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Biomedical subjects

A B Schultz

Publications and source records attributed to A B Schultz.

99 records · Page 6Linked to original sources
PubMedDate not supplied

Mechanical properties of human lumbar spine motion segments. Influence of age, sex, disc level, and degeneration.

The influences of age, sex, disc level, and degree of degenration on the mechanical behavior of 42 fresh cadaver lumbar motion segments are reported. The motions and intradiscal pressure changes that result from the application of flexion, extension, lateral bending, and torsional moments; compression; and anterior, posterior, and lateral shears are described. The authors find that the mean behaviors of the different segment classes sometimes differ, but these differences are seldom pronounced. Scatter in the behavior of individual motion segments is pronounced, and very often overshadows any class differences.

Adult↗
PubMedDate not supplied

Measurement of spine morphology in children, ages 10-16.

Measurements of vertebral body diameters and spine lengths in 248 Swedish children, ages 10-16, who had structurally normal spines are reported. Spine slenderness factors were calculated from these data. The spines of girls were found to be significantly more slender than those of boys. There was little dependence of slenderness on age in either sex.

Adolescent↗
PubMedDate not supplied

The effects of chemonucleolysis on the mechanical properties of the canine lumbar disc.

One hundred and twenty-two lumbar intervertebral discs from 43 mongrel dogs were used to study the effect of chemonucleolysis on the flexion, torsion, and lateral bending flexibilities of the disc. The dogs were killed 2, 4, 12, 26, and 52 weeks following injection with 0.1-0.15 ml of either crude collagenase, semipurified collagenase, or chymopapain. Controls consisted of saline-injected and uninjected discs. The bending and torsional properties of each disc were determined by applying incremental moments up to 0.8 Nm and measuring the resultant rotations 60 seconds after each load increment was applied. The discs were then sectioned for morphologic evaluation. Increases in disc flexibilities ranging from 1.4 to 5.8-fold were found 2 weeks after injection with all three enzymes. The largest increase was noted in flexion in discs injected with chymopapain. By 3 months, all lateral bending flexibilities had returned to control values. In general, however, flexion and torsion flexibilities did not return to control values 6 months following chemonucleolysis. The extent of the gross morphologic changes produced by each of the three enzyme preparations did not correlate with the acute increases in disc flexibilities. Chymopapain and semipurified collagenase had similar morphologic and mechanical effects. The temporary increases in flexibility appeared to be due to decreases in the overall compression, tensile and shear stiffness of the annulus caused by the enzymes.

Animals↗
PubMedDate not supplied

Correlation of objective measure of trunk motion and muscle function with low-back disability ratings.

A study was undertaken to examine relations among some objective and subjective measures of low-back-related disability in a group of 41 low-back pain patients and in seven pain-free control subjects. Subjective measures of disability were obtained by Oswestry patient questionnaires. Oswestry disability score related significantly (P less than 0.001) to presence or absence of relaxation in back muscles during flexion. Mean trunk strength ratios were inversely related to disability score (P less than .05), and trunk mobility was meaningfully reduced (P less than .01). Despite loss of motion, a large enough excursion was observed to predict presence of back muscle relaxation. These findings imply that myoelectric signal levels, trunk strength ratios, and ranges of trunk motion may be used as objective indicators of low-back pain disability.

Activities of Daily Living↗
PubMedDate not supplied

The costs of body mass index levels in an employed population.

We studied 3,066 First Chicago NBD employees by using health risk appraisals and personnel data to determine the direct and indirect costs (in 1996 dollars) associated with varying levels of body mass index (BMI). The BMI is the most widely used measure of weight adjusted by height. We found that as BMI increases, so do the number of sick days, medical claims and health care costs and that the mean annual health care costs for the BMI "at risk" population (men with a BMI of > or = 27.8 kg/m2, women > or = 27.3 kg/m2) was $2,274 versus $1,499 for the "not at risk" group. Major differences in health care costs were observed for employees 45 years old and older, particularly among the women in this age group. Analysis was completed for those employees with and without a risk for BMI. A "J-shaped" curve between medical claims costs and BMI exists, with the low point occurring at about 25 to 27 kg/m2. We conclude that indirect and direct costs to an employer increase with increasing BMI. Employers may benefit from helping employees achieve a healthier weight. The initial target population should be those who are at highest risk of complications from obesity.

Adult↗
PubMedDate not supplied

Motions of the head and thorax during neck manipulations.

OBJECTIVE: The purpose of this study was to determine the amplitudes and variations of preload positioning and displacements of the head and thorax during spinal manipulative therapy (SMT) applied to C2. DESIGN: This experimental study measured the biomechanics of SMT applied to C2. SETTING: Biomechanics Laboratory, Mechanical Engineering and Applied Mechanics, University of Michigan and Spinal Ergonomics and Joint Research Laboratory, National College of Chiropractic. PARTICIPANTS: Eighteen healthy volunteers from the University of Michigan and the National College of Chiropractic were manipulated by a total of eight experienced chiropractic physicians licensed in the state in which they participated. INTERVENTION: Sixty-six Direct Break (DB) and twenty-three Rotary Break (RB) diversified procedures were administered to C2. Randomization of the DB was made on two variables, direction and intended load intensities. The RB was administered only from the right by each physician. MAIN OUTCOME MEASURES: Linear and angular displacement time histories for the head and thorax mass centers were monitored during the preload setup of each procedure and the dynamic delivery of the treatment procedures. CONCLUSIONS: DB procedures were found to have sagittally symmetric positioning and displacements as a function of intended direction of the procedure. Both DB and RB methods consisted of preload positioning with head flexion. RB rotation and lateral bending preload positions approached the maximal voluntary ranges of motion for the upper cervical spine. Variations among procedures by one manipulator were approximately the same as for variations among manipulators. Data indicates that SMT procedures can be successfully modified to control amplitude and direction of body segment displacements that arise.

Adult↗