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Biomedical subjects

A C Croft

Publications and source records attributed to A C Croft.

10 recordsLinked to original sources
PubMed2000

Sitting biomechanics, part II: optimal car driver's seat and optimal driver's spinal model.

BACKGROUND: Driving has been associated with signs and symptoms caused by vibrations. Sitting causes the pelvis to rotate backwards and the lumbar lordosis to reduce. Lumbar support and armrests reduce disc pressure and electromyographically recorded values. However, the ideal driver's seat and an optimal seated spinal model have not been described. OBJECTIVE: To determine an optimal automobile seat and an ideal spinal model of a driver. DATA SOURCES: Information was obtained from peer-reviewed scientific journals and texts, automotive engineering reports, and the National Library of Medicine. CONCLUSION: Driving predisposes vehicle operators to low-back pain and degeneration. The optimal seat would have an adjustable seat back incline of 100 degrees from horizontal, a changeable depth of seat back to front edge of seat bottom, adjustable height, an adjustable seat bottom incline, firm (dense) foam in the seat bottom cushion, horizontally and vertically adjustable lumbar support, adjustable bilateral arm rests, adjustable head restraint with lordosis pad, seat shock absorbers to dampen frequencies in the 1 to 20 Hz range, and linear front-back travel of the seat enabling drivers of all sizes to reach the pedals. The lumbar support should be pulsating in depth to reduce static load. The seat back should be damped to reduce rebounding of the torso in rear-end impacts. The optimal driver's spinal model would be the average Harrison model in a 10 degrees posterior inclining seat back angle.

Automobile Driving↗
PubMed1999

A review and methodologic critique of the literature refuting whiplash syndrome.

The validity of whiplash syndrome has been a source of debate in the medical literature for many years. Some authors have published articles suggesting that whiplash injuries are impossible at certain collision speeds; others have stated that the problem is psychological, or is feigned as a means to obtain secondary financial gain. These articles contradict the majority of the literature, which shows that whiplash injuries and their sequelae are a highly prevalent problem that affects a significant proportion of the population. The authors of the current literature critique reviewed the biomedical and engineering literature relating to whiplash syndrome, searching for articles that refuted the validity of whiplash injuries. Twenty articles containing nine distinct statements refuting the validity of whiplash syndrome were found that fit the inclusion criteria. The methodology described in these articles was evaluated critically to determine if the authors' observations regarding the validity of whiplash syndrome were scientifically sound. The authors of the current critique found that all of the articles contained significant methodologic flaws with regard to their respective authors' statements refuting the validity of whiplash syndrome. The most frequently found flaws were inadequate study size, nonrepresentative study sample, nonrepresentative crash conditions (for crash tests), and inappropriate study design. As a result of the current literature review, it was determined that there is no epidemiologic or scientific basis in the literature for the following statements: whiplash injuries do not lead to chronic pain, rear impact collisions that do not result in vehicle damage are unlikely to cause injury, and whiplash trauma is biomechanically comparable with common movements of daily living.

Accidents, Traffic↗
PubMed1998

"Whiplash associated disorders: redefining whiplash and its management" by the Quebec Task Force. A critical evaluation.

STUDY DESIGN: The two publications of the Quebec Task Force on Whiplash-Associated Disorders were evaluated by the authors of this report for methodologic error and bias. OBJECTIVES: To determine whether the conclusions and recommendations of the Quebec Task Force on Whiplash-Associated Disorders regarding the natural history and epidemiology of whiplash injuries are valid. SUMMARY OF THE BACKGROUND DATA: In 1995, the Quebec Task Force authored a text (published by the Societe de l'Assurance Automobile du Quebec) and a pullout supplement in Spine entitled "Whiplash-Associated Disorders: Redefining Whiplash and its Management." The Quebec Task Force concluded that whiplash injuries result in "temporary discomfort," are "usually self-limited," and have a "favorable prognosis," and that the "pain [resulting from whiplash injuries] is not harmful." METHODS: The authors of the current report reviewed the text and the supplement for methodologic flaws that may have threatened the validity of the conclusions and recommendations of the Quebec Task Force. RESULTS: Five distinct and significant categories of methodologic error were found. They were: selection bias, information bias, confusing and unconventional use of terminology, unsupported conclusions and recommendations, and inappropriate generalizations from the Quebec Cohort Study. CONCLUSION: The validity of the conclusions and recommendations of the Quebec Task Force regarding the natural course and epidemiology of whiplash injuries is questionable. This lack of validity stems from the presence of bias, the use of unconventional terminology, and conclusions that are not concurrent with the literature the Task Force accepted for review. Although the Task Force set out to redefine whiplash and its management, striving for the desirable goal of clarification of the numerous contentious issues surrounding the injury, its publications instead have confused the subject further.

Accidents, Traffic↗
PubMed1996

Basal metabolic temperature vs. laboratory assessment in "posttraumatic hypothyroidism".

OBJECTIVES: To compare standard laboratory analytical methods with measurement of basal metabolic temperature in cases of hypothyroidism arising posttraumatically. SETTING: Private medical office. SUBJECTS: One hundred and one consecutive status post-whiplash trauma patients. DESIGN: All subjects were evaluated with standard laboratory tests (T3RU, T4, FT4I, TSH) for thyroid function. Ninety-four were also evaluated with the newer fluorescence-activated microsphere assay test (FAMA) and basal metabolic temperature (BMT) was measured in all. Correlations were investigated between BMT, age, gender, standard laboratory values and the FAMA test. The differences between low and high BMT vs. normal and abnormal standard laboratory values and the differences between normal and abnormal standard laboratory values vs. normal and elevated FAMA test results were also investigated. RESULTS: In 86.4%, the BMTs were below normal. Of this subgroup, 30% had abnormal standard laboratory values. Of the 13% whose BMT was within the normal range, 33% had abnormal standard laboratory values and 66% had increased FAMA titers. Statistically significant correlation was found between BMT and T3RU (p = .05), whereas the correlation between BMT and T4 was somewhat weaker (p = .07). Correlations between BMT and all other laboratory indices failed to reach significance. The laboratory abnormalities observed in this group of subjects were atypical for common types of hypothyroidism. A significant portion of our posttraumatic hypothyroid group (30%) were not identified with either standard laboratory tests or the FAMA test-a group we referred to as lab-normal. CONCLUSIONS: Measurement of BMT seems to be a sensitive screening test, in combination with laboratory analysis, for the hypothyroidism seen after whiplash trauma. Whiplash seems to result in a form of hypothyroidism suggesting direct injury to central tissues.

Adolescent↗
PubMed1994

Videofluoroscopy in cervical spine trauma: an interinterpreter reliability study.

OBJECTIVE: The primary purpose of this study was to determine if, when confronted with a series of cervical videofluoroscopic (VF) studies, board certified radiologists who are trained in the interpretation of VF spinal examinations would be in agreement with one another with regard to the findings of normal, hypomobile or hypermobile intersegmental motion. As a secondary objective, we polled participating physicians regarding demographic issues such as time in practice, self-assessment of proficiency, the type of training received in VF interpretation and the number of VF studies read per year, in order to determine if any of these factors had any predictive value in terms of interexaminer agreement. DESIGN: Seven patients who had been exposed to cervical acceleration/deceleration (CAD) trauma from motor vehicle accidents were randomly selected from the practice of two of the authors (ACC and JSK). Three volunteers, who were asymptomatic and had no history of neck pain or injury to the neck, were also recruited. In all cases, informed consent was obtained in accordance with the Helsinki guidelines. Ten board qualified chiropractic radiologists were recruited to participate in this study. Blinded to the history and identity of the patients and volunteers, the participants were asked to view the 10 VF studies and, in each case, to report either "normal," "hypomobile" or "unable to determine" for all segments from OCC/C1 through C7/T1. The resulting data was analyzed for concordance using the kappa statistic. Kappa was calculated for all segments (OCC-T1) for agreement in "normal" vs. "abnormal" motion. The two possible choices for abnormal (i.e., hypermobility and hypomobility) were pooled together. We also compared the results of participants' responses to demographic questions with the results of their interpretations of the VF studies. SETTING: An urban group practice. Four of the patients were those of an orthopedist (ACC) and three were those of a general practitioner (JSK). PATIENT/OTHER PARTICIPANTS: Seven patients were randomly selected from a larger group of patients satisfying our selection criteria. Patients were chosen who had been exposed to CAD trauma and had been provided with at least 6 months of conservative chiropractic care, yet remained symptomatic as a result of their injuries. All had evidence of intersegmental instability in the cervical spine as defined by other investigators and none had any history of injury or pain in the cervical spine prior to their motor vehicle accident. Four males and three females with a mean age of 16 yr comprised the patient group. Two asymptomatic atraumatic volunteers were males and one was female. They were age matched to the patient group with a mean age of 38 yr. INTERVENTION: This study did not entail any form of intervention. MAIN OUTCOME MEASURES: Our primary outcome measure was that of concordance or agreement between our group of 10 participant radiologists in regard to their interpretations of the 10 VF studies provided to them, i.e., that of interinterpreter reliability. Higher values of kappa suggested that agreement between the radiologists was not likely due to chance alone. Our secondary outcome measure was a correlation between the results of our demographic questionnaires, completed by participating radiologists, and the overall interinterpreter reliability concordance. The hypothesis tested was that radiologists who have institutional training in VF, more years of experience, and those who read more VF studies annually and self-rank their proficiency as "high" are more likely to agree with others and/or are more likely to correctly analyze intersegmental motion than those whose training was less formal, and who have less experience, read fewer VF studies and self-rank their proficiency in reading VF as only "adequate" or lower. (ABSTRACT TRUNCATED)

Adolescent↗
PubMed1977

Behavioral objectives for a hospital pharmacy residency program.

The purpose and design of behavioral objectives in educational programs are reviewed, and the behavioral objectives of a pharmacy residency program are listed. The behavioral objectives for the program follow, as a guide, the ASHP Accreditation Standard for Pharmacy Residency in a Hospital.

Accreditation↗
PubMedDate not supplied

Sitting biomechanics part I: review of the literature.

OBJECTIVE: To develop a new sitting spinal model and an optimal driver's seat by using review of the literature of seated positions of the head. spine, pelvis, and lower extremities. DATA SELECTION: Searches included MEDLINE for scientific journals, engineering standards, and textbooks. Key terms included sitting ergonomics, sitting posture, spine model, seat design, sitting lordosis, sitting electromyography, seated vibration, and sitting and biomechanics. DATA SYNTHESIS: In part I, papers were selected if (1) they contained a first occurrence of a sitting topic, (2) were reviews of the literature, (3) corrected errors in previous studies, or (4) had improved study designs compared with previous papers. In part II, we separated information pertaining to sitting dynamics and drivers of automobiles from part 1. RESULTS: Sitting causes the pelvis to rotate backward and causes reduction in lumbar lordosis, trunk-thigh angle, and knee angle and an increase in muscle effort and disc pressure. Seated posture is affected by seat-back angle, seat-bottom angle and foam density, height above floor, and presence of armrests. CONCLUSION: The configuration of the spine, postural position, and weight transfer is different in the 3 types of sitting: anterior, middle, and posterior. Lumbar lordosis is affected by the trunk-thigh angle and the knee angle. Subjects in seats with backrest inclinations of 110 to 130 degrees, with concomitant lumbar support, have the lowest disc pressures and lowest electromyography recordings from spinal muscles. A seat-bottom posterior inclination of 5 degrees and armrests can further reduce lumbar disc pressures and electromyography readings while seated. To reduce forward translated head postures, a seat-back inclination of 110 degrees is preferable over higher inclinations. Work objects, such as video monitors, are optimum at eye level. Forward-tilting, seat-bottom inclines can increase lordosis, but subjects give high comfort ratings to adjustable chairs, which allow changes in position.

Biomechanical Phenomena↗