Newer assessment approaches for the patient with low back pain.
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Adult↗
Biomedical subjects
D M Spengler
Publications and source records attributed to D M Spengler.
Spinal cord injury and glucocortical steroid therapy: good news and bad.
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Animals↗
The role of spinal flexibility in back pain complaints within industry. A prospective study.
Commonly used clinical measurements of spinal flexibility in the sagittal and frontal planes were examined as predictors of future back pain reports within industry. The study sample consisted of 3,020 aircraft manufacturing employees who were examined and tracked for more than 4 years for reports of back pain. Modified Schober, sit-and-reach, and lateral bending measurements were not significantly associated with risk of future back pain reporting, nor were any trends present. There was a statistically significant relationship between decreased flexibility and reports of current or previous back problems. However, the differences in flexibility between subjects with and without a history of back problems were too small to be of practical significance.
Adult↗
Anthropometric and clinical measures as predictors of back pain complaints in industry: a prospective study.
A prospective, longitudinal investigation was conducted to investigate anthropometric and clinical examination measures as predictors of future back pain reports in industry. Associations between these measures and a history of back problems were examined as well. Participants in the study included 3,020 aircraft manufacturing employees who underwent an examination and then were tracked for greater than 4 years for subsequent back pain reports. Back symptoms elicited on straight leg raising (SLR) was the measure most significantly associated with subsequent back pain reporting among both men and women (p less than 0.0001). The only variables to add predictive value in addition to back pain on SLR were age and weight in women, and history of back problems and age in men.
Adult↗
Elective discectomy for herniation of a lumbar disc. Additional experience with an objective method.
An objective evaluation for the assessment of patients who have persistent low-back pain and sciatica was tested in eighty-four patients who were operated on by one of us (D.M.S.). In this scoring system, there are four major categories for preoperative assessment: neurological signs, sciatic-tension signs, psychological factors, and imaging studies. When the preoperative scores of the eighty-four patients were correlated with the findings at operation, the three patients who had the lowest scores were the only ones in whom the operative findings were negative. As shown by statistical analysis, the score for imaging studies correlated best with the operative findings. In contrast, in the sixty-one patients who were followed sufficiently to determine the clinical outcome, the psychological score was the best predictor of the outcome of treatment. On the basis of these studies, we concluded that the use of this objective scoring system reduced the incidence of negative findings at exploration of the disc and improved the clinical result after elective discectomy. The higher the score was preoperatively, the more likely the patient was to have a good result after discectomy.
Adolescent↗
Regulation of bone stress and strain in the immature and mature rat femur.
Bone in vivo stresses and moments were determined from rosette strain recordings obtained from the mid-diaphysis of growing exercising rats. Two activity groups were examined beginning at 3 weeks of age: 2 min day-1 and 45 min day-1 at 0.2 ms-1 in an exercise wheel. In vitro moment-strain curves were obtained during mechanical calibration tests on intact femora, and area inertial properties were determined from the mid-diaphysis cross-sections. The mechanical calibration and histomorphometry procedures were then used to compute functional stresses and moments based on the in vivo rosette strain recordings. During the period 6-30 weeks of age the rats increased in body weight over threefold, but no significant changes in principal strain and stress magnitude or orientation were found. Peak in vivo compressive and tensile moments increased during growth in proportion to the animal mass squared, but the ratio of these moments to animal body weight times bone length (BWBL) remained constant throughout growth and in the adult. The parameter BWBL appears, therefore, to be a useful predictor of long bone functional strength. Peak torsional moments remained a constant 8.1 +/- 3.0% of the ultimate torsional strength, providing a safety factor of approximately 12. Differences in the in vivo moments between the two activity groups were found, which were due primarily to adaptive, but not significant, changes in bone geometry. These findings support the hypothesis that long bones model and model during growth and altered activity in order to regulate the functional strains at a predefined level.
Aging↗
Flexible device for vertebral body replacement.
A novel vertebral prosthesis is presented. The prosthesis was developed for surgical procedures requiring the resection of a complete vertebral body and the adjacent intervertebral discs, the design objective being to develop a flexible implant that would be robust enough to withstand the in vivo stress environment of the human spine. In theory, a flexible implant should preserve a more normal range of motion and apply less stress to surrounding tissue than a rigid implant. A prototype implant was constructed so as to combine a rigid stainless steel structure with flexible silicon rubber elements in order to form an implant with static and dynamic mechanical characteristics similar to those of the anterior spinal column. Implant flexibility characteristics were determined from ex vivo stress-strain behaviour during bending and compressive creep testing. Results from the bending tests indicated good agreement for the lateral and sagittal bending characteristics in comparison with in vitro bending tests of human lumbar motion segments. Comparison of the implant compressive creep response with similar in vitro tests on human lumbar intervertebral discs also demonstrated similarities in the time-dependent mechanical parameters.
Elasticity↗
A prospective study of the role of cardiovascular risk factors and fitness in industrial back pain complaints.
The authors conducted a prospective study of risk factors for industrial back pain complaints among 3,020 aircraft manufacturing employees. The study subjects completed a cardiovascular risk questionnaire, and were asked about their smoking status and past medical history, including previous back problems. Premorbid submaximal treadmill testing to predict maximum oxygen uptake (Vo2max) was completed in 2,434 subjects who were not excluded from testing due to cardiovascular risk screening. During several years of subsequent follow-up, 279 subjects reported back problems. Those who reported smoking at the time of the premorbid examination were significantly more likely to report a subsequent back problem than nonsmokers (P = 0.002). When controlling for sex and age, cardiovascular fitness, as measured through VO2max, was not predictive of future back injury reports (P = 0.26).
Adult↗
Regional variations in the compressive properties of lumbar vertebral trabeculae. Effects of disc degeneration.
The compressive mechanical properties of human lumbar vertebral trabeculae were examined on the basis of anatomic origin, bone density, and intervertebral disc properties. Trabecular bone compressive strength and stiffness increased with increasing bone density, the latter proportional to strength and stiffness to the one-half power. Regional variations within each segment were found, the most prevalent differences occurring in regions of bone overlying the disc nucleus in comparison with bone overlying the disc anulus. For normal discs, the ratio of strength of bone overlying the disc nucleus to bone overlying the disc anulus was 1.25, decreasing to 1.0 for moderately degenerated discs. These results suggest that an interdependency of trabecular bone properties and intervertebral disc properties may exist.
Aged↗
A biomechanical assessment of plate fixation, with insufficient bony support.
The use of an internal fixation plate in the presence of a bone defect was studied using a theoretical model of an idealized long bone having a circular cross section and loaded using a combination of axial and bending loads. The analysis showed that the "bending-open" loading mode does not occur if, in the normal unplated bone, the line of action of the resultant axial load passes within the outer cortex at the location where the plate is to be applied. In this situation the fracture will deform in a "bending-closed" mode regardless of whether the plate is attached to the tension or the compression side. If bony contact cannot be achieved, lower plate stress is always encountered when the plate is attached to the compression side instead of the tension side. In vivo verification of the model was addressed in a pilot experiment using instrumented metal plates applied bilaterally to the femora of one dog. Bilateral bone defects were created in the midfemoral canine diaphysis. On one leg the plate was applied to the lateral aspect ("tension" side), and on the other leg the plate was applied to the medial aspect ("compression" side). The plate attached to the lateral aspect deformed plastically in the bending-closed mode. The contralateral plate that was attached to the medial aspect (compression side) of the femur did not show signs of plastic deformation. Furthermore, the plate strains were lower in the plate attached to the medial aspect than those in the plate attached to the lateral aspect.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The effects of simulated weightlessness on bone biomechanical and biochemical properties in the maturing rat.
Histomorphometric and biomechanical changes in bone resulting from hypogravity (simulated weightlessness) were examined in this study. Using a head-down hindlimb suspension model, three groups of six male rats underwent simulated weightlessness for periods of one, two and three weeks while a fourth recovery group was suspended for two weeks followed by two weeks of normal activity. Biomechanical data were collected during static and dynamic bending and torsion tests on intact femora. Histomorphometric values were determined from midshaft bone cross sections and material properties were obtained using ash and calcium assays. The experimental groups exhibited significantly lower geometric and material properties than the controls, resulting in structural hypotrophy; geometric and material changes contributed equally to the structural changes. Recovery following a return to normal activity was indicated, although full recovery may take longer than the weightlessness period. In the rat, altered maturation and reduced bone strength were the sequelae of weightlessness.
Aging↗
A comparison of Harrington rod fixation with and without segmental wires for unstable thoracolumbar injuries.
Between January 1, 1975 and November 1, 1986, 77 patients with acute unstable thoracic or lumbar spine fractures underwent reduction, posterior stabilization with dual Harrington distraction rods, and fusion with autogenous iliac crest bone graft at Vanderbilt University Medical Center. Beginning March 1985, in 25 patients, segmental interspinous wires were employed, in addition to the Harrington rods, to augment the surgical construct. Clinical and radiographic analysis was performed to determine if differences existed between the two groups. Average time to surgery, hospital stay, and time to brace discontinuance were lower in the segmental wire group. Pain and work status at final follow-up were similar in the two groups. There was a higher incidence of superior and inferior hook migration and reoperation for this complication in patients treated with Harrington rods alone. There was no significant difference in postoperative correction of deformity, although at follow-up, there was greater recurrence of deformity in the Harrington rod group. In summary, the use of segmental wires to supplement Harrington rod fixation appears to offer advantages over Harrington rods alone, with minimal or no increased risk.
Adolescent↗
Hematogenous osteomyelitis complicating a closed compression fracture of the spine.
A case of hematogenous osteomyelitis of a vertebral body following a closed compression fracture is presented. Staphylococcus septicemia developed 7 days after the injury. In spite of prompt antibiotic treatment, osteomyelitis of the compressed T12 was recognized 5 weeks later. The role of indium white blood cell (WBC) scanning in establishing the diagnosis is highlighted.
Fractures, Closed↗
In vivo creep behavior of the normal and degenerated porcine intervertebral disk: a preliminary report.
The viscoelastic properties of normal and surgically altered lumbar intervertebral disks from eight immature swine were examined in vivo. Rheological models were used to mathematically characterize the compressive creep-relation behavior of the disks before and after alteration by either chemonucleolysis [chymopapain (Chymodyactin) injection] or denucleation. In the normal disks, a significant modulating effect of respiration was observed that tended to increase the creep deformation response in comparison to that observed during similar in vitro and in situ studies. These results suggest that, in terms of assessing the absolute magnitude of the viscoelastic properties of lumbar disks, the influence of normal physiological function on adjacent vertebrae and surrounding tissues cannot be neglected. Preliminary results obtained from the experimentally altered disks indicated that partial denucleation primarily affected the initial stiffness behavior of the disk (24% decrease in elastic modulus), whereas chemonucleolysis caused changes in both the time-dependent (15% increase in creep rate) and instantaneous (23% decrease in elastic modulus) properties of the disk. Both partial denucleation and acute chemonucleolysis produced biomechanical changes that were comparable to grade II or slightly degenerative, age-related changes found in human lumbar intervertebral disks.
Animals↗
Mechanical behavior of the human lumbar spine. I. Creep analysis during static compressive loading.
The in vitro viscoelastic "creep" behavior was examined in 18 cadaveric human lumbar motion segments subjected to static axial compressive loads. Axial deformation was followed for 30 min under constant applied load. Compressive material constants (moduli and viscosity coefficients) were then determined for each intervertebral disc using a linearization method based on a Taylor series expansion of experimental data for the "three parameter" viscoelastic creep model. The degree of disc degeneration and bone mineral content (BMC) were also assessed. Good correlation between the experimentally determined and model predicted strain values were found, with the average error less than 1%. We found that motion segments from older and more degenerated lumbar discs were less stable and had lower material constants than segments from younger and less degenerated discs. Material constants and BMC correlated closely, suggesting that an interdependency of disc and vertebral body properties exists. No correlation between the creep characteristics and disc height, disc area, segment level, or sex were noted.
Adult↗
Mechanical behavior of the human lumbar spine. II. Fatigue strength during dynamic compressive loading.
Seventeen cadaveric human lumbar motion segments from eight spines were cyclically loaded in vitro under axial compression. Loading frequency and magnitude were chosen to simulate rigorous activity within an in vivo physiological level. The load magnitude was determined as a percentage of the ultimate compressive load, the latter estimated from the bone mineral content (BMC) of lumbar vertebrae determined by dual-photon absorptiometry. Following testing, the degree of macroscopic disc degeneration was assessed and the type of fracture in each specimen was determined from serial sagittal sections. Fractures were found in all but one specimen. Three types of fractures were formed: the node of Schmorl and Junghanns (type I), central endplate fracture (type II), and a crush or burst fracture (type III). The results suggested that type I fractures were predominantly associated with segments with normal discs, type II fractures were found primarily in segments with moderately degenerated discs, and type III fractures were associated with segments that failed on the first cycle. Segment stiffness and fatigue strength (cycles to failure) were correlated with disc degeneration, age, and segment BMC, the latter an in vivo measure of bone density. Fatigue strength also decreased in proportion to a power coefficient with increasing relative stress (cyclic stress range/ultimate stress).
Adult↗
Degenerative stenosis of the lumbar spine.
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Aged↗
Geometric, elastic, and structural properties of maturing rat femora.
Geometric, elastic, and structural properties of growing rat femora were determined from bending and torsion tests followed by bone sectioning and measurement of areal properties. Rosette strain gages bonded to the bone surface measured the strain during testing. A computer generated elliptical cross-sectional representation of the cross section geometry was used for calculation of material and structural properties. All structural and material properties increased with increasing age, exhibiting age-related changes that were best represented by an allometric or "heterauxic" growth pattern (y = axb) up to maturity. The femoral axial, flexural, and torsional rigidity increased 5.7, 10.1, and 14.8 fold, respectively, during maturation from 21 to 119 days of age. The increase in whole bone rigidity during maturation was caused primarily by changes in geometry. The bone tissue tensile longitudinal elastic modulus and shear modulus approximately doubled, and the shear strength increased approximately fourfold over this same period. Following maturity, a much slower increase in bending and torsional properties was noted. The results suggest that bone structural properties are regulated by changes in both geometric and material properties.
Aging↗