Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Aug;29(8):1193-8.
doi: 10.1002/jor.21373. Epub 2011 Mar 4.

The effects of multiple freeze-thaw cycles on the biomechanical properties of the human bone-patellar tendon-bone allograft

Ho-Joong Jung  1 , Gautum Vangipuram, Matthew B Fisher, Guoguang Yang, Shanling Hsu, John Bianchi, Chad Ronholdt, Savio L-Y Woo
Affiliations
Free PMC article

The effects of multiple freeze-thaw cycles on the biomechanical properties of the human bone-patellar tendon-bone allograft

Ho-Joong Jung et al. J Orthop Res. 2011 Aug.
Free PMC article

Abstract

Soft tissue allografts, such as the bone-patellar tendon-bone (BPTB) graft, have been frequently used for anterior cruciate ligament (ACL) reconstruction. As allografts are subjected to freezing and thawing for multiple cycles, the objective of this study was to measure the changes of the biomechanical properties of the human BPTB allograft after 4 and 8 freeze-thaw cycles in comparison to a single freeze-thaw cycle. Three BPTB specimens were procured from 21 human donors and divided into three groups: 1, 4, or 8 freeze-thaw cycles. Each freeze-thaw cycle consisted of freezing at -20 ± 10°C for more than 6 h and thawing at 22 ± 3°C for at least 6 h. Tensile testing of the BPTB specimens consisted of loading between 50 N and 250 N for 100 cycles and then loading to failure. Cyclic loading revealed a similar amount of creep (∼0.5 mm) among the three freeze-thaw cycles groups (p = 0.38). The stiffness of the BPTB graft for the 1, 4, and 8 freeze-thaw cycle groups were 244 ± 42 N/mm, 235 ± 39 N/mm, and 231 ± 40 N/mm, respectively (p = 0.43). Similar findings were obtained for the ultimate load of the BPTB graft (p = 0.14) and the tangent modulus of the PT substance (p = 0.41). The results of this study suggest that there would be little measurable effect on the structural properties of the BPTB graft or mechanical properties of the PT tissue substance following 8 freeze-thaw cycles. These BPTB allografts could potentially be re-frozen without a loss in their biomechanical properties, given appropriate storage and care.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Typical BPTB specimen following isolation.
Figure 2
Figure 2
(A) Experimental apparatus for tensile testing. The patellar and tibial bone blocks were gripped using custom clamps. Markers were placed on PT substance for strain tracking. (B) Typical load-elongation behavior of a BPTB specimen.
Figure 3
Figure 3
Graphical representation of the stiffness (A) and ultimate load (B) representing the structural properties of the BPTB grafts for the freeze–thaw cycle groups (mean ± SD).
Figure 4
Figure 4
Graphical representation of the tangent modulus of the PT for the freeze–thaw cycle groups (mean ± SD).
See this image and copyright information in PMC

References

    1. Goldstein JL, Verma N, McNickle AG, et al. Avoiding mismatch in allograft anterior cruciate ligament reconstruction: Correlation between patient height and patellar tendon length. Arthroscopy. 2010;26:643–650. - PubMed
    1. Barker JU, Drakos MC, Maak TG, et al. Effect of graft selection on the incidence of postoperative infection in anterior cruciate ligament reconstruction. Am J Sports Med. 2010;38:281–286. - PubMed
    1. Poehling GG, Curl WW, Lee CA, et al. Analysis of outcomes of anterior cruciate ligament repair with 5-year follow-up: Allograft versus autograft. Arthroscopy. 2005;21:774–785. - PubMed
    1. Carey JL, Dunn WR, Dahm DL, et al. A systematic review of anterior cruciate ligament reconstruction with autograft compared with allograft. J Bone Joint Surg Am. 2009;91:2242–2250. - PMC - PubMed
    1. Kurosaka M, Yoshiya S, Andrish JT. A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction. Am J Sports Med. 1987;15:225–229. - PubMed

Publication types