Effects of barefoot and shod running on lower extremity joint loading, a musculoskeletal simulation study

PURPOSE: The aim of the current investigation was to utilize a musculoskeletal simulation based approach, to examine the effects of barefoot and shod running on lower extremity joint loading during the stance phase. METHODS: Twelve male runners, ran over an embedded force plate at 4.0 m/s, in both barefoot and shod conditions. Kinematics of the lower extremities were collected using an eight camera motion capture system. Lower extremity joint loading was also explored using a musculoskeletal simulation and mathematical modelling approach, and differences between footwear conditions were examined using paired samples t-tests. RESULTS: Peak Achilles tendon force was significantly larger (P=0.039) when running barefoot (6.85 BW) compared to shod (6.07 BW). In addition, both medial (P=0.013) and lateral (P=0.007) tibiofemoral instantaneous load rates were significantly larger in the barefoot (medial = 289.17 BW/s & lateral = 179.59 BW/s) in relation to the shod (medial = 167.57 BW/s & lateral = 116.40 BW/s) condition. Finally, the barefoot condition (9.70 BW) was associated with a significantly larger (P=0.037) peak hip force compared to running shod (8.51 BW). CONCLUSIONS: The current investigation indicates that running barefoot may place runners at increased risk from the biomechanical factors linked to the aetiology of chronic lower extremity pathologies. However, future analyses using habitual barefoot runners, are required before more definitive affirmations regarding injury predisposition can be made

Effects of second-generation and indoor sports surfaces on knee joint kinetics and kinematics during 45° and 180° cutting manoeuvres, and exploration using statistical parametric mapping and Bayesian analyses

Purpose: The aim of the current investigation was to examine the influence of second generation (2G) and indoor surfaces on knee joint kinetics, kinematics, frictional and muscle force parameters during 45° and 180° change of direction movements using statistical parametric mapping (SPM) and Bayesian analyses. Methods: Twenty male participants performed 45° and 180° change of direction movements on 2G and indoor surfaces. Lower limb kinematics were collected using an eight-camera motion capture system and ground reaction forces were quantified using an embedded force platform. ACL, patellar tendon and patellofemoral loading was examined via a musculoskeletal modelling approaches and the frictional properties of the surfaces were examined using ground reaction force information. Differences between surfaces were examined using SPM and Bayesian analyses. Results: Both SPM and Bayesian analyses showed that ACL loading parameters were greater in the 2G condition in relation to the indoor surface. Conversely, SPM and Bayesian analyses confirmed that patellofemoral/ patellar tendon loading alongside the coefficient of friction and peak rotational moment were larger in the indoor condition compared to the 2G surface. Conclusions: This study indicates that the indoor surface may improve change of direction performance owing to enhanced friction at the shoe-surface interface but augment the risk from patellar tendon/ patellofemoral injuries; whereas the 2G condition may enhance the risk from ACL pathologies

Reduced mechanical load decreases the density, stiffness, and strength of cancellous bone of the mandibular condyle

Contains fulltext : 186402.pdf (publisher's version ) (Closed access)OBJECTIVE: To investigate the influence of decreased mechanical loading on the density and mechanical properties of the cancellous bone of the human mandibular condyle. DESIGN: Destructive compressive mechanical tests were performed on cancellous bone specimens.Background. Reduced masticatory function in edentate people leads to a reduction of forces acting on the mandible. As bone reacts to its mechanical environment a change in its material properties can be expected. METHODS: Cylindrical bone specimens were obtained from dentate and edentate embalmed cadavers. Mechanical parameters were determined in the axial and in the transverse directions. Subsequently, density parameters were determined according to a method based on Archimedes' principle. RESULTS: The apparent density and volume fraction of the bone were about 18% lower in the edentate group; no age-related effect on density was found. The decrease of bone in the edentate group was associated with a lower stiffness and strength (about 22% and 28%, respectively). The ultimate strain, however, did not differ between the two groups. Both groups had similar mechanical anisotropy; in axial loading the bone was stiffer and stronger than in transverse loading. CONCLUSIONS: Reduced mechanical load had affected the density and herewith the mechanical properties of condylar cancellous bone, but not its anisotropy. RELEVANCE: The change in material properties of the cancellous bone after loss of teeth indicate that the mandibular condyle is sensitive for changes in its mechanical environment. Therefore, changes in mechanical loading of the condyle have to be accounted for in surgical procedures of the mandible

Architectural measures of the cancellous bone of the mandibular condyle identified by principal components analysis.

Item does not contain fulltextAs several morphological parameters of cancellous bone express more or less the same architectural measure, we applied principal components analysis to group these measures and correlated these to the mechanical properties. Cylindrical specimens (n = 24) were obtained in different orientations from embalmed mandibular condyles; the angle of the first principal direction and the axis of the specimen, expressing the orientation of the trabeculae, ranged from 10 degrees to 87 degrees. Morphological parameters were determined by a method based on Archimedes' principle and by micro-CT scanning, and the mechanical properties were obtained by mechanical testing. The principal components analysis was used to obtain a set of independent components to describe the morphology. This set was entered into linear regression analyses for explaining the variance in mechanical properties. The principal components analysis revealed four components: amount of bone, number of trabeculae, trabecular orientation, and miscellaneous. They accounted for about 90% of the variance in the morphological variables. The component loadings indicated that a higher amount of bone was primarily associated with more plate-like trabeculae, and not with more or thicker trabeculae. The trabecular orientation was most determinative (about 50%) in explaining stiffness, strength, and failure energy. The amount of bone was second most determinative and increased the explained variance to about 72%. These results suggest that trabecular orientation and amount of bone are important in explaining the anisotropic mechanical properties of the cancellous bone of the mandibular condyle