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Biomedical subjects

J R Stott

Publications and source records attributed to J R Stott.

22 records · Page 2Linked to original sources
PubMedDate not supplied

The resistance to flexion of the lumbar intervertebral joint.

Cadaveric lumbar intervertebral joints were subjected to physiologic loads to simulate flexion. The resistance to bending was measured first with the joint intact and again after cutting in turn through the supraspinous/interspinous ligaments, the ligamentum flavum, and the capsular ligaments of the apophyseal joints. In this way the part played by each of these structures, and the intervertebral disc, in resisting and limiting flexion was determined. The results show that at the limit of flexion the supraspinous and interspinous ligaments sprain first and that the capsular ligaments and the intervertebral disc offer considerably more resistance than the ligamentum flavum and the supraspinous/interspinous ligaments. The intervertebral joint was found, on average, to be sufficiently stiff to balance about half the bending moment exerted by the trunk in full flexion.

Biomechanical Phenomena↗
PubMedDate not supplied

Forces under the hallux valgus foot before and after surgery.

Abnormalities in the hallux valgus foot and changes after surgery were investigated by measuring the distribuiion of load on the foot in walking. Hallux valgus was associated with reduced load imposed on the toes, and on the medial side of the forefoot, compared with a large sample of healthy feet. Abnormalities correlated with the degree of the deformity. Both Keller's operation and a wedge displacement osteotomy of the first metatarsal not only failed to restore normal loading but increased the abnormalities of loading seen preoperatively. A large decrease in the angle between first and second metatarsals as a result of surgery minimized this increase. A silastic arthroplasty did not carry high loads when used to treat hallux valgus, but near normal loads were imposed on it when used for hallux rigidus. Considerable variability was found in the loading distribution on the healthy feet. The distribution between first and second metatarsal heads was partially dependent upon their protrusions, relative to the direction of walking. The changes in the relationships between the loadings on the forefoot and skeletal shape in response to surgical operations are important for our understanding of treatment of the hallux valgus foot.

Adolescent↗
PubMedDate not supplied

Objective and subjective time courses of recovery from motion sickness assessed by repeated motion challenges.

The aim of this study was to determine whether the time course of recovery of tolerance, as assessed objectively by rechallenge with motion, paralleled the subjective recovery from motion sickness. Subjects (n = 20) were exposed to 5 pairs of nauseogenic motion challenges in which the time interval between the end of the first and the start of the second of each pair ranged from 15 min to 2 h. The cross-coupled motion challenge had an incrementing profile of rotational velocity from 4 degrees to 92 degrees.s-1 in steps of 4 degrees.s-1 every 30 s, with 8 head movements per 30 s, of approximately 45 degrees, and was continued to the point of moderate nausea. Objective loss of tolerance decreased from 15 min to 60 min after the first challenge, but increased again at 2 h. By contrast, most individuals reported subjective recovery by 15 min to 30 min. It was concluded that there is an underlying effect of motion sickness that sensitizes the response to subsequent motion for a period of at least 2 h. This underlying objective effect can occur in the absence of subjective symptoms, has a slower time course than the subjective recovery from symptoms, and appears to be non-monotonic.

Adult↗