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Biomedical subjects

G B Andersson

Publications and source records attributed to G B Andersson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Trunk kinematics and trunk muscle activity during a rapidly applied load.

This study investigated the trunk kinematics and electromyographic (EMG) activity of eight trunk muscles when "expected" and "unexpected" loads were applied directly to the torso. Twenty individuals (mean age: 25.1 yr; range 20-33 yr) participated in this mixed model study in which gender was the between-subjects factor, and expectancy and symmetry of the applied load were within-subject factors. The sudden load was delivered to the subject via a cable attached to a thoracic harness and motion was restricted to the lumbar spine by strapping the pelvis to a rigid fixation apparatus. Surface EMG was recorded bilaterally from the longissimus thoracis (LGT), erector spinae (ERS), rectus abdominis (RAB) and the external obliques (EXO). Trunk kinematics were measured with a Lumbar Motion Monitor. During expected loading conditions, the peak muscle activity was reduced for the RAB and EXO bilaterally, and for the ERS(R) (p < 0.01) relative to the unexpected conditions. Conversely, the normalized area of EMG activity prior to the onset of load was increased for the ERS and EXO bilaterally, and for the RAB(R) (p < 0.05) during an expected loading event. Trunk motion in the sagittal and frontal planes was reduced during expected loading. Activation of the trunk muscles just prior to a rapid loading event increases trunk stiffness, decreasing trunk displacement and peak muscle activity.

Adult↗
PubMed1998

Trunk muscle use during pulling tasks: effects of a lifting belt and footing conditions.

Pulling tasks require the torso to act as a rigid link in order to facilitate the force transmission between the ground and the hands. In this study, we tested the hypothesis that a lifting belt increases the rigidity of the torso, thereby increasing pulling strength or reducing trunk muscle forces, or both, as pulling tasks are performed. Twelve volunteers performed maximal and submaximal isometric pulling exertions; the latter were performed on nonslippery and slippery surfaces. Electromyographic data from 8 trunk muscles, trunk kinematic data, and ground reaction forces were sampled during each exertion. Results indicated that the lifting belt had no effect during maximal exertions on the maximal pull forces generated or the muscle recruitment levels, irrespective of the pulling posture. The lifting belt did not affect the EMG data obtained during the submaximal (40% of maximum) exertions, even when participants pulled on a slippery surface. However, the slippery surface increased the coactivation within the trunk musculature, perhaps stiffening the torso in the event of a slip. The absence of a statistical interaction effect between the lifting belt and the footing condition (slipperiness) indicates that the belt did not alter the coactivation pattern and hence was not relied upon by the participants as a protective mechanism. The data presented here will assist those who must make decisions regarding lifting-belt use and those who train individuals in manual materials handling techniques.

Adult↗
PubMed1998

A prospective study of 342 patients using transpedicular fixation instrumentation for lumbosacral spine arthrodesis.

The objective of this research was to determine the efficacy and safety of an experimental instrumentation device designed for transpedicular spinal fixation by evaluating fusion rates and clinical pain and function scores; to determine complication rates associated with the device; and to compare the obtained data with that previously published in the literature. Four hundred forty-two consecutive patients were enrolled in this 4-year, Food and Drug Administration-monitored investigational device exemption trial to undergo surgery for implantation of the device. Eighteen surgeons at 11 nationwide medical centers performed the operations and subsequent evaluations. The study population was derived from three diagnostic categories: degenerative disc disease, multioperated back, and vertebral fracture. The data source consisted of radiographs, clinical examination, and structured forms and questionnaires. Patients were evaluated preoperatively, intraoperatively, and postoperatively at 3, 6, 12, and 24 months. By the 24-month postoperative interval, attrition had reduced the study population to 342 patients, among whom bony fusion was obtained in 91.5%. Pain scores demonstrated a statistically significant improvement in clinical outcome. Intraoperative complications occurred in 21.9% of patients. Of the 442 study patients, 2.9% experienced device-related complications. Moreover, a total of 2,304 screws and bolts were implanted in this patient population. Of these, 0.39% were reported to have fractured. Among the 342 study patients observed during 24 months, the breakage rate of device components (bolt or screw) was 2.63%. These data compare favorably to existing reports of spinal arthrodesis effected with other types of instrumentation and without device implantation. In a 4-year trial, the experimental transpedicular fixation instrumentation produced successful spinal fusion in the majority of our study population, with acceptable complication rates.

Activities of Daily Living↗
PubMed1998

Diagnostic considerations in patients with back pain.

It should be obvious from this article that usually only a focused history and physical examination are needed to evaluate a back patient. A summary of guideline recommendations presented by the Agency for Health Care Policy and Research is provided in Table 7. If followed, few serious mistakes will occur, and a more cost-effective management of the back patient will be possible.

Back Pain↗
PubMed1997

Metabolism of the extracellular matrix formed by intervertebral disc cells cultured in alginate.

STUDY DESIGN: Cells from normal rabbit nucleus pulposus (NP) and anulus fibrosus (AF) were cultured in alginate beads for as long as 14 days to allow them to reform a matrix made up of two compartments: the cell-associated matrix (CM) and further removed matrix (FRM). At different time points, the CM and FRM made by each cell population were analyzed using histologic, biochemical, and immunologic assays. OBJECTIVES: To study the metabolism of normal rabbit NP and AF cells in alginate by characterizing the CM and FRM formed by each cell population, and to identify metabolic properties that may shed light on mechanisms at play in disc degeneration. SUMMARY OF BACKGROUND DATA: Little is known about the metabolism of intervertebral disc cells, in part because of the lack of microculture systems appropriate for the study of these cells in vitro. In recent studies from our laboratories, it was suggested that articular chondrocytes cultured in alginate beads remain phenotypically stable and reform a matrix similar to the one they populate in vivo. This culture system appears ideally suited for the study of intervertebral cells available only in limited numbers. METHODS: Rabbit NP and AF cells released from the matrix by sequential enzyme digestion were encapsulated in alginate beads (20,000 cells/bead) and cultured for as long as 14 days. At selected time points, beads were solubilized with calcium chelating agents, and the CM and FRM were isolated. The rate of 35S-sulfate incorporation into proteoglycans, and the contents of various extracellular matrix molecules (total sulfated proteoglycans, antigenic keratan sulfate, hyaluronan, collagen, and pyridinium crosslinks) were measured. RESULTS: Both NP and AF cells remained phenotypically stable in the alginate gel throughout the culture period and reestablished a matrix composed of CM and FRM compartments. The two cell populations exhibited numerous differences in their metabolic activities in vitro. Nucleus pulposus cells synthesized fewer proteoglycan and collagen molecules and were less effective in incorporating these into the CM than AF cells. CONCLUSIONS: Intervertebral disc cells, especially NP cells, are extremely sluggish in reforming a CM, a protective shell rich in proteoglycans and collagen molecules. This may help explain why damage to the NP often is accompanied by progressive degeneration of the disc in vivo.

Alginates↗
PubMed1997

Low back pain.

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Humans↗
PubMed1996

Disc herniation.

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Humans↗
PubMed1996

History and physical examination in patients with herniated lumbar discs.

To outline the usefulness of the medical history and physical examination in the diagnosis of herniated lumbar discs, and to review the essential properties of a test, including sensitivity, specificity, and clinical value. None of the tests that are part of a history and physical examination of a patient with a disc herniation has a high diagnostic accuracy by itself. This is because positive and negative predictive values of common clinical indicators are limited. Confirmatory tests are necessary for a definitive diagnosis when making management decisions. Combining the results of history and physical findings will increase the predictive value of these basic diagnostic tools.

Humans↗
PubMed1996

Consensus summary of the diagnosis and treatment of lumbar disc herniation.

Clinicians must not simply decide that a patient with symptoms and a positive diagnostic test has a reason for a specific treatment, and likewise clinicians must not decide that a patient with symptoms and a negative test does not have a clinically important problem. We must also consider the sensitivity, specificity and predictive value of the diagnostic test and the individual characteristics of the patient. Treatment outcome depends on many factors. Point of service decisions vs population based decisions are obviously different. Each patient presents to the treating practitioner on a given day, at a given time, and it is this picture upon which a plan of care is formulated.

Humans↗
PubMed1996

Bacterial discitis caused by limb gangrene requiring below-knee amputation.

Two patients presented with disabling back pain and were unable to participate in physical therapy activities after being admitted to an acute rehabilitation center. Both patients had bacterial discitis of the lumbar spine that was apparently caused by infected ischemic limb tissue, ultimately removed at below-knee amputation. The literature describes many cases of bacterial discitis infected from many sources, but not from ischemic limb tissue requiring subsequent amputation. Many such cases may exist, however, and earlier recognition of this condition will enable appropriate treatment before vertebral destruction and/or neurological sequelae.

Aged↗