title: Strain-rate sensitivity of the rabbit MCL diminishes at traumatic loading rates.
abstract: This study was performed to determine whether the viscoelastic behavior of ligaments persists at high rates of loading, such as those associated with sports-related trauma or motor vehicle accidents. Medial collateral ligaments (MCLs) from 22 skeletally mature New Zealand White rabbits were tensile tested quasi-statically and via two impact conditions at displacement rates of 0.17 mm/s (n=22), 640+/-160 mm/s (n=10) and 2500+/-270 mm/s (n=12) (corresponding to strain rates of approximately 1.0%/s, 3660%/s and 14,000%/s, respectively). Despite dramatic increases in displacement rate, only a modest strain-rate effect was observed when the specimens tested quasi-statically were compared to those tested via impact (24% and 37% increases in stiffness and failure load, respectively). There were no differences in the structural (e.g. 145+/-30 and 136+/-29 N/mm stiffness values, respectively) or failure properties (e.g. 434+/-91 and 443+/-154 N failure load values, respectively) of the two impact-tested groups. Our findings suggest that the rabbit MCL is not viscoelastic at loading rates approximating those associated with high-energy trauma.
authors.affiliation: Bioengineering Laboratory, Department of Orthopaedics, Brown Medical School and Rhode Island Hospital, Providence, RI, USA. joseph_crisco@brown.edu
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Crisco
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Moore
authors.forename: Robert D
authors.initials: RD
authors.lastname: McGovern
mesh_terms: D000818:Animals; D004548:Elasticity; D066298:In Vitro Techniques; D017888:Medial Collateral Ligament, Knee / Q000293:injuries* / Q000503:physiopathology*; D009038:Motion; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013718:Tensile Strength; D014783:Viscosity; D016474:Weight-Bearing