Abstract

Background: Type 2 odontoid fractures are associated with a high rate of nonunion without surgical treatment. If neglected, they may become fixed in an abnormal position, causing progressive myelopathy. Conventionally, odontoidectomy or transoral release is performed to relieve symptoms in such cases. Here, were report our experience with a transcervical approach for odontoid release (i.e., of a chronically fractured dens) followed by a posterior C1–C2 fusion.

Methods: The 11 patients (2017–2021) retrospectively included; in this study, all had a history of remote trauma and the radiological appearance of an old odontoid fracture that was displaced and could not be reduced with traction. There were eight males and three females who averaged 52.6 years of age.

Results: All 11 patients underwent anterior retropharyngeal release with a C4–C5 level incision followed by a posterior C1–C2 fusion. The mean Japanese orthopedic association on presentation was 9.9 ± 2.7 which improved to 13.8 ± 2.7 on final follow-up (P

Conclusion: Anterior release through a retropharyngeal approach coupled with posterior C1–C2 instrumentation proved to be an effective alternative to the traditional transoral approach to treat a chronic malunited odontoid fracture.

Keywords: Atlantoaxial instability, IAAD, Irreducible atlantoaxial dislocation, Irreducible dislocation, Odontoid fracture

INTRODUCTION

C2 fractures comprise 9–20% of all cervical spine fractures.[ 2 ] Most studies have focused on the treatment of these fractures during the acute stage. However, when timely management is not instituted, the fractured dens may become fixed in an abnormal position, leading to a progressive myelopathy, and/or neck pain.[ 4 ] If these fractures cannot be reduced by traction, they may require anterior decompression or transoral odontoid release followed by a posterior C1–C2 instrumented fusion.[ 4 , 8 ] Here, were report our experience with a transcervical approach for odontoid release (i.e., of a chronically fractured dens) followed by a posterior C1–C2 fusion.

MATERIALS AND METHODS

Demographics and patient presentations

Of the 11 patients included in this study, there were eight males and three females. The mean age was 52.6 years (33–71 years). All patients had a history of head or neck trauma, and the mean time from injury to presentation was 4.7 years (range: 6 months–15 years) [ Table 1 ]. The most common presenting signs and symptoms were neck pain, gait abnormalities, limb weakness, paresthesia, and sphincter dysfunction. The mean Japanese orthopedic association (JOA) score on presentation was 9.9 ± 2.7 (mean ± SD) [ Table 2 ]. Imaging studies included; dynamic cervical X-rays, MR, and CT examinations confirming chronic angulated type 2 odontoid fractures.

Table 1:

Demographics and presentations.

Table 2:

Comparison of preoperative and postoperative JOA scores.

Statistical analysis

Data analysis was performed using the IBM SPSS 21. JOA scores were compared using a paired sample t-test. P < 0.05 was considered significant.

RESULTS

Surgery

Eleven patients (2017–2021) underwent transcervical odontoid release followed by C1–C2 posterior fixation [ Table 3 ]. A horizontal incision was centered over the medial edge of the sternocleidomastoid muscle at the C4–C5 level. We used a gloved finger to identify the depression between the fractured odontoid and the C2 vertebral body; this was confirmed on a lateral X-ray [ Figure 1a ]. An attempt at blunt dissection between the posterior surface of the C1 arch/odontoid complex and the C2 vertebral body failed due to release adhesions. They had to be “broken” using a small chisel and mallet under direct radiological guidance [ Figure 1b ]. The lower surface of the odontoid and the upper surface of the C2 vertebral body were then curetted to prepare for fusion. Direct pressure over the C1 tubercle and cranial traction was subsequently applied; nevertheless, full reduction of the fracture could not be achieved. Next, the patient was turned prone, and the C1–C2 facet joints were opened and curetted to release adhesions. After adequate reduction, a C1–C2 instrumented fusion was performed using C1 lateral mass and C2 pedicle screws. Grafts were taken from C2 spinous process and occiput to complete the fusion mass [ Figures 1c and d ]. Although all procedures were performed without neuromonitoring or navigation, the additional use of both of these modalities is recommended to enhance surgical safety. A cervical collar was placed for just a few days postoperatively, and X-rays showed adequate reduction of the fracture.

Table 3:

Inclusion and exclusion criteria.

Figure 1:

(a) Intraoperative X-ray with patient in supine position. Anterior arch of atlas confirmed with lateral image. (b) Small curette inserted between C2 vertebral body and lower surface of fractured odontoid after release. The surfaces are being prepared for fusion. (c and d) Patient in prone position. C1 Lateral mass and C2 pedicle screws inserted.

Postoperative follow-up

At mean follow-up of 9.6 postoperatively months, CT scans showed good alignment and reduction [ Figures 2 - 4 ]. The average JOA score at that time was 13.8 ± 2.7 (mean ± SD) [ Table 2 ]. Postoperatively, one patient developed an infection of the posterior midline wound that was treated with antibiotics and debridement.

Figure 2:

A 60-year-old male with a history of bike accident 7 year ago presented on a wheel chair with a history of progressive weakness and numbness in all four limbs for the past 6 months. (a and b) Preoperative CT and MRI shows old type 2 odontoid fracture with anterolisthesis of C1/odontoid complex on C2 body and some bony fusion with significant cord compression and signal changes. (c and d) Sagittal and coronal CT scan taken in the immediate postoperative period showing alignment of the released odontoid. (e and f) Sagittal and parasagittal CT cuts taken at 1-year postoperative show that the alignment is maintained.

Figure 3:

A 56-year-old man presented with clumsy hands, difficulty micturition, and gait disturbance for the past 1 year. The patient had a history of motor vehicle accident with neck injury 15 years ago. (a) Extension lateral radiograph, (b) midsagittal CT scan shows old odontoid type 2 fracture fixed in anterolisthesis and resultant spinal canal narrowing, (c) immediate postoperative X-ray to confirm alignment and screw position and (d and e) coronal and sagittal CT scan taken at 6 months follow-up showing the alignment is maintained.

Figure 4:

A 37-year-old male with a history of neck pain and clicking, which started after a fall at a construction site 3 years ago presented with progressive upper and lower limb weakness and impaired bowel bladder function. (a and b) Sagittal, parasagittal preoperative views with fixed anterolisthesis of odontoid over C2 body and resultant canal narrowing. (c) Sagittal MRI shows extreme cord compression. (d and e) Flexion and extension radiographs show irreducibility atlantoaxial dislocation. (f) Intraoperative image of posterior C1–C2 fixation being done in the patient following release of odontoid. (g) Postoperative CT showing reduction of the displaced odontoid.

DISCUSSION

Type II odontoid fractures have a high rate of nonunion.[ 7 ] Transoral decompression with posterior C1–C2 fusion has traditionally been used for irreducible AAD.[ 4 , 8 ] Here, we proposed another alternative treatment for these lesions.

Pros of retropharyngeal odontoid release

Several authors have reported on the utility of the retropharyngeal approach for the release of chronic angulated odontoid fractures. Hao et al. used an incision that was 2 cm below and parallel to the mandible for an anterior release.[ 3 ] Yuan et al. used a similar method, but focused on other diagnostic parameters.[ 10 ] Ren et al. reported their experience with the submandibular anterior release.[ 6 ] Aggarwal et al.[ 1 ] used the same incision and performed posterior fixation with C1–C2 transarticular screws and posterior wiring in one of their two reported cases. Wu et al.[ 9 ] reported microendoscopic anterior release and anterior transarticular screw fixation in patients with irreducible atlantoaxial dislocation. Klimov et al.[ 5 ] used a three-stage method with anterior release and posterior fusion, followed by bone graft placement between C1 and C2 again from the anterior approach [ Table 4 ].

Table 4:

Summary of studies included in discussion.

Need for accompanying posterior fusion

Following mobilization of the dens, the degenerated C1–C2 facet joints must be opened and released to achieve complete reduction of the AAD and instrumented fixation using a posterior approach. However, unlike patients with congenital AAD, posterior manipulation/fusion alone is usually ineffective in achieving the complete reduction of the malunited remote fractures. This is because the bony and fibrous adhesions between the odontoid and C2 body found intraoperatively, fixing the fractured dens in anterolisthesis, are not accessible using the posterior approach alone. These findings along with severe C1-2 facet joint degenerative changes justify the dual circumferential procedures, that is, release of both the anterior fixed odontoid malunion and the posterior C1-2 facet joint adhesions followed by posterior fusion.

CONCLUSION

Anterior release through a retropharyngeal approach coupled with posterior C1–C2 instrumentation proved to be an effective alternative to the traditional transoral approach to treat a chronic malunited odontoid fracture.

Declaration of patient consent

Patient’s consent not required as patients identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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