Cervical Spinal Immobilization: A Head-to-Head Comparison of a One-Step Spray-on Foam Splint Versus Structural Aluminum Malleable Splint Immobilization
Authors: Roebke Austin J , Bates Nathaniel , Jurenovich Kathryn , Yu Elizabeth , Karnes Jonathan , Khan Safdar , Kman Nicholas , Groth Adam , Martin Kevin D 
Published: March 2023

ABSTRACT

Introduction
Cervical spine immobilization in a low-resource environment is difficult secondary to limited equipment, prolonged transportation, and secondary complications. A structural aluminum malleable (SAM) splint is commonly utilized because of its availability and multipurpose intention. A one-step spray-on foam immobilization technique (Fast Cast) has been shown to be effective in lower-extremity splinting. The aim of this study was to demonstrate the ability of the Fast Cast to effectively immobilize the cervical spine in a head-to-head comparison against the SAM splint. We hypothesized that there would be no difference in surgeon scoring between Fast Cast and SAM splints for the immobilization of the cervical spine.

Methods
This was a cadaveric experimental comparative study that compared a SAM splint versus Fast Cast for the immobilization of an unstable cervical spine. Each of the three cadaveric specimens had a corpectomy without fixation performed. A board-certified emergency medicine physician specialized in disaster medicine performed all SAM immobilizations. An orthopedic surgeon performed Fast Cast immobilizations. Each method of immobilization was done on each cadaver. Lateral fluoroscopic imaging was taken before and after immobilization and after log roll/gravity stress. Five board-certified orthopedic surgeons served as graders to independently score each splint. A 5-point Likert scale based on 10 splinting criteria (50 total points possible) was utilized to evaluate cervical spine immobilization. The lead statistical analyst was blinded to the immobilization groups. The statistical significance was assessed via a Wilcoxon signed-rank test and chi-square Fisher’s exact test with significance between groups set at α &lt; .05. Inter-rater reliability of the Likert scale results was assessed with the interclass correlation coefficient.

Results
Inter-rater reliability for the current Likert scale in the evaluation of cervical spine stabilization was good (interclass correlation coefficient = 0.76). For the cumulative Likert scale score, Fast Cast (32 [28–34]) exhibited a higher total score than SAM (44 [42–47]; P &lt; .01). Likewise, Fast Cast exhibited a greater likelihood of higher Likert scores within each individual question as compared to SAM (P ≤ 0.04). In 100% of cases, raters indicated that Fast Cast passed the gravity stress examination without intrinsic loss of reduction or splinting material, whereas 33% of SAM passed (P &lt; .01). In 100% of cases, raters indicated that Fast Cast passed the initial radiographic alignment following immobilization, whereas 66% of SAM passed (P = .04). In 100% of cases, raters indicated that Fast Cast passed radiographic alignment after the gravity stress examination, whereas 47% of SAM passed (P &lt; .01).

Conclusion
The Fast Cast exceeded our expectations and was shown to be rated not equivalent but superior to SAM splint immobilization for the cervical spine. This has significant clinical implications as the single-step spray-on foam is easy to transport and has multifaceted applications. It also eliminates pressure points and circumferential wrapping and obstruction to airway/vascular access while immobilizing the cervical spine and allowing for radiographic examination. Further studies are needed for human use and application.