Force-displacement curve analysis showing whole bone biomechanical performance.

Values are means ± SE of raw data; N, no of mice; PY, post-yield; disp, displacement; N, newtons.*Data analyzed using ANCOVA with a covariate of body mass.tData transformed to satisfy assumptions of normality and variance.rNon-transformable data was ranked.agenotype effect,bsex effect,cdiet effect,dgt*sex effect,egt*sex*diet effect.PY disp: Males had a greater PY disp than females. WT mice had a greater PY disp than PKU mice.Total disp: Males had a greater total disp than females. WT mice had a greater total disp than PKU mice.Stiffness: All female groups except PKU females fed GMP or casein had stiffer bones than males. Among female groups WT females fed casein and GMP had the stiffest bones. There was no difference between female mice fed AA diet and female PKU mice fed GMP, however PKU females fed casein had a significant reduction in stiffness. Among male mice the only significant difference was a reduction in stiffness in male PKU mice fed AA compared to WT males fed casein.Yield load: Female mice tolerated a higher load at the yield point than male mice. WT mice tolerated a higher load at the yield point compared to PKU mice.Max Load: Females had a greater maximum load before fracture compared to males. Moreover, WT females had a greater max load than PKU females, however there were no difference between genotypes for the males. Mice fed the GMP diet had a significant increase in maximum load compared to mice fed the AA diet, but there was no difference between mice fed the GMP and casein diets, additionally there was no difference between mice fed the casein and AA diets.Energy: It required more energy to fracture the femurs of WT mice than it did to fracture the femurs of PKU mice.