Anterior odontoid screw fixation of a type III odontoid fracture aided by transoral digital manipulation: illustrative case

Abstract

BACKGROUND

Odontoid process fractures make up 10%–20% of all cervical spine fractures, with type III fractures having a considerable amount of heterogeneity. Most simple type III fractures can be managed nonoperatively. However, 21% of complex type III fractures with significant displacement and angulation are inadequately treated with external immobilization and require surgery. Achieving a reduction via traction can pose a great challenge during intraoperative manipulation, especially when presentation is delayed.

OBSERVATIONS

A 36-year-old male patient, who presented 2 weeks after a motor vehicle crash, had a Glasgow Coma Scale score of 14 and intact motor and sensory function. A craniocervical computed tomograpy scan revealed a normal brain with a type III odontoid fracture. The patient underwent anterior odontoid screw fixation (AOSF) aided by a transoral digital manipulation to achieve a reduction of the irreducible proximal fracture segment at 8 weeks postinjury. The treatment resulted in preserved neurological function and a satisfactory odontoid fracture reduction.

LESSONS

Delayed presentation of a complex type III odontoid fracture can be challenging to treat; however, AOSF with the aid of transoral digital manipulation of the irreducible proximal segment can help to achieve good reduction and fusion with the preservation of neurological function in a young patient.

https://thejns.org/doi/10.3171/CASE24294

The cervical spine is the most common segment injured following trauma to the spine. About 10%–20% of all cervical fractures are C2 fractures, with odontoid process fractures accounting for 50%–60% of all axis fractures.^1–4 The classification of this fracture is based on the location of the fracture line, with type I fractures seen in 1%–3%, whereas type II fractures occur in up to 74% of cases. Type III fractures account for about 39%–42% of these injuries.^{1, 5, 6}

Type III odontoid fractures are a type of hyperextension or hyperflexion injury, similar to type II fractures. The difference, however, is the location of the fracture line. Type III fractures have been shown to have a considerable amount of heterogeneity, with complex variants having > 50% comminution of the lateral mass or a secondary fracture line extending into the vertebral body or pars interarticularis.⁷ Nonsurgical management with an external orthosis is the initial and widely used treatment approach for simple type III odontoid fractures, with expected healing rates of 87%–100%.^{2, 3, 8–10} However, for complex type III fractures that exhibit the same deforming forces as all odontoid fractures with additional instability in the rotatory or coronal plane, surgical fusion is the most appropriate therapeutic approach.⁷ Niemeier et al. reported that 21% of complex type III odontoid fractures could not be adequately treated with external immobilization and thus required surgical fusion.⁷

Surgical fusion of these fractures can be achieved via a posterior or an anterior approach. The anterior approach, which includes anterior odontoid screw fixation (AOSF), has been shown to preserve atlantoaxial motion with immediate rigid stabilization and high union rates.^11–14 However, this requires a reduced odontoid, an intact transverse ligament, and a favorable fracture line to achieve adequate fracture compression.^{13, 14} Adequate reduction of the fracture segment with tong traction under image guidance is a requirement for achieving an acceptable AOSF. As a result, some authors consider an irreducible fracture with an anterior obliquely sloping fracture line to be an absolute contraindication to AOSF.^{13, 14} This has led some authors to use a transoral, digitally aided reduction in type II odontoid fractures during AOSF.^15–17 However, Lee is the only author in the literature who has employed a similar technique in the treatment of a type III fracture.¹⁸

In this report, we describe the use of direct C2–3 access for a delayed AOSF with a transoral, digitally aided reduction of an 8-week-old complex type III odontoid fracture in a 36-year-old man who underwent an AOSF with preserved postoperative neurological function.

Illustrative Case

A 36-year-old man was referred to us from a tertiary health care facility with confusion and neck pain of 2 weeks’ duration following a motor vehicle crash with a fatality. On admission, he was confused, with an admitting Glasgow Coma Scale (GCS) score of 14 (E4, V4, M6) and no motor or sensory deficit, although the patient was not fully compliant with the clinical examination. The cervical spine was initially immobilized with a rigid neck collar. A craniocervical computed tomography (CT) scan showed normal brain parenchyma and an Anderson and D’Alonso type III odontoid fracture with a fracture line extending to the left lateral mass, anterior displacement, and angulation of the fracture segment (Fig. 1). CT angiography and magnetic resonance imaging showed a normal left vertebral artery and an intact transverse ligament, respectively. The patient was found to have a mild traumatic brain injury and a type III odontoid fracture. He improved to a GCS score of 15 while awaiting odontoid fracture fusion. The patient was scheduled for AOSF. The surgery was delayed for about 6 weeks due to the unavailability of an odontoid screw.

FIG. 1.

Sagittal (A), coronal (B), and volume-rendering (C) cervical CT scans showing an odontoid fracture with anterior displacement and angulation, extension to the body of C2, and fracture of the left lateral mass of the axis.

With the patient under general anesthesia with cuffed endotracheal intubation, we applied Gardner-Wells tongs skull traction, with the patient supine and the head in a neutral position. An attempt at a gradual reduction by continuous longitudinal traction under image-intensifier guidance failed to achieve an anatomical reduction of the displaced segment (Fig. 2).

FIG. 2.

A: Intraoperative localization of C2–3 access. B: Two C-arms used for intraoperative guidance. C: Intraoperative image guide for C2 AOSF.

The patient’s mouth was held open with a radiolucent bite block (gauze roll). A right anterolateral skin incision site at C2–3 (angle of the mandible) was marked with the aid of an image intensifier, followed by skin cleansing and draping. A 4-cm transverse skin crease incision was made, and the dissection was developed using routine steps to the C2–3 disc. An anterior midline annulectomy was done over the inferior aspect of C2. Transoral manual reduction of the fracture was performed with the aid of an index finger, while a guidewire was then drilled through the anteroinferior aspect of C2 beyond the fracture line and just short of the tip of the dens. The cannulated screw was then driven directly into the C2 vertebra beyond the fracture line until about 5 mm of the fracture dens was secured under image guidance (Fig. 3). This procedure is safer when intraoperative neuromonitoring is used, which was lacking in our practice. However, intraoperative neuromuscular paralysis was avoided, and the patient’s limbs were monitored for involuntary jerky movements during the manipulation.

FIG. 3.

A: Immediate postoperative lateral radiograph showing an odontoid screw with a reduced type III odontoid fracture; note the fracture line. B: Open mouth view showing the screw in situ.

Follow-up cervical spine radiography performed 45 months later showed satisfactory bony fusion and an intact screw. The patient has remained neurologically intact and has since resumed his usual activities of daily living (Fig. 4).

FIG. 4.

Lateral cervical radiograph obtained 45 months postoperatively, showing satisfactory fusion and an intact screw.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Observations

The observations made and our experience in the management of this patient, who presented 2 weeks postinjury with a complex type III odontoid fracture with angulation and displacement of the fractured proximal segment, includes the following points. The initial difficulty was getting an odontoid screw locally, which resulted in a 6-week delay in the surgical intervention. Intraoperatively, there was nonreduction of the proximal fracture segment with Gardner-Wells tongs traction. As a result, a transoral, digitally aided reduction of the proximal odontoid fracture segment to aid the AOSF procedure was done, even though it was 8 weeks postinjury. Unlike the first reported case of a type III odontoid fracture with a transoral digital reduction, where the immediate postoperative and follow-up period showed a failed reduction, we were able to achieve a good intraoperative reduction with no procedure-related or neurological complications even without intraoperative neuromonitoring capabilities (Figs. 3 and 4). At 45 months postsurgery, the patient maintained the reduction with good union and fusion (Fig. 4).

The management of odontoid fractures has evolved since its description in 1907 by Lambotte and the first surgical treatment by Mixter and Osgood.¹⁹ Despite numerous published articles over the past 2 decades, the optimal treatment option and approach have remained a controversial subject, as there are many contributing factors to a patient’s eventual outcome.²⁰ However, surgical treatment has proved over time to have a higher rate of fusion and shorter bone healing times than conservative treatment, especially in type II fractures.¹³

In the 1980s, Nakanishi and Böhler each initially described AOSF.^{21, 22} This approach achieves osteosynthesis, preserves atlantoaxial (C1–2) motion with immediate rigid stabilization and high union rates, and results in optimal anatomical and functional outcomes.^{13, 14, 23, 24} However, complications such as dysphagia and respiratory problems can occur, and the need for an intact transverse cruciate ligament and reduction of the fractured segment to achieve appropriate screw placement are among the problems that can mitigate adequate fracture compression.^{13, 14, 25} Posterior surgical approaches, on the other hand, rely on C1–2 arthrodesis. This approach is associated with higher fusion rates as well as higher surgery-related morbidity, particularly in the elderly.^{19, 26, 27} A recently published meta-analysis showed a significantly higher fusion rate in elderly patients who had posterior C1–2 fusion.²⁸ However, in younger patients, the potential loss of C1–2 axial rotation should be taken into consideration. Thus, in younger individuals, osteosynthesis with 1 or 2 screws via an anterior approach is recommended as a standard operative treatment in patients with good bone quality if adverse modifiers are absent.²⁰

A review of the existing literature showed that most cases of simple type III odontoid fractures can be managed with external immobilization using a halo vest or rigid cervical collar, especially in the elderly, with a satisfactory fusion rate of almost 100% and 84%, respectively. The use of AOSF for type III dens fractures has also been shown to improve the fusion rate to nearly 100%.^{23, 24} However, debates exist regarding the treatment of complex type III fractures.^{7, 18} Niemeier et al. reported treatment failure with external immobilization in 21% of complex type III odontoid fractures that subsequently required surgical fusion.⁷ Pryputniewicz and Hadley reported that early internal stabilization may be considered if displacement is larger than 5 mm in type III odontoid fractures.²⁹ Nonreduction of a displaced or an angulated odontoid fracture has been a major limitation of AOSF. However, three authors reported the use of transoral digital manipulation for the reduction of type II odontoid fractures to overcome these challenges and aid alignment during AOSF.^15–17 Lee is the only author who has documented the use of a similar technique in type III odontoid fractures.¹⁸ Although there was a satisfactory reduction intraoperatively, the reduction could not be maintained postoperatively and at follow-up. The failed reduction was attributed to a broader fracture base and the presence of a partial fracture of the left superior articular process, which disturbed the anatomical reduction.

Lessons

Despite the challenges experienced in the management of our patient, such as delayed presentation, difficulty sourcing an odontoid screw locally, and failed intraoperative reduction by traction, this case further supports the use of transoral digital reduction of an irreducible, anteriorly displaced proximal fracture segment of a type III odontoid fracture in young patients undergoing AOSF. The use of direct C2–3 access provides easy manipulation, a reduced extent of tissue dissection, and good surgical ergonomics for appropriate screw trajectory and placement. Therefore, AOSF using a direct C2–3 approach does provide optimal access and good surgical ergonomics for appropriate screw trajectory and fixation of type III odontoid fractures. The use of transoral digital reduction of irreducible odontoid fractures helps to achieve good reduction and fusion with the preservation of axial rotation, especially in young patients.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: all authors.Acquisition of data: Alfin, Mahmud. Analysis and interpretation of data: all authors. Drafting the article: all authors.Critically revising the article: Alfin, Mahmud. Reviewed submitted version of manuscript: Alfin, Mahmud.Approved the final version of the manuscript on behalf of all authors: Alfin. Administrative/technical/material support: Mahmud. Study supervision: Mahmud, Salman. Lead surgeon: Mahmud.

Supplemental Information

Previous Presentations

An abstract of this article was presented at the Nigerian Academy of Neurological Surgeons conference, held November 19–21, 2015, in Sokoto, Sokoto State, Nigeria.

Correspondence

Dumura J. Alfin: Jos University Teaching Hospital, Jos, Plateau State, Nigeria. jeneralalfin@gmail.com.