[The quality of insurance medicine].
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Documentation↗
Biomedical subjects
G Sigholm
Publications and source records attributed to G Sigholm.
Graft perforations favor osteoinduction. Studies of rabbit cortical grafts sterilized with ethylene oxide.
The healing of freeze-dried, ethylene oxide sterilized, segmental, allogenic cortical bone grafts was investigated in 15 rabbits using a 2-cm ulnar diaphyseal defect. Five different groups of bone grafts were evaluated: 1) unperforated undemineralized, 2) perforated undemineralized, 3) unperforated demineralized, 4) perforated demineralized, and 5) perforated demineralized grafts enclosed by silicone rubber (Silastic) sheets. There were 3 animals in each group. At 18 days, the study was terminated, and the implants were examined using radiographs and qualitative histologic preparations. We observed that healing of perforated demineralized bone was superior to unperforated demineralized bone, that undemineralized bone was partially sequestered in reactive lacunae, and that perforations in demineralized bone became centers of osteoinduction. Demineralized bone sterilized with ethylene oxide by this method vigorously formed new bone.
Animals↗
Biomechanical model of the human shoulder joint--II. The shoulder rhythm.
A method to investigate the rhythm of the human shoulder, i.e. the interplay between the motion of constituent parts of the shoulder, has been devised and tested. The method is based upon numerical evaluation of low dose roentgenstereophotogrammetric motion pictures of subjects equipped with radiation dense implantations in the bones. Evaluation of the method shows that it may be used in determining motion patterns and that the employed interpolation techniques can be used to simulate motions not actually performed in the laboratory. The shoulder rhythm has been previously poorly investigated and quantified results published pertain to one plane only. Our results on motion patterns correlate with previous investigations. With this method, we show that the absolute position of the bones varies significantly between individuals while the relative displacement of the bones during motion exhibit similarities. In particular the results show that, under normal conditions, the individual rhythm is very stable and insensitive to small hand-loads.
Acromion↗
The effect of simulated fracture-angulations of the tibia on cartilage pressures in the knee joint.
The effects of angular deformities of the tibia on the contact areas and pressures on cartilage in the knee were measured with use of pressure-sensitive film. Six cadaver knees were mounted in a test-frame, such that the offset and tilt of the knee relative to the load-axis simulated that due to angular deformities of the tibia of 5, 10, 15, or 20 degrees of varus or valgus at the levels of the proximal, middle, and distal thirds. Angulation had little effect on the contact area. The change in pressure was least for fractures of the distal third and greatest for fractures of the proximal third. For example, a 20-degree angulation of the distal third increased the maximum contact pressure by an average of 26 per cent in the compartment toward the load-axis and reduced it by 32 per cent in the opposite compartment. With an angulation of 20 degrees at the level of the proximal third of the tibia, the increase in pressure averaged 106 per cent and the decrease averaged 89 per cent. The changes in pressure with fractures at the middle third were between these extremes.
Biomechanical Phenomena↗
Pressure recording in the subacromial bursa.
The microcapillary infusion (MCI) technique was evaluated in monitoring pressure in the subacromial bursa in 30 shoulders in healthy volunteers. The total pressure in the bursa was studied as the volunteers held their arms at rest and as they lifted their arms and held them lifted with or without a weight of 1 kg in the hands. The pressure in the bursae at rest averaged 8 mm Hg and was found stable during a 40-min period. When the arms were lifted, the average bursa pressure increased from 8 to 39 mm Hg. As the arms were held up, the weights were put in the hands, and the average bursa pressure then further increased to 56 mm Hg. When the infusion catheters were repeatedly flushed, during a period of 5 min and with a total of 1.2 ml of saline, the average bursa pressure doubled regardless of arm position and load in the hands. The compliance of the bursae decreased from 0.09 to 0.04 ml/mm Hg when the arms were lifted and from 0.04 to 0.02 ml/mm Hg when the arms were lifted and the hands were loaded. The MCI method was found suitable for recording pressure in the subacromial bursa during exercise.
Adult↗
Biomechanical model of the human shoulder--I. Elements.
In a first step of a biomechanical modelling of the human shoulder the points of application of muscle forces to the bones were determined in a dissection study on four human shoulder specimens. A kinematic description of the shoulder was presented employing bone fixed coordinate systems. Actions of the shoulder muscles were modelled as a system of forces acting along ideal strings. The shoulder complex was treated as a three rigid body twelve degrees of freedom system.
Biomechanical Phenomena↗
Electromyographic analysis of shoulder muscle load.
The influence of hand tool weight and arm position on shoulder muscle load was studied by electromyography. The investigation was made to facilitate recommendations on work place design. The aim is to reduce the occurrence of occupational shoulder disorders in industry. Nine volunteers held 21 different arm positions with the hand over waist level. In each position, the hand was loaded with 0, 1, and 2 kg. Each load was maintained for 15 s. The myoelectric activity in six shoulder muscles was recorded and analyzed automatically with respect to the amplitude. The results indicate that the degree of upper arm elevation is the most important parameter influencing shoulder muscle load. Short rotator muscles stabilizing the shoulder joint were found to be more hand-load dependent than the deltoid muscle. The ergonomic implications of this study are that work situations should be designed so that the arm can be kept close to the body and the hand load minimized.
Adult↗
Shoulder pain and heavy manual labor.
The problem of the increasingly common shoulder pain syndromes in industry was investigated by biomechanic and epidemiologic methods. Rotator cuff tendinitis constitutes a major problem in people with arduous occupations, i.e., shipyard welders (prevalence ratio, 18.3%), and steel plateworkers (16.2%). Static work seems to induce symptoms at an earlier age. The clinical diagnosis was supraspinatus tendinitis. The biomechanic studies confirmed the view that the shoulder muscles are heavily loaded when the arm is elevated. Excessive hand tool mass increases the strain markedly in some muscles, particularly the supraspinatus and the infraspinatus. The hypovascularity of the supraspinatus tendon is then likely to be accentuated by high intramuscular pressure that reduces the blood flow through the muscle. The strain on the supraspinatus muscle in overhead work is an important factor contributing to prolonged shoulder disability. An analysis of the distribution of loads imposed on the shoulder in practical working situations can be based on observations of working postures and external forces.
Adult↗
Secular changes in craniofacial dimensions in a homogeneous population.
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Adult↗