Journal of biomechanics
-
Journal of biomechanics · Jul 2017
Amputee locomotion: Frequency content of prosthetic vs. intact limb vertical ground reaction forces during running and the effects of filter cut-off frequency.
Compared to intact limbs, running-specific prostheses have high resonance non-biologic materials and lack active tissues to damp high frequencies. These differences may lead to ground reaction forces (GRFs) with high frequency content. If so, ubiquitously applying low-pass filters to prosthetic and intact limb GRFs may attenuate veridical high frequency content and mask important and ecologically valid data from prostheses. ⋯ To evaluate whether these differences in frequency content interact with filter cut-offs and alter results, we filtered GRFs with cut-offs from 1 to 100Hz and calculated vertical impact peak (VIP). Changing cut-off had inconsistent effects on VIP across speeds and limbs: Faster speeds had significantly larger changes in VIP per change in cut-off while, compared to controls, prosthetic limbs had significantly smaller changes in VIP per change in cut-off. These findings reveal differences in GRF frequency content between prosthetic and intact limbs and suggest that a cut-off frequency that is appropriate for one limb or speed may be inappropriate for another.
-
Journal of biomechanics · Jul 2017
Dynamic in vivo 3D atlantoaxial spine kinematics during upright rotation.
Diagnosing dysfunctional atlantoaxial motion is challenging given limitations of current diagnostic imaging techniques. Three-dimensional imaging during upright functional motion may be useful in identifying dynamic instability not apparent on static imaging. Abnormal atlantoaxial motion has been linked to numerous pathologies including whiplash, cervicogenic headaches, C2 fractures, and rheumatoid arthritis. ⋯ We believe this is the first study describing 3D dynamic atlantoaxial kinematics under true physiologic conditions in healthy subjects. C1/C2 rotation accounts for approximately half of total head axial rotation. Additionally, C1 undergoes coupled flexion/extension and contralateral bending, in addition to inferior, lateral and posterior translation.
-
Journal of biomechanics · Jul 2017
Chronic low back pain patients walk with locally altered spinal kinematics.
Various studies have reported alterations of spinal kinematics in patients with chronic low back pain (CLBP) during gait. However, while recent findings stressed the importance of multi-segment analysis, most of prior gait studies modelled the lumbar spine as one segment, when it was not the entire trunk that was considered as a single segment. Therefore, there is a need for comprehensive multi-segment research that could improve our understanding of CLBP pathomechanism and thus possibly contribute to better care for CLBP. ⋯ The results also suggested that patients had more asymmetrical LTS motion in the transverse plane. In conclusion, this work extended prior literature by showing specific CLBP-related alterations in multi-segment spinal kinematics during gait. Further research is necessary to understand the factors influencing kinematics alterations and how treatment strategies might improve motor behaviour in CLBP patients.