Biomedical subjects

O D Schipplein

Publications and source records attributed to O D Schipplein.

9 recordsLinked to original sources

PubMed1995

The influence of initial horizontal weight placement on the loads at the lumbar spine while lifting.

STUDY DESIGN: This was a biomechanical study of the effect of the initial horizontal distance between a person lifting and the load. Experimental data were analyzed using a dynamic rigid link model. OBJECTIVE: To determine the effect of the initial horizontal load placement on the moments acting on the lumbar spine and the lower extremity joints during lifting, and to determine the role of the lower extremities during lifting from the floor. SUMMARY OF BACKGROUND DATA: Epidemiologic studies have implicated lifting as a cause of back pain, and over 80% of all worker's compensation back injuries are considered to be caused by manual material handling Guidelines have been proposed to increase the safety of lifting, but they are primarily based on static biomechanical analyses, psychophysical data, and physiologic limitations. METHODS: Each of 12 male subjects lifted a weight box containing 0 to 300 N, in 100-N increments. Each subject performed 20 lifts--four weights at five horizontal distances (20, 30, 40, 50 and 60 cm). Motion was measured with an optoelectronic system, ground reaction forces were measured with a force plate, and moments were calculated using a rigid link model. RESULTS: The peak predicted L5-S1 moment increased as the weight and horizontal distance increased. The influence of horizontal distance on moment magnitude was nonlinear. As the distance changed from 20 to 40 cm, the distance-related rate of increase was approximately one-half of that occurring with a distance change from 40 to 60 cm. This can be explained by the need to reach out further, beyond 40 cm, which is accomplished by a deeper flexion of the knees and ankles and an anterior translation of the upper body and arms. CONCLUSION: As the horizontal distance at the start of a lift increased, the peak moment acting on the lumbar spine also increased, but the increase was nonlinear. This is explained by a change in the technique of lifting when the distance is 40 cm or greater.

Adolescent↗

PubMed1993

The effects of quadriceps fatigue on the technique of lifting.

A biomechanical analysis was performed of lifting before and after fatiguing the quadriceps muscles. The hypothesis tested was that when the quadriceps muscles were fatigued the lifter would change lifting technique from more of a squat (leg) lift to more of a stoop (back) lift to decrease the demand on the quadriceps muscles. The hypothesis was broadly supported, and three variables changed significantly with fatigue: trunk angular velocity, which increased, and knee moment integral and hip angles, which both decreased. These changes are all consistent with a change from more of a squat toward a stoop technique. The fact that the technique of lifting changes with quadriceps muscle fatigue underlines the importance of the physiologic condition of these muscles and suggests that rehabilitation of low-back-injured workers should include the quadriceps muscles. The amount of work performed should be controlled to avoid the development of local muscle fatigue and subsequent changes in performance.

Adult↗

PubMed1993

The influence of load knowledge on lifting technique.

The purpose of this study was to analyse the influence of load knowledge on lifting technique. Ten men lifted a box containing either no weight or weights of 150, 250 or 300 N with and without knowledge of what was inside the box. The kinetics and kinematics of the lift were analysed using a force plate, an optoelectronic motion analysis system, and a rigid body link model. At 0 N lifting, the unknown load resulted in a jerk-like motion and a significantly increased peak L5-S1 flexion-extension moment. At 150 N there was also a significant increase in the speed of trunk extension with unknown weights, but the L5-S1 moment remained unchanged. At higher load levels there were only minor differences between lifting techniques when knowing and not knowing the load. We conclude that lifts are approached assuming a certain weight, and that when the assumption is wrong and the load lighter than anticipated lifting is performed with a 'jerking' motion, creating unnecessary loads on the lower back.

Adult↗

PubMed1992

Influence of body segment dynamics on loads at the lumbar spine during lifting.

Flexion-extension moments acting at the L5/S1 level and hip joints were calculated using three different techniques; a pure static analysis, a static analysis including the inertial force of the load, and a dynamic analysis. Ten subjects participated in the study and were asked to lift a box weighing either 50 N or 150 N, using a freestyle technique. The lifts were performed at normal and fast speed. The intra-subject lifting techniques were consistent when lifting the same loads. The moments predicted by the dynamic analysis and the static analysis were the same when holding weights in static postures. When performing the lifts, differences in the peak moments occurred between static and dynamic analyses. These differences were influenced by external load and by lifting speed. Taking the effect of the inertia of load into account in the static analysis resulted in an increase in the moment magnitude, but the predicted moment was still much less than in the dynamic analysis which yielded the largest moment magnitudes. The difference between dynamic and static analysis was greatest when lifting 50 N at fast speed; an 87% increase in L5/S1 moment and a 95% increase in hip moment was observed when replacing the pure static with a dynamic analysis.

Adult↗

PubMed1991

Interaction between active and passive knee stabilizers during level walking.

The gait of normal subjects and patients with varus deformities at the knee was studied by analyzing the interaction between the dynamic (muscular) and passive (ligamentous) restraints affecting lateral stability of the knee. A statistically determinant model predicted that the midstance-phase adducting moment during normal gait would cause lateral knee joint opening if either antagonistic muscle force and/or pretension in the lateral soft tissues were not present at the knee. The patient group tended to compensate for a high midstance-phase adducting moment by walking with a style of gait that demanded more muscle force (greater flexion-extension moments). This walking style reduced the chance of lateral joint opening. It can be speculated that this style of gait would help to maintain equilibrium at the knee. The higher muscle force would aid in resisting the adducting moment, keeping the joint closed laterally and thus increasing the stability of the knee.

Adult↗

PubMed1990

Relationship between moments at the L5/S1 level, hip and knee joint when lifting.

A study was performed to determine the influence of load magnitude on the self selected technique of lifting. Specifically, it was hypothesized that with heavier weights a tendency would occur to lift more with the back and less with the legs. Flexion-extension moments at the L5/S1 level, hip and knee joints were calculated for subjects when lifting boxes weighing from 50 to 250 N. Lifts were performed using a freestyle technique at normal speed. The moment profiles (moment plotted vs time) were analyzed kinematically and as a function of the weight lifted. The kinematics of the lift changed as the weight increased. The moment at the L5/S1 level increased with increasing weight, however, the corresponding knee moment decreased. Thus, an inverse relationship was found between the moment at the L5/S1 level and the knee joint moment. An increase in weight lifted was also associated with an increase in the angular velocity at the knee while lifting. Apparently with heavier weights there is a tendency to extend the knees earlier during the lift than with lighter weights, confirming our hypothesis. This explains the reduced knee moment. Our findings lead to the hypothesis that quadriceps muscle strength limits the subjects' ability to lift with their knees flexed.

Adult↗

PubMed1988

Influence of dynamic factors and external loads on the moment at the lumbar spine in lifting.

Flexion-extension moments occurring at the L5-S1 level of the spine were calculated when subjects lifted a box weighing from 50 to 250 N. Lifting was performed at normal and fast speed, and the lifts were performed using a freestyle and a leglifting technique. The peak moment increased linearly with increasing load. The moment/load relationship was significantly influenced by lifting speed, and a higher moment occurred at each load level when lifting fast. Lifting speed was reduced when the external load was increased, particularly when the load was 150 N and higher. Moments when lifting using the leglifting technique were lower than when lifting freestyle.

Adult↗

PubMedDate not supplied

Trunk muscle geometry and centroid location when twisting.

The trunk muscles of the lumbar region were studied using magnetic resonance imaging (MRI) in five male volunteers placed in neutral and in two twisted postures. Using a CAD digitizing system, the positions of trunk muscle centroids and the cross-sectional areas of these muscles were measured from the transverse scans at 1 cm intervals from L2 to S1. Muscle lines of action were created by connecting the muscle centroids from the successive sections. Changes in cross-sectional areas and displacements of centroids in a three-dimensional coordinate system and the local two-dimensional coordinate system were estimated at each disc level. In the three-dimensional coordinate system, all muscle centroids were displaced when twisting. Thus, the locations and orientations of all muscle lines of action changed. In the local two-dimensional coordinate system, only the muscle centroids of four abdominal muscles were displaced. Most of these displacements occurred in the first 25 degrees of twisting. Higher up in the lumbar spine, the displacement was greater. The changes in moment arms were sometimes as great as twofold. Only the abdominal oblique muscles (AOM) changed their cross-sectional area significantly; the area of the right AOM ipsilateral to the side of twisting increased, while that of the left AOM was decreased.

Abdominal Muscles↗

PubMedDate not supplied

The anterior cruciate ligament-deficient knee with varus alignment. An analysis of gait adaptations and dynamic joint loadings.

Thirty-two patients with an ACL-deficient knee and lower limb varus alignment and 16 healthy controls were analyzed during level walking using a force-plate and optoelectronic system. The forces and moments of the lower limb and knee joint were measured and knee joint loads and ligament tensile forces were calculated using a mathematical model. The majority of patients (20 of 32) had an abnormally high adduction moment at the affected knee. The adduction moment showed a statistically significant correlation to high medial tibiofemoral compartment loads and high lateral soft tissue forces, but not to the degree of varus alignment on standing roentgenograms. Fifteen of 32 knees had abnormally high lateral soft tissue forces. We interpreted these gait findings as indicative of a medial shift in the center of maximal joint pressure and an increase in lateral soft tissue forces to achieve coronal plane stability. Further, there is the likelihood of separation of the lateral tibiofemoral joint and "condylar lift-off" during periods of the stance phase. If this occurs, all of the load-bearing forces would shift to the medial tibiofemoral joint and relatively large tensile forces would occur in the lateral soft tissue restraints. The flexion moment, as related to the quadriceps muscle force, was significantly lower than the control knees in 40% of the involved knees, and the extension moment, as related to the hamstring muscle force, was significantly higher in 50% of the involved knees. We interpret this finding as a gait adaptation tending to diminish quadriceps muscle activity and enhance hamstring muscle activity to provide dynamic anteroposterior stability of the knee joint. The fundamental assumption of this paper is that any combination of conditions leading to higher medial joint forces is associated with factors leading to more rapid degeneration of the medial compartment in patients with ACL deficiency, varus deformity, and lax lateral ligaments.

Adolescent↗