Ex-vivo Mechanical Testing of Novel Laryngeal Clamps Used for Laryngeal Advancement Constructs

Abstract

Rostral laryngeal advancement, also known as laryngeal tie-forward, is used to treat horses for intermittent dorsal displacement of the soft palate and has a morbidity rate of about 6%. We hypothesized that a novel laryngeal clamp would prevent morbidity associated with the sutures tearing through the thyroid cartilage. Larynges (n = 35 horses) were used for ex vivo testing. For uniaxial testing, 15 equine larynges were tested in one of three laryngeal tie-forward constructs [standard laryngeal tie-forward; modified laryngeal tie-forward using a suture-button; and modified laryngeal tie-forward using a laryngeal clamp]. For biaxial testing, 20 larynges were tested in one of two treatment groups: laryngeal tie-forward and laryngeal tie-forward using a laryngeal clamp. Constructs were tested in single cycle-to-failure. Statistical analyses were performed using ANOVA for uniaxial testing and t-tests for biaxial testing. The laryngeal tie-forward using a laryngeal clamp construct was superior to laryngeal tie-forward and laryngeal tie-forward using a suture-button constructs in resistance to pullout in uniaxial testing. The laryngeal tie-forward using a laryngeal clamp presented a significantly different method of failure than the standard laryngeal tie-forward in the biaxial testing. Failure modes for each construct were primarily by suture failure at the clamp (laryngeal tie-forward using a laryngeal clamp), suture pullout through the thyroid cartilage, or, less commonly, tearing of the cricothyroid ligament (laryngeal tie-forward). In uniaxial testing, the laryngeal tie-forward using a laryngeal clamp failed most commonly due to tearing of the cricothyroid ligament, whereas the standard laryngeal tie-forward and the laryngeal tie-forward using a suture-button failed due to the tearing of the cartilage. The laryngeal clamps provided greater stiffness, load at yield, and tensile stress at yield than did the standard construct. Laryngeal clamps may offer an alternative to standard methods of anchoring the thyroid cartilage when performing the laryngeal tie-forward procedure. Further testing and clinical trials are needed to elucidate the utility of the laryngeal tie-forward using a laryngeal clamp.

Effect of cyclic loading on the stability of screws placed in the locking plates used to bridge segmental bone defects

“…The actuator displacement as well as stiffness of each specimen was measured and recorded in real‐time by the manufacturer software (Bluehill 3). Displacement of the actuator was defined as the distance from the actuator original position to its position during the application of 600 N load 25,26 . Stiffness of the specimen was defined as the resistance to deformation during cyclic loading and described with load over the displacement curve 25,26 .…”

“…Displacement of the actuator was defined as the distance from the actuator original position to its position during the application of 600 N load 25,26 . Stiffness of the specimen was defined as the resistance to deformation during cyclic loading and described with load over the displacement curve 25,26 . After mechanical testing, PRT of each screw was measured prior to screw extraction with the hand‐held torque measuring device.…”

Bone and Cartilage Interfaces With Orthopedic Implants: A Literature Review

“…Primary stability can be evaluated under in-vivo and ex-vivo conditions by using common mechanical testing methods, such as resonance frequency analysis (RFA), percussion testing (Periotest M, Medizintechnik Gulden, Germany), IT, and cutting torque resistance analysis (CRA) (165)(166)(167)(168)(169)(170)(171)(172)(173)(174)(175)(176). Measures of primary stability of an implant, including pullout, pushout, and bending, can be evaluated under ex-vivo conditions and in select in vivo applications (177)(178)(179)(180)(181)(182)(183)(184)(185).…”

“…Pullout tests have been commonly used to test the stability of orthopedic implants ( 143 , 177 – 179 ). Tensile stress is applied to an implant or entire construct in a testing frame until the implant breaks or the implant is pulled from the tissue into which it has been implanted becomes displaced ( 177 , 178 , 180 , 181 ). The rate of displacement must be adjusted according to the method of testing a specific construct.…”

“…The most important values examined by mechanical testing are maximum tension load, actuator displacement, and construct stiffness. The maximum tension load is the maximum tensile load measured at the point the implant or construct fails ( 181 ). The actuator displacement is the distance measured between the original position of the implant within the construct to the position of the implant at the end of mechanical testing, and construct stiffness is the calculated load over the slope of displacement ( 181 ).…”