Transoral digital reduction of complete anterior odontoid dislocation followed by fiducial-based navigated transcondylar screw fixation: illustrative case

BACKGROUND Posterior atlantoaxial dislocations (i.e., complete anterior odontoid dislocation) without C1 arch fractures are a rare hyperextension injury most often found in high-velocity trauma patients. Treatment options include either closed or open reduction and optional spinal fusion to address atlantoaxial instability due to ligamentous injury. OBSERVATIONS A 60-year-old male was struck while on his bicycle by a truck and sustained an odontoid dislocation without C1 arch fracture. Imaging findings additionally delineated a high suspicion for craniocervical instability. The patient had neurological issues due to both a head injury and ischemia secondary to an injured vertebral artery. He was stabilized and transferred to our facility for definitive neurosurgical care. LESSONS The patient underwent a successful transoral digital closed reduction and posterior occipital spinal fusion via a fiducial-based transcondylar, C1 lateral mass, C2 pedicle, and C3 lateral mass construct. This unique reduction technique has not been recorded in the literature before and avoided potential complications of overdistraction and the need for odontoidectomy. Furthermore, the use of bone fiducials for navigated screw fixation at the craniocervical junction is a novel technique and recommended particularly for placement of technically demanding transcondylar screws and C2 pedicle screws where pars anatomy is potentially unfavorable.

Repeated Ct-based Hounsfield Unit Measurements as a Proxy Measure of Intercorporal Bone Graft Remodelling Towards Spinal Fusion; a Feasibility Study.

Background: There is a lack of knowledge about the biological process of intercorporal bone graft remodelling towards successful lumbar spine fusion with bridging vital bone between two adjacent vertebrae. Hounsfield Units (HU) highly correlate with Bone Mineral Density (BMD) and changes in HU may be valuable as proxy measure to monitor ongoing fusion. The aims of this study were to explore the feasibility to quantify BMD changes in the intercorporal bone graft after spinal fusion on consecutive CT-scans, and to explore whether trends in the individual changes in HU over time may serve as a proxy measure for successful fusion or non-fusion.Methods: A retrospective case series was conducted using available one-year and two-year CT-data from patients after posterior lumbar interbody fusion surgery. First, a standardized measuring procedure was developed, incorporating internal phantomless calibration, to establish the HU values of the grafted region of interest using consecutive CT-slices. Subsequently, changes in the participants’ bone graft HU over time between their first and second year after surgery were explored.Results: Between one and two years after surgery, seven out of nine (78%) participants showed an increase in their bone grafts’ HU, ranging from 3% to 41%. In two participants HU-values decreased 14% and 32%, respectively. The intraobserver reliability of the HU measuring procedure was excellent (ICC 0.93 (95% confidence interval 0.91 to 0.95)).Conclusion: The majority (78%) of participants in the current study showed increases in their bone graft HU, which suggests ongoing bone graft remodelling towards lumbar fusion. This result corresponds with the established percentages of achieved rigid bony fusion after lumbar spinal fusion surgery reported in the literature. Thus, prospective follow-up of CT-based HU measurements may have potential as diagnostic measure to monitor bone graft remodelling in time and trends may predict successful fusion or non-fusion. The measurement procedure developed in this study, using internal phantomless calibration, showed excellent intraobserver reliability and merits further study in larger patient numbers.

Metal allergy hypersensitivity after posterior thoracic spinal fusion: A case report and review of the literature

Background: Spine surgeons rarely consider metal allergies when placing hardware, as implants are thought to be inert. Case Description: A 32-year-old male presented with a skin rash attributed to the trace metal in his spinal fusion instrumentation. Patch testing revealed sensitivities to cobalt, manganese, and chromium. He underwent hardware removal and replacement with constructs of commercially pure titanium. His skin findings resolved at 2 weeks after surgery and were stable at 6 weeks. Conclusion: Hypersensitivity to metal (i.e., metal allergy) should be considered before performing instrumented spinal fusions.

Efficacy of Platelet-rich Plasma Impregnation for Unidirectional Porous Β-tricalcium Phosphate in Lateral Lumbar Interbody Fusion: Study Protocol for a Randomized Controlled Trial

BackgroundPlatelet-rich plasma has been increasingly used in spinal fusion surgery. However, the efficacy of platelet-rich plasma in lateral lumbar interbody fusion is unclear. In Japan, Affinos® (Kuraray Co., Tokyo, Japan), which is a β-tricalcium phosphate artificial bone, has been increasingly used for spinal fusion as a bone graft. The purpose of this trial is to demonstrate whether Affinos® impregnated with platelet-rich plasma can achieve a higher fusion rate, more rapid fusion, and better clinical outcomes than Affinos® alone.Methods/DesignThe current study is a prospective randomized controlled trial. The current trial will include consecutive patients scheduled for lateral lumbar interbody fusion. Since an intervertebral cage for lateral lumbar interbody fusion has two spaces for a bone graft, two bone grafts are inserted for each intervertebral level. In the current study, an artificial bone with plate-rich plasma will be inserted into one space and an artificial bone without platelet-rich plasma will be inserted into the other space. We will compare the fusion rates between the bone graft with and without platelet-rich plasma. Our primary endpoint will be the interbody fusion rate at 1 year after surgery. DiscussionThe current trial will verify the efficacy of platelet-rich plasma with Affinos® for bony fusion in lateral lumbar interbody fusion. This trial will provide substantial evidence for the effectiveness and safety of platelet-rich plasma in spinal fusion surgery.Trial registrationJapan Registry of Clinical Trials (jRCT), ID: jRCTb032200199. First registered on 13 November 2020, https://jrct.niph.go.jp/latest-detail/jRCTb032200199. jRCT is approved as a member of the Primary Registry Network of WHO ICTRP.