Clinical biomechanics
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Clinical biomechanics · Jun 2020
How pre-strain affects the chemo-torsional response of the intervertebral disc.
The role of the axial pre-strain on the torsional response of the intervertebral disc remains largely undefined. Moreover, the chemo-mechanical interactions in disc tissues are still unclear and corresponding data are rare in the literature. The paper deals with an in-vitro study of the pre-strain effect on the chemical sensitivity of the disc torsional response. ⋯ The combination of a compressive pre-strain with twisting amplifies the nucleus hydrostatic pressure on the annulus and the annulus collagen fibers tensions. The proteoglycans density increases with the compressive pre-strain and leads to higher chemical imbalances, which would explain the increase in chemical sensitivity of the disc torsional response.
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Clinical biomechanics · Jan 2020
The early failure of the gamma nail and the dynamic hip screw in femurs with a wide medullary canal. A biomechanical study of intertrochanteric fractures.
Intertrochanteric fractures may occur in a bone with a wide medullary canal that may lead to significant mobility of a intramedullary nail, contrary to an extramedullary device. This study evaluates the Dynamic Hip Screw and the gamma nail in AO 31.A2.1 fractures in these circumstances. ⋯ This study shows that the gamma nail is unstable in a large medullary canal but offers better rotational stability of the proximal fragment. A modification of the nail design or the operative technique may be considered.
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Clinical biomechanics · Jan 2020
Short term outcomes of hip arthroscopy on hip joint mechanics and cartilage health in patients with femoroacetabular impingement syndrome.
Femoroacetabular acetabular impingement syndrome consists of abnormal hip joint morphology resulting in painful hip joint impingement. Hip arthroscopy corrects the abnormal morphology and reduces clinical symptoms associated with femoroacetabular impingement syndrome yet the effects of hip arthroscopy on gait mechanics and cartilage health are not well understood. ⋯ Femoroacetabular impingement syndrome patients exhibited improved clinical symptoms yet ambulated with altered sagittal plane hip joint loading after hip arthroscopy. Increased hip flexion moment impulse post-surgery was associated with improved cartilage health within the surgical limb. These study findings suggest that sagittal plane hip joint loading at short-term follow-up after hip arthroscopy is associated with cartilage health and may be an important biomechanical parameter in post-operative rehabilitation programs.
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Clinical biomechanics · Dec 2019
Locking plate constructs benefit from interfragmentary lag screw fixation with decreased shear movements and more predictable fracture gap motion in simple fracture patterns.
A mechanical characterisation of lag screw fixation plus locking plate - although clinically widely used as either "mixed fixation concept" or absolutely stable fixation - is so far missing. This study aimed to evaluate the influence of an interfragmentary lag screw on the resulting motion at the fracture site of locking plate constructs using a simple fracture at the distal femur. ⋯ An interfragmentary lag screw next to locking bridge plating reduces fragment motion in vitro for a simple fracture pattern and provides a sufficient tool to decrease detrimental shear movements. Prospective clinical trials with interfragmentary lag screw fixation should prove these findings in wide clinical use to treat simple fracture patterns.
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Clinical biomechanics · Aug 2019
Kinematic and spatiotemporal gait characteristics in pregnant women with pelvic girdle pain, asymptomatic pregnant and non-pregnant women.
Walking difficulties are common among pregnant women with pelvic girdle pain. This cross-sectional study investigated the influence of pelvic girdle pain, pregnancy and speed on spatiotemporal and trunk, pelvic and hip kinematics during gait in the 2nd trimester of pregnancy. ⋯ Gait is primarily influenced by pelvic girdle pain and less by pregnancy. Pregnant women with pelvic girdle pain walked slower and with a more rigid gait pattern compared to asymptomatic pregnant women, presumably related to altered load transfer. Our results may assist clinical evaluation of pelvic girdle pain, as well as direct future research.