Purpose of the study Bone grafts and bone substitutes must be biocompatible osteoconductors with satisfactory mechanical properties similar to native bone. When the bone treatment is conducted under specific conditions, the elasticity module under infra-maximal loading can be optimized to achieve reproducible values. The purpose of this work was to determine the effect of the cleaning and sterilization process using Osteopure(R) on the biomechanical properties of trabecular bone harvested from human femoral heads.Material and method Seventy trabecular bone samples were tested: group 1F (fresh samples); group 1N (after application of Osteopure(TM) cleaning); group 1S (after Osteopure(TM) cleaning and sterilization). Non-destructive and destructive tests (group 1D) were performed. Two fresh femoral heads were used as controls for the destructive test (group 2). The first non-destructive test was applied directly after section (group 1F). Other samples were then purified with Osteopure(TM) treatment and a second non-destructive test was conducted (group 1N). A third non-destructive test was conducted after sterlization with 25kgray radiation (group 1S).Treatments 1 and 2 were performed by OST Developpement SA (Clermont-Ferrand). Finally a destruction test was applied along the directional axis (group 1D). For the 31 samples in group 2 (control) the destructive test was applied along the directional axis immediately after section. Compression tests were performed at a deformation speed of 3 mm/min for 0.3% deformation.Results The Young module did not exhibit any significant difference between the three steps of the testing in the three orthogonal directions. The Young module was not significantly different between group 1 F and group 2 (controls). Maximal force of compression was significantly different (P<0.01). There was a linear relationship between maximal force at rupture and the Young module obtained during destructive tests, for groups 1D and 2 respectively. The compression curves obtained from sterilized samples (group 1D) were not significantly different from those observed for fresh trabecular bone in group 2 (controls).Discussion The Young module values measured from 70-673 MPa. For non-destructive tests, the module values were to the order of 64% of those obtained for destructive tests. Decreased maximal force of rupture observed for treated samples in comparison with fresh samples can be explained by the extraction of most of the lipids.Conclusion The Osteopure(TM) method does not alter stiffness of bone allografts. The elasticity module observed in treated bones is close to that observed in fresh bones. Mechanical resistance to compression is however only half the force of compression observed in the hip joint for daily activities. The linear relationship between the elasticity mode and loading required for rupture is not affected by treatment with Osteopure(TM). The advantages related to elimination of prions or viral contamination appear by far to be more important than the minor changes observed in the mechanical characteristis of allografts.

L’étude a comparé les propriétés mécaniques de l’os trabéculaire humain cryoconservé avec une nouvelle allogreffe issue de tissu humain traitée par Osteopure™. Nous avons utilisé une procédure de test par compression, non destructive, sur trois faces orthogonales (70 échantillons 10x10x10 mm provenant de têtes fémorales humaines). Les tests mécaniques ont été appliqués sur les échantillons frais et après la procédure de nettoyage Osteopure™ et de stérilisation. Des tests destructifs ont finalement été appliqués suivant la direction axiale et les résultats comparés à ceux d’un groupe contrôle (31 échantillons). Les courbes contrainte-déformation obtenues pour les échantillons traités ne diffèraient pas significativement de celles observées pour des échantillons cryoconservés humains. Les modules de Young obtenus, aussi bien pour les procédures non-destructives (os frais, dégraissé et après stérilisation) que destructives (os frais et après stérilisation) n’ont pas été significativement différents (respectivement 183 ± 71, 192 ± 96, 202 ± 92 et 325 ± 200, 311 ± 92 MPa).

INTRODUCTION The evaluation of the bite forces coupled with EMG activity of masseter muscles allows to point out temporo-mandibular joint disorders. The intense practice of sports induces stress which may affect the mandibular statics, due to an hyperfunction of the elevator masticatory muscles, especially the masseter muscles. This concept has led us to compare the maximum isometric bite forces of sedentary and physically trained subjects. MATERIAL AND METHODS The aim of this experimentation is to study the maximum isometric bite forces of the premolars, with a force transducer, for two groups of physically trained and sedentary volunteers (25 subjects), with distinction between male and female subjects. Subjects with normal denture and no temporo-mandibular joint disorder were retained. EMG and force recording were synchronized and recorded during 10 seconds of maximal contraction. RESULTS The male subjects developed a maximal bite-force significantly higher (p < 0.05) compared to the female subjects. There is no significant difference between subjects practising a sport (at least 6 hours a week) and sedentary ones. The evolution of force during the contraction is different between sexes. EMG activity allowed to control that subjects developed a maximal force and an increase in muscular fatigability of physically active females compared to sedentary ones was noticed. DISCUSSION The difference of maximal force between men and women is similar to the one found for the locomotor muscles. The analysis of the evolution of the force according to the contraction duration, might be linked to a different distribution of muscular fibers according to the sex. The practice of a sport might increase the fatigability of the masseter muscles and might be a factor inducing a muscular imbalance of the mandibular posture. But the relatively low number of subjects and the absence of well defined distinctions between different kinds of sport limit our conclusions.

Aims - The aim of this study was to examine the effect of an external apport of protein after a tiring exercise, Surface electromyography was used to evaluated muscular activity.Methods and results - The subjects were lied on the back and performed 3 sets (2 of 10 repetitions and I of 5) isometric contraction of the leg during 20 s. Bipolar surface electromyography (EMG) was used to assess the level of electrical activity for vastus lateralis (VL) at 1000 Hz. Integrated electromyography (EMGi) and mean power frequency (MPF) were calculated using the raw signal collected throughout the entire phases. The linear increase of the EMGi was very significant (p < 0.001), is associated with an increase in fiber recruitment and/or motor neurone firing rates.Conclusion - The study show the interest for electromyography to approximate the muscular activity and particularly muscular fatigue. (C) 2001 Editions scientifiques et medicales Elsevier SAS.

The purpose of this study was to find if the performance of the vertical jump is improved by the result of increasing the force, velocity, and muscle adaptation(s). For the experiment, there were four groups (Gr): three groups did the training programs and the fourth group was the control group (CG). In order to establish improvements in force and velocity, the groups performed three variations using eccentric (Ecc) and concentric (Con) movement. Finally, the leg presses, squat jumps (SJ) and countermovement jumps (CJ) were used to determine the changes in the muscle adaptations before and after the training program. For measuring the force, four force transducers were used. In determining the velocity, a displacement transducer was used. A surface EMG was used to measure the muscle activations during all of the tests that were performed. After eight weeks of training, Gr 1 and Gr 2 improved the isometric force and the power during the Con. movement for the leg press. For the SJ, Gr. 1 and 2 increased their height, muscle activity, force, and power, but only group one improved the velocity. However, group three improved the isometric force and power for the leg presses, the squat jump and the countermovement jump. For both of the jumps, they also increased velocity, muscle activity and height. There were no changes observed for group four. Although the three combinations of Ecc/Con movements existed during the training program, the force, velocity and muscle adaptations increased, but not all of the improvements were of the same degree.