title: [Effects of multiple freeze-thaw on biomechanical properties of human allograft tendons].
abstract: OBJECTIVE
  To explore the biomechanic effects of multiple freeze-thaw on human allograft tendons.
  
  
  METHODS
  Thirty tendons (24 flexor digitorum superficialis tendons and 6 flexor pollicis longus tendons) were harvested from 3 fresh cadaver donors and were divided into 6 groups randomly (fresh group; 1 cycle, 2 cycle, 3 cycle, 5 cycle, and 10 cycle freeze-thaw groups). There was 4 flexor digitorum superficialis tendons and 1 flexor pollicis longus tendon in each group. The structural and mechanical properties as well as viscoelastic change were estimated.
  
  
  RESULTS
  The results of the structural and mechanical properties in 1 cycle, 2 cycle, and 3 cycle freeze-thaw groups were similar to that of the fresh group (P > 0.05). The tendons in 5 cycle and 10 cycle freeze-thaw groups showed a significantly lower ultimate load and maximum stress when compared with those of fresh group (P < 0.05), but there was no significant difference in maximum tensile or maximum strain (P > 0.05). Moreover, the tendons in 5 cycle and 10 cycle freeze-thaw groups had a significant increase in viscoelastic properties when compared with fresh group (P < 0.05).
  
  
  CONCLUSIONS
  In the cryopreservation of tendon allografts, the cycle of freeze-thaw should not exceed 3 times. Multiple cycle freeze-thaw will weaken the biomechanical properties of tendon allografts, which make grafts easier to fatigue or even rupture.
authors.affiliation: Department of Articular Surgery, Affiliated Hospital of Qingdao University Medical College, Qingdao Shandong, PR China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Huang
authors.forename: Xinyan
authors.initials: X
authors.lastname: Shi
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Zhang
authors.forename: Peitao
authors.initials: P
authors.lastname: Wang
authors.forename: Shaoqi
authors.initials: S
authors.lastname: Tian
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Kang
authors.initials: K
authors.lastname: Sun
mesh_terms: D001696:Biomechanical Phenomena; D015925:Cryopreservation; D005615:Freezing; D006801:Humans; D013710:Tendons / Q000502:physiology* / Q000637:transplantation; D013718:Tensile Strength; D014184:Transplantation, Homologous