Bilateral occipital condyle fracture with an avulsion fracture of the foramen magnum: nonoperative care guided by a traction test. Illustrative case

Amit R Persad Department of Neurosurgery, Stanford University, Palo Alto, California; and

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Eva Liu Division of Neurosurgery, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

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Adam Wu Division of Neurosurgery, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

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Daryl R Fourney Division of Neurosurgery, Royal University Hospital, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

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BACKGROUND

Bilateral occipital condyle fractures (OCFs) with involvement of the inferior clivus, otherwise known as “avulsion of the anterior foramen magnum,” are an exceedingly rare injury with only a few published reports.

OBSERVATIONS

A 24-year-old male presented with bilateral OCFs with involvement of the clivus after a motor vehicle accident. The patient had no neurological deficits and was successfully managed nonoperatively using a halo vest. The authors used a traction test to guide the duration of nonoperative care. The operative and nonoperative management of this rare injury is discussed with respect to other cases in the literature.

LESSONS

External immobilization through a halo vest is an effective treatment option for bilateral OCFs with clivus involvement. The traction test can be used, along with computed tomography, to guide the duration of treatment.

ABBREVIATIONS

CT = computed tomography; MRI = magnetic resonance imaging; OC = occipital condyle; OCF = occipital condyle fracture

BACKGROUND

Bilateral occipital condyle fractures (OCFs) with involvement of the inferior clivus, otherwise known as “avulsion of the anterior foramen magnum,” are an exceedingly rare injury with only a few published reports.

OBSERVATIONS

A 24-year-old male presented with bilateral OCFs with involvement of the clivus after a motor vehicle accident. The patient had no neurological deficits and was successfully managed nonoperatively using a halo vest. The authors used a traction test to guide the duration of nonoperative care. The operative and nonoperative management of this rare injury is discussed with respect to other cases in the literature.

LESSONS

External immobilization through a halo vest is an effective treatment option for bilateral OCFs with clivus involvement. The traction test can be used, along with computed tomography, to guide the duration of treatment.

ABBREVIATIONS

CT = computed tomography; MRI = magnetic resonance imaging; OC = occipital condyle; OCF = occipital condyle fracture

Occipital condyle fractures (OCFs) are rare injuries with an incidence of 0.4% among trauma patients.1–3 Bilateral OCFs occur in less than one-quarter of cases.1 Bilateral OCFs with extension through the clivus are rare with only six prior reports.4–9 This injury, an avulsion of the anterior foramen magnum, can result in occipitoatlantal instability. Management options include surgical fusion and a halo vest. Traction testing has been proposed as an ancillary test to assess the stability of the craniocervical junction, as surgical fusion has significant long-term functional consequences.10

In this study, we present the case of bilateral OCFs with extension through the clivus that was successfully treated with halo traction. This is the first documented case in which the traction test was used to guide the duration of nonoperative management of this injury.

Illustrative Case

A 24-year-old, previously healthy male was brought to the emergency department in a cervical collar after a highway-speed collision. He was neurologically intact. Computed tomography (CT) scanning revealed multiple injuries including a right frontal contusion, right mandibular fracture, multiple orthopedic injuries, and bilateral Anderson-Montesano type III11 OCFs with extension through the tip of the clivus (Fig. 1), resulting in avulsion of the anterior portion of the foramen magnum. Emergent magnetic resonance imaging (MRI) showed intact alar ligaments, tectorial membrane, transverse ligament, and occipital condyle (OC) joint capsules (Fig. 2). Although the alar ligaments were intact, avulsion of the occipital condyles and anterior foramen magnum implied that they were no longer performing a stabilizing function. Furthermore, there was no bone connection between the upper spine and skull. At this point, the only stabilizers of the craniocervical junction in this patient were the OC joint capsules. Thus, we considered this to be an unstable fracture pattern.

FIG. 1
FIG. 1

Axial (A), sagittal (B), and coronal (C) CT images showing bilateral type III OCFs with involvement of the inferior clivus. Arrows indicate the fracture.

FIG. 2
FIG. 2

A: Coronal T1-weighted MRI showing an intact tectorial membrane. B: Sagittal T2-weighted MRI showing no spinal cord injury.

Operative management with occipitocervical fusion from the occiput to C2 was considered, but we decided to place the patient in a halo vest, because there was no overt occipitoatlantal dislocation and the patient was neurologically intact. The halo vest was placed in the intensive care unit while the patient was supine, with inline precautions and normal alignment. No traction was applied during placement. Adequate positioning and alignment were verified with postplacement radiographs. After treatment of his orthopedic injuries and a course of inpatient rehabilitation, the patient was discharged home in the halo vest with a plan for follow-up in the short term.

The patient was seen as an outpatient at 2 weeks and was doing well. Radiographs showed adequate alignment. We planned for 16 weeks in a halo vest with follow-up in the community. However, the patient presented 8 weeks later to the emergency department after an attempt to remove his own halo vest, with the ring partially removed. He refused an attempt to replace the halo, stating that he would prefer fusion rather than further treatment in the halo vest. He did, however, agree to a traction test12 to determine whether the halo was still required.

We proceeded with the traction test, with a plan to proceed with surgery if the injury still appeared unstable. We performed the traction test in the fluoroscopy suite. We first applied mild manual traction and performed imaging to ensure that there was no gross instability. We then used the halo headpiece, and traction was applied via a pulley system. We placed incremental weights from 5 to 20 lbs. We watched on live fluoroscopy for any increase of the basion-axial interval or basion-dens interval over the normal limit of 12 mm or any widening of the fracture line at the foramen magnum. The traction test was normal with a basion-dens interval of 11 mm and a basion-axial interval of 10 mm (normal <12 mm) and no change with traction up to 20 lbs (Fig. 3). Widening of the fracture line or separation of the clivus was not seen during traction. We also obtained a craniocervical CT scan, which showed bony bridging across the fracture (Fig. 4).

FIG. 3
FIG. 3

Traction test to assess for occipitoatlantal dissociation, at rest (A) and under 20 lbs of traction (B). The basion-dens interval and basio-atlantal interval are within normal limits. There is no widening of the basion fracture line during the application of traction.

FIG. 4
FIG. 4

Axial (A), sagittal (B), and coronal (C) CT images showing bony bridging of the fracture. Arrows indicate the healing fracture line.

After the traction test, the halo was removed and the patient was discharged in a Philadelphia collar with outpatient follow-up. At the 6-week follow-up, after having his halo vest removed, his fracture was deemed to be stable and he was cleared of his collar. At the 2-year follow-up, the patient had no pain or restriction of range of motion or evidence of nonunion or cranial settling and was discharged from neurosurgical care.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

OCFs are classified based on mechanism. Type I and II fractures are stable, whereas type III fractures can be unstable due to a high rate of disruption of the alar ligament.11 This has been challenged, as the only potentially relevant differentiator is whether there is craniocervical misalignment.2,10,12 The mechanism of bilateral OCFs with clival involvement is debated.4,9 Tanabe at al.9 hypothesized that a rotational element explains the avulsion of the clivus and contralateral OCF. Dashti et al.4 theorized that it is most likely a flexion/compression injury as in type I fractures. The true instability of this fracture likely depends on the biomechanical mechanism; if the fracture is a compression fracture that extends through the occipital condyles, the behavior would be more like a type II fracture and therefore stable. If, as is more commonly believed, the fracture is an avulsion of both occipital condyles that joins through the base of the clivus, then the behavior is more like a type III fracture and therefore unstable. If the fracture is an avulsion type, the extension across the lower clivus may be in part due to avulsion of that bone by the tectorial membrane.

The major stabilizers of the craniocervical junction are the alar ligaments, OC joint capsules, and tectorial membrane. Disruption of all three results in frank instability of the craniocervical junction.10 The alar ligaments connect to the occipital condyles, and the tectorial membrane connects to the inferior clivus. With both structures avulsed, there is very little or no structural support offered by these ligaments, despite the lack of overt injury to the ligaments themselves. Thus, it is likely that the only truly intact stabilizer in our case is the OC joint capsule. As such, the potential instability of this fracture pattern is very high.

The fracture pattern in our case, an avulsion of the foramen magnum, has been reported only six times.4–9 In one patient, the injury was found postmortem.6 Three patients were symptomatic, with two having tetraplegia5,7 and one having upper-extremity weakness with cranial neuropathies.9 In the living patients, three were treated surgically,5,7,8 with one undergoing decompression alone5 and two undergoing fusion.7,8 Two were treated with a halo vest.4,9 In injuries involving the occipitocervical junction, minimal instrumentation is preferred to preserve cervical motion. For example, Maughan et al.8 performed a single-segment occiput-C1 fusion to minimize motion loss. The majority of these patients were, however, able to be successfully treated without fusion.4,5,9

Given the rarity of this injury, it is unknown how long the halo vest needs to remain in place for adequate stabilization. We used a provocative test to determine whether our patient had craniocervical dissociation.10 We performed the test because our patient had not completed the originally prescribed duration of treatment in the halo vest and wanted to stop halo immobilization. We used the traction test described by Child et al.10 Bellabarba et al.12 have previously used the traction test in the setting of acute injury to guide the need for surgical stabilization.

Although the CT scan did demonstrate bone healing, it is uncertain to what extent that bridging reflects stability. The median time to healing of cervical spine fractures, which are the fractures closest to the type we describe, is 8.5 weeks.13 In the time course of fracture healing, the initial type of bone deposited at the fracture site is woven bone, which is disorganized. After a time, lamellar bone is formed, which has much more strength.14 There is no way to know based on the CT scan if the bone seen in our case was strong lamellar bone or weak woven bone. The traction test offers a functional correlate to the bone deposition seen on CT, proving that supraphysiological strain did not result in displacement of the fracture or dislocation of the craniocervical junction. Because this injury is high risk because of the bony dissociation of the craniocervical junction and the neurological deficits incurred by damage to this region would be devastating, we recommend this test to ascertain safety before stepping down immobilization to a collar.

Observations

The CT scan showed bony bridging, which in combination with a normal traction test suggested that removing the halo would be safe. If the CT scan had shown no bridging, we may have instead proceeded with instrumentation given the patient’s refusal to continue further treatment in the halo. The same applies if the traction test had been abnormal. The CT scan showing bony bridging demonstrates the progression of fracture healing, and the traction test demonstrates the physiological integrity of the occiput-C1 complex. The absence of either piece of information would predispose us to perform surgery or further halo immobilization in this high-risk, uncommon injury.

The cadaveric study by Child et al.10 revealed that there is an all-or-nothing phenomenon with disruption of the major stabilizers of the OC junction, including the OC joint capsule, tectorial membrane, and alar ligaments. Only the disruption of all three resulted in a positive traction test.10 We observed the fracture line at the clivus during the traction test, as an unhealed fracture may have separated during traction.

Care must be taken using this technique to assess anterior foramen magnum avulsion fractures. The fracture line is not easily appreciated, and in bony cases the basion-dens interval and basio-atlantal interval, as well as the traction test, may all be normal. We suspect that if the fracture was not healed, the fracture line would widen during traction testing, resulting in separation of the clivus.

After reassurance by the traction test and CT, it should be noted that the collar alone was adequate for stabilization for the remainder of the healing period, with a good result.

Lessons

This is the first case of using a traction test to guide nonoperative treatment for bilateral occipital condyle fractures with clival involvement. Attention should be paid to the fracture line during testing. We recommend corroboration of this information with a CT scan. Foramen magnum avulsion fractures can likely be treated routinely without fusion.

Author Contributions

Conception and design: Fourney, Persad, Liu. Acquisition of data: Fourney, Persad, Wu. Analysis and interpretation of data: Fourney, Persad, Liu. Drafting the article: Fourney, Persad. Critically revising the article: Fourney, Persad, Liu. Reviewed submitted version of manuscript: Fourney, Persad, Liu. Approved the final version of the manuscript on behalf of all authors: Fourney. Administrative/technical/material support: Fourney. Study supervision: Fourney.

References

  • 1

    Hanson JA, Deliganis AV, Baxter AB, et al. Radiologic and clinical spectrum of occipital condyle fractures: retrospective review of 107 consecutive fractures in 95 patients. AJR Am J Roentgenol. 2002;178(5):12611268.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Maserati MB, Stephens B, Zohny Z, et al. Occipital condyle fractures: clinical decision rule and surgical management. J Neurosurg Spine. 2009;11(4):388395.

  • 3

    Mueller FJ, Fuechtmeier B, Kinner B, et al. Occipital condyle fractures. Prospective follow-up of 31 cases within 5 years at a level 1 trauma centre. Eur Spine J. 2012;21(2):289294.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Dashti R, Ulu MO, Albayram S, Aydin S, Ulusoy L, Hanci M. Concomitant fracture of bilateral occipital condyle and inferior clivus: what is the mechanism of injury? Eur Spine J. 2007;16(suppl 3):261264.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Fuentes S, Bouillot P, Dufour H, Grisoli F. Occipital condyle fractures and clivus epidural hematoma. Case report. Article in French. Neurochirurgie. 2000;46(6):563567.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Imamura T, Kojima T, Yashiki M, Namera A. Traumatic avulsion fracture of the occipital condyles and clivus: a case report. Leg Med (Tokyo). 2000;2(1):4953.

  • 7

    Jones DN, Knox AM, Sage MR. Traumatic avulsion fracture of the occipital condyles and clivus with associated unilateral atlantooccipital distraction. AJNR Am J Neuroradiol. 1990;11(6):11811183.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Maughan PH, Horn EM, Theodore N, Feiz-Erfan I, Sonntag VK. Avulsion fracture of the foramen magnum treated with occiput-to-c1 fusion: technical case report. Neurosurgery. 2005;57(3):E600.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Tanabe M, Watanabe T, Matsumoto S, Okamoto H, Shirakashi K. Avulsion fracture of the anterior half of the foramen magnum involving the bilateral occipital condyles and the inferior clivus—case report. Neurol Med Chir (Tokyo). 1999;39(5):358361.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Child Z, Rau D, Lee MJ, et al. The provocative radiographic traction test for diagnosing craniocervical dissociation: a cadaveric biomechanical study and reappraisal of the pathogenesis of instability. Spine J. 2016;16(9):11161123.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Anderson PA, Montesano PX. Morphology and treatment of occipital condyle fractures. Spine (Phila Pa 1976). 1988;13(7):731736.

  • 12

    Bellabarba C, Mirza SK, West GA, et al. Diagnosis and treatment of craniocervical dislocation in a series of 17 consecutive survivors during an 8-year period. J Neurosurg Spine. 2006;4(6):429440.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Tomaszewski R, Sesia SB, Studer D, Rutz E, Mayr JM. Conservative treatment and outcome of upper cervical spine fractures in young children: a STROBE-compliant case series. Medicine (Baltimore). 2021;100(13):e25334.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Bigham-Sadegh A, Oryan A. Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures. Int Wound J. 2015;12(3):238247.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
  • FIG. 1

    Axial (A), sagittal (B), and coronal (C) CT images showing bilateral type III OCFs with involvement of the inferior clivus. Arrows indicate the fracture.

  • FIG. 2

    A: Coronal T1-weighted MRI showing an intact tectorial membrane. B: Sagittal T2-weighted MRI showing no spinal cord injury.

  • FIG. 3

    Traction test to assess for occipitoatlantal dissociation, at rest (A) and under 20 lbs of traction (B). The basion-dens interval and basio-atlantal interval are within normal limits. There is no widening of the basion fracture line during the application of traction.

  • FIG. 4

    Axial (A), sagittal (B), and coronal (C) CT images showing bony bridging of the fracture. Arrows indicate the healing fracture line.

  • 1

    Hanson JA, Deliganis AV, Baxter AB, et al. Radiologic and clinical spectrum of occipital condyle fractures: retrospective review of 107 consecutive fractures in 95 patients. AJR Am J Roentgenol. 2002;178(5):12611268.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Maserati MB, Stephens B, Zohny Z, et al. Occipital condyle fractures: clinical decision rule and surgical management. J Neurosurg Spine. 2009;11(4):388395.

  • 3

    Mueller FJ, Fuechtmeier B, Kinner B, et al. Occipital condyle fractures. Prospective follow-up of 31 cases within 5 years at a level 1 trauma centre. Eur Spine J. 2012;21(2):289294.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Dashti R, Ulu MO, Albayram S, Aydin S, Ulusoy L, Hanci M. Concomitant fracture of bilateral occipital condyle and inferior clivus: what is the mechanism of injury? Eur Spine J. 2007;16(suppl 3):261264.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Fuentes S, Bouillot P, Dufour H, Grisoli F. Occipital condyle fractures and clivus epidural hematoma. Case report. Article in French. Neurochirurgie. 2000;46(6):563567.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Imamura T, Kojima T, Yashiki M, Namera A. Traumatic avulsion fracture of the occipital condyles and clivus: a case report. Leg Med (Tokyo). 2000;2(1):4953.

  • 7

    Jones DN, Knox AM, Sage MR. Traumatic avulsion fracture of the occipital condyles and clivus with associated unilateral atlantooccipital distraction. AJNR Am J Neuroradiol. 1990;11(6):11811183.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Maughan PH, Horn EM, Theodore N, Feiz-Erfan I, Sonntag VK. Avulsion fracture of the foramen magnum treated with occiput-to-c1 fusion: technical case report. Neurosurgery. 2005;57(3):E600.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Tanabe M, Watanabe T, Matsumoto S, Okamoto H, Shirakashi K. Avulsion fracture of the anterior half of the foramen magnum involving the bilateral occipital condyles and the inferior clivus—case report. Neurol Med Chir (Tokyo). 1999;39(5):358361.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Child Z, Rau D, Lee MJ, et al. The provocative radiographic traction test for diagnosing craniocervical dissociation: a cadaveric biomechanical study and reappraisal of the pathogenesis of instability. Spine J. 2016;16(9):11161123.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Anderson PA, Montesano PX. Morphology and treatment of occipital condyle fractures. Spine (Phila Pa 1976). 1988;13(7):731736.

  • 12

    Bellabarba C, Mirza SK, West GA, et al. Diagnosis and treatment of craniocervical dislocation in a series of 17 consecutive survivors during an 8-year period. J Neurosurg Spine. 2006;4(6):429440.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Tomaszewski R, Sesia SB, Studer D, Rutz E, Mayr JM. Conservative treatment and outcome of upper cervical spine fractures in young children: a STROBE-compliant case series. Medicine (Baltimore). 2021;100(13):e25334.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Bigham-Sadegh A, Oryan A. Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures. Int Wound J. 2015;12(3):238247.

    • PubMed
    • Search Google Scholar
    • Export Citation

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