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Biomedical subjects

W C Hutton

Publications and source records attributed to W C Hutton.

At least 91 records · Page 5Linked to original sources
PubMed1987

Tendon implantation into bone: an experimental study.

We report the results of an experimental study to investigate the mechanical properties and histological structure of the tendon-bone junction following surgical implantation of tendon into bone in the rabbit. The results following tendon transfer and tendon grafting were compared. The normal four-zone tendon junction was not reproduced histologically, in either group. After 20 weeks, the mechanical strength of the tendon transfers had reached 60% of the controls and that of the tendon grafts 20% of the controls. Microangiography demonstrated that these differences were not related to the vascularisation of the tendon bone junction. The mechanical properties of the tendon-bone junction may be dependent more on the functional state of the implanted tendon than on its structure.

Animals↗
PubMed1987

Diurnal variations in the stresses on the lumbar spine.

Two complementary experiments were performed, the first on living people and the second on cadaveric spines. In the first experiment, electronic inclinometers were used to measure the range of lumbar flexion of 21 volunteers in the early morning and in the afternoon. The results showed that the range of movement increased by 5 degrees during the day. In the second experiment, cadaveric lumbar motion segments were creep loaded to simulate a day's activity and their bending properties were measured before and after creep. The results showed that creep loading reduces the spine's resistance to bending (the effect being particularly marked in the disc) and increases the range of lumbar flexion by 12.5 degrees. The results of the two experiments were combined to show that in life, forward bending movements subject the lumbar spine to higher bending stresses in the early morning compared with later in the day. The increase is about 300% for the discs and 80% for the ligaments of the neural arch. It is concluded that lumbar discs and ligaments are at greater risk of injury in the early morning.

Adolescent↗
PubMed1987

The short-term effects of chymopapain on intervertebral discs.

Cadaveric lumbar discs were injected with chymopapain and subjected to a series of mechanical tests over a period of up to 19 hours. Discs from the same spine injected with saline were used as controls. The results showed that chymopapain had no measurable effect on the mechanical properties of the disc apart from the increased height and stiffening caused by fluid injection. Another series of tests on isolated pieces of disc material showed that chymopapain could reduce the size of prolapsed nuclear material by 24% in one hour and by 80% in 48 hours. It is concluded that, in the short-term, chymopapain has a negligible effect on the mechanics of a disc but it can reduce the size of any prolapsed nuclear material with which it comes in contact.

Adult↗
PubMed1987

Contact pressures in the human hip joint.

The pressure distribution between the cartilaginous surfaces in the human hip joint was measured using pressure-sensitive film. Five cadaveric hip joints (aged between 58 and 87 years) were measured at three positions and loads, representing three instants in the stance phase of the walking cycle. The pressure distribution was not uniform, indicating that the cartilage did not, to any great extent, distribute the applied load. The maximum pressures recorded were about 10 MN/m2. The anterosuperior surface of the cartilage was identified as an area of high pressure.

Aged↗
PubMed1986

The stages of disc degeneration as revealed by discograms.

One hundred and thirty-nine discs from cadaveric lumbar spines were injected with a mixture of radio-opaque fluid and dye. Discograms were taken and the discs were then sectioned in the sagittal plane. Examination of the sections revealed that injected fluid did not at first mix with the disc matrix but pushed it aside to form pools of injected fluid. The location of these pools, and hence the appearance of a discogram, depended on the stage of degeneration of the disc. It is concluded that useful clinical information can be obtained from discograms.

Adolescent↗
PubMed1986

The effect of posture on diffusion into lumbar intervertebral discs.

The diffusion of small solutes into the intervertebral discs of cadaveric lumbar motion segments was measured using a radioactive tracer technique. The motion segments were wedged and loaded to simulate erect posture and flexed sitting postures. The results show that erect posture favours diffusion into the anterior half of the disc compared to the posterior half. Flexed posture, by deforming the annulus fibrosus, reverses this imbalance.

Adolescent↗
PubMed1985

Load cell analysis following silastic arthroplasty of the hallux.

The first metatarsophalangeal joint was replaced by a flexible silastic hinge prosthesis in 33 joints of 25 patients. Most patients were pleased with the operation but one third had some discomfort under the second and third metatarsal heads. We used a computer linked load cell matrix to analyse the forces under these feet during normal walking. After silastic arthroplasty there was a rise of 65% in peak load under the second and third metatarsal heads compared with that found in the opposite feet which had not undergone operation (P less than 0.001). This was associated with a fall in peak load under the hallux of 43% (P less than 0.03) compared to normal and a less significant fall averaging 23% in the peak pressure experienced under the first metatarsal head. There was a rise in peak heel loading and a reduction in the normal pronation which occurs during the stance phase of walking.

Hallux↗
PubMed1985

The effect of posture on the lumbar spine.

A series of experiments showing how posture affects the lumbar spine is reviewed. Postures which flatten (that is, flex) the lumbar spine are compared with those that preserve the lumbar lordosis. Our review shows that flexed postures have several advantages: flexion improves the transport of metabolites in the intervertebral discs, reduces the stresses on the apophyseal joints and on the posterior half of the annulus fibrosus, and gives the spine a high compressive strength. Flexion also has disadvantages: it increases the stress on the anterior annulus and increases the hydrostatic pressure in the nucleus pulposus at low load levels. The disadvantages are not of much significance and we conclude that it is mechanically and nutritionally advantageous to flatten the lumbar spine when sitting and when lifting heavy weights.

Humans↗
PubMed1984

Synovial fluid circulation in the hip joint.

Early in our study of the role of incongruency in the hip (Ref. 1) we observed by x-ray screening that, under load, a drop of barium sulphate placed between the articular surfaces spread out between them and a substantial portion was extruded from the intercartilage space into the fossa; all the barium was drawn back as load was reduced. This observation and others (Ref. 2) which demonstrated the location, size and behaviour of intercartilage space with movement and load, prompted exploration of the hypothesis that the space due to joint incongruency serves as a pump to transport synovial fluid in the articular cavity in aid of nutrition and lubrication. This had already been suggested by others (Ref. 3); but none have closely studied the hypothesis. The following is an expansion of this idea, which leads to the concept of a systematic circulation of fluid through the hip joint.

Adult↗
PubMed1984

The incongruous hip joint: a loading study.

Hip incongruency was studied by load-displacement and casting methods. Twenty-five joints were loaded in 5 different positions of the walking cycle. Seventeen of them had a space at the apex in all positions, while 3 were congruent at low loads, and the remaining 5 had femoral heads smaller than their acetabula. No trends with age were apparent.

Adult↗
PubMed1984

Disc space narrowing and the lumbar facet joints.

Cadaveric lumbar spine specimens of "motion segments", each including two vertebrae and the linking disc and facet joints, were compressed. The pressure across the facet joints was measured using interposed pressure-recording paper. This was repeated for 12 pairs of facet joints at four angles of posture and with three different disc heights. The results were that pressure between the facets increased significantly with narrowing of the disc space and with increasing angles of extension. Extra-articular impingement was found to be caused, or worsened, by disc space narrowing. Increased pressure or impingement may be a source of pain in patients with reduced disc spaces.

Adult↗
PubMed1983

The mechanical function of the lumbar apophyseal joints.

Experiments were carried out on cadaveric lumbar spines to determine the mechanical function of the apophyseal joints. It was found that they resist most of the intervertebral shear force and share in resisting the intervertebral compressive force, but only in lordotic postures. They prevent excessive movement from damaging the discs: the posterior annulus is protected in torsion by the facet surfaces and in flexion by the capsular ligaments.

Humans↗
PubMed1983

The effect of posture on the fluid content of lumbar intervertebral discs.

Cadaveric lumbar motion segments were creep loaded for 4 hours, and the fluid content of the intervertebral discs was measured and compared with that of unloaded discs. Half of the specimens were wedged to simulate sitting with the lumbar spine flexed, and the other half were wedged to simulate sitting or standing erect. The results showed that "flexed" discs lost more fluid, especially from the nucleus pulposus, than did the "erect" discs. It is concluded that fluid flow in flexed postures can aid the nutrition of the lumbar discs.

Adult↗
PubMed1983

The effect of fatigue on the lumbar intervertebral disc.

Forty-one cadaveric lumbar intervertebral joints from 18 spines were flexed and fatigue loaded to simulate a vigorous day's activity. The joints were then bisected and the discs examined. Twenty-three out of 41 of the discs showed distortions in the lamellae of the annulus fibrosus and, in a few of these, complete radial fissures were found in the posterior annulus.

Adolescent↗
PubMed1982

The mechanics of prolapsed intervertebral disc.

Cadaveric lumbar intervertebral joints were subjected to compressive loads while wedged in forward flexion. In some specimens disc lesions were produced and we have been able to identify three different types: postero-lateral radial fissure, annular protrusion and nuclear extrusion. The type of lesion depended on the loading regime but all occurred more readily in slightly degenerated discs.

Adult↗
PubMed1981

Vertical forces acting on the feet of diabetic patients with neuropathic ulceration.

The vertical forces acting on the sole of the foot in walking have been measured in 24 diabetic patients with neuropathic ulceration of the foot using a load-sensitive surface divided into 128 load cells, and compared with those in two groups of controls: (a), 21 diabetic patients with peripheral neuropathy but no ulceration and (b) 47 normal individuals. The results showed that the patients with neuropathic ulceration were significantly heavier, that diabetic patients with neuropathy, with or without ulceration, transmitted proportionally less force through the toes than normal individuals, and showed a medial shift of the force transmitted through the metatarsal heads. All plantar ulcers occurred at the site of maximum loading. The absolute force at the site of maximum loading was significantly greater in the patients with ulcers than in both control groups, through there was a considerable overlap. A significant difference remained even when the absolute force had been corrected for differences in toe loading and body weight, indicating that a further factor (or factors) must contribute to the development of these localized areas of high loading.

Adult↗