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Trunk muscle myoelectric activity in girls with structurally-normal spines and girls with idiopathic scoliosis
282
Abstracts
the pelvis in 41 girls aged from 9 to 19 years the trunk rotation angle (measured directly an overall correlation coefficient of 0.6, and those obtained by others using the Moire
of age with untreated idiopathic scoliosis. An initial study correlating from photographs) with spine lateral deviation (Cobb angle) yielded a coefficient of 0.7 for the 11 single curves. These results are similar to technique.
TRUNK MUSCLE MYOELECTRIC ACTIVITY STRUCTURALLY-NORMAL SPINES AND GIRLS scoLIosIs
IN GIRLS WITH WITH IDIOPATHIC
M. REUBER, A. SCHULTZ, D. SPENCER and T. MCNEILL (Department of Materials Engineering, University of Illinois at Chicago Circle, Box 4348, Chicago, IL 60680, U.S.A.) Trunk muscle myoelectric activity was measured in 12 girls with structurally-normal spines and 20 female patients with mild-to-moderate idiopathic scoliosis (mean Cobb measure of 23.7 degrees). Seven curves had progression documented by roentgenographs. Myoelectric activity was monitored at six locations on the upper and lower trunk while subjects performed biomechanically-well-defined exercises. Patients with curves of more than 25” had myoelectric signals which were significantly more asymmetric than those of normal girls (p < 0.01). No other satistically significant differences between the myoelectric activity in normal and scoliotic girls were found. Myoelectric activity in patients whose lateral curves progressed was not significantly different from activity in patients who did not progress. Since substantial asymmetries in trunk muscle myoelectric activity arose only in patients with curves larger than 25, it seems that these differences resulted from rather than helped create those lateral curves. ANALYSIS
OF THE EFFECT
OF VARIABLE STRAIN EMISSION IN BONE
RATE ON ACOUSTIC
R. A. FISCHER, M. H. POPE, and D. SELIGSON, (Department of Orthopaedics and Rehabilitation, University of Vermont College of Medicine, Burlington, VT 05405, U.S.A.) Bovine metatarsals were machined into standard sized specimens and were divided into three groups of five specimens each. These groups were subjected to tensile testing in an MTS machine at strain rates of 0.0001 s-i, 0.001 s-l and 0.01 s-l respectively. The acoustic emission (AE) response of the bone during these tests was monitored and the amplitude distributions of the three groups were compared. There was no statistically significant difference in the amplitude distributions between the three groups. It appears from this study that if AE in bone is affected by strain rate, extremes in strain rate greater than 0.0001 s- ’ to 0.01 _ ’ will be necessary to demonstrate this.
CT OBTAINED
BONE
GEOMETRY AND DENSITY MEASUREMENTS SECOND ORDER CORRECTION
USING
D. D. ROBERTSON (Department of Physiology and Biophysics, Georgetown University Medical School, 3900 Reservoir Road, N.W., Washington, DC 20007, U.S.A.) H. K. HUANG (Department of Radiological Sciences, UCLA, Los Angeles, CA 90024, U.S.A.) The early detection of bone loss or gain is of paramount importance in the diagnosis and treatment of many metabolic bone diseases. Several non-invasive methods have been developed and modified, however to date no method provides the required sensitivity, precision, versatility of choice of bony sites, and easy availability to clinicians necessary to be helpful to the millions of patients with metabolic bone disease. The use of a second order bone correction algorithm for X-ray beam hardening allows computed tomography (CT) to meet the above requirements. This paper describes a series of experiments performed to establish the accuracy and usefulness of a second order bone correction. CT scans of embalmed human cortical (femur, humerus, radius, ulna) and trabecular bone (lumbar vertebrae, distal femur) were performed and images reconstructed with and without second order correction. Comparisons of cortical bone’s total cross-sectional area, medullary canal area, and bone density, with and without correction were done. Comparisons between corrected and uncorrected trabecular bone density were also done. All the CT obtained values were compared to the bone’s real area and density as determined by physical methods. Results show that second order bone correction significantly corrects CT generated values of bony geometry (especially the medullary canal area) and CT generated density values of cortical and trabecular bone. In view of these results we feel that second order correction can be used as an important adjunct in the diagnosis and evaluation of treatment of metabolic bone disease.
Abstracts
the pelvis in 41 girls aged from 9 to 19 years the trunk rotation angle (measured directly an overall correlation coefficient of 0.6, and those obtained by others using the Moire
of age with untreated idiopathic scoliosis. An initial study correlating from photographs) with spine lateral deviation (Cobb angle) yielded a coefficient of 0.7 for the 11 single curves. These results are similar to technique.
TRUNK MUSCLE MYOELECTRIC ACTIVITY STRUCTURALLY-NORMAL SPINES AND GIRLS scoLIosIs
IN GIRLS WITH WITH IDIOPATHIC
M. REUBER, A. SCHULTZ, D. SPENCER and T. MCNEILL (Department of Materials Engineering, University of Illinois at Chicago Circle, Box 4348, Chicago, IL 60680, U.S.A.) Trunk muscle myoelectric activity was measured in 12 girls with structurally-normal spines and 20 female patients with mild-to-moderate idiopathic scoliosis (mean Cobb measure of 23.7 degrees). Seven curves had progression documented by roentgenographs. Myoelectric activity was monitored at six locations on the upper and lower trunk while subjects performed biomechanically-well-defined exercises. Patients with curves of more than 25” had myoelectric signals which were significantly more asymmetric than those of normal girls (p < 0.01). No other satistically significant differences between the myoelectric activity in normal and scoliotic girls were found. Myoelectric activity in patients whose lateral curves progressed was not significantly different from activity in patients who did not progress. Since substantial asymmetries in trunk muscle myoelectric activity arose only in patients with curves larger than 25, it seems that these differences resulted from rather than helped create those lateral curves. ANALYSIS
OF THE EFFECT
OF VARIABLE STRAIN EMISSION IN BONE
RATE ON ACOUSTIC
R. A. FISCHER, M. H. POPE, and D. SELIGSON, (Department of Orthopaedics and Rehabilitation, University of Vermont College of Medicine, Burlington, VT 05405, U.S.A.) Bovine metatarsals were machined into standard sized specimens and were divided into three groups of five specimens each. These groups were subjected to tensile testing in an MTS machine at strain rates of 0.0001 s-i, 0.001 s-l and 0.01 s-l respectively. The acoustic emission (AE) response of the bone during these tests was monitored and the amplitude distributions of the three groups were compared. There was no statistically significant difference in the amplitude distributions between the three groups. It appears from this study that if AE in bone is affected by strain rate, extremes in strain rate greater than 0.0001 s- ’ to 0.01 _ ’ will be necessary to demonstrate this.
CT OBTAINED
BONE
GEOMETRY AND DENSITY MEASUREMENTS SECOND ORDER CORRECTION
USING
D. D. ROBERTSON (Department of Physiology and Biophysics, Georgetown University Medical School, 3900 Reservoir Road, N.W., Washington, DC 20007, U.S.A.) H. K. HUANG (Department of Radiological Sciences, UCLA, Los Angeles, CA 90024, U.S.A.) The early detection of bone loss or gain is of paramount importance in the diagnosis and treatment of many metabolic bone diseases. Several non-invasive methods have been developed and modified, however to date no method provides the required sensitivity, precision, versatility of choice of bony sites, and easy availability to clinicians necessary to be helpful to the millions of patients with metabolic bone disease. The use of a second order bone correction algorithm for X-ray beam hardening allows computed tomography (CT) to meet the above requirements. This paper describes a series of experiments performed to establish the accuracy and usefulness of a second order bone correction. CT scans of embalmed human cortical (femur, humerus, radius, ulna) and trabecular bone (lumbar vertebrae, distal femur) were performed and images reconstructed with and without second order correction. Comparisons of cortical bone’s total cross-sectional area, medullary canal area, and bone density, with and without correction were done. Comparisons between corrected and uncorrected trabecular bone density were also done. All the CT obtained values were compared to the bone’s real area and density as determined by physical methods. Results show that second order bone correction significantly corrects CT generated values of bony geometry (especially the medullary canal area) and CT generated density values of cortical and trabecular bone. In view of these results we feel that second order correction can be used as an important adjunct in the diagnosis and evaluation of treatment of metabolic bone disease.