixation. During AR, the C1LM-C2/3TA–instrumented spine failed to maintain segmental stability. After adding a cross-link, the rotational stability was significantly increased in the C1LM-C2/3TACL–instrumented spine compared with the C1LM-C2/3TA–instrumented spine. Although inferior to C1LM-C2TL fixation, the C1LM-C2/3TACL–instrumented spine showed equivalent rotational stability to the C1LM-C2PS–instrumented spine.CONCLUSIONSOn the basis of our biomechanical study, C1LM-C2TL and C1LM-C2/3TACL fixation resulted in satisfactory atlantoaxial stabilization compared with C1LM-C2PS. Therefore, the authors believe that the C1LM-C2TL and C1LM-C2/3TACL fixation may serve as alternative procedures when the Goel-Harms technique (C1LM-C2PS) is not feasible due to anatomical constraints.

POSTERIOR C1-C2 FUSION FOR ATLANTOAXIAL ROTATORY FIXATION AFTER POSTERIOR FOSSA CRANIOTOMY IN A 4-YEAR-OLD: A CASE REPORT

Study Design: Case report Objective: This study aimed to highlight that Atlantoaxial rotatory fixation (AARF) can be related to neurosurgery procedures in children with an afterwards demonstration of good results after halo-gravity traction and C1-C2 stabilization using the Harms technique. Summary of Background Data: AARF is characterized by dislocation or subluxation of the atlantoaxial joint, leading to a rotational deformity which may cause pain. Such a condition is mostly found in pediatric patients. Trauma, upper respiratory infections, surgery of the head and the neck, and even rheumatoid arthritis and Down syndrome have been designated as predisposing factors. It is important to note that in some cases AARF evolves with no apparent cause and to date, the choice of optimal surgical procedure should be carefully selected, considering the anatomical and bone conditions, as well as the surgeon’s experience with each technique. Methods: We report the first case related, in our knowledge, of a 4-year-old boy who presented atlantoaxial rotatory fixation after a posterior fossa craniotomy to treat a cerebellar astrocytoma. Results: At our medical facility, we diagnosed AARF by plain radiograph and CT image, and he was treated with continuous cranial traction for 14 days. Initially, we detected that he had no C1 posterior arch or C2 spinous process, so our choice was to perform Harms technique. Postoperatively, the patient was placed in a cervical collar for four weeks. At him 4-years postoperative follow-up, he was doing well and did not develop any complication. Conclusion: We call the attention to the fact of AARF can be developed after neurosurgical procedures. A surgical technique to be used in Atlantoaxial subluxation should be carefully select. In our case, Harms technique after cranial traction was an excellent option to correct and stabilize the abnormal neck position presented. However, further studies are required to determine the best technique to be used in the pediatric population.