- Email: [email protected]
Bone stability after lyophilization and gamma-irradiation in argon athmosphere
458
Abstracts
ADAPTATION OF RAT TIBIAE IN RESPONSR TO REPETITIVE LOADING. M.R. Forwood and A.W. Parker Anatomy Department, The University of Queensland, Australia 4072
Forty eight male rats, aged 12 weeks, were subjected to approximately 20,ooO loading cycles per day of treadmill running (2 hrs/day, 26.8 m.min-* and 10% gradient) for 5 (Group A) and 10 days (GroupB); with corresponding controls (C5) and (CIO). Rats in groups B and Cl0 were given weekly doses of tetracycline 4 days prior to training. Following training, right tibiae were tested to failure in torsion at 180 deg.s-l. Following bulk staining in basic fuchsin, six transverse sections (50 pm) were cut from the diaphysis of left bones and examined formicrodamageand fluonxcence.Resultsformechanicaltesting showedasignificantreduction in stiffness (P < 0.01) for groups A and B and a significant increase in twist angle (P < 0.01) for group A compared with controls. No evidence of microdamage was observed from histological analysis, but labelling demonstrated reduced appositional growth of the periosteal and endosteal surface at the mid-diaphysis of exercised tibiae (P < 0.01). These tibiae also showed fewer regions of measurable labelling than controls (P < 0.05). Changes observed in mechanical properties and the periosteal and endocortical surface of exercised tibiae are consistent with long term effects observed in growing bones following intensive running training (Keller et al. O.R.S., 1983, Matsudaet al., J. Appl. Physiol. 60: 2028, 1986; Salem et al. I.C.B. XII: 353, 1989) but are inconsistent with Frost’s mechanostat theory which wouldpredict stimulated modelling inresponse to increased mechanical usage.
BONN STABILITY AFTER LYOPNILI2ATION AND OANNA-IRRADIATION IN ARGON ATIIMOBPEBRE J.Jerosah, N.Muahow, N.Claheen Orthopedic Department, Heinriah-Heine University Diiaseldorf, FRO The purpose of the study was to evaluate the breaking stability of human cortical bone after lyophilization and/or gamma irradiation in normal air and argon athmosphere. Standardized cortical bone pieces (30x5~5 mm) of 5 human multiorgan donors were broken with a 3 point breaking machine. A total of 240 tests has been run. The bone was treatgd at random in 5 different groups (control group, water steam steril. at 123 C and 2,3 bar, lyophilization, lyophil.+ gamma-irradiation in air, lyophil. and gamma-irradiation in argon). The statistic evaluation was performed by an analysis of variance for a significance level of p
:
strenath in % control Steam sterilization Lyophilization Lyo + Gamma Lyo + Gamma + Argon
100
91,3 118,9 98,3
103,4
In our model the lyophilized and irradiated bone showed only small changes concerning breaking strength. The irradiation in argon athmosphere seems to protect the bone stability.
EFFBCISOF P~SERVATlONANDSTERnlZATlONONTHEBIOMECHANlCALPROPER~ESOFCORTIC~BO~ G_ G.VOGGENREITER,R.ASCHERL,MA.SCHERER,HJ. FRijH,O.BALK,G.Bliimel Institut fiir Expwimentellc
ChirurgIe der TU MUnchen,Ismaningerstr.22, D-LIOOO Miinchen 80, FRG The aim ofthis study was to evaluate the biomechanical properties of cryopreserved, irradiated and autoclaved cortical bone. EqeciaIIy we were interested in a combination of cryopreservation following sterilization and sterilization respectively after freezing The tibiae (8 per group) of adult male w&r-rats (390 +/- 3og) were harvested and treated as follows: 1, 5, 25, SO kGy Co gammairradiation, autoclaving (W’C, 3 and 5 min), freezing (-60°C, 28d); further sterilization (2SkGy or l34’C, 3min) then freezingorviceversa. Freshbonesserved ascontrols.Forbiomechanicaltesting athree-pointbendingprocedure wasused.Bending load, stiftixess, faihue energy and deflection were calculated from the load-deformation curves. After computing mean values and standard deviations the WiIwxon, Mann and Whitney U-test wasused for statistical analysis. Cryopreservation or 1 and 5kGy irradiation don‘t induce any change of the strength parameters. Raising the doses up to 25 or MkGy din&i&es the bending load (74% resp. 48% of fresh controls). AutocIaving bone at 134’C over 3min results in a significant reduction of the bending load (82%). Prolongation of the autoelaving time to Smin yields a highly significant reduction of the bending load (28%). Autoclaving of frozen specimens reduces bending load (69%) and stiffness. A comparison of the groups autoclaving/cryopreservation and cryoprcservation/autoclaving resp. indicates that better biomechanical results are obtained (~~0.05) by autoclaving before t&zing. Irradiation after freezing reduces the bending load significantly compared to irradiation before freezing. Better biomechanical values are obtained (pcO.01) by combining autodaving with cryopreservation than by a combination of radiosterilization and t&zing. For autoclaving cortical bone grafts high temperatures and short sterilization periods should be applied. If a sterilizing process is combined with deep freezing, sterilization should be performed before freezing and in respect to sterilization autoclaving is superior to irradiation.
Abstracts
ADAPTATION OF RAT TIBIAE IN RESPONSR TO REPETITIVE LOADING. M.R. Forwood and A.W. Parker Anatomy Department, The University of Queensland, Australia 4072
Forty eight male rats, aged 12 weeks, were subjected to approximately 20,ooO loading cycles per day of treadmill running (2 hrs/day, 26.8 m.min-* and 10% gradient) for 5 (Group A) and 10 days (GroupB); with corresponding controls (C5) and (CIO). Rats in groups B and Cl0 were given weekly doses of tetracycline 4 days prior to training. Following training, right tibiae were tested to failure in torsion at 180 deg.s-l. Following bulk staining in basic fuchsin, six transverse sections (50 pm) were cut from the diaphysis of left bones and examined formicrodamageand fluonxcence.Resultsformechanicaltesting showedasignificantreduction in stiffness (P < 0.01) for groups A and B and a significant increase in twist angle (P < 0.01) for group A compared with controls. No evidence of microdamage was observed from histological analysis, but labelling demonstrated reduced appositional growth of the periosteal and endosteal surface at the mid-diaphysis of exercised tibiae (P < 0.01). These tibiae also showed fewer regions of measurable labelling than controls (P < 0.05). Changes observed in mechanical properties and the periosteal and endocortical surface of exercised tibiae are consistent with long term effects observed in growing bones following intensive running training (Keller et al. O.R.S., 1983, Matsudaet al., J. Appl. Physiol. 60: 2028, 1986; Salem et al. I.C.B. XII: 353, 1989) but are inconsistent with Frost’s mechanostat theory which wouldpredict stimulated modelling inresponse to increased mechanical usage.
BONN STABILITY AFTER LYOPNILI2ATION AND OANNA-IRRADIATION IN ARGON ATIIMOBPEBRE J.Jerosah, N.Muahow, N.Claheen Orthopedic Department, Heinriah-Heine University Diiaseldorf, FRO The purpose of the study was to evaluate the breaking stability of human cortical bone after lyophilization and/or gamma irradiation in normal air and argon athmosphere. Standardized cortical bone pieces (30x5~5 mm) of 5 human multiorgan donors were broken with a 3 point breaking machine. A total of 240 tests has been run. The bone was treatgd at random in 5 different groups (control group, water steam steril. at 123 C and 2,3 bar, lyophilization, lyophil.+ gamma-irradiation in air, lyophil. and gamma-irradiation in argon). The statistic evaluation was performed by an analysis of variance for a significance level of p
:
strenath in % control Steam sterilization Lyophilization Lyo + Gamma Lyo + Gamma + Argon
100
91,3 118,9 98,3
103,4
In our model the lyophilized and irradiated bone showed only small changes concerning breaking strength. The irradiation in argon athmosphere seems to protect the bone stability.
EFFBCISOF P~SERVATlONANDSTERnlZATlONONTHEBIOMECHANlCALPROPER~ESOFCORTIC~BO~ G_ G.VOGGENREITER,R.ASCHERL,MA.SCHERER,HJ. FRijH,O.BALK,G.Bliimel Institut fiir Expwimentellc
ChirurgIe der TU MUnchen,Ismaningerstr.22, D-LIOOO Miinchen 80, FRG The aim ofthis study was to evaluate the biomechanical properties of cryopreserved, irradiated and autoclaved cortical bone. EqeciaIIy we were interested in a combination of cryopreservation following sterilization and sterilization respectively after freezing The tibiae (8 per group) of adult male w&r-rats (390 +/- 3og) were harvested and treated as follows: 1, 5, 25, SO kGy Co gammairradiation, autoclaving (W’C, 3 and 5 min), freezing (-60°C, 28d); further sterilization (2SkGy or l34’C, 3min) then freezingorviceversa. Freshbonesserved ascontrols.Forbiomechanicaltesting athree-pointbendingprocedure wasused.Bending load, stiftixess, faihue energy and deflection were calculated from the load-deformation curves. After computing mean values and standard deviations the WiIwxon, Mann and Whitney U-test wasused for statistical analysis. Cryopreservation or 1 and 5kGy irradiation don‘t induce any change of the strength parameters. Raising the doses up to 25 or MkGy din&i&es the bending load (74% resp. 48% of fresh controls). AutocIaving bone at 134’C over 3min results in a significant reduction of the bending load (82%). Prolongation of the autoelaving time to Smin yields a highly significant reduction of the bending load (28%). Autoclaving of frozen specimens reduces bending load (69%) and stiffness. A comparison of the groups autoclaving/cryopreservation and cryoprcservation/autoclaving resp. indicates that better biomechanical results are obtained (~~0.05) by autoclaving before t&zing. Irradiation after freezing reduces the bending load significantly compared to irradiation before freezing. Better biomechanical values are obtained (pcO.01) by combining autodaving with cryopreservation than by a combination of radiosterilization and t&zing. For autoclaving cortical bone grafts high temperatures and short sterilization periods should be applied. If a sterilizing process is combined with deep freezing, sterilization should be performed before freezing and in respect to sterilization autoclaving is superior to irradiation.