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Biomedical subjects

V K Goel

Publications and source records attributed to V K Goel.

At least 127 records · Page 7Linked to original sources
PubMed1985

Biomechanical study of cervical spine stabilization with methylmethacrylate.

Polymethylmethacrylate (PMMA) has been used to provide immediate fixation in the spine, especially in the cervical region. With its use spreading to nontumor cases and a younger patient population, its biomechanical contribution to the stability and strength of the injured spine becomes increasingly important. The present study is unique, as it provides, for the first time, results of a three-dimensional stability and flexion strength testing of a surgical specimen removed at autopsy after 7 years. Also tested, in the identical manner, is a normal specimen to provide control data. The PMMA specimen, as compared with the control, was generally found to have less motion. Its flexion strength was at par with that of the control, although it did not exhibit the initial low-stiffness region of the normal spine specimen.

Biomechanical Phenomena↗
PubMed1985

An epidemiologic study of the relationship between postural asymmetry in the teen years and subsequent back and neck pain.

This epidemiologic study examined the relationship between postural discrepancies in the posterior plane and the subsequent development of back and neck pain. The study population comprised women who were members of the graduating classes of 1957, 1958, and 1959 of an eastern U.S. women's college. Information on postural asymmetry was gathered from two sources: (1) measurements made from posture pictures taken early in the freshman year of college and obtained from each woman in the study, and (2) subjective evaluations made by the physical education department faculty at the time of examination. Information on the development of back and neck disorders and associated risk factors during the subsequent 25 years was obtained by a postal questionnaire. Three parameters of postural asymmetry were examined from the posture picture measurements: elevation of one shoulder, elevation of one hip, and deviation of the spine from the midline of the body. None of these parameters nor the physical education department evaluations was associated with a subsequent report of low-back pain, mid-back pain, or neck pain.

Adolescent↗
PubMed1985

Torsional fatigue of the lumbar intervertebral joints.

The effect of cyclic torsional loads on the behavior of intact lumbar intervertebral joints was investigated. A total of 24 specimens, divided in two groups, were tested. In the first group, a specimen was subjected to a specified constant cyclic torque, and the resulting change in angular displacement with time was recorded. The specimens in the second group were subjected to a specified constant angular displacement and the resultant torque recorded. The results of the constant torque tests showed that fatigue failure was primarily a function of the averaged initial angular displacement and secondarily of the applied torque. The critical threshold values appear to be an initial angular displacement of +/- 1.5 degrees. All specimens, displaying an averaged initial angular displacement of less than +/- 1.5 degrees, did not fail in fatigue, while the others did. However, the specimens with angular displacements of less than +/- 1.5 degrees had lower applied torques (11.3 and 22.6 Nm), while specimens with higher applied torques (33.9 and 45.2 Nm) all exceeded the +/- 1.5 degrees threshold and failed in fatigue. Failure locations occurred in such diverse regions as end-plates, facets, laminae, capsular ligaments, etc. All specimens exhibited a synovial fluid discharge from the apophyseal joint capsule sometime during testing. Post-test examinations of all the cartilage surfaces showed fibrillation, whether or not the intervertebral joint failed.

Adult↗
PubMed1984

An in-vitro study of the kinematics of the normal, injured and stabilized cervical spine.

The relative motion between various vertebrae of multi-level cervical ligamentous spinal segments (C2-T2), using Bryant angles, is described. A three-dimensional sonic digitizer was utilized to study the motion in flexion, extension, right lateral bending and right axial rotation. Effects of a number of injuries and stabilization (interspinous wiring and acrylic cement, PMMA) on the motion behavior of C5-C6 (injured) and C4-C5 (superior to injured) levels were investigated. The data were normalized with respect to intact specimens. The injury to capsular ligaments at C5-C6 produced a significant increase in the relative motion at C4-C5. Although the interspinous wiring reduced the motion at C5-C6 the C4-C5 motion was still higher. The application of PMMA made the motion at C4-C5 comparable to the intact specimen.

Adult↗
PubMed1983

Effect of pressurization on methylmethacrylate-bone interdigitation: an in vitro study of canine femora.

Aseptic mechanical loosening of the femoral and acetabular components is a major long term complication of total hip arthroplasty. Pressurized injection of bone cement (polymethylmethacrylate) has been advocated for increasing cement-bone interlock. To determine the relationship between cement intrusion pressure and its penetration into cancellous bone, an in-vitro study of paired, fresh frozen canine femora was conducted. Methacrylate cement was injected at predefined constant pressures from 0.11 to 1.23 MPa (16-175 psi). The penetration was quantified for each injection pressure. The results showed a positive logarithmic relationship between the relative penetration and the intrusion pressure, the former reaching a near asymptotic value at approximately 0.70 MPa (100 psi). Unequal radial distribution of cement within the metaphysis was demonstrated. Greater penetration was observed into the proximal postero-lateral cancellous bone bed as compared to other regions. The relationship between cement penetration and bone size was explored at a single-constant pressure of 0.35 MPa (50 psi). Although absolute cement penetration was found to be linearly related to the bone size, the relative penetration remained nearly constant with bone size.

Animals↗
PubMed1982

Errors in kinematic parameters of a planar joint: guidelines for optimal experimental design.

Kinematic characteristics of a body joint performing planar motion are precisely defined by the centers and angles of rotation as the joint undergoes its full range of physiological movement. These potentially (clinically) useful non-invasive kinematic parameters are, however, highly sensitive to input coordinate measurement errors and the experimental design. This paper compares results of an experimental study and a statistically based mathematical model of the errors in the centers and angles of rotation. Guidelines are provided to design optimal kinematic experiments so that, for given measurement equipment, the highest possible precision may be achieved in the results.

Biomechanical Phenomena↗
PubMed1982

Contact areas in human elbow joints.

The paper describes the results of in-vitro experiments to determine the contact areas in the elbow joint during different anatomical positions. The casting technique, using wax as a casting material, was used in this study. The shape and size of the contact areas change, in different elbow positions ranging from full extension to full flexion. The joint stability was preserved during the experiments. In full extension the area of contact was observed on the lower-medial aspect of the ulna while in other postures the pressure areas were found as a strip extending from posterolateral to anteromedial. The radio-capitulum joint also revealed contact during flexion under no externally applied loads.

Elbow Joint↗
PubMed1982

Errors in the center and angle of rotation of a joint: an experimental study.

The error sensitivity in the determination of center and angle of rotations of a body joint performing planar motion is studied. A simple experiment is described to measure the errors in these two kinematic parameters as functions of errors in the input coordinates of markers. The effect of varying the marker locations and the size of motion-step is also studied. The errors in the center of rotation are found to increase dramatically when the two markers subtend angles of about 0 deg or 180 deg and when the motion step size decreases to 1 deg or less. Similar results are found for errors in the angle of rotation which, in addition, increase with decrease in the radius of the markers.

Biomechanical Phenomena↗
PubMed1980

Pituitary gonadotropin content and gonadosomatic index in Clarias batrachus a fresh water teleost.

The pituitary gonadotropin content in Clarias batrachus was determined by radiophosphorus assay in chicks. The levels in spawning male, post spawning male, spawning female and post spawning female were found to be 65.66, 27.7, 36.69 and 49.98 micrograms LH activity/kg body weight respectively. The gonadosomatic index (GSI) in the above groups was found to be 0.3599, 0.0763, 9.2327 and 0.4334 respectively. Correlation between the gonadotropins and GSI was also worked out but was found to be statistically non-significant (P > 0.05).

Animals↗
PubMed1978

Effect of progesterone on the magnum proteins during primary stimulation of chick oviduct.

The effect of progesterone on the secretion of protein by the magnum of 5-d-old, female chicks was determined. 2. The supernatant prepared by centrifuging an homogenate of the magnum at 105 000g was found, by immunodiffusion, to contain an antigenic component which precipitated the antisera for conalbumin 1, conalbumin 2 and ovalbumin after 5 d treatment with progesterone: there was no reaction to ovomucoid, lysozyme and avidin antisera. 3. Disc-electrophoresis of the homogenate revealed two bands at the site of ovalbumin. 4. Incorporation of 3H-lysine into the magnum proteins of progesterone-treated chicks did not differ from that of controls. 5. The secretion available in the magnum may be only a transudate from the serum and not a true secretory product. Progesterone behaved qualitatively as oestrogen in this study although the action is much less pronounced and was delayed.

Albumins↗