C1 Lateral Mass Displacement and Transverse Atlantal Ligament Failure in Jefferson's Fracture: A Biomechanical Study of the “Rule of Spence”

    loading  Checking for direct PDF access through Ovid

Abstract

BACKGROUND

Jefferson's fracture, first described in 1927, represents a bursting fracture of the C1 ring with lateral displacement of the lateral masses. It has been determined that if the total lateral mass displacement (LMD) exceeds 6.9 mm, there is high likelihood of transverse atlantal ligament (TAL) rupture, and if LMD is less than 5.7 mm TAL injury is unlikely. Several recent radiographic studies have questioned the accuracy and validity of the “rule of Spence” and it lacks biomechanical support.

OBJECTIVE

To determine the amount of LMD necessary for TAL failure using modern biomechanical techniques.

METHODS

Using a universal material testing machine, cadaveric TALs were stretched laterally until failure. A high-resolution, high-speed camera was utilized to measure the displacement of the lateral masses upon TAL failure.

RESULTS

Eleven cadaveric specimens were tested (n = 11). The average LMD upon TAL failure was 3.2 mm (±1.2 mm). The average force required to cause failure of the TAL was 242 N (±82 N). From our data analysis, if LMD exceeds 3.8 mm, there is high probability of TAL failure.

CONCLUSION

Our findings suggest that although the rule of Spence is a conceptually valid measure of TAL integrity, TAL failure occurs at a significantly lower value than previously reported (P < .001). Based on our literature review and findings, LMD is not a reliable independent indicator for TAL failure and should be used as an adjunctive tool to magnetic resonance imaging rather an absolute rule.

Related Topics

    loading  Loading Related Articles