The 'nutcracker' spino-laminar fracture: evaluation as a sentinel lesion of a hyperextension mechanism in cervical spine trauma.

Objective: We hypothesised that the orientation of the fracture line in the cervical vertebral arch depends on the traumatic mechanism, specifically focusing on frontal oblique spino-laminar fractures to determine if this pattern can serve as an indicator of a hyperextension mechanism of injury of the cervical spine.
Materials and Methods: We reviewed the imaging records of 114 adult patients admitted to the emergency department of the Strasbourg University Hospital for severe polytrauma between January 2016 and December 2021 and who presented with a fracture of the posterior vertebral arch of the lower cervical spine on the whole-body CT scan. A radiology resident (R1) and a musculoskeletal radiologist (R2) independently read the CT scans to determine the type of vertebral arch fracture; inter- and intra-observer agreements were calculated using Cohen's Kappa test. Two musculoskeletal radiologists (R2 and R3) then reviewed the CT scans and possible MRIs to identify specific hyperextension injuries of the cervical spine. The association between frontal oblique spino-laminar fracture and hyperextension injuries was assessed using chi ² test.
Results: Thirty-five patients had frontal oblique spino-laminar fractures of the cervical spine. These fractures were significantly associated (p = 0.001) with hyperextension injuries of the cervical spine. The inter- and intra-observer agreements for the identification of these spino-laminar fractures were very good (0.86 (0.75-0.96) and 0.90 (0.81-0.99)).
Conclusion: Frontal oblique spino-laminar fractures are easily recognisable on CT scans and significantly associated with other traumatic injuries known as resulting from hyperextension. Their identification should lead to a search for potential associated unstable vertebral disco-ligamentous injuries with MRI.
(© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)