Summary of replies

[S.d.malcolm]

To all of those who replied, thanks a plenty. Here is a summary of
the responses.
-Spencer Malcolm

Original Message:
Dear Subscribers,
I am in the process of compiling some measurements (the knee)
in order to model the joint on the ASIC, ANSYS, or IDEAS software and
for the life of me, I cannot find any publically available info
concerning the dimensions of the knee. Is there some type of data
base, or one book with at least that might have lengths, widths, etc.
of the femur, tibia and major soft tissue components?
I am this close to performing surgery on myself, ruler in hand.
Thanks for the help.
Spencer Malcolm
S.D.Malcolm@sms.ed.ac.uk
University of Edinburgh-Mechanical Engineering
King's Buildings-Sanderson
Mayfield Rd.
Edinburgh, UK
EH9 1JD

REPLIES:

I forgot to mention that we had a paper on modeling the knee with IDEAS
soft ware at the ISB last year, and would send the abstract if you are
interested.

AMH

Anne Hollister, MD
LSUMC-S / Orthopaedic Surgery
1501 Kings Hwy.
Shreveport, LA 71130-3932
email: anne@www.ortho.lsumc.edu



I am currently creating a knee model using Pro/Engineer software which works
much like IDEAS. I am using a combination of CT scan cross sections and
geometric entities. I have parameters from an unpublished study, "Dimensional
and Geometric Anaysis of Human Long Bones in Asian Population" by E.Y.S. Chao
and others from the Johns Hopkins University Department of Orthopeadic Surgery.

Here are caucasian parameters NO GENDER (mm):

Femur parameters:
BL Bone length 453 mean, 405 min, 504 max
HNL Head Neck Length 102, 90,119
LTw Width of Lesser Trochanter 48, 39,59 (AP view)
Wsf Width of Distalfemur 84,70,97 (AP view)

Tibia parameters:
BL Bone length 365,310,420

Here are oriental paramters NO GENDER (mm):

Femur parameters:
BL Bone length 400,355, 431
HD Head Diameter 44, 38, 49
HNL Head neck length 89,79,106
Alpha 132,118,140
LTw Width of Lesser Trochanter 42,36,49
Wdf Width of distal Femur 74,63,80
Wmc Width of medial Condyle 56,47,67
Wlc Width of lateral Condyle 57,46,66

Tibia parameter:
BL Bone Length 326,288,384
Wtp Width of tibial plateau 68,59,77
Htp Height of tibial plateau 14,10,21
Theta lp Lateral slope angle 60,51,69
Theta mp Medial slope angle 68,61,87
Alpha Tibial plateau-shaft angle 87,5,95
Beta Posterior slope angle 11,2,18
Gamma Tibial plateau sagital slope angle 18,9,31

Other references:
REFERENCES


Chao, E.Y.S., "Biomechanics Of High Tibial Osteotomy". In Evarts, C. M> (ed.):
Management of Knee Disorders, St. Louis, C. V. Mosby, 1978 p143.


Conventry, M. B., "Upper Tibial Osteotomy for Osteoarthritis of the Knee", J.
Bone Joint Surg. 67A:1136, 1985

Erkman, M. J. and Walker, P. S. "A study of Knee geometry Applied to the design
of condylar prosthesis", Biomed. Eng. 9:14 1974

Highgenboten, C. L., Jackson, A. Asschliman M. and Meske, N. B. " The
estimation of femoral condyle size", Clin Orthop. 174: 96-106, 1983

Condyles of similar width have similar contours and dissimilar widthd have
dissimilar contours. Variablility in the measurement of Roentgenograms. Hight
and Gender are better predictors. This method would be the reverse process by
which anthropoplogic researchers determine height and weight from the
measurment of specific skeletal parts.

Himeno, S., Chao, E. Y. S., Tsumura, H. Hsu, R. W. W., Sim, F. H. and Coventry,
M. B. , "Plateau pressure distribution before and after knee osteotomy", AAOS
55th Annual Meeting, Atlanta, Georgia. Feb. 4-9, 1988

The axial alignment and distribution of plateau pressure are two biomedical
factors wich could be shanged during surgery to alter the outcome of the
treatment. Preoperative simulation of tibial osteotomy anc careful wedge angel
selection seems to enhance clinical results.

Huiske, r., Kremers, L. Lange A, Wolting H. J., Selvic, G. and Rens J. G.
"Analytic sterophtogrammetric determination of three-dimensional knee joint
geopmetry." J. Biomech. 18: 559-570, 1985

Hungerford, D. S., Kenna, R. V., and Krackow, K. A. "The porous-coated anatomic
Total Knee ", Orthop. Clin. North Am. 13:103, 1982

"Normal knee kinematics are a complex function of surface geometry of the
component parts, orientation and tension of ligaments, and applied external
forces." "As flexion proceeds, the condyles roll posteriorly on their
respective tibial plateaus. However there is a concomitant torsional movement
known as the "screw home" movement. This rotation about the long axis of the
tibia occurswith each flexion and extension . It is automatic, thst is , not a
function of imparted muscle forces but a function of the anatomic shape of the
tibia and femur and the ligamentous attachments. It provides greater stability
in extension and relative freedom of rotation in flexion. By 40 to 50 degrees
of flexion, through a combination of rolling and sliding motion the condyles
have reached the posterior margins of their respective tibial plateaus.

The asymmetry of the rolling sliding motion of the medial and lateral femoral
condyles results in a greater posterior roll of the condyle on the lateral
tibial plateau trhan on the medial side. The posterior roll averages 6mm on
the medial side compared with 12mm on the lateral side . This difference
results in 20 degrees of automatic rotation."

Posterior slope of the tibial plateaus and the decreasing radii of curvature of
the condyles, the femoral and tibial points of attachment of the medial and
lateral collateral ligaents are moving closer to one another. Since the
decrease in the radius of cuvature is greater for the lateral tibial plateau
slopes more sharply posteriorly than the medial plateau, the lateral collateral
ligament becomes more lax than the medial collateral ligament, This has
important consequences in terms of elective or active rotation of the tibia
relative to the femur."

Paper includes torque rotation curves for the knee during flexion.
Also design characteristics of the replacement.

Hsu, R. W. W., Himeno, S., Coventry, M. B., Chao, E. Y. S. "Normal Axial
Alignment of the Lower Extremity and Load-Bearing Distribution at the Knee"
Clin Orthop. 255: 215-227, 1990

Geometry of the knee joint analyzed using a full length weight bearing
roentgenogram of the lower extremity (X-Ray). "The eccentric redistribution of
normal stress is induced by abnormal axial alignment. A vicious cycly may
occur with continuing cartilage and subchondral bone degeneration associated
with progressively abnormal axial alignment. Osteotomy is one of the surgical
methods that can correct joint pathomechanics and may break down this vicious
cycle.

The tibial mechanical angle measured 1.2x varus. Distal Femoral anatomic
valgus 4.9x Center of femoral head defined using the Mose hip template. The
knee center is the midpoint of the tibial spines halfway between the
intercondylar notch.

Install, J. N. Joseph, D. M. and Misika, C.: High tibial osteotomy for vargus
gonerarthrosis: A long -term follow-up Study: J. Bone Joint Surg. 66A:1040, 1984

Johnson. F. Leitl. S. and Waugh, W.: The assessment of loads in the knee joint.
Med. Biol. Eng. 19:237, 1980

Kurosawa, H., Walker, P. S., Abe, S., Garg. A. and Hunter T., "Geometry and
Motion of the Knee for Implant and Orthotic Design" J. Biomechanics 18:7, 1985

Most knee replacements anre consylar replacement types that ignor the apparent
asymmetry of both the femoral and tibial condyles. Need most important
contours and landmarks for sugery. "An important objective should be to resore
the normal internal kinematics of the joint, so ass to achieve normal ligament
length patterns, as well as normal lever arms of the muscles and of the
external forces." Posterior condyles represented as spheres with medial-
lateral spacing defined. Onaverage the medial radious was slightly larger than
the lateral, at 21 mm and 18.6mm. Average spacing was 45.9mm

Laskin, R. S., " Alignment of total knee components", Orthopedics 7:62 1984

Lotke, P. A. and Ecker, M. L."Influence of Position of prosthesis in total Knee
Replacement". J. Bone Joint Surg. 59A:77, 1977

Mensch. J. S. and Amstutz, H. C. "Knee morphology as a guide to knee
replacement" Clin. Orthop. 112:231, 1975

Molton, A. and Upadhyay, S. S. , "A dirct method of measuring femoral
anteversion using ultrasound" JBJS, 64B, 1982

Moreland, J. R., Bassett, L. W., and Hanker, G. J, "Radiographic analysis of
the axial allignment of the lower extemity", J. Bone Joint Surg. 69A:745, 1987

Morrison, J. B. "The mechanics of knee joint in relation to normal walking" J.
Biomech. 3:51, 1970

Parsons, F. G., "The Characteristics of the English thigh bone" Anat. Physiol.
48:238, 1914

Pick , J. W. Stack, J. K. and Anson, B. J. " Measurements of the human femur"
Lengths, diameters and angles" Quart. Bull. Northwester Univ. Med. School
15:281-290, 1941

Prodromas, C. C., Andriacchi, T. P., and Galante, J. O.,"A relationship between
gait and clinical shanges fowwowing high tibial osteotomy", J. Bone Joint Surg.
67A:1188, 1985

Ruby, L., Mital, M. A. , O'Conner, J. and Petal, U., "Anteversion of the
femoral neck, "Comparison of methods of measurement in Patients", JBJS, 61A, 46-
51, 1979

Seedhom, B. B., Longton, E. B., Wright, V., and Dowson, D., "Dimensions of the
knee: Radiographic and autopsy study of sizes required for a knee prosthesis",
Ann. Rheum. Dis. 31:54, 1972

Smith, D.K. Berquist, T. H. An, K. N. , Chao E. Y. S. "The validation of three
dimensional reconstruction of knee anatomy: CT versus MRI imaging." J of Comp
Ass

-Hold that scalpel! You might want to take a look at the National Library of
Medicine's Virtual Human project. Apparently, they have digitized entire
cadavers and placed them on the Internet. The address is:
http://www.nlm.nih.gov. Also, this work is outlined in the Journal of the
American Medical Association (JAMA) in the following issues:
273(4): 273-275, 1995
275(4): 269-270, 1996

Hope this is helpful - good luck with your work.

Sincerely,


David Curd, M.S.
Director of Research
Hughston Sports Medicine Foundation
Columbus, GA USA

-Dear Mr. Malcom,

I do not know a lot about it, but I suggest you to give a look to the
ANSYS web page (http://www.ansys.com) under "case study". I saw there is
something, with pictures, about knee.
Regards,
Giuseppe

-While not attempting to sound redundant, factors taking in skelatal mass,
failure to take in soft tissue, taking in soft tissue you must then add to
your data base the entire populace of the world +1.A reliable source of
Information , would be any mfg. of knee joints - Otto Bock, U.s.M.c> or
Becker Orthopedics, they can break down there demensions. I am sure that they
will be very informative.


Tom LeTourneau C.P. , B.O.C.,O
President
LeTourneau Lifelike Orthotics and Prosthetics.

-Hi Malcolm,

You can get polygonal surfaces for the knee that were digitized from
a model from a company in Orem, Utah called Viewpoint. Here is their
web address:
http://www.viewpoint.com/datashop/
Also, you may want to check out the web page for XYZ Scientific
Applications, since they make a mesh generator that will read the
viewpoint data. There are also examples there of meshes. They
are at:
http://www.xyzsa.com/

Enjoy,

Jeff Weiss

-You could start with:
Erkman MJ, Walker PS: A study of knee geometry applied
to the design of condylar prostheses. Med Biol Eng.
14, Jan 1974

They provide avg dimensions of 25 male and 25 female knees.
The data are also summarized in Peter Walkers book: Human
Joints and their artifical replacements. Charles C. Thomas
1977

Good Luck

--------------------------------------------------------------------------
John A. Hipp, Ph.D. voice: (617) 667-4564
Orthopaedic Biomechanics Laboratory FAX: (617) 667-4561
Beth Israel Hospital and page: (617) 667-5555 ID 1657
Harvard Medical School email: jah@bihobl2.bih.harvard.edu
330 Brookline Ave
Boston MA 02215

--------------------------------------------------------------------------

-I recently published chapter 22 entitled "Joint-articulating surface motion"
in the Biomedical Engineering Handbook, Joseph D. Bronzino editor, CRC Press,
Inc, 1995, which contains information you will need.

Kenton Kaufman, Ph.D.
Motion Analysis Laboratory
Children's Hospital
3020 Children's Way
San Diego, CA 92123


-You can probably find some public CT scans on the WEB. Also NIH Image is a
program you can use (Public Software) to look at the scans, and figure out
dimensions.

Good luck.

-Hi Spencer,
I've just completed some fe models of the patella and have had to construct the model geometry out of MRI scanned data slices.
There are models of the knee available, for instance I know SDRC (I-DEAS) may have a database containing this info, see the ICONN usr group archives. Also you can get access to the visual human proj
ct at the Nation Library.
However, for a complete model e.g. the inner bon distribution, I found these slice to be not of an extremely good enough quality. Aprt from that and access to
the NASA model, I think, (its referenced in a paper on 3D modelling) then I'm afraid you are going to have to create one from scratch.
Good Luck, You'll need it

Andrew Hart
Univeristy of Teesside.
a.hart@tees.ac.uk

-Spencer,

I know NASA (National Aeronautical and Space Administration) has done some
extensive studies and have developed regression equations for individual
body segments. The will provide segment length, mass, and volume given race,
height, weight, and age(?). These equations are public domain and I found
them at the local university library. If you cannot locate them let me know
and I will get the reference numbers for you, sorry I don't have them at
hand. Good Luck!

Dwight G. Bronson
Texas Scottish Rite Hospital for Children
Dallas, TX 75219

Thanks again to everyone.
Spencer Malcolm
S.D.Malcolm@sms.ed.ac.uk
University of Edinburgh-Mechanical Engineering
King's Buildings-Sanderson
Mayfield Rd.
Edinburgh, UK
EH9 1JD