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Biomedical subjects

J W Frymoyer

Publications and source records attributed to J W Frymoyer.

At least 19 recordsLinked to original sources
PubMed1992

Lumbar disk disease: epidemiology.

Sciatica is a common symptom that affects as many as 40% of the adult population at some time. However, clinically significant sciatica is much less common and occurs in only 4% to 6% of the population. Exactly how often the symptom is caused by lumbar disk herniation is uncertain; it is known that herniation can occur independent of symptoms. Among the factors associated with its occurrence are age, gender, occupation, cigarette smoking, and exposure to vehicular vibration. The contribution of other factors such as height, weight, and genetics is less certain. The majority of patients with sciatica appear to recover. Approximately 20% of patients with sciatica caused by lumbar herniation have a strong indication for surgical intervention. In the remainder, indications are based primarily on pain rather than functionally significant neurologic deficits. Because pain is the principle indication, there are wide variations in the rates of surgical intervention between countries, and, even within countries, there are significant regional variations. These variations appear to be driven less by specific medical factors and more by gender, occupation, income, education, and the surgeon's preference. Although the contribution of sciatica to low back pain disability remains uncertain, disability caused by low back pain and sciatica appears to be increasing at a rate disproportionate to population growth. To what degree surgery now contributes to that disability is uncertain, but limited information suggests that it may be substantial.

Adult↗
PubMed1992

Predicting disability from low back pain.

Since World War II, the incidence of chronic low back disability has increased dramatically, at a rate disproportionate to all other health conditions. The factors that contribute to this disability are reviewed. Psychosocial and work environmental factors are far more accurate predictors of disability than physical factors. A predictive risk model is described that allows an estimate of the patient's risk of becoming chronically disabled early in the course of a low back pain episode. This model demonstrates that work environment, perception of compensability, and the duration of the current episode are significantly predictors. Surprisingly, psychologic factors, as measured by the Minnesota Multiphasic Personality Inventory (MMPI), are not predictive in the cohorts studied to date. Although there are inherent limitations in study design, the results offer additional credence to the hypothesis that low back pain disability is often the result of psychosocial and work environmental factors. The model may also be used to address the hypothesis that patients at risk for future disability are more effectively treated by early, aggressive rehabilitation programs.

Back Pain↗
PubMed1992

Diagnosing instability.

The various definitions of instability are reviewed and preference is given to the definition of instability as a loss of stiffness. This definition fits with current laboratory observations. Roentgenographic changes, particularly those associated with degeneration, have no relationship to instability. Multiple roentgenographic images can be of use, but accuracy is limited, and often valuable information at midmotion range or in other planes is missing. Stereoroentgenography appears to offer some promise, but implanted metallic markers are necessary to attain adequate accuracy. Ionizing radiation dose levels are of concern in these techniques. External fixation techniques appear to be of use in some patients. Kinematic linkages and frames containing infrared light emitting diodes are extremely promising, because they give kinematic information in detail.

Humans↗
PubMed1991

Identifying patients at risk of becoming disabled because of low-back pain. The Vermont Rehabilitation Engineering Center predictive model.

A predictive risk model of low-back pain (LBP) disability was developed by a panel of six experts in the fields of chronic pain and disability. It comprised 28 factors organized into eight categories: job, psychosocial, injury, diagnostic, demographic, medical history, health behaviors, and anthropometric characteristics and was administered as a 15-minute written questionnaire. The model was tested prospectively on 250 patients (age range, 18-65 years) attending two secondary-care low-back clinics. Disability, as predicted by the model, was compared with 1) actual disability assessed 3 and 6 months later; 2) predictions of disability made by the attending physicians; and 3) predictions obtained from an empirically derived model. These results showed that 1) the expert-generated risk model had a predictive accuracy of 89% and did better in predicting disability than the physicians across all samples and 2) the empirically weighted model did best of all (91% predictive accuracy), suggesting that the expert model used appropriate factors but that the weights assigned to these factors by the panel of experts could be improved.

Adult↗
PubMed1991

Clinical tests applicable to the study of chronic low-back disability.

This symposium has evaluated the possible directions to be taken in designing reliable and valid questionnaires, screening examinations, and paraclinical tests applicable to studies in LBP. The detailed design of such test instruments, field testing, measures of reliability, and validity represent the next step if the current barriers to collaborative clinical research in LBP are to be overcome.

Back Pain↗
PubMed1991

An overview of the incidences and costs of low back pain.

The basic premise of this article is that low back disorders are extremely prevalent in all societies, and probably have not increased substantially over the past two decades. What has increased is the rate of disability, the reasons for which are uncertain. Not only has this phenomenon heightened the awareness of low back pain, but it has led to an explosion in costs. Although a precise estimate is impossible, it is plausible that the direct medical and indirect costs of these conditions are in the range of more than $50 billion per annum, and could be as high as $100 billion at the extreme. Of these costs, 75% or more can be attributed to the 5% of people who become disabled temporarily or permanently from back pain--a phenomenon that seems more rooted in psychosocial rather than disease determinants. Within this overall equation, spinal surgery plays a relatively small role, although the contribution to disability probably has more than passing significance. The future challenge, if costs are to be controlled, appears to lie squarely with prevention and optimum management of disability, rather than perpetrating a myth that low back pain is a serious health disorder.

Back Pain↗
PubMed1991

Low back pain. The role of spine fusion.

The major objectives of spinal surgery are to relieve pain, improve function, and correct deformity. The surgical strategies to meet these objectives are decompression of neural elements or surgical stabilization by arthrodesis. This article analyzes spinal fusion from the perspective of indications, the broad principles of surgical technique, the results that can be obtained, and the complications of the procedure.

Back Pain↗
PubMed1989

Hip arthroplasty after biplanar femoral osteotomy.

Hip arthroplasty in patients who have had previous biplanar femoral osteotomy (eg, Southwick) is a technical surgical problem. Distorted proximal femoral anatomy may make routine insertion of a femoral prosthesis impossible. The authors report the short-term results in three patients with hip arthroplasty after biplanar femoral osteotomy. The technique consists of a biplanar closing wedge osteotomy at the level of the lesser trochanter to correct the previous surgical deformity. The remaining proximal femur becomes a vascularized bone graft that is skewered by the femoral prosthesis, which also gains purchase in the medullary canal of the proximal femoral shaft. This technique allows restoration of anatomic femoral alignment and the use of standard prostheses with preservation of bone stock. The initial results have been very good. The appearance of the hip is very similar to that in primary hip arthroplasty.

Adult↗
PubMed1989

Experimental instability in the rabbit lumbar spine.

The authors performed mechanical, biochemical, and histologic analyses of changes in the rabbit lumbar spine occurring after instability had been induced by facet removal to find whether this intervention produced an experimental model for intervertebral disc degeneration. Sham operated animals and an unoperated control group were used for comparison. Half of the operated animals were housed under conditions to promote higher physical activity than the other animals housed individually in small cages. Acutely, the removal of facet joints increased the flexibility of intervertebral joints. Over the following year, this increase in flexibility was reduced to close to control levels in all groups of animals. Within the intervertebral discs, there was no significant change in proportions or solubility of collagen or proteoglycans after surgery, nor was there microscopic or macroscopic evidence of disc degeneration. The surgical procedure produced hypermobility of the spine, but there was a subsequent restabilization, and the intended disc degeneration was not produced. These findings indicate that some as yet unidentified soft tissue repair process, facilitated by activity, overcame the hypermobility created at surgery, so degenerative changes in the intervertebral discs did not result. We suggest that other animal models of disc degeneration may represent a failure of reparative response to acute injury.

Animals↗
PubMed1989

Functional restoration with behavioral support. A one-year prospective study of patients with chronic low-back pain.

Patients with chronic disabling low-back pain have poor prospects of returning to work. The authors tested a treatment program of functional restoration with behavioral support through 1 year prospective observation of patients disabled for an average of 19 months without evidence of surgically correctable disease. Ninety patients were studied: 59 program graduates, five program dropouts, 17 patients denied program authorization by their insurance carriers, and six crossover patients. Three patients were admitted but refused to participate in the treatment program. Initial demographic, physical, and self-assessment attributes were similar for all four groups. At year's end, 81% of program graduates, 40% of the dropouts, and 29% of those denied the program had returned to work. All six crossover patients were working 6 months after treatment. Program graduates showed significant improvements in self-assessed pain, disability, and depression, and in physical capacities after 3 weeks of treatment. These improvements were maintained through the year except for partial decreases in frequent lifting, cycling endurance, and isokinetic trunk extension strength. Functional restoration with behavioral support is an effective treatment for patients with chronic, disabling low-back pain, as measured by self-assessments, physical capacities, and return to work.

Back Pain↗
PubMed1989

Determinants of vocational disability in patients with low back pain.

Eighty-seven unemployed subjects with low back pain were recruited from an orthopedic back pain clinic and were given a battery of physical and psychologic tests. Subjects were contacted six months later to determine their current compensation status and whether they had returned to work. Age, length of time out of work, how much they had lifted in their previous job, the number of weeks they had been compensated, current activity levels, leg pain, and various psychologic factors significantly differentiated those who worked from those who did not. Physical examination findings and testing of the ability to lift were not significantly related to return to work. It is suggested that demographic, job-related, and psychologic factors should be emphasized, rather than only physical capacity, in the evaluation of vocational potential and the assessment of disability in patients with low back pain.

Adult↗
PubMed1988

The biomechanics of lumbar disc herniation and the effect of overload and instability.

A multipart study has been performed to provide a mechanical explanation for the epidemiologic association between sitting in static (e.g., factory or office) or vibration (e.g., car or truck driving) environments and acute herniated lumbar discs. It was shown that a 1 h exposure to sitting environments caused significant changes in the mechanical properties of the lumbar intervertebral disc. During many of the latter tests, specimens were unstable (exhibited by a sudden, large flexion and/or lateral bend rotation response to an axially applied load). This showed that a motion segment in the lumbar spine could suddenly buckle and apply a tensile impact loading to the posterolateral region of the disc. We also demonstrated that a combined lateral bend, flexion, and axial rotation vibration loading could cause tracking tears proceeding from the nucleus through the posterolateral region of the anulus. It suggests that a mechanism for disc herniation is mechanical changes leading to instability of the motion segment. These experiments complete the argument that lumbar disc herniations can be a direct mechanical consequence of prolonged sitting in static or vibration environments.

Aged↗
PubMed1987

Musculoskeletal status and disability of MMPI profile subgroups among patients with low back pain.

The Minnesota Multiphasic Personality Inventory (MMPI) profiles of 205 male and 157 female patients with acute and chronic low back pain (LBP) were studied for replicable homogeneous subgroups using three cluster-analysis procedures. Two normal and three clinically elevated profile subgroups were identified. The two normal subgroups were characterized by relatively normal musculoskeletal condition and were least disabled, but they differed somewhat from each other in duration of pain, presence of physical abnormalities, and daily functioning. The third subgroup had the following characteristics: an elevated neurotic triad, greatest duration of symptoms, most abnormal physical findings, greatest limitation of motion, most pain complaints during physical examination, and the fewest number of intact functional activities. The fourth subgroup, with an elevated neurotic triad plus subclinical elevations on other scales, had somewhat less musculoskeletal impairment but had extensive work disability, financial compensation, and previous surgeries. The fifth and most pathologic profile subgroup surprisingly consisted largely of acute-pain patients whose musculoskeletal condition and daily functioning were similar to those of the normal subgroups. Patients in the three abnormal MMPI subgroups were exposed to more LBP physical-risk factors in the workplace. Implications for psychological treatment with these different profile types are discussed.

Adolescent↗