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Biomedical subjects

M H Pope

Publications and source records attributed to M H Pope.

At least 127 records · Page 7Linked to original sources
PubMed1986

Electromyographic studies of the lumbar trunk musculature during the development of axial torques.

The myoelectric activity of selected trunk muscles at the L3 level was studied during the development of a controlled isometric axial torque. Muscle activity was recorded with surface electrodes bilaterally over the erector spinae muscles, the rectus abdominus, the obliques externus, and the obliques internus. Subjects applied graded isometric axial torque efforts with the addition of a Valsalva. The largest myoelectric activities were recorded over the obliques externus and internus. The side of the muscle developing the torque did show the greatest myoelectric activity, but considerable antagonistic activity was also present. Neither the rectus abdominus nor the internal oblique muscles showed any difference from side to side. The calculated forces in the rectus abdominus and the erectores spinae were high, suggesting that a considerable amount of the muscle contraction was used to control the posture. A Valsalva did not decrease myoelectric activity, but did increase the torque developed.

Abdominal Muscles↗
PubMed1986

Analysis of the effect of using two different strain rates on the acoustic emission in bone.

To study the effect of strain rate on the acoustic emission amplitude signature of bone, bovine cortical bone was milled into standard tensile specimens which were tested at two different strain rates while being monitored with acoustic emission equipment. It was demonstrated that the amplitude distribution of the acoustic events in bone is dependent on strain rate. Greater numbers of events occurred with the slower strain rate (0.0001 s-1), but these events were of lower amplitude than those emitted during the more rapid strain rate (0.01 s-1). The plot of the cumulative event amplitude distribution followed the power-law model, and the slope of this output, the b-value, represented a signature of the amplitude distribution. The mechanical test results were consistent with the behavior of a viscoelastic multi-phase composite material.

Acoustics↗
PubMed1986

Mounting of the transducers in measurement of segmental motion of the spine.

A seated female subject was subjected to sinusoidal whole body vibration at 2, 4, 5 and 6 Hz. Accelerations were measured by accelerometers on pins screwed into the spinous process. The pins were also fitted with light emitting diodes (LED). The displacement of these LEDs were compared to LEDs attached directly to the skin. Substantial differences in measured displacements were noted between surface mounted LEDs and those mounted on pins rigidly attached to the skeleton. These differences were more marked further out from the center line.

Adult↗
PubMed1986

An internal fixator for posterior application to short segments of the thoracic, lumbar, or lumbosacral spine. Design and testing.

A new spinal implant has been designed and biomechanical testing completed, intended for application to "short-segment" spinal defects such as disc degeneration, fracture, spondylolisthesis, or tumor. Major improvements over currently available devices include: only 2-3 vertebrae are spanned, not 5-7 as with Harrington rods; true three-dimensional fixation is achieved, preventing such problems as hook or rod dislocation; three-dimensional adjustment is easily accomplished, allowing fracture or spondylolisthesis reduction to be readily performed; attachment to vertebrae is by means of transpedicular screws eliminating deliberate encroachment into the spinal canal, such as Luque wires or Harrington hooks; no special alignment between screws is needed (such as with holes or slots in a plate), allowing screw placement to fully conform to anatomic structures; and laminectomy sites and lumbosacral junction are readily instrumented. Background investigations presented here for design of this device include: CT-defined pedicle morphometry showing that screws may be larger than those currently used; effect of pitch, minor diameter, and tooth profile on screw pull-out strength; mechanical testing of a compact, three-dimensionally adjustable, strong, nonloosening articulating clamp; and establishing of the relationship between depth of penetration and strength of fixation of transpeduncular screws.

Adolescent↗
PubMed1985

Biomechanical definitions of spinal instability.

Instability is a mechanical entity, and an unstable structure is one that is not in a optimal state of equilibrium. In the spine, stability is affected by restraining structures that, if damaged or lax, will lend to altered equilibrium and thus instability. Instability is defined as loss of stiffness.

Biomechanical Phenomena↗
PubMed1985

The relationship between anthropometric, postural, muscular, and mobility characteristics of males ages 18-55.

Three hundred twenty-one males, ages 18-55, had standardized tests to determine height, weight, Davenport Index, leg length inequality, determination of flexion and extension torques, flexion/extension balance, range of motion, straight leg raising, and lumbar lordosis. A total of 106 (33.0%) had never experienced low-back symptoms; 144 (44.9%) had or were having moderate low-back pain (LBP); and 71 (22.1%) had or were having severe low-back symptoms. These three subgroups showed no significant differences in height, weight, Davenport Index, lumbar lordosis, or leg length inequalities. LBP patients had less flexor and extensor strength and were flexor overpowered, had diminished range of motion for spinal extension and axial rotation (P = 0.003, P = 0.0005), and diminished straight leg raising capacity (P = 0.04). A multivariate correlation matrix demonstrated no typical pattern of associated abnormalities except a diminished spinal range of motion in one plane was associated with the anticipated diminishment in all other planes of motion, and often with greater restrictions of straight leg raising tests.

Adolescent↗
PubMed1985

Psychologic factors in low-back-pain disability.

UNLABELLED: Biomechanical tests, physical examination, spinal radiographs, a modified Minnesota Multiphasic Personality Inventory (MMPI), and a psychologic health inventory derived from the Hopkins Symptom Checklist were applied in 321 randomly selected men, ages 18-55. Each subject was evaluated for prior and current low-back pain (LBP) complaints by use of a modification of the McGill pain questionnaire. Subjects were then categorized as having no LBP (n = 106, 33%), moderate LBP (n = 144, 44.8%), and severe LBP (n = 71, 22.1%). Subjects were further subcategorized as not disabled (defined as equal or less than seven days of work lost in the previous year) and disabled (work loss greater than seven days in the prior year). RESULTS: cumulative scores of the Hopkins Checklist showed that a mean score for no LBP equaled 2.5 +/- 2.9; moderate LBP was 4.3 +/- 3.2; and severe LBP was 4.6 +/- 3 (p = .0000). The disabled group was significantly different on both MMPI and Hopkins Checklist. The 20 disabled subjects had significant elevations of hypochondriasis (p = .0006) and hysteria (p = .005) when compared with nondisabled subjects with LBP. The mean score for disabled subjects on the Hopkins Checklist was 7.35 +/- 4.49, while the score was 4.17 +/- 3.15 (p = .0001) for the nondisabled subjects with LBP. In the general male population, patients with disabling LBP conditions form a distinctive subgroup comparable to those patients seen in selected LBP clinics.

Adult↗
PubMed1985

Setting temperatures of synthetic casts.

We used a glass tube containing water at body temperature to simulate a lower limb and applied commonly used synthetic-cast materials to this artificial limb in order to measure the exotherm created by these materials. Tests were limited to six plies and were done with and without a pillow under the cast. If the instructions called for the use of dip water, we used water at 24, 32, and 40 degrees Celsius. Under these conditions, none of the commonly used synthetic materials created temperatures that were high enough to cause burns.

Casts, Surgical↗
PubMed1984

Spine radiographs in patients with low-back pain. An epidemiological study in men.

A cohort of 321 men between the ages of eighteen and fifty-five was randomly selected from a group of 1221 men who had been surveyed by a questionnaire. They then had radiographs made of the lumbar spine. Of the 292 subjects fulfilling the criteria for inclusion in the study, ninety-six (32.9 per cent) had never had low-back pain, 134 (45.9 per cent) had had or were having moderate low-back pain, and sixty-two (21.2 per cent) had had or were having severe low-back pain. In the three groups there was a similar frequency of transitional vertebrae, Schmorl's nodes, the disc vacuum sign, narrowing of the disc space between the third and fourth lumbar and the fifth lumbar and first sacral vertebrae, and claw spurs. When there were traction spurs or disc-space narrowing, or both, between the fourth and fifth lumbar vertebrae, an increased incidence of severe low-back pain was evident. There also was a significant association of these two radiographic findings with symptoms (pain, weakness, and numbness) in the lower limbs. The measured lumbar lordosis, the length of the transverse process of the fourth lumbar vertebra, and the relationship between the fourth and fifth lumbar vertebral bodies with reference to the intercristal line had no association with the low-back pain. Increased lumbar lordosis had a significant association with decreased disc-space height and wedging deformity of the disc between the fourth and fifth lumbar vertebrae.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Five- to ten-year follow-up evaluation after reconstruction of the anterior cruciate ligament.

Long-term follow-up evaluation of a large number of patients who had undergone reconstruction of the anterior cruciate ligament (ACL) was performed. Of these patients, 87 were treated by reconstruction with the medial one third of the medial patellar tendon, and they were examined a mean of 7.9 years after surgery. All patients were extensively evaluated and examined by standard clinical techniques and a machine specifically designed to quantify primary laxity during the anterior drawer and Lachman tests. Seventy-one percent of the patients were satisfied with the results, and 69% had good to excellent results by the authors' subjective functional criteria. Patients who had the least motion and the best check or end points to the Lachman and anterior drawer tests had the best functional results. Only ten of the 27 unsatisfactory results occurred because of complete failure of the graft. Arthrosis and parapatellar pain were the most frequently observed contributing factors to failure in the presence of a clinically intact ligament (11 instances each).

Adolescent↗
PubMed1984

The biomechanics of scoliosis.

A review of the epidemiology of scoliosis reveals that it is costly in human suffering and health care resources. The terminology is defined and classifications explained. The full geometric description of scoliosis includes the three-dimensional description of the vertebral column, as well as the rib cage. Stereoradiographic and stereophotogrammetric (Raster and Moire) techniques are introduced. The coupling in a kinematic sense between, for example, lateral bend and rotation is compared to the orientation coupling in scoliosis. Genetic, biochemical, hormonal, neurological, and mechanical factors do not as yet explain the etiology. Column buckling models do not incorporate coupling, especially that occurring in scoliosis and thus do not improve our understanding of the deformity or its progression.

Adolescent↗
PubMed1982

Setting temperatures of plaster casts. The influence of technical variables.

It is known that plaster-of-Paris casts can cause burns. Experiments were done to determine what factors are involved in causing an elevation of the temperature in a freshly applied cast. A glass tube filled with water between the temperatures of 36 and 39 degrees Celsius was used to simulate a leg for this study. Standard plaster casts were applied to the tube and the following variables were studied: different temperatures of the dip water; different thicknesses of the cast; the presence of plaster residue in the dip water; and the effect of the plaster of a pillow placed under the tube. It was found that if the temperature of the dip water was higher than 24 degrees Celsius or the thickness of the cast was greater than eight ply, or both, and if the pillow was used to limit the dissipation of heat from the cast, temperatures high enough to cause skin burns could occasionally be reached. Variable results indicated that these were the factors operating in practice and that a combination of them posed the greatest hazard.

Burns↗
PubMed1982

Skiing and spinal trauma.

Spinal injury in skiers can either be acute or chronic. Acute spinal injury accounts for 3 to 3.6 per cent of all injuries occurring in Alpine skiing. Fewer acute injuries occur in cross-country skiing, and those that do usually are the result of a sudden, compressive force from a seated fall. The prevalence of chronic spinal trauma in skiing is unknown. Both cross-country and Alpine skiers appear to have greater complaints of mild to moderate low back pain as compared with their nonskiing counterparts. These differences may be the result of a complex interaction between recreational and occupational activities. Theoretical analyses suggest a risk for low-grade torsional injury to the Alpine skier's spine, whereas in cross-country skiing significant shear forces are applied to lumbar discs during the kick but not the double-poling phase.

Acute Disease↗
PubMed1981

Measurement of fracture gap motion in external fixation.

A testing machine to study fracture gap motion ex vivo was devised. The apparatus permits direct measurement of bending and shear at a fracture site under different loading conditions. Using this device the single and double frame Hoffmann external fixateurs were compared to a Küntscher medullary nail. Shear displacements of (0.4-1.7 mm) were observed for the fixateurs as opposed to 0.3 mm for the intermedullary nail. Changing from a single to a double frame halved hinge motion at the fracture site and reduced shear by 25%.

Animals↗