This renewal is designed to test our governing hypothesis that gamma irradiation produces dose-dependent reductions in ligament allograft biomechanics, but that these reductions are more significant before surgery than 6 months after surgery. While allografts have certain advantages, surgeons remain concerned about how effectively methods like gamma irradiation sterlize the graft against viral contaminants such as HIV-1 and hepatitis. Several authors have estimated, for example, that dosage levels of 4 MRad or more might be needed to satisfactorily inactivate the HIV-1 virus in these grafts. Unfortunately, such high levels of gamma irradiation can compromise initial biomechanical properties of frozen allograft tissues and may have deleterious effects on the structures after surgery as well. Furthermore the treatment may also reduce the concentration of permanent, covalent hydroxypyridinium crosslinks [HP] which likely transmit tissue forces. In this grant, we test four hypotheses related to these potential structural and material alterations using goat patellar tendon-bone (PTB) allografts. HYPOTHESIS 1. Goat PTB allografts undergo significant, dose-dependent reductions in initial mechanical and material properties up to 8 Mirads of gamma irradiation. The reductions in material properties are associated with decreases in [HP]. HYPOTHESIS 2. Increasing gamma irradiation level significantly increases the knee's anterior motion limits by decreasing graft stiffness immediately after surgery. These changes are caused, in part, by unfolding of the irradiated tissue substance and by increased motion at the graft's fixation sites. HYPOTHESIS 3. Four megarads of gamma irradiation produces no significant reductions in ACL allograft biomechanics 6 months postop. These studies should permit the mechanical dose-dependent curve for irradiation of ligament allograft tissues to be established and forum the basis for immunological, ultrastructural, and biochemical studies of grafted knees at various time intervals post surgery.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR038719-06
Application #
2079344
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
1989-05-20
Project End
1996-06-30
Budget Start
1994-08-15
Budget End
1996-06-30
Support Year
6
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Engineering (All Types)
Type
Schools of Engineering
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Schwartz, Herbert E; Matava, Matthew J; Proch, Frank S et al. (2006) The effect of gamma irradiation on anterior cruciate ligament allograft biomechanical and biochemical properties in the caprine model at time zero and at 6 months after surgery. Am J Sports Med 34:1747-55
Cummings, J F; Grood, E S; Butler, D L et al. (2002) Subject variation in caprine anterior cruciate ligament reconstruction. J Orthop Res 20:1009-15
Korvick, D L; Cummings, J F; Grood, E S et al. (1996) The use of an implantable force transducer to measure patellar tendon forces in goats. J Biomech 29:557-61
Salehpour, A; Butler, D L; Proch, F S et al. (1995) Dose-dependent response of gamma irradiation on mechanical properties and related biochemical composition of goat bone-patellar tendon-bone allografts. J Orthop Res 13:898-906
Rasmussen, T J; Feder, S M; Butler, D L et al. (1994) The effects of 4 Mrad of gamma irradiation on the initial mechanical properties of bone-patellar tendon-bone grafts. Arthroscopy 10:188-97
Feder, S M; Butler, D L; Holden, J P (1993) A technique for the evaluation of the contributions of knee structures to knee mechanics in the knee that has a reconstructed anterior cruciate ligament. J Orthop Res 11:448-51
Glos, D L; Butler, D L; Grood, E S et al. (1993) In vitro evaluation of an implantable force transducer (IFT) in a patellar tendon model. J Biomech Eng 115:335-43
Xu, W S; Butler, D L; Stouffer, D C et al. (1992) Theoretical analysis of an implantable force transducer for tendon and ligament structures. J Biomech Eng 114:170-7
Oster, D M; Grood, E S; Feder, S M et al. (1992) Primary and coupled motions in the intact and the ACL-deficient knee: an in vitro study in the goat model. J Orthop Res 10:476-84
Gibbons, M J; Butler, D L; Grood, E S et al. (1991) Effects of gamma irradiation on the initial mechanical and material properties of goat bone-patellar tendon-bone allografts. J Orthop Res 9:209-18