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Dear BIOMECH-L'ers,
Recently, our group has been doing some dynamic modeling on the full
body motions, and are interested in simple mechanical models of the
lumbar/sacral joint. We have two main questions:
(1) We are looking for reasonable estimates of the moment arms of intra-
abdominal pressure acting about the L5/S1 joint. We are aware of a
reference in an article by Chaffin:
Chaffin (1975) "On the validity of biomechanical models
of the low back for weightlifting analysis," ASME
Proceedings, 75-WA-bio-1.
This is also cited in Chaffin and Andersson's book:
Chaffin and Andersson, Occupational Biomechanics,
Wiley, New York, 1991.
Are there any other approaches we can take in modeling intra-abdominal
pressure? We are particularly interested in subject-specific models
based on scaling schemes based on bony landmark measurements. We are
hoping to obtain a simple relation between TORSO ANGLE and the L5/S1
intra-abdominal pressure MOMENT ARM.
(2) We also are trying to find a subject-specific scaling scheme (based
on bony landmarks, hopefully) for the distance from the skin surface to
L5/S1 joint center of rotation. Is there a database or study out there
that relates to this estimate in some way? We are aware of the work of
McNeill et al:
McNeill, T, Warwick, D, Andersson, GBJ, Schultz (1980)
"Trunk Strengths in attempted flexion, extension and
lateral bending in healthy subjects with low back
disorders," Spine 5: 529-538
This study places the L5/S1 joint center 34% from posterior on the
anteroposterior diameter. Is there any other related information out
there?
As always, we will post a summary of responses. Thanks in advance,
Hsin-I Chang, B.S.
Wynne Lee, Ph.D.
Jim Patton, M.S.
Aileen Russo, M.S.
Julie Steege, B.S.
Motor control and learning group
Programs in Physical Therapy and Biomedical Engineering
Northwestern University
Chicago, Illinois, USA
Recently, our group has been doing some dynamic modeling on the full
body motions, and are interested in simple mechanical models of the
lumbar/sacral joint. We have two main questions:
(1) We are looking for reasonable estimates of the moment arms of intra-
abdominal pressure acting about the L5/S1 joint. We are aware of a
reference in an article by Chaffin:
Chaffin (1975) "On the validity of biomechanical models
of the low back for weightlifting analysis," ASME
Proceedings, 75-WA-bio-1.
This is also cited in Chaffin and Andersson's book:
Chaffin and Andersson, Occupational Biomechanics,
Wiley, New York, 1991.
Are there any other approaches we can take in modeling intra-abdominal
pressure? We are particularly interested in subject-specific models
based on scaling schemes based on bony landmark measurements. We are
hoping to obtain a simple relation between TORSO ANGLE and the L5/S1
intra-abdominal pressure MOMENT ARM.
(2) We also are trying to find a subject-specific scaling scheme (based
on bony landmarks, hopefully) for the distance from the skin surface to
L5/S1 joint center of rotation. Is there a database or study out there
that relates to this estimate in some way? We are aware of the work of
McNeill et al:
McNeill, T, Warwick, D, Andersson, GBJ, Schultz (1980)
"Trunk Strengths in attempted flexion, extension and
lateral bending in healthy subjects with low back
disorders," Spine 5: 529-538
This study places the L5/S1 joint center 34% from posterior on the
anteroposterior diameter. Is there any other related information out
there?
As always, we will post a summary of responses. Thanks in advance,
Hsin-I Chang, B.S.
Wynne Lee, Ph.D.
Jim Patton, M.S.
Aileen Russo, M.S.
Julie Steege, B.S.
Motor control and learning group
Programs in Physical Therapy and Biomedical Engineering
Northwestern University
Chicago, Illinois, USA