- Email: [email protected]
Undulatory swimming in anuran larvae without waves of muscular contraction
478
Abstracts
by the flight. The local anguhr momentum contribution accounted for to”, or less of the total and SO-90 Onof the former was due to the local component of the trunk-head segment. The dominant role of the lower extremities was apparent in all the dives. With the exception of the forward dive layout, the upper extremities contributed substantially to the total angular momentum.
GAIT ANALYSIS OF PATIENTS
WITH ACHILLES’ TENDON
RUPTURE
Y. L. CHOU and K. M. HWA;VG (Institute of Engineering Science, National Cheng-Kung Republic of China)
University,
The achilles tendon, the common tendon of the gastrocnemius and soleus, is the thickest and strongest in the body. When it is ruptured, the function of plantar flexion in the foot is weakened and tenoplasty surgery is usually required. The purpose of this study is to compare the gait parameters at various walking speeds in patients with Achilles tendon rupture, preoperatively and postoperatively with those of normal subjects; also to compare those who have had successful surgeries with those who have had surgeries that failed.
JOINT
FORCES IN THE CANINE LIMB DURING THE WALK AND TROT
GERALD J. PIJANOWSKI(Department of Veterinary Biosciences) and MANSSOURH. MOEINZADEH (Department of General Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A.)
The purpose of this study is to determine the three-dimensional forces and moments acting on the major joints of the fore and hindlimbs of the dog during the walk and trot. The kinematics of the limb segments were determined using high-speed cinematography and the photogrammetric technique of Karara. The ground reaction forces were measured with a six-component force platform. The segment parameters were measured directly. A system of nonlinear equations were developed to relate the forces and moments of the major limb joints to the gait. limb, body weight, speed of the dog and point in the step.
BILATERAL
ASYMMETRY
IN GALLOP
MOTION:
HANDEDNESS
IN HORSES
N. R. DEUEL (University of New Hampshire, Durham, NH 03824, U.S.A.) and L. M. LAWRENCE (Department of Animal Science, University of Illinois, Urbana, IL 61801, U.S.A.) Four 2 yr old fillies were trained to initiate the left or right lead gallop in response to a rider’s signal. Films were taken (243 frames s-t) of each horse galloping with the rider on a straightaway, velocities IO-15 ms-I. Even though signaled for each gallop lead an equivalent number of times, horses consistently switched leads to the left lead. Velocities and stride lengths were greater Cp< 0.05) for the left lead than the right. The contact duration for the trailing (right) fore limb on the left lead exceeded (p < 0.05) the contact duration for the trailing (left) fore limb on the right lead. Findings indicate that the right fore limb was preferentially used for support. The trailing fore limb experiences greater stresses than the leading fore limb. Therefore, selecting the right fore limb as the trailing fore limb allowed horses to use it to withstand the greatest stresses and caused them to preferentially gallop with the left fore limb leading.
UNDULATORY
SWIMMING
K. V. S. HOFF (Department
IN ANURAN LARVAE CONTRACTION
WITHOUT
WAVES OF ,MUSCULAR
of Biology, Dalhousie University, Halifax, Nova Scota, Canada)
During normal swimming in many aquatic vertebrates waves of bending pass along the body from anterior to posterior. These waves can be produced by: (1) serial contraction of muscles along the length of the body, or (2) alternate contractions of all muscles on each side. A kinematic analysis of high speed tine recordings of normally swimming American toad larvae (Bufi americanu.~) was used to distinguish between these two mechanisms. Local bending in four short segments along the tails of four tadpoles shows no phase lag in the rate of bending from anterior to posterior segments. Although the maximum rate ofchange of bending was far greater in posterior than in anterior segments, the maximum rates for all Four tail segments occurred at the same time
479
Abstracts
during the tail beat cycle. This suggests that alternate contraction of all muscles on each side of the body is the more plausible mechanism for the observed waves of bending.
G. ORTHOPEDICS
MECHANXCAL CONSEQUENCES OF FIBROUS MEMBRANE BONE/CEMENT INTERFACE IN PROXIMAL FEMORAL
FORLMATION AT THE ARTHROPLASTY
T. D. BROWNand D. R. PEDERSEN(Department of Orthopaedic Surgery, University of Iowa), E. L. RADIN (Department of Orthopaedic Surgery, West Virginia University) and R. M. ROSE (Department of Materials Science, Massachusetts Institute of Technology, MA, U.S.A.) An anatomical three-dimensional finite element model of a proximal femur with cemented Harris CD prosthesis was developed to study stress distribution changes due to progressive degradation of the rigidity of attachment at the bone/cement interface following fibrous membrane development. An automated pre-processing routine was used to construct the finite element mesh from digitized CT scans. The membrane was assumed to be linearly elastic and isotropic, with modulus values inferred from recent animal studies. Increases in membrane compliance caused increased bending stresses in the femur/cement complex, and reduced equivalent stress levels in the proximo-medial cancellous bone. Equivalent stresses were substantially elevated in the proximo-lateral cancellous bone, due primarily to increased transverse-plane tension associated with pistoning of the curved, tapered cement mantle.
EXPERIAMENTAL STRAIN ANALYSIS OF A FEMUR WITH LONG STEM PRESS FIT BONE INGROWTH PROSTHESIS JOAN
E. BECHTOLD.PETER HOLMBERG,BING-NAN SUN, RICHARD F. KYLE and RAMON B. GUSTLO (Metropolitan and Hennepin County Medical Centers, Minneapolis, MN, U.S.A.)
Experimental strain analysis of a normal femur, and femur with an anatomically shaped long stem press fit titanium prosthesis with anterior and posterior bone ingrowth pads, with and without collar. A fresh human femur was instrumented with strain gages monitoring medial, lateral, anterior and posterior strains at the lesser trochanter, midstem, tip of stem, and distal to the stem tip. 1.5 and 3 times body weight were applied to the femoral head (compression) and 0.6 and 1.2 x B.W. to abductor muscles (tension) at 20” to the vertical. The intact femur was loaded, then the femoral head osteotomized, and prosthesis inserted and loaded. The collar was filed off without removing the prosthesis, and the head loaded. Loading was repeated three times to check repeatability. Compressive strain was found primarily along the medial cortex, at proximal level along posterior cortex, and at mid stem along anterior cortex. Tension was greatest laterally. At proximal medial cortex, strains were 40% normal with collar, 20”, normal without collar. Strains with prosthesis were decreased overall.
STRESSES AT THE PIN-BONE INTERFACE OF EXTERNAL FIXATORS: EMPLOYING REFLECTIVE PHOTOELASTIC COATINGS
A STUDY
R. D. ARMSTRONG,J. B. FINLAYand C. H. RORABECK(Division of Orthopaedic Surgery, University of Western Ontario, London, Ontario, Canada, N6A 5A5) Reflective photoelastic coatings have been used in oitro, to study the stresses at the pin-bone interface of a Hoffmann half-frame unilateral external fracture-fixation device applied to a cadaveric human tibia, In order to place the maximum demand on the pin-bone interface, a transverse osteotomy was created in the tibia and, using the external fixator, the ‘fracture’ was set with a IO mm gap. Axial loads of 550 N produced plastic deformation of the bone around the 5 mm diameter pins, as evidenced by residual isochromatic fringes upon load-removal. Angular malalignment of the three fixation pins, in a given cluster, by only 3” produced shear stresses with magnitudes beyond the fatigue shear-strength ofcortical bone. An axial load of 795 N on the tibia produced shear stresses beyond the shear-strength of the bone-i.e. evidenced by catastrophic failure of the pin-bone interface.
Abstracts
by the flight. The local anguhr momentum contribution accounted for to”, or less of the total and SO-90 Onof the former was due to the local component of the trunk-head segment. The dominant role of the lower extremities was apparent in all the dives. With the exception of the forward dive layout, the upper extremities contributed substantially to the total angular momentum.
GAIT ANALYSIS OF PATIENTS
WITH ACHILLES’ TENDON
RUPTURE
Y. L. CHOU and K. M. HWA;VG (Institute of Engineering Science, National Cheng-Kung Republic of China)
University,
The achilles tendon, the common tendon of the gastrocnemius and soleus, is the thickest and strongest in the body. When it is ruptured, the function of plantar flexion in the foot is weakened and tenoplasty surgery is usually required. The purpose of this study is to compare the gait parameters at various walking speeds in patients with Achilles tendon rupture, preoperatively and postoperatively with those of normal subjects; also to compare those who have had successful surgeries with those who have had surgeries that failed.
JOINT
FORCES IN THE CANINE LIMB DURING THE WALK AND TROT
GERALD J. PIJANOWSKI(Department of Veterinary Biosciences) and MANSSOURH. MOEINZADEH (Department of General Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A.)
The purpose of this study is to determine the three-dimensional forces and moments acting on the major joints of the fore and hindlimbs of the dog during the walk and trot. The kinematics of the limb segments were determined using high-speed cinematography and the photogrammetric technique of Karara. The ground reaction forces were measured with a six-component force platform. The segment parameters were measured directly. A system of nonlinear equations were developed to relate the forces and moments of the major limb joints to the gait. limb, body weight, speed of the dog and point in the step.
BILATERAL
ASYMMETRY
IN GALLOP
MOTION:
HANDEDNESS
IN HORSES
N. R. DEUEL (University of New Hampshire, Durham, NH 03824, U.S.A.) and L. M. LAWRENCE (Department of Animal Science, University of Illinois, Urbana, IL 61801, U.S.A.) Four 2 yr old fillies were trained to initiate the left or right lead gallop in response to a rider’s signal. Films were taken (243 frames s-t) of each horse galloping with the rider on a straightaway, velocities IO-15 ms-I. Even though signaled for each gallop lead an equivalent number of times, horses consistently switched leads to the left lead. Velocities and stride lengths were greater Cp< 0.05) for the left lead than the right. The contact duration for the trailing (right) fore limb on the left lead exceeded (p < 0.05) the contact duration for the trailing (left) fore limb on the right lead. Findings indicate that the right fore limb was preferentially used for support. The trailing fore limb experiences greater stresses than the leading fore limb. Therefore, selecting the right fore limb as the trailing fore limb allowed horses to use it to withstand the greatest stresses and caused them to preferentially gallop with the left fore limb leading.
UNDULATORY
SWIMMING
K. V. S. HOFF (Department
IN ANURAN LARVAE CONTRACTION
WITHOUT
WAVES OF ,MUSCULAR
of Biology, Dalhousie University, Halifax, Nova Scota, Canada)
During normal swimming in many aquatic vertebrates waves of bending pass along the body from anterior to posterior. These waves can be produced by: (1) serial contraction of muscles along the length of the body, or (2) alternate contractions of all muscles on each side. A kinematic analysis of high speed tine recordings of normally swimming American toad larvae (Bufi americanu.~) was used to distinguish between these two mechanisms. Local bending in four short segments along the tails of four tadpoles shows no phase lag in the rate of bending from anterior to posterior segments. Although the maximum rate ofchange of bending was far greater in posterior than in anterior segments, the maximum rates for all Four tail segments occurred at the same time
479
Abstracts
during the tail beat cycle. This suggests that alternate contraction of all muscles on each side of the body is the more plausible mechanism for the observed waves of bending.
G. ORTHOPEDICS
MECHANXCAL CONSEQUENCES OF FIBROUS MEMBRANE BONE/CEMENT INTERFACE IN PROXIMAL FEMORAL
FORLMATION AT THE ARTHROPLASTY
T. D. BROWNand D. R. PEDERSEN(Department of Orthopaedic Surgery, University of Iowa), E. L. RADIN (Department of Orthopaedic Surgery, West Virginia University) and R. M. ROSE (Department of Materials Science, Massachusetts Institute of Technology, MA, U.S.A.) An anatomical three-dimensional finite element model of a proximal femur with cemented Harris CD prosthesis was developed to study stress distribution changes due to progressive degradation of the rigidity of attachment at the bone/cement interface following fibrous membrane development. An automated pre-processing routine was used to construct the finite element mesh from digitized CT scans. The membrane was assumed to be linearly elastic and isotropic, with modulus values inferred from recent animal studies. Increases in membrane compliance caused increased bending stresses in the femur/cement complex, and reduced equivalent stress levels in the proximo-medial cancellous bone. Equivalent stresses were substantially elevated in the proximo-lateral cancellous bone, due primarily to increased transverse-plane tension associated with pistoning of the curved, tapered cement mantle.
EXPERIAMENTAL STRAIN ANALYSIS OF A FEMUR WITH LONG STEM PRESS FIT BONE INGROWTH PROSTHESIS JOAN
E. BECHTOLD.PETER HOLMBERG,BING-NAN SUN, RICHARD F. KYLE and RAMON B. GUSTLO (Metropolitan and Hennepin County Medical Centers, Minneapolis, MN, U.S.A.)
Experimental strain analysis of a normal femur, and femur with an anatomically shaped long stem press fit titanium prosthesis with anterior and posterior bone ingrowth pads, with and without collar. A fresh human femur was instrumented with strain gages monitoring medial, lateral, anterior and posterior strains at the lesser trochanter, midstem, tip of stem, and distal to the stem tip. 1.5 and 3 times body weight were applied to the femoral head (compression) and 0.6 and 1.2 x B.W. to abductor muscles (tension) at 20” to the vertical. The intact femur was loaded, then the femoral head osteotomized, and prosthesis inserted and loaded. The collar was filed off without removing the prosthesis, and the head loaded. Loading was repeated three times to check repeatability. Compressive strain was found primarily along the medial cortex, at proximal level along posterior cortex, and at mid stem along anterior cortex. Tension was greatest laterally. At proximal medial cortex, strains were 40% normal with collar, 20”, normal without collar. Strains with prosthesis were decreased overall.
STRESSES AT THE PIN-BONE INTERFACE OF EXTERNAL FIXATORS: EMPLOYING REFLECTIVE PHOTOELASTIC COATINGS
A STUDY
R. D. ARMSTRONG,J. B. FINLAYand C. H. RORABECK(Division of Orthopaedic Surgery, University of Western Ontario, London, Ontario, Canada, N6A 5A5) Reflective photoelastic coatings have been used in oitro, to study the stresses at the pin-bone interface of a Hoffmann half-frame unilateral external fracture-fixation device applied to a cadaveric human tibia, In order to place the maximum demand on the pin-bone interface, a transverse osteotomy was created in the tibia and, using the external fixator, the ‘fracture’ was set with a IO mm gap. Axial loads of 550 N produced plastic deformation of the bone around the 5 mm diameter pins, as evidenced by residual isochromatic fringes upon load-removal. Angular malalignment of the three fixation pins, in a given cluster, by only 3” produced shear stresses with magnitudes beyond the fatigue shear-strength ofcortical bone. An axial load of 795 N on the tibia produced shear stresses beyond the shear-strength of the bone-i.e. evidenced by catastrophic failure of the pin-bone interface.