Effect of multiple freeze–thaw cycles on intervertebral dynamic motion characteristics in the porcine lumbar spine

• Published in: Journal of biomechanics Vol. 41; no. 4; pp. 916 - 920
• Main Authors: Hongo, Michio, Gay, Ralph E, Hsu, Jui-Ting, Zhao, Kristin D, Ilharreborde, Brice, Berglund, Lawrence J, An, Kai-Nan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.01.2008; Elsevier Limited
• Subjects: Animals; Biomechanical Phenomena; Biomechanics; Female; Freeze; Freezing; Intervertebral Disc - physiology; Intervertebral disk; Lumbar spine; Lumbar Vertebrae - physiology; Mechanical properties; Physical Medicine and Rehabilitation; Porcine; Range of Motion, Articular - physiology; Specimen handling; Sus scrofa; Vertebrae; Biomechanics; Porcine; Lumbar spine; Specimen handling; Freeze; Intervertebral disk
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2007.11.003

Abstract Fresh frozen spine specimens are commonly used in biomechanical investigations of the spine. Since many study designs require staged preparation and testing, the effect of multiple freeze–thaw cycles on motion behavior should be understood. The objective of this study was to investigate the effect of multiple freeze–thaw cycles on the biomechanical parameters measured during dynamic pure moment loading. Ten porcine lumbar motion segments were harvested immediately after death and potted in acrylic fixtures. Specimens were tested in continuous pure moment flexion–extension, lateral flexion, and rotation cycles up to a limit of ±5 N m. Moment-angular displacement data were analyzed and parameters quantified including range of motion, elastic zone, transitional zone (neutral region) size and slope, and width of the hysteresis loop. All specimens were tested at baseline and after each of three subsequent cycles of freezing and thawing. The transitional zone size decreased and the transitional zone slope increased during flexion–extension and lateral bending after the initial freeze–thaw cycle. These parameters were not altered after subsequent cycles. No significant change was observed in the elastic zone or width of hysteresis loop. Although freezing porcine spine specimens increased the stiffness in the neutral region of motion, up to three subsequent cycles of freezing and thawing did not further affect these motion characteristics. This suggests that data obtained from porcine spines which have been frozen and thawed multiple times are stable after initial freezing.