PT  - JOURNAL ARTICLE
AU  - Rees, Andrew B.
AU  - Croft, Andrew J.
AU  - Varas-Rodrguez, Emil
AU  - Stephens, Byron F.
AU  - Abtahi, Amir M.
TI  - Case Report—Traumatic L5-S1 Instability: Are Upright Radiographs Potentially Dangerous?
AID  - 10.14444/8432
DP  - 2023 Apr 13
TA  - International Journal of Spine Surgery
PG  - 8432
4099  - https://www.ijssurgery.com/content/early/2023/04/13/8432.short
4100  - https://www.ijssurgery.com/content/early/2023/04/13/8432.full
AB  - Background Traumatic lumbosacral instability is a rare but potentially devastating injury. These injuries are frequently associated with neurologic injury and often result in long-term disability. Despite their severity, radiographic findings can be subtle, and multiple reports exist in which these injuries were not recognized on initial imaging. Transverse process fractures, high-energy mechanisms, and other injury features have been suggested as indications for advanced imaging, which has a high degree of sensitivity in detecting unstable injuries.Case Presentation A 21-year-old man presented to our level I trauma center after being ejected in a rollover motor vehicle collision. He sustained multiple injuries, including multiple lumbar transverse process fractures and a unilateral superior articular facet fracture of S1.Primary Outcomes Initial supine computed tomography (CT) images showed no displacement of the fracture and no listhesis or instability. Subsequent upright imaging in a brace, however, demonstrated significant displacement of the fracture with dislocation of the contralateral L5-S1 facet joint and significant anterolisthesis. The patient underwent open posterior reduction and stabilization of L4-S1 followed by L5-S1 anterior lumbar interbody fusion. The patient demonstrated excellent alignment on postoperative imaging. At 3 months postoperatively, he had returned to work, was ambulating without assistance, and reported minimal back discomfort and no lower extremity pain, numbness, or weakness.Conclusion This case serves as a warning that supine CT imaging alone may not be sufficient to rule out unstable lumbar spine injuries, such as traumatic L5-S1 instability, and that upright radiographs in these potentially unstable injuries may represent a hazard to patients. Fractures involving the pedicle, pars, or facet joints as well as multiple transverse process fractures and/or a high-energy mechanism of injury should all raise suspicion of instability and warrant additional imaging.Clinical Relevance This article provides guidance on approaching treatment for patients with potential traumatic lumbosacral instability.Level of Evidence 5.