Effects of chair restraint on the strength of the tibia in rhesus monkeys

Abstract

To determine the effects of the relative inactivity and unloading on the strength of the tibias of monkeys, Macaca mulatta, we used a non-invasive test to measure bending stiffness, or EI (Nm2), a mechanical property. The technique was validated by comparisons of in vivo measurements with standard measures of EI in the same bones post-mortem (r2 = 0.95, P < 0.0001). Inter-test precision was 4.28+/-1.4%. Normative data in 24 monkeys, 3.0+/-0.7 years and 3.6+/-0.6 kg, revealed EI to be 16% higher in the right than left tibia (4.4+/-1.6 vs. 3.7+/-1.6 Nm2, P < 0.05). Five monkeys, restrained in chairs for 14 days, showed decreases in EI. There were no changes in EI in two chaired monkeys that lost weight during a 2-week space flight. The factors that account for both the decreases in bone mechanical properties after chair restraint at 1 g and lack of change after microgravity remain to be identified. Metabolic factors associated with body weight changes are suggested by our results.

Ulnar and tibial bending stiffness as an index of bone strength in synchronized swimmers and gymnasts

“…EI MRTA is consistently twice as high as EI Instron due to differences in the support systems for the test algorithm to determine the physical parameters of skin, bone and muscle. The results of this algorithm are highly correlated with breaking strength in long bones (Roberts et al 1996;Hutchinson et al 2001). The mathematical model for the ulna was modified for the analysis of the more complex curve from the human tibia by adding mass, stiffness and damping elements at both ends of the bone, where a firm support is difficult to achieve (Roberts and Steele 1995).…”

“…EI was similar in both groups of athletes in spite of such different loading histories and a slightly higher ulnar width in GYM than SYN. The technique is well validated not only by us in the nonhuman primate (Roberts et al 1996;Hutchinson et al 2001) but also by others (Lowet et al 1991). There are significant differences in ulnar EI in right and left handed men (Arnaud et al 1991).…”

Accuracy and reproducibility of bending stiffness measurements by mechanical response tissue analysis in artificial human ulnas

“…The only previously reported direct comparison of MRTA and QMT measurements (Hutchinson et al, 2001;Roberts et al, 1996) was made in 21 monkey tibias. EI calculations were confounded by differences in end conditions and length between the in vivo and in vitro methods.…”

Rationale, design and clinical performance of the mechanical response tissue analyser: a non-invasive technology for measurement of long bone bending stiffness

“…Hutchinson and colleagues [22,23] obtained in vivo tibial EI measurements in 24 rhesus monkeys and, post-mortem, subjected the bones to three-point bending tests. The relationship between in vivo EI and postmortem EI was almost perfect (R 2 ¼ 0.95).…”

“…The product of these measures, EI, yields bending stiffness, which is defined as the ability of a bone to resist deformation under a given load and is an excellent predictor of long bone structural integrity and strength [21,22].…”