Teardrop fracture following head-first impact in an ice hockey player: Case report and analysis of injury mechanisms

Abstract

Background: We report a case of a young male athlete who sustained a three column displaced teardrop fracture of the C5 vertebra due to a head-first impact in hockey, suffered neurapraxia, yet made full neurological recovery. This full recovery was in sharp contrast to multiple case series which reported permanent quadriplegia in the vast majority of teardrop fracture patients. We investigate the etiology and biomechanical mechanisms of injury.

Methods: Admission imaging revealed the teardrop fracture which consisted of: a frontal plane fracture which separated an anterior quadrilateral-shaped fragment from the posterior vertebral body; a vertical fracture of the posterior vertebral body in the sagittal plane; and incomplete fractures of the neural arch that initiated superiorly at the anterior aspect of the spinous process and left lamina adjacent to the superior facet. Epidural hematoma in the region of the C5 vertebra was observed in addition to disc and ligamentous disruptions at C4-5 and C5-6. Our patient was ultimately treated surgically with anterior fusion from C4 through C6 and subsequently with bilateral posterior fusion at C5-6.

Results: The injuries were caused by high-energy axial compression with the neck in a pre-flexed posture. The first fracture event consisted of the anterior vertebral body fragment being sheared off of the posterior fragment under the compression load due in part to the sagittal plane concavity of the C5 inferior endplate. The etiology of the vertical fracture of the posterior vertebral body fragment in the sagittal plane was consistent with a previously described hypothesis of the mechanistic injury events. First, the C4-5 disc height decreased under load which increased its hoop stress. Next, this increased hoop stress transferred lateral forces to the C5 uncinate processes which caused their outward expansion. Finally, the outward expansion of the uncinate processes caused the left and right sides of the vertebral body to split and spread. Evidence in support of this mechanistic event sequence was provided by the neural arch fractures which initiated superiorly, average angulation of the C5 uncinate processes, and similar well-established mechanisms causing vertical fractures at other spinal regions.

Conclusions: Our case study and analyses provide insight into the etiology of the specific teardrop fracture patterns observed clinically.

Keywords: Cervical Spine; hockey; impact biomechanics; injury mechanism; teardrop fracture.

Fig. 1

Admission CT scans demonstrating teardrop fracture of the C5 vertebra. The sagittal plane sequence shows forward displacement and extension of the anterior VB fragment and retropulsion of the posterior VB fragment into the canal: a) left, b) midsagittal, and c) right. The frontal plane sequence shows the vertical fracture at the: d) anterior, e) mid, and f) posterior regions of the posterior VB fragment. The transverse plane sequence shows the aforementioned injuries in addition to the neural arch fractures indicated with arrows: g) inferior, h) mid-inferior, i) mid-superior, and j) superior. Note from the sagittal place sequence that the spine is tilted anteriorly relative to the axes of the scanner. Consequently, the anteroinferior region of the C4 VB appears in panels i and j of the transverse plane sequence.

Fig. 2

Admission T2-weighted MRI of the cervical spine demonstrating posterior displacement of the upper cervical spinal column, at and above the C5 vertebra, with epidural hematoma noted in the region of C5.

Fig. 3

Lateral radiographs demonstrating the corrected spinal alignment and stability resulting from the anterior fusion at C4 through C6 with bone graft restoring height of the C5 VB: a) post-op and b) 3.5 months. Nonunion at C5-6 was observed at 5 months (c). Bilateral posterior fusion was subsequently performed at C5-6 (d).