Clinical biomechanics
-
Clinical biomechanics · Nov 2006
A short plate compression screw with diagonal bolts--a biomechanical evaluation performed experimentally and by numerical computation.
Decreasing the length of the side plate of the dynamic hip screw would theoretically allow a smaller surgical incision, a shorter surgical time, decreased operative blood loss and minimal periosteal stripping. A new design of a very short plate dynamic hip screw based on two diagonal screws has been developed. Our study compares the new design and the four-hole side plate in respect to mechanical properties and bio-mechanical outcomes utilizing the Finite Element Analysis method. ⋯ Although the new design offers a minimally invasive approach to subtrochanteric femur fracture fixation, it was found to have insufficient biomechanical performance resulting in high probability of mechanical failure. The authors believe that the finite element method may have the potential to serve as an additional clinical tool for performing surgical preplanning and assist in decision making.
-
Clinical biomechanics · Aug 2006
Clinical TrialWrapping of trunk thoracic extensor muscles influences muscle forces and spinal loads in lifting tasks.
An improved assessment of risk of spinal injury during lifting activities depends on an accurate estimation of trunk muscle forces, spinal loads and stability margin which in turn requires, amongst others, an accurate description of trunk muscle geometries. The lines of action of erector spinae muscles are often assumed to be linear despite the curved paths of these muscles in forward flexion postures. ⋯ Consideration of global extensor muscles with curved paths and realistic lever arms is important in biomechanical analysis of lifting tasks. Reduction in the erector spinae lever arms during flexion tasks could vary depending on the lumbar posture. Results advocate small flattening of the lumbar curvature in isometric lifts yielding smaller compression and shear forces at the critical L5-S1 level.
-
Clinical biomechanics · Aug 2006
Biomechanical performance of the new BeadEx implant in the treatment of osteoporotic vertebral body compression fractures: restoration and maintenance of height and stability.
Vertebral compression fractures are counted among the most common complications of osteoporosis. For treatment, a new, alternative implant has been developed (BeadEx, Expandis, Hof HaCarmel, Israel). The aim of the present in vitro study was to evaluate whether this implant is able to restore the initial height and three-dimensional stability after fracture and whether it is able to maintain this height and stability during complex cyclic loading. ⋯ From a biomechanical point of view, BeadEx plus bone cement can be recommended as an alternative to vertebroplasty in the treatment of osteoporotic vertebral body fractures. BeadEx plus fixator can be recommended if additional stability is needed.
-
Rotation about a longitudinal axis of the forearm has been a matter of investigation for over 100 years. However, most studies were limited to only a few muscles and to their action in specific set positions of elbow and forearm rotation. This investigation aims at determining the moment arms of muscles that contribute to pronation and supination at three different angles of elbow flexion throughout the entire range of forearm rotation. ⋯ The observations drawn from this study could be of eminent value in planning rotator muscle transplantation, in understanding functional disorders after injury, and in the physical treatment of forearm rotator muscle deficiency. Reconstruction of the physiological anatomical arrangement in the treatment of injuries is strongly recommended for restoration of function.
-
Clinical biomechanics · Jul 2006
Clinical TrialThe duration and plantar pressure distribution during one-leg stance in Tai Chi exercise.
Tai Chi exercise improved the balance control and muscle strength of the lower extremities. The aim of this study is to quantify the one-leg stance duration and plantar pressure distribution during the one-leg stance in Tai Chi and to try to elaborate on its probable effects on the ability to balance on one leg. ⋯ The longer duration of each one-leg stance and the plantar pressure distribution characteristics during the one-leg stance in Tai Chi exercise may be associated with an improved ability to balance on one leg. The findings may provide useful information toward the development of strengthening programs, strategies for the prevention of falls, and the promotion of a physically active lifestyle.