Non-instrumented management of traumatic atlanto-axial rotatory subluxation: surgical technique

Introduction

Atlantoaxial rotatory subluxation (AARS) is a rare entity in adults (1-3). AARS in adults usually results from a traumatic etiology, compared to the pediatric population, which is more closely associated with ligamentous laxity or underlying diseases (4). Due to the rarity of this pathology, ample evidence is lacking on the best therapeutic approach. Fielding and Hawkins introduced the term atlantoaxial rotatory fixation (AARF) in 1977 and developed a classification system (5). Conservative and surgical treatments have both been used successfully in treating AARS, with an individualized focus due to the rarity of the injury (6,7). With the failure of conservative measures, the general treatment approach is to perform open reduction and fusion (8-10).

In this report, we present a novel surgical approach designed to reduce AARS without instrumentation. Following unsuccessful conservative treatments, the patient underwent successful open reduction in the operating room, where the decision was made against fusion. This approach prioritizes effectively reducing AARS while also avoiding the impact a fused C1–2 may have on a patient’s quality of life. Based on our experience, we formulated a guideline for evaluating patients presenting with traumatic AARS (Figure 1). We present this article in accordance with the SUPER reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-24-44/rc).

Figure 1 Algorithm for management of adult patients with suspected traumatic atlanto-axial subluxation. AARS, atlanto-axial rotatory subluxation; CT, computed tomography; OAA, occipito-atlanto-axial; MRI, magnetic resonance imaging; TAL, transverse atlantal ligament; ADI, anterior atlanto-dens interval; SAC, space available for the cord.

Preoperative preparations and requirements

A 48-year-old restrained female driver was traveling approximately 35–40 mph when her vehicle was t-boned on the driver’s side. Positive airbags deployed, and she was able to self-extricate from the vehicle and ambulate at the scene. She denied pain and complained of only neck stiffness and an inability to completely turn her head to the right. She denied any weakness, sensory changes, and bowel or bladder incontinence. Neurological examination showed no abnormalities. Imaging demonstrated rotatory subluxation of C1–2 with widening of the right C1–2 facet and comminuted and displaced fracture of right C1–2 facet joint, as well as a nondisplaced fracture of the base of occiput (Figures 2,3). The patient’s unilateral facet injury in combination with an intact transverse atlantal ligament (TAL) makes her injury most consistent with a combination of Fielding and Hawkins type 1 and 2 injuries (Figure 3) (5). Patient was initially managed with Gardner Wells Tongs for cervical traction and manual traction, both of which failed to demonstrate improvement of the subluxation on X-ray and computed tomography (CT) scans. The patient was subsequently taken to the operating room.

Figure 2 CT images showing C1–2 rotatory subluxation with joint displacement. Sagittal (A-C) and axial (D) CT of the cervical spine demonstrating C1–2 rotatory subluxation with anterior displacement of the right C1–2 joint (A) and posterior displacement of the left C1–2 joint. CT, computed tomography.

Figure 3 Sagittal and axial T2 MRI images showing hyperintensity in the right C1–2 facet joint with subluxation and an intact TAL. Sagittal T2 MRI of the cervical spine (A) demonstrating hyperintense signal in the right C1–2 facet joint with 8 mm of subluxation. The axial T2* sequence (B) shows intact TAL (arrow). These images are published with the patient’s consent. MRI, magnetic resonance imaging; TAL, transverse atlantal ligament.

Step-by-step description

The patient was transferred to the operating room at a Level I trauma University Hospital following unsuccessful conservative reduction attempts. General anesthesia was administered, and precautionary antibiotics were given prior to the procedure. A timeout was performed. The scalp was prepped with chloraprep, and Gardner Wells Tongs were applied in the standard fashion. Under fluoroscopy, weights were added, and gentle manual traction and manipulation of the head were attempted; however, this approach did not achieve reduction, prompting an open approach to reduction (Figure 4).

Figure 4 Patient images showing pre-operative torticollis, post-operative resolution, and sustained improvement at 3-month follow-up. (A) Patient photograph demonstrating persistent torticollis in Gardner Wells Tongs. (B) Patient photograph post-operatively without evidence of torticollis. (C) Patient photograph at 3-month follow-up without evidence of torticollis. These images are published with the patient’s consent.

The patient was positioned prone on the operating table with adequate padding for pressure points and comfort. Her hair was clipped, and she was prepped and draped in the sterile fashion. An incision was marked, followed by infiltration of local anesthetic. A precise incision was made with a skin knife, and dissection proceeded using a bovie to expose the spinous process and lamina of the right side of C2. We extended the exposure to reveal approximately 1 cm of the posterior arch of C1. At this point, we gently placed a Cloward spreader on the C1 arch and C2 lamina and spinous process. An assistant surgeon scrubbed out to manipulate and supervise the neck under the drapes. We distracted approximately 3 clicks on the Coward spreader, and the C1–2 subluxation was easily reduced with open manual rotation.

Reduction and restoration of the normal C1–2 articulation was confirmed with an O-arm 3D X-ray tomography scan intraoperatively (Figure 5). The now reduced atlantoaxial joint did not demonstrate any significant laxity with manual manipulation. To be further sure of our reduction, we used a variety of instruments to attempt manual rotation of C2, checking for gross extreme laxity or instability; it did not appear to be hyperunstable. Additionally, we gently rotated the head to put gentle force on C1 and C2. There was no evidence of resubluxation or laxity while in motion. Considering the preservation of the patient’s main cervical spine rotator and weighing the risks associated with additional stabilization, the decision was made not to instrument or fuse the segment. We felt it in the best interest of the patient to maintain her main cervical spine rotation. At this point, we copiously irrigated the wound with antibiotic saline. Vancomycin powder was sprinkled into the wound for infection prophylaxis. The fascia and subcutaneous fat were closed with vicryl, and the skin was stapled. A clean dressing was applied with bacitracin ointment. The patient tolerated the procedure, and there were no complications.

Figure 5 Post-op cervical X-rays showing proper spine alignment, with 3-month follow-up images confirming stable alignment and no C1–2 dynamic instability. Immediate post-operative upright cervical X-ray open mouth (A), lateral (B), and AP (C) views showing good alignment of the cervical spine. 3-month follow-up cervical X-ray in lateral (D), flexion (E), and extension (F) showing good alignment of the cervical spine and no evidence of dynamic instability at C1–2. AP, anteroposterior.

Surgery was performed by an attending neurosurgeon with a chief resident assist. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Postoperative considerations and tasks

The patient was counseled to remain in a cervical collar and that if she develops any instability or recurrence then she would require stabilization with fusion.

At 3-week follow-up, she denied any weakness, sensory changes, or bowel or bladder incontinence. On exam, the patient was neurologically intact and complained of only intermittent neck stiffness but denied any pain. Follow-up upright radiographs demonstrated satisfactory alignment of the atlantoaxial joint with reduction of the subluxation. At 3-month follow-up, the patient remained asymptomatic, and she was cleared to remove her cervical collar (Figures 4,5). Given her reliability as a patient, she was advised to return to the clinic if any symptoms arose or mobility worsened, and she has not to this point.

Tips and pearls

When determining whether to employ instrumentation, it is crucial to thoroughly and gently manipulate C1–2 to ensure complete reduction. In the operating room, this can be accomplished through various methods, including gentle manual rotation of the head, intraoperative imaging, and utilizing instruments such as Cloward spreaders, surgical hooks or retractors, or cervical spine distractors or rotators to assess for any gross instability. Additionally, surgeons may apply gentle force on C1 and C2 while rotating the head to detect any evidence of resubluxation or laxity during motion. These steps help confirm the successful reduction of the atlantoaxial joint and aid in the decision-making process regarding instrumentation.

Discussion

Adult AARS resulting from trauma are exceedingly rare, with recent literature reviews documenting 25 and 55 cases in the English literature (1,3,11,12). Notably, there have been no published cases of open reduction without instrumentation for the treatment of traumatic AARS in adults refractory to conservative treatment. Indications for surgical treatment include cases with persistent C1–2 instability, neurological symptoms, re-subluxation risk, complete TAL injury, and failure of conservative measures to achieve and or maintain reduction (3,5). Furthermore, concerns over persistent instability following closed reduction in adult patients have led to a preference for surgical stabilization by some authors (13).

In a patient with AARS, the typical presentation is a patient complaining of cervical pain in the cock-robin position, which manifests as torticollis and contralateral neck bending (7,14,15). In the adult patient presenting with AARS, the etiology is almost always traumatic in nature (3,16).

Delayed intervention can result in neurologic deficits or respiratory depression secondary to upper cervical cord injury (15). Early diagnosis and treatment is crucial for improved outcomes, as delays correlate with higher recurrence rates and non-surgical intervention failures (17). Radiological assessment should include plain radiographs, CT, and magnetic resonance imaging to evaluate for damage to the transverse and alar ligaments (18,19).

In the context of imaging, several signs indicate AARS instability. Notably, an anterior atlanto-dens interval (ADI) measurement exceeding 3.5 mm is often considered abnormal and suggestive of potential ligamentous disruption or instability in healthy adults. A space available for the cord (SAC) measurement less than 14 mm may indicate spinal cord compression, corroborating instability (20,21). Lateral mass displacement should also be assessed, with greater than 4 mm displacement suggesting potential instability (22). Occurrences of hypoplastic or displaced dens and ligamentous disruption or degeneration may reveal underlying causes of the instability, providing valuable information for the management and treatment of AARS. Collectively, the identification of these imaging signs combined with concurrent clinical observations aid in diagnosing and assessing the severity of AARS instability.

First-line management for both adults and children involves bracing for comfort and spasmolytics, particularly in early diagnoses (5,23-28). Immobilization and manual reduction also play roles in the conservative treatment of AARS when first-line management fails (29,30). Unfortunately, the success rate of conservative treatment decreases when delay in diagnosis exceeds one month (31,32). If C1–2 is stable and without TAL injury, treatment with a rigid cervical brace or halo vest is typically appropriate (5). When closed reduction fails to restore alignment, atlantoaxial arthrodesis is typically pursued. Historically, there have been a variety of surgical approaches to treating AARS, with posterior-only approaches becoming more common (3). Posterior fusion with C1 lateral mass screws and C2 pedicle screws allows for more direct manipulation and intraoperative reduction. Other techniques include occiput to C2 fixation, C1–2 transarticular screws, laminar clamps, and wiring (33).

To our knowledge, we present the only known case in literature of an adult patient with acute traumatic AARS managed with open reduction without instrumentation or fusion. Open reduction with instrumentation and fusion is generally considered the necessary treatment course when conservative management and closed reduction fail. However, it is important to note that atlantoaxial fixation has significant disadvantages, as it carries a risk of pseudarthrosis and a resulting significant loss of range of motion (ROM) (34). Although open reduction without instrumentation was performed, it effectively addressed a scenario that theoretically could have been managed with Gardner Wells Tongs and manual traction if successful. This suggests the condition was likely a positional misalignment rather than a structural issue requiring fusion due to potential ongoing instability. The need to manually correct the subluxation, following the failure of conservative treatment, led to the decision for open reduction. Preoperative imaging revealed rotatory subluxation of C1–2 with widening of the right C1–2 facet and a comminuted, displaced fracture of the right C1–2 facet joint, alongside a nondisplaced fracture of the base of the occiput. Literature indicates that such presentation can be managed conservatively in neurologically intact patients (35,36). Both preoperative imaging and intraoperative assessment confirmed instability without evidence of ligamentous or other structural injuries predisposing to re-subluxation. Therefore, the absence of such injuries supported the decision against fusion surgery, as primary resolution was achieved through realignment.

In addressing the appropriate indications for open reduction without fusion versus open reduction with fusion from a preoperative standpoint, it is crucial to consider several factors. Preoperative assessment should include detailed imaging studies to evaluate the extent of the injury and the presence of any ligamentous damage or instability. Patients who demonstrate isolated fractures without significant ligamentous injury and exhibit neurological integrity are potential candidates for conservative management or open reduction without instrumentation. However, if imaging reveals significant structural damage or instability that cannot be corrected non-invasively, fusion may be warranted.

Our decision against fusion surgery was influenced by achieving treatment goals typically addressed by instrumentation, specifically the resolution of the subluxation and prevention of vertebral laxity. Given the successful attainment of these objectives, instrumentation was deemed unnecessary. This conclusion was based on our evaluation during manual rotation testing of C2, where we employed techniques such as gentle manipulation of the head and utilization of Cloward spreaders, surgical hooks, and retractors to assess for gross instability. These mechanical maneuvers, supplemented with intraoperative imaging and the assessment of an experienced surgeon, confirmed the absence of hyperinstability. This approach offers the distinct advantage of maintaining normal cervical ROM while minimizing soft tissue trauma associated with extensive dissection for instrumentation.

Strengths and limitations

While our report provides valuable insights into an unconventional surgical approach for traumatic AARS, this study focuses on a single case, limiting the generalizability of our findings. Further research with extended follow-up periods and larger sample sizes is warranted to validate this alternative surgical method in managing traumatic AARS.

Conclusions

This case supplements the available literature on acute traumatic AARS in adults and provides the only known case in literature of a motion-preserving, fusion-sparing surgical treatment of traumatic AARS in adults. Avoiding fusion and instrumentation in appropriate patients may afford significant benefits such as maintenance of normal physiologic cervical ROM coupled with the less invasive need for tissue dissection.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the SUPER reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-24-44/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-24-44/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-24-44/coif). C.G. serves as an unpaid associate editor of Journal of Spine Surgery from November 2022 to October 2024. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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