Structural Response of Cadaveric Ribcages Under a Localized Loading: Stiffness and Kinematic Trends

Abstract

To improve understanding of structural coupling and deformation patterns throughout the loaded ribcage, the present study reports the force-displacement and kinematic responses under a highly-localized loading condition using three PMHS ribcages (ages 44, 61, and 63 years). The ribcages were quasi-statically loaded locally to a non-failure displacement (nominally 15% of the ribcage depth at the loaded rib level) at approximately 25 unilateral locations and 5-7 geometrically symmetric bilateral locations on the anterior surface of each ribcage, for a total of 94 tests. The translations of 56 points distributed around the anterior, lateral, and posterior portions of the superficial surface of the ribcage were measured while under loading. Each of the first through sixth rib levels was then separated from the remaining ribs, and this "rib ring" structure was individually loaded at the sternum in the anterior-posterior direction. The force when the ribcage was deflected to 8% of its initial depth was normalized to the force at the upper sternum (viz. 81.232.2 N). The normalized unilateral force at the costo-chondral junction was found to vary from 0.760.29 at rib 1 to 0.150.02 at rib 9, while bilateral forces (sum of left and right aspects) varied from 0.92 to 1.11. The rib rings were generally less stiff, ranging from 0.780.24 for rib 1 to 0.190.01 for rib 6. The deformation patterns under all loading conditions were quantified. In general, bilateral loading produced an approximately symmetric deformation pattern, while unilateral loading resulted in approximately twice as much resultant deformation on the ipsilateral side compared to the contralateral side.

A parametric ribcage geometry model accounting for variations among the adult population

“…Field data analyses, computer simulations and cadaver tests have all shown that the incidence of AIS 2+ thoracic injuries increased with age (Carter et al, 2014;Ridella et al, 2012;Zhou et al, 1996). The risk of ribcage injuries in crashes also differs significantly between men an women (Bellemare et al, 2003;Cerney and Adams, 2004;Kimpara et al, 2005;Kindig et al, 2010). In particular, the risk of being seriously injured in crashes is higher for women than men (Bose et al, 2011;Parenteau et al, 2013), and the increase of thoracic injury risk with age is greater for women than men (Carter et al, 2014;Parenteau et al, 2013;Ridella et al, 2012).…”

Characterization of the Centroidal Geometry of Human Ribs

“…Rib 1, which is attached to both the sternum and the clavicle, plays a major role in load-sharing through the ribcage [59], and (although rare) can be fractured during severe trauma or physical stress [60][61][62][63][64] or surgery [65]. Preliminary testing suggests that the proposed model would capture rib 1 geometry with accuracy comparable to ribs 2-10.…”

Thoracic response targets for a computational model: A hierarchical approach to assess the biofidelity of a 50th-percentile occupant male finite element model

“…Quasi-static point loading of the ribcage was simulated, using the method outlined in Kindig et al (2010). In that study, isolated eviscerated ribcages mounted upright from three PMHS were quasi-statically loaded by a plate interfacing with a spherical segment glued to the superficial surface of the ribs.…”

“…(a) Scaled force-scaled displacement, (b) CORA ratings. Experimental corridors are adapted fromKindig et al (2010).…”