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In vivo loads acting at the hip joint have so far only been measured in few patients and without detailed documentation of gait data. Such information is required to test and improve wear, strength and fixation stability of hip implants. Measurements of hip contact forces with instrumented implants and synchronous analyses of gait patterns and ground(More)
BACKGROUND A slightly degenerated disc adjacent to a segment that has to be fused is sometimes instrumented with a dynamic fixator. The dynamic implant is assumed to reduce disc loads at that level and to preserve disc function, thus inhibiting the progression of degeneration. METHODS A three-dimensional finite element model of the lumbar spine was used(More)
The loads acting in knee joints must be known for improving joint replacement, surgical procedures, physiotherapy, biomechanical computer simulations, and to advise patients with osteoarthritis or fractures about what activities to avoid. Such data would also allow verification of test standards for knee implants. This work analyzes data from 8 subjects(More)
Knowledge of the loads to which orthopedic implants are subjected is a fundamental prerequisite for their optimal biomechanical design, long-term success, and improved rehabilitation outcomes. In vivo load measurements are more accurate than those obtained using mathematical musculoskeletal models. An inductively powered integrated circuit inside the(More)
A bilateral dynamic stabilization device is assumed to alter favorable the movement and load transmission of a spinal segment without the intention of fusion of that segment. Little is known about the effect of a posterior dynamic fixation device on the mechanical behavior of the lumbar spine. Muscle forces were disregarded in the few biomechanical studies(More)
Muscle forces stabilize the spine and have a great influence on spinal loads. But little is known about their magnitude. In a former in vitro experiment, a good agreement with intradiscal pressure and fixator loads measured in vivo could be achieved for standing and extension of the lumbar spine. However, for flexion the agreement between in vitro and in(More)
Total disc arthroplasty (TDA) has been successfully used for monosegmental treatment in the last few years. However, multi-level TDA led to controversial clinical results. We hypothesise that: (1) the more artificial discs are implanted, the stronger the increases in spinal mobility and facet joint forces in flexion and extension; (2) deviations from the(More)
Compared to a healthy intervertebral disc, the geometry and the material properties of the involved tissues are altered in a degenerated disc. It is not completely understood how this affects the mechanical behaviour of a motion segment. In order to study the influence of disc degeneration on motion segment mechanics a three-dimensional, nonlinear finite(More)
The influence of the different lumbar spinal ligaments on intersegmental rotation is not fully understood. In order to explore this effect, a finite element model of the functional spinal unit L3/L4 was loaded with pure moments in the three main anatomic planes. The two extremes--minimum and maximum--ligament stiffness values reported in the literature were(More)
Gap junctions are metabolic and electrotonic pathways between cells and provide direct cooperation within and between cellular nets. They are among the cellular structures most frequently investigated. This chapter primarily addresses aspects of the assembly of the gap junction channel, considering the insertion of the protein into the membrane, the(More)