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Biomedical subjects

L D Haugh

Publications and source records attributed to L D Haugh.

At least 19 recordsLinked to original sources
PubMed1997

Early physician notification of patient disability risk and clinical guidelines after low back injury: a randomized, controlled trial.

STUDY DESIGN: Back-injured workers with high disability risk scores on a predictive questionnaire participated in a randomized, controlled trial of physician notification, with outcomes follow-up 3 months after injury. OBJECTIVES: To test whether physician intervention improves return to work and self-assessment outcomes for people at relatively high risk for disability. SUMMARY OF BACKGROUND DATA: Only a small number of back-injured workers suffer significant disability. Quick identification of these people would facilitate more efficient targeting and trials of interventions. Controlling variations in practice through practice guidelines has been recommended as a promising strategy for improving care and reducing disability. METHODS: Workers filing back injury reports responded to a disability prediction questionnaire. Those with high risk scores were randomly assigned to control or intervention groups. Patient-designated physicians in the intervention group received two letters identifying the patient's risk and making recommendations for care, including the Agency for Health Care Policy and Research's algorithms for acute low back pain. Predictive accuracy of the questionnaire and efficacy of physician intervention were evaluated on the basis of work status and self-assessments 3 months after injury. RESULTS: Of the 268 workers completing the questionnaire portion of the study, 32 (12%) were out of work because of back pain 3 months after injury. The questionnaire's predictive accuracy included maximum kappa of 0.277 and a receiver operating curve area of 0.78. Fifty-three people completed the physician intervention trial. The intervention had no significant impact on return to work, self-assessed pain, or satisfaction with health care. CONCLUSIONS: Stratification of back-injured people according to disability risk can can increase intervention efficiency by identifying those who require treatment and sparing those who do not. The apparent failure of risk notification and practice guidelines to reduce disability in this study may be improved by different application methods in the future.

Adolescent↗
PubMed1997

Effect of test environment on intervertebral disc hydration.

STUDY DESIGN: Water content of fresh human lumbar intervertebral discs (with adjacent endplates) was assessed in three studies: 1) after each of seven specimen preparation steps. 2) during exposure to either saline spray or a saline bath, and 3) during exposure to a saline bath and 445 N axial compression, either without or with previous exposure to the bath and no compression ("free swelling"). OBJECTIVE: To assess the effect on disc hydration of various aspects of specimen preparation and testing environments. SUMMARY OF BACKGROUND DATA: Water content is an important determinant of disc behavior. Specimen preparation method and testing environments may be important determinants of water content, yet no work appears to have been reported specifically on this topic. METHODS: Endplate-disc-endplate specimens were prepared from refrigerated cadavers within 24 hours of death by transverse sectioning of adjacent vertebral bodies. Water content change was determined by specimen weight change across each time interval of interest. RESULTS: Specimen preparation (including multiple freeze-thaw cycles) produced no water content change. Saline spray and plastic film wrap resulted in no change, but saline bath exposure resulted in a 24% increase over 7 hours, 44% of which occurred in the first 0.5 hour. A subsequent 7 hours of 445 N compression reduced the overall increase to 10%. This was not significantly different from the 8% increase that resulted from initial exposure to saline bath and compression. CONCLUSIONS: Specimen preparation as typically performed and specimen exposure to saline spray and plastic film wrap do not result in hydration change. Exposure to saline bath results in substantial swelling, which can either be reversed or prevented by axial compression in the physiologic range. Whether discs exposed to saline spray and wrap without compression and those exposed to saline bath with compression behave the same and which of these more closely mimics the in vivo condition are important issues for the experimentalist to test.

Adult↗
PubMed1997

Laxity and flexibility of the ankle following reconstruction with the Chrisman-Snook procedure.

The effect of reconstruction of the anterior talofibular ligament with the Chrisman-Snook procedure on neutral zone laxity (anterior-posterior displacement at low loads) and flexibility (a measure of the nonlinear load-displacement response) of the ankle was investigated in vitro during the anterior drawer test. Neutral zone laxity was defined as the magnitude of anterior-posterior displacement of the ankle joint at +/- 2.5 N of applied load. The flexibility parameter was defined as the slope of a line between the natural logarithm of the anterior load applied to the ankle and the resulting displacement. After reconstruction with the Chrisman-Snook procedure, the values for neutral zone laxity of the ankle were significantly less than normal at 0 degree of plantar flexion, whereas the flexibility values were significantly greater than normal. This study revealed that, after the Chrisman-Snook procedure, values for ankle flexibility are not restored to normal even if those for neutral zone laxity are reduced to less than normal. The findings suggest that this nonanatomical reconstruction procedure does not reproduce normal kinematics of the ankle joint. This may help explain some of the adverse clinical reports associated with the Chrisman-Snook reconstruction procedure.

Adolescent↗
PubMed1996

Early prediction of chronic disability after occupational low back injury.

STUDY DESIGN: An inception cohort design was used to study a consecutive sample of back-injured workers. OBJECTIVE: To refine and to test the Vermont Disability Prediction Questionnaire's ability to indicate an individual's relative risk for chronic disability after occupational low back injury. SUMMARY OF BACKGROUND DATA: Although most back-injured workers return to work quickly, the minority who do not account for the majority of associated costs and health care. Early identification of workers at high risk for disability would facilitate intervention strategies. METHODS: During the study recruitment period, people aged 18-60 years reporting occupational low back injury to the Vermont Department of Labor and Industry within 11 days of onset were eligible. A Vermont Disability Prediction Questionnaire was mailed to the 442 subjects who could be contacted and who gave informed consent. One hundred sixty-three of the 166 subjects who completed and returned the questionnaire within 15 days of initial injury were telephoned 3 months later to determine work status. Those who returned the questionnaire were compared with those who would not consent or did not return the questionnaire in time according to age, sex, residence, wages, work hours per week, and length of employment. Employment status (inability to work because of low back pain) was evaluated by telephone interview 3 months after initial injury. RESULTS: The follow-up interviewer was blinded to the Vermont Disability Prediction Questionnaire scores. of the 163 subjects, 16 (10%) were not working because of low back pain. Using a simple dichotomous scoring system for 11 questionnaire items, a cut-off score of 0.48 identified 3-month postinjury work status, with 0.94 sensitivity and 0.84 specificity. CONCLUSIONS: The Vermont Disability Prediction Questionnaire is a brief, easily administered and scored tool for identifying back-injured workers at relative risk for chronic disability. Such early identification should increase the efficiency of disability prevention strategies by directing them toward people who need them most. The accuracy of the questionnaire needs to be tested in a variety of different clinical and socioeconomic settings.

Adult↗
PubMed1994

A prospective randomized three-week trial of spinal manipulation, transcutaneous muscle stimulation, massage and corset in the treatment of subacute low back pain.

STUDY DESIGN: A randomized prospective trial of manipulation, massage, corset and transcutaneous muscle stimulation (TMS) was conducted in patients with subacute low back pain. OBJECTIVES: The authors determined the relative efficacy of chiropractic treatment to massage, corset, and TMS. SUMMARY OF BACKGROUND DATA: Although all of these treatments are used for subacute low back pain treatment, there have been few comparative trials using objective outcome criteria. Patients were enrolled for a period of 3 weeks. They were evaluated once a week by questionnaires, visual analog scale, range of motion, maximum voluntary extension effort, straight leg raising and Biering-Sorensen fatigue test. The dropout rate was highest in the muscle stimulation and corset groups and lowest in the manipulation group. Rates of full compliance did not differ significantly across treatments. A measure of patient confidence was greatest in the manipulation group. RESULTS: After 3 weeks, the manipulation group scored the greatest improvements in flexion and pain while the massage group had the best extension effort and fatigue time, and the muscle stimulation group the best extension. CONCLUSION: None of the changes in physical outcome measures (range of motion, fatigue, strength or pain) were significantly different between any of the groups.

Adult↗
PubMed1994

Distinguishable groups of musculoskeletal low back pain patients and asymptomatic control subjects based on physical measures of the NIOSH Low Back Atlas.

STUDY DESIGN: The authors performed an empirical prospective study of 115 patients referred to physical therapy for low back pain and 112 control subjects of similar age and gender. OBJECTIVES: The authors defined and compared subgroups based on physical tests and described demographic and psychosocial characteristics by group. SUMMARY OF BACKGROUND DATA: Prospective studies of intervention for persons with low back pain are limited by inability to randomize subjects into distinguishable groups. Previous attempts have not been empirical and have not focused on musculoskeletal LBP. METHODS: Ten physical therapists administered 52 tests and 6 questionnaires to subjects in seven different clinics. Data were subjected to reliability and cluster and comparative analyses. RESULTS: Tests were reliable. Groups were distinguished by measures of symmetry, flexibility, strength, and dynamic mobility. CONCLUSION: Distinguishable groups can be determined; decreased trunk mobility characterized all groups of patients and imbalances in muscle length, strength, and symmetry described specific groups of subjects with and without low back pain.

Cluster Analysis↗
PubMed1994

Chronic low back pain: The relationship between patient satisfaction and pain, impairment, and disability outcomes.

STUDY DESIGN: Treatment outcomes for low back pain have been measured by varying standards of pain, impairment, and disability. This study examines the relationship between these three outcomes and treatment satisfaction in patients with chronic low back pain (CLBP). METHODS: Ninety CLBP patients underwent initial pain (VAS), impairment (PIS), and disability (OPQ) evaluations. RESULTS: Correlation coefficients between initial VAS, PIS, and OPQ were all less than 0.50. At 5-year follow-up, pain and disability scores were closely matched, more with lower mean scores among workers (P = 0.04 and 0.001). For 65 rehabilitation participants, 5-year patients satisfaction scores did not relate closely with VAS, PIS, and OPQ improvements during treatment (r = 0.15, 0.01, and 0.14). Five-year satisfaction correlated weekly with current pain and disability (r = 0.32, -0.36). Satisfaction levels were higher for workers after 1 year (P = 0.01), and after 5 years (P = 0.34. CONCLUSIONS: This study suggests that CLBP patients and their health care practitioners mutually set distinct pretreatment pain, impairment, and disability goals and judge outcomes accordingly.

Adult↗
PubMed1994

A dynamic material parameter estimation procedure for soft tissue using a poroelastic finite element model.

A three-dimensional finite element model for a poroelastic medium has been coupled with a least squares parameter estimation method for the purpose of assessing material properties based on intradiscal displacement and reactive forces. Parameter optimization may be based on either load or displacement control experiments. In this paper we present the basis of the finite element model and the parameter estimation process. The method is then applied to a test problem and the computational behavior is discussed. Sequential optimization on different parameter groups was found to have superior convergence properties. Some guidelines for choosing the starting parameter values for optimization were deduced by considering the form of the objective function. For load control experiments, in which displacement data is used for the optimization, the starting values for the elastic modulus should be lower in magnitude than an "anticipated" modulus. The permeability starting values should be higher than an anticipated permeability. For displacement control experiments, the reverse is true. The optimization scheme was also tested on data with random variations.

Anisotropy↗
PubMed1994

The measurement of elongation of anterior cruciate-ligament grafts in vivo.

Many investigators who have studied the mechanical behavior of anterior cruciate-ligament grafts have attributed the increase in anterior translation of the tibia relative to the femur (an increase in the anterior laxity of the knee joint) to the temporal changes in the material behavior (strength and elastic properties) of the graft that occur throughout the process of remodeling. However, with the onset of motion of the joint, it is unclear whether the repeatable mechanical behavior of the graft remains unchanged immediately after fixation, if the fixation slips, or if the length of the graft changes and produces an increase in anterior translation of the tibia relative to the femur. It is also unknown if procedures performed by different surgeons, using similar graft material and similar operative techniques, can produce similar mechanical behavior of the graft, or if the behavior of the graft is similar to that of the normal anterior cruciate ligament. In an effort to address these questions, two surgeons performed a reconstruction of the anterior cruciate ligament on ten patients each (groups 1 and 2) with use of a bone-patellar ligament-bone graft. Immediately after fixation of the graft, a Hall-effect transducer was implanted to measure the changes in the length of the mid-substance of the graft while the knee was moved through twenty cycles of passive flexion-extension. Unlike the length pattern of the normal anterior cruciate ligament, the length pattern of the graft changed during the initial cycles of passive motion of the knee. We defined this phenomenon as the cyclic response of the graft and characterized it by calculation of the changes in the length of the graft at fixed positions of the knee across the multiple cycles of passive motion. In some patients, the length of the graft increased through the initial passive-motion cycles, while in others, it decreased. With the knee nearly extended, the predicted increase in anterior translation of the tibia relative to the femur, resulting from the increase in the length of the graft, was a maximum of 1.0 millimeter. This indicates that increases in anterior translation of the tibia relative to the femur can occur immediately after reconstruction of the anterior cruciate ligament and that changes in the length of the graft occur after fixation at loads that are less than the ultimate failure load of the graft or of the fixation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1994

Some endurance measures in persons with chronic low back pain.

Muscle fatigue and lack of endurance are complaints of persons with chronic low back pain, but there are no standard ways to assess endurance in this population. The purposes of this study were to examine three measures of endurance; to determine relationships of these measures to each other; and to describe effects of gender, obesity, smoking, and self-reported fitness on the clinical measures. The measures of endurance selected were not dependent on maximal voluntary muscular contractions. They were the Sorensen test, median frequency decline of selected muscles, and a submaximal bicycle ergometer test. Thirty-five consenting individuals who were referred for treatment answered questions about their daily exercise prior to being tested. Repeatability of the Sorensen test holding time and of the slope measure of decline in the median frequencies was acceptable for subjects who reported a higher activity level. The decline of the median frequency in the biceps femoris muscles correlated with holding time of the Sorensen test. Smoking, gender, or obesity level did not affect test results on any of the endurance measures. Subjects who reportedly were more active achieved significantly higher scores on the Sorensen test. The importance of controlling for self-perception of activity in physical testing is discussed.

Adult↗
PubMed1993

A poroelastic-swelling finite element model with application to the intervertebral disc.

The swelling process that occurs in soft tissue is incorporated into a poroelastic finite element model. The model is applied to a spinal segment consisting of two vertebrae and a single intervertebral disc. The theory is an extension of the poroelastic theory developed by Biot and the model is an adaptation of an axisymmetric poroelastic finite element model of the intervertebral disc by Simon. The model is completely three-dimensional although the results presented here assume symmetry about the sagittal plane. The theory is presented in two stages. First the development of the poroelastic theory. Following this, the effects of swelling caused by osmotic pressure are developed and expressed as a modification of the constitutive law and initial stresses. In the case of the disc, this pressure is produced mainly by the fixed negative charges on the proteoglycans within the disc. In this development we assume that the number of fixed charges remains constant over time and that the distribution of mobile ions has reached equilibrium. The variations over time in osmotic pressure, and thus in swelling effects are therefore only dependent on the initial state and the change in water content. Variations of the swelling effects caused by changes in mobile ion concentrations will be the subject of a future paper. The results reported in this article illustrate the dramatic effect of swelling on the load carrying mechanisms in the disc. The authors believe it is likely that this will have important useful implications for our understanding not only of normal disc function, but also of abnormal function, such as disc degeneration, herniation, and others.

Elasticity↗
PubMed1993

Endurance training of trunk extensor muscles.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the effects of an endurance exercise protocol on the isometric holding time of the trunk extensor muscles (mechanical fatigue measure) and on the recorded median frequency (MF) measurements from the surface electromyogram (physiological fatigue measure). SUBJECTS: Twenty-eight healthy female volunteers were selected to participate in the study. METHODS: The subjects were stratified by activity level and then assigned to an exercise or a control group and tested at weeks 0, 3, and 6. Reliability (r) of the measurements, established by testing each subject twice at week 0, was .87. Exercise group subjects trained at home twice daily for 6 weeks, progressing by established protocol. RESULTS: The exercise group subjects increased their isometric holding time by 22% after 6 weeks. The control group showed no significant changes. CONCLUSION AND DISCUSSION: The home program was believed to be effective for increasing isometric endurance of the trunk extensors, measured by holding time. The MF measurements prior to and just after a fatiguing contraction remained stable over time. The change in the slope of the MF with fatigue did not reach statistical significance. This physiologic measure of fatigue did not show commensurate changes with training in this group of subjects. Possible reasons for the results are discussed.

Adult↗
PubMed1991

Hole preparation techniques for transpedicle screws. Effect on pull-out strength from human cadaveric vertebrae.

In each of eight thoracolumbar human cadaveric vertebrae, a hole was made through one pedicle into the vertebral body with a drill bit and through the contralateral pedicle with a probe. Identical metal screws were implanted into the holes to equal depths, and maximum pull-out force was determined for each screw. Using a paired Student t test, no significant difference (P = 0.87) was found in pull-out strength between the screws implanted into drilled holes and those implanted into probed holes. In fact, the average pull-out strengths for the two groups differed by less than 2%. The pedicular cortex was broken through during hole preparation in 5 of the 16 pedicles: 3 as a result of drilling and 2 secondary to probing. The average pull-out strength of the screws in these five pedicles was 11.0% less than the average pull-out strength of the screws implanted into the contralateral intact pedicles. Although this does not represent a statistically significant difference (P = 0.15), it suggests that damaging the pedicular cortex may weaken pedicle screw fixation.

Aged↗
PubMed1990

Phase I trial of intraperitoneal recombinant interleukin-2/lymphokine-activated killer cells in patients with ovarian cancer.

Ten patients with ovarian cancer refractory to conventional therapy were treated with intraperitoneal (i.p.) recombinant interleukin-2 (rIL-2) and lymphokine-activated killer cells (LAK). The 28-day protocol consisted of 6 priming i.p. rIL-2 infusions on days 0, 4, 6, 8, 10, and 12. Leukapheresis was performed for mononuclear cell collection on days 15, 16, 17, and 18 and lymphokine-activated killer cells were given i.p. with the rIL-2 on days 19 and 21. Three additional i.p. rIL-2 infusions were given on days 23, 25, and 27. Three dose levels of rIL-2 were tested: 5 X 10(5), 2 X 10(6), and 8 X 10(6) units/m2 body surface area. The dose-limiting toxicity was abdominal pain secondary to ascites accumulation with significant weight gain. Other toxic effects included decreased performance status, fever, nausea and vomiting, diarrhea, and anemia. Peripheral lymphocytosis and eosinophilia were seen at all dose levels. The maximum tolerated dose is 8 X 10(6) units/m2/dose. Peripheral and peritoneal IL-2 levels were measured with a bioassay using an IL-2-dependent cell line. At the highest dose level, serum IL-2 was greater than 10 units/ml for 18 h. After the first infusion, a 2-log dilution of the i.p. IL-2 was measured in the serum. In the postleukapheresis i.p. IL-2-dosing period less IL-2 was detected in the serum than in the earlier i.p. IL-2-priming period. The induction and persistence of LAK activity were studied. Peritoneal LAK activity was detected as early as 4 days after the first i.p. infusion, by day 11 in all evaluable patients, and persisted for the 6-day interval between priming IL-2 and LAK/IL-2 infusion. Peritoneal lytic activity persisted until day 28 in 5 tested patients. These peritoneal cells retained lytic activity 48 h in culture medium without rIL-2 present. Peritoneal LAK activity correlated with the percentage of mononuclear cells and the percentage of CD56-positive mononuclear cells in the peritoneum. The yield of peripheral lymphocytes after the six i.p. priming doses of rIL-2 correlated with the dose level of rIL-2 infused. Peripheral blood LAK activity showed a minimal, however progressive, increase during the treatment protocol. LAK activity could be enhanced if rIL-2 was present during the 4-h assay. These studies indicate that i.p. rIL-2 infusion induced durable regional LAK activity and primes peripheral blood cells for LAK activity if exposed briefly to additional IL-2.

Adult↗
PubMed1990

Body height change during upright and recumbent posture.

Body height changes are known to occur in response to changes in loads acting along the spine, such as those produced by movement from a recumbent to an upright posture. Lack of previously available data is addressed here by body height measurements closely spaced in time of ten normal subjects during 8 hours upright and 4 hours recumbent, with particular attention paid to the initial changes. Experimental errors are carefully defined and determined. A Kelvin-unit model is fitted to the mean data for each phase and confidence limits provided for the model equation parameters. Rapid height changes are shown to occur: 26% of the 8-hour loss occurred in the first hour upright, and 41% of the 4-hour recovery occurred in the first hour recumbent.

Adult↗
PubMed1989

Effects of long-term storage on salivary thiocyanate concentration.

The stability of thiocyanate (SCN) concentration in frozen saliva samples stored for up to one year was examined. Fifteen adult smokers and five adult nonsmokers each provided six saliva samples, which were analyzed in duplicate pairs after 0, 2, and 12 months of storage at -20 degrees C in airtight containers. No significant changes in average SCN levels occurred over the storage interval. Although within-subject variability for duplicate samples analyzed at the same time was high, the mean levels in regular smokers were significantly higher than the levels in nonsmokers.

Adult↗
PubMed1989

EMG to torque relationship in rectus abdominis muscle. Results with repeated testing.

Rectus abdominis muscles of young healthy female volunteers were studied to determine both the maximum strength in isometric flexion and the relation between the surface electromyogram (RMS EMG) and torque. Both the upper and lower portions of the abdominal muscle were studied during graded increase and decrease of torque. Repeated testing was performed over 6 weeks. The form of the relation between torque and EMG was better described by a quadratic than by a linear regression relationship, but with considerable variability about the best-fit line. The torque-increasing and torque-decreasing parts of each test were different and were analyzed separately. After 6 weeks of repeated testing, maximum voluntary isometric flexion torque increased 16.8% (P less than 0.01). There was a decrease in the ratio of electromyographic activity to torque production, which was statistically significant in the torque-increasing recordings. These changes in maximum torque and in the EMG-torque relation were attributed to learning through a test-retest effect, rather than to a true change in muscle characteristics. These findings, which show changes in normal subjects undergoing repeated testing, do not support the reliability of isometric strength measurements, or measurements based on RMS EMG recordings, for quantifying abdominal muscle function in patients with back pain, or those undergoing strengthening exercises.

Abdominal Muscles↗