No announcement yet.

Femoral anteversion: summary of replies

This topic is closed.
  • Filter
  • Time
  • Show
Clear All
new posts

  • Femoral anteversion: summary of replies

    Dear biomch-l subscribers

    a while ago I posted a question about the measurement of femoral
    anteversion from CT and conventional X-ray scans. Thanks to all who
    replied. Below you will find my original question followed by a summary
    of the responses I got.

    Thanks again.

    Francesco La Palombara

    Francesco La Palombara

    Istituti Ortopedici Rizzoli Tel: +39.(0)51.636 6520
    Lab. di Biomeccanica Fax: +39.(0)51.583789

    via di Barbiano 1/10 E-mail:
    I-40136 Bologna (please use "To Franz" as subject)


    ************************************************** *********************

    I am looking for a reliable and accurate manual or
    computer-assisted technique for measuring femoral anteversion using data
    deriving from CT and/or conventional X-ray scans.

    I am particularly interested in methods which have been validated
    through comparison with intraoperative or post-mortem direct
    measurements. I would also like to know where to retrieve information on
    normal and pathological value ranges for this parameter. One more
    question: does anybody have the complete reference to the paper(s) in
    which Reikerås proposes his approach?

    ************************************************** *********************


    Dr Georg Bergman and his collaborators at the Biomechanics
    Laboratory of the Orthopaedic Hospital of the Free University of Berlin
    Oskar-Helene-Heim (Clayallee 229, 14195 Berlin, Germany, Tel: +49 30
    81004 273, Fax: +49 30 81004 275, E-mail:,
    WWW: have developed a
    computer-assisted technique for the evaluation of ultrasound
    measurements, featuring a reproducibility of about 3 degrees. They are
    now validating the technique through clinical trials.

    Dr Patrick Costigan of the School of Physical and Health Education
    at Queen's University (Kingston, Ontario, Canada, Tel: ++613 545 6603
    E-mail: developed a method for computing femoral
    anteversion from two X-ray views as part of his PhD thesis. Here is an
    overview of his method:

    The method involves taking two x-rays; one is an AP view of the hip
    while the other is the AP view rotated by 30 degrees about the long
    axis. This method was developed using dry bones as test specimens. The
    actual anteversion angle was also measured directly with a 3D digitizer
    and with measurements from CT images. The data for dry bones follows:

    The anteversion angle measured by three methods.

    Bone Direct CT X-ray
    A76 0.6 0.5 11.0
    AD58 -4.6 0.0 10.3
    S100 20.4 22.3 23.7
    S104 19.5 24.8 19.4
    S105 -8.3 -5.0 7.5
    S162 0.1 4.0 15.2
    S175 -25.4 -14.5 0.2
    S192 10.6 7.3 14.1
    S212 2.0 -2.0 6.6
    S237 18.8 20.5 26.1
    S244 -2.4 18.8 19.0
    S250 2.3 1.5 11.7
    S262 22.4 26.8 28.4
    S269 25.6 22.3 26.9
    S316 12.9 16.0 18.4
    S338 10.3 20.8 21.4
    S341 11.8 18.5 21.1
    S342 5.0 8.0 13.6
    S346 19.2 23.0 23.7
    S8 -10.4 -7.0 4.5
    S89 12.3 15.0 15.9
    XYZ 0.5 3.8 13.9

    Using a regression procedure I developed regression equations to predict
    both the direct and CT measurements from the x-ray measurement. The
    resulting equations were:

    Direct = -17.5 + (1.50 * radiographic) r2=0.82 S.E.E. = 5.51
    CT = -14.0 + (1.51 * radiographic) r2=0.92 S.E.E. = 3.55

    The Standard Error of The Estimate (SEE) is the standard deviation of
    differences between the actual measures (either direct or CT) and the
    respective predicted measure (the mean is approximately zero).

    Dr Dieter Rosenbaum of the Kinesiology Lab at the Klinik und
    Poliklinik fuer Allgemeine Orthopaedie of the Westfaelische
    Wilhelms-Universitaet Muenster (Albert-Schweitzer-Str. 33, D-48129
    Muenster, Germany, Tel: +49 251 834 7981/7995, Fax: +49 251 834 7989,
    E-mail: suggested to contact Martin Simnacher and
    Peter Keppler at the University of Ulm, who developed a technique based
    on ultrasound measurements. Their E-mail address is

    Leonard D'Addesi of the Human Performance Laboratory at Thomas
    Jefferson University (130 South 9th Street, Suite 830, Philadelphia, PA
    19107-5233, USA, E-mail: is completing
    his MS thesis on the assessment of femoral anteversion using motion
    analysis. He sent a large list of references which you can find below.


    Aamodt, A., Terjesen, T., Eine, J., and Kvistad, K.A. (1995). Femoral
    Anteversion Measured by Ultrasound and CT: A Comparative Study.
    Radiology, 24; 105-109.

    Anda, S., Terjensen, T., Sundalsfoll, S., and Tangerud, A. (1988).
    Anteversion Measured by Ultrasonography and Radiography: An Anatomic
    Investigation. Acta Radiologica, 29 (6); 695-699.

    Apkarian, J., Naumann, S., and Cairns, B. (1989). A Three-Dimensional
    Kinematic and Dynamic Model of the Lower Limb. Journal of Biomechanics,
    (2); 143-155.

    Arkin, A.M. and Katz, J.F. (1956). The Effects of Pressure on
    Growth. Journal of Bone and Joint Surgery, 38-A (5); 1056-1076.

    Basmajian, J.V. (1975). Grant's Method of Anatomy. Ninth edition. The
    William's and Wilkins Co., Baltimore.

    Berman, L., Mitchell, R., and Katz, D. (1987). Ultrasound Assessment of
    Femoral Anteversion: A Comparison With Computerised Tomography. Journal
    Bone and Joint Surgery, 69-B (2); 268-270.

    Billing, L. (1954). Roentgen Examination of the Proximal Femur End in
    Children and Adolescents. Acta Radiologica Supp., 110; 1-79.

    Bjersand, A.J. and Eastgate, R.J. (1982). The Accuracy of CT-Determined
    Femoral NeckAnteversion. European Journal of Radiology, 2; 1-4.

    Blankevoort, L., Huiskes, R., and De Lange, A. (1990). Helical Axes of
    Passive Knee Joint Motions. Journal of Biomechanics, 23 (12);

    Bleck, E. (1982). Developmental Orthopaedics. III: Toddlers.
    Developmental Medicine in Child Neurology, 24; 533-555.

    Bleck, E. (1987). Orthopaedic Management in CP. Mac Keith Press, J.B.
    Lippincott Co., Philadelphia, Pa.

    Brattstrom (1962). Two Sources of Error in Measurement of the
    Angle of the Femur. Acta Orthop Scand, 32; 252-256.

    Brookes, M. and Wardle, E.N. (1962). Muscle Action and the Shape of the
    Femur. Journal of Bone and Joint Surgery, 44-B (2); 398-411.

    Budin, E. and Chandler, M.E. (1957). Measurement of Femoral Neck
    Anteversion by a Direct Method. Radiology, 69; 209-213.

    Burr, D.B., Cook, L.T., Martin, N.L., and Asher, M. (1981). Measurement
    Accuracy of Proximal Femoral Geometry Using Biplanar Radiography.
    of Pediatric Orthopedics, 1; 171-179.

    Butler-Manuel, P.A., Guy, R.L., and Heatley, F.W. (1992). Measurement
    Tibial Torsion - A New Technique Applicable to Ultrasound and Computed
    Tomography. The British Journal of Radiology, 65; 119-126.

    Castagno, P., Richards, J., Miller, F., and Lennon, N. (1995).
    of 3-Dimensional Lower Extremity Kinematics During Walking Gait Using
    Different Marker Sets. Gait and Posture, 3 (2); 87.

    Chao, E.Y. (1980). Justification of Triaxial Goniometer for the
    Measurement of Joint Rotation. Journal of Biomechanics, 13; 989-1006.

    Chao, E.Y. and Morrey, B.F. (1978). Three-Dimensional Rotation of the
    Elbow. Journal of Biomechanics, 11; 57-73.

    Clark, J.M., Freeman, M.A.R., and Witham, D. (1987). The Relationship
    Neck Orientation to the Shape of the Proximal Femur. Journal of
    Arthroplasty, 2 (2); 99-109.

    Clarkson, H.M. and Gilewich, G.B. (1989). Musculoskeletal Assessment:
    Joint Range of Motion and Manual Muscle Strength. Williams and Wilkins,
    Philadelphia, Pa.

    Crane, L. (1959). Femoral Torsion and Its Relation to Toeing-in and
    Toeing-out. Journal of Bone and Joint Surgery, 41-A (3); 421-428.

    Cusick, B.D. (1990). Progressive Casting and Splinting for Lower
    Deformities in Children with Neuromotor Dysfunction, Therapy Skill
    Builders, Tucson, Az.

    Davis, R.B., Ounpuu, S., Tyburski, D. and Gage, J.R. (1991). A Gait
    Analysis Data Collection and Reduction Technique. Human Movement
    10 pp. 575-587.

    Delp, S.L., Komattu, A.V., and Wixson, R.L. (1994). Superior
    of the Hip in Total Joint Replacement: Effects of Prosthetic Neck
    Neck-Stem Angle, and Anteversion Angle on the Moment-Generating Capacity
    the Muscles. Journal of Orthopaedic Research, 12 (6); 860-870.

    Dietz, F.R. (1994). Intoeing - Fact, Fiction and Opinion. American
    Physician, 50 (6); 1249-1259.

    Dostal, W.F. and Andrews, J.G. (1981). A Three Dimensional
    Model of Hip Musculature. Journal of Biomechanics, 14 (11); 803-812.

    Dunlap, K., Shands, A.R., Hollister, L.C., Gual, J.S., and Streit, H.A.
    (1953). A New Method for Determination of Torsion of the Femur.
    of Bone and Joint Surgery, 35-A (2); 289-311.

    Dunn, D.M. (1952). Anteversion of the Neck of the Femur: A Method of
    Measurement. Journal of Bone and Joint Surgery, 34-B (2); 181-186.

    Durham, H.A. (1915). Anteversion of the Femoral Neck in the Normal
    and its Relation to Congenital Dislocation of the Hip. JAMA, 65;

    Edgren, W. and Laurent, L.E. (1956). A Method of Measuring the Torsion
    the Femur in Congenital Dislocation of the Hip in Children. Acta
    Radiologica, 45; 371-376.

    Egund, N., and Palmer, J. (1984). Femoral Anatomy Described in
    Coordinates Using Computed Tomography. Acta Radiologica Diagnosis, 25

    Fisher, R.L., Duncan, A.S., and Bronzino, J.D. (1972). The Application
    Axial Transverse Tomography to the Measurement of Femoral Anteversion.
    Clinical Orthopaedics and Related Research, 86; 6-12.

    Gage, J.R. (1991). Gait Analysis in Cerebral Palsy. Mac Keith Press,
    Netherhall, London.

    Galbraith, R.T., Gelberman, R.H., Hajek, P.C., Baker, L.A., Sartoris,
    Rab, G.T., Cohen, M.S., and Griffin, P.P. (1987). Obesity and Decreased
    Femoral Anteversion in Adolescence. Journal of Orthopaedic Research, 5;

    Gardner, E., Gray, D.J., and O'Rahilly, R. (1975). Anatomy: A Regional
    Study of Human Structure. Fourth edition. W.B. Saunders Co.,
    Philadelphia, Pa.

    Ghelman, B. (1979). Three Methods for Determining Anteversion and
    Retroversion of a Total Hip Prosthesis. AJR, 133; 1127-1134.

    Giannini, S., Catani, F., Benedetti, M.G., Leardini, A. (1994). Gait
    Analysis: Methodologies and Clinical Applications, IOS Press for
    Bioengineering Technology and Systems, Washington, DC.

    Grood, E.S. and Suntay, W.J. (1983). A Joint Coordinate Description for
    the Clinical Description of Three-Dimensional Motions: Application to
    Knee. Transactions of the ASME Journal of Biomechanical Engineering,

    Harris, G.F. and Wertsch, J.J. (1994). Procedures for Gait Analysis.
    Archives of Physical Medicine and Rehabilitation, 75; 216-225.

    Hartley, A. (1995). Practical Joint Assessment: Lower Quadrant. Second
    edition. Mosby-Year Book, Inc., Phialdelphia, Pa.

    Henriksson, L. (1980). Measurement of Femoral Neck Anteversion and
    Inclination: A Radiographic Study in Children. Acta Orthopaedica
    Scandinavica Supplementum, 186; 5-22.

    Hernandez, R.J., Tachdjian, M.O., Poznanski, A.K., and Dias, L.S.
    CT Determination of Femoral Torsion. AJR, 137; 97-101.

    Herrlin, K. and Ekelund, L. (1983). Radiographic Measurements of the
    Femoral Neck Anteversion: Comparison of Two Simplified Procedures. Acta
    Orthopaedica Scandinavica, 54; 141-147.

    Hinderaker, T., Uden, A., and Reikeras, O. (1994). Direct
    Measurement of Femoral Anteversion in Newborns. Skeletal Radiology, 23;

    Hoiseth, A., Reikeras, O., and Fonstelien, E. (1988). Aspects of
    Neck Anteversion: Theoretical Considerations and Experimental Results.
    Acta Radiologica, 29 (6); 689-694.

    Hoiseth, A., Reikeras, O., and Fonstelien, E. (1989). Evaluation of
    Methods for Measurement of Femoral Neck Anteversion. Acta Radiologica,
    (1); 69-73.

    Hoppenfeld, S. (1976). Physical Examination of the Spine and
    Appelton-Century-Crofts, New York, New York.

    Hubbard, D.D. and Staheli, L.T. (1972). A Direct Radiographic
    of Femoral Torsion Using Axial Tomography: Technic and Comparison with
    Indirect Radiographic Method. Clinical Orthopaedics and Related
    86; 16-20.

    Kadaba, M. (1996). Personal communication.

    Kadaba, M.P., Ramakrishnan, H.K., and Wooten, M.E. (1990). Measurement
    Lower Extremity Kinematics During Level Walking. Journal of Orthopaedic
    Research, 8; 383-392.

    Kane, T.J., Henry, G., and Furry, D. (1992). A Simple Roentgenographic
    Measurement of Femoral Anteversion. Journal of Bone and Joint Surgery,
    74-A (10); 1540-1542.

    Kapandji, I.A. (1970). The Physiology of the Joints: Volume Two, Lower
    Limb. Second Edition. Churchill Livingstone, New York.

    Kepple, T.M. (1989). Validation of a Video-Based, Six Degree-of-Freedom
    Mechanical Analysis Procedure for Application to Human Motion. M.S.
    Thesis, University of Maryland.

    Kingsley, P.C. and Olmsted, K.L. (1948). A Study to Determine the Angle
    Anteversion of the Neck of the Femur. Journal of Bone and Joint
    30-A (3); 745-751.

    Laage, Barnett, Brady, Dulligan, Fett, Gallagher, and Schneider (1953).
    Horizontal Lateral Roentgenography of the Hip in Children: A Preliminary
    Report. Journal of Bone and Joint Surgery, 35-A (2); 387-398.

    LaGasse, D.J. and Staheli, L.T. (1972). The Measurement of Femoral
    Anteversion: A Comparison of the Fluoroscopic and Biplane
    Methods of Measurement. Clinical Orthopaedics and Related Research, 86;

    Laskin, R.S. (1984). Alignment of Total Knee Components. Orthopedics,
    (1); 62-72.

    Lausten, G.S., Jorgensen, F., and Boesen, J. (1989). Measurement of
    Anteversion of the Femoral Neck: Ultrasound and Computerised Tomography
    Compared. Journal of Bone and Joint Surgery, 71-B (2); 237-239.

    Lee, D.Y., Lee, C.K., and Cho, T.J. (1992). A New Method for
    of Femoral Anteversion: A Comparative Study With Other Radiographic
    Methods. Internaltional Orthopaedics (SICOT), 16; 277-281.

    Magilligan, D.J. (1956). Calculation of the Angle of Anteversion by
    of Horizontal Lateral Roentgenography. Journal of Bone and Joint
    38-A (6); 1231-1246.

    Mahboubi, S. and Horstmann, H. (1986). Femoral Torsion: CT
    Radiology, 160 (3); 843-844.

    Mann, R.W., Antonsson, E.K. (1983). Gait Analysis - Precise, Rapid,
    Automatic, 3-D Position and Orientation Kinematics and Dynamics.
    of the Hospital for Joint Diseases Orthopaedic Institute, 43 (2):

    McKibbin, B. (1970). Anatomical Factors in the Stability of the Hip
    in the Newborn. Journal of Bone and Joint Surgery, 52-B (1); 148-159.

    Merchant, A.C. (1965). Hip Abductor Muscle Force: An Experimental Study
    the Influence of Hip Position With Particular Reference to Rotation.
    Journal of Bone and Joint Surgery, 47-A (3); 462-476.

    Mesgarzadeh, M., Revesz, G., and Bonakdarpour, A. (1987). Femoral Neck
    Torsion Angle Measurement by Computed Tomography. Journal of Computer
    Assisted Tomography, 11 (5); 799-803.

    Michele, A.A. (1962). Iliopsoas: Development of Anomalies in Man,
    C. Thomas, Publisher, Springfield, Il.

    Miller, F., Merlo, M., Liang, Y., Kupcha, P., Jamison, J., and Harcke,
    (1993). Femoral Version and Neck Shaft Angle. Journal of Pediatric
    Orthopaedics, 13; 382-388.

    Moseley, C.F. (1980). The Biomechanics of the Pediatric Hip.
    Clinics of North America, 11 (1); 3-16.

    Motion Analysis Corporation (1993). Definitions of Joint Angles and
    Segment Coordinate Systems. OrthoTrak II Manual; 8-1 - 8-10.

    Moulton, A. and Upadhyay, S.S. (1982). A Direct Method of Measuring
    Femoral Anteversion Using Ultrasound. Journal of Bone and Joint
    64-B (4); 469-472.

    Murphy, S.B, Simon, S.R., Kijewski, P.K., Wilkinson, R.H., and Griscom,
    N.T. (1987). Femoral Anteversion. Journal of Bone and Joint Surgery,
    (8); 1169-1176.

    Neptune, R.R. and Hull, M.L. (1995). Accuracy Assessment of Methods for
    Determining Hip Movement in Seated Cycling. Journal of Biomechanics, 28
    (4); 423-437.

    Ogata, K. and Goldsand, E.M. (1979). A Simple Biplanar Method of
    Femoral Anteversion and Neck-Shaft Angle. Journal of Bone and Joint
    Surgery, 61-A (6); 846-851.

    Parsons, F.G. (1914). The Characters of the English Thigh-Bone.
    of Anatomy and Physiology, 48; 238-267.

    Perry, J. (1992). Gait Analysis Normal and Pathological Function.
    Inc., New Jersey.

    Persson, T., Lanshammar, H., and Medved, V. (1995). A Marker-Free
    to Estimate Joint Centre of Rotation By Video Image Processing.
    Methods and Programs in Biomedicine, 46; 217-224.

    Peterson, H.A., Klassen, R.A., McLeod, R.A., and Hoffman, A.D. (1981).
    Use of Computerised Tomography in Dislocation of the Hip and Femoral
    Anteversion in Children. Journal of Bone and Joint Surgery, 63-B (2);

    Phillips, H.O., Greene, W.B., Guilford, W.B., Mittelstaedt, C.A.,
    G., Vincent, L.M., and Durell, C. (1985). Measurement of Femoral
    Comparison of Standard Roentgenographic Techniques With Ultrasound.
    Journal of Pediatric Orthopedics, 5; 546-549.

    Ramakrishnan, H.K. and Kadaba, M.P. (1991). On the Estimation of Joint
    Kinematics During Gait. Journal of Biomechanics, 24 (10); 969-977.

    Reikeras, O., Hoiseth, A., and Reigstad, A. (1985a). Evaluation of the
    Dunlap/Rippstein Method for Determination of Femoral neck Angles. Acta
    Radiologica Diagnosis, 26 (2); 177-179.

    Reikeras, O., Hoiseth, A., and Reigstad, A. (1985b). Femoral
    Measured by the Dunlap/Rippstein and Norman Methods. Acta Radiologica
    Diagnosis, 26 (3); 303-305.

    Reynolds, T.G. and Herzer, F.E. (1959). Anteversion of the femoral
    Clinical Orthopaedics, 14; 80-89.

    Riley, P.O., Fijan, R.S., Hodge, W.A., and Mann, R.W. (1987).
    Determination of Joint Centers for Posture Studies. In Proceedings of
    Winter Annual Meeting of the American Society of Mechanical Engineers.
    Boston, Massachussets, 131-136.

    Rogers, S.P. (1931). A Method for Determining the Angle of Torsion of
    Neck of the Femur. Journal of Bone and Joint Surgery, 13; 821-825.

    Roth, B. (1967). Finite-Position Theory Applied to Mechanism
    Journal of Applied Mechanics, Transactions of the ASME, September;

    Rothstein, J.M. and Echternach, J.L. (1993). Primer on Measurement: An
    Introductory Guide to Measurement Issues. American Physical Therapy
    Association, Alexandria, VA.

    Ruby, L., Mital, M.A., O'Conner, J., and Patel, U. (1979). Anteversion
    the Femoral Neck. Journal of Bone and Joint Surgery, 61-A (1); 46-51.

    Ruwe, P.A., Gage, J.R., Ozonoff, M.B., and DeLuca, P.A. (1992).
    Determination of Femoral Anteversion: A Comparison With Established
    Techniques. Journal of Bone and Joint Surgery, 74-A (6); 820-830.

    Ryder, C.T. and Crane, L. (1953). Measuring Femoral Anteversion: The
    Problem and a Method. Journal of Bone and Joint Surgery, 35-A (2);

    Seireg, A. and Arvikar, R. (1989). Biomechanical Analysis of the
    Musculoskeletal Structure for Medicine and Sports. Hemisphere
    Corporation, Philadelphia, Pa.

    Shiavi, R., Limbird, T., Frazer, M., Stivers, K., Strauss, A., and
    Abramovitz, J. (1987a). Helical Motion Analysis of the Knee - I.
    Methodology for Studying Kinematics During Locomotion. Journal of
    Biomechanics, 20 (5); 459-469.

    Shiavi, R., Limbird, T., Frazer, M., Stivers, K., Strauss, A., and
    Abramovitz, J. (1987b). Helical Motion Analysis of the Knee - II.
    Kinematics of Uninjured and Injured Knees During Walking and Pivoting.
    Journal of Biomechanics, 20 (7); 653-665.

    Soutter, R. and Bradford, E.H. (1903). Twists in Normal and in
    Congenitally Dislocated Femora. New York Medical Journal and
    Medical Journal, 1071-1077.

    Staheli, L.T. (1993). Rotational Problems in Children. Journal of Bone
    and Joint Surgery, 75-A (6); 939-949.

    Staheli, L.T., Corbett, M., Wyss, C., and King, H. (1985). Lower
    Rotational Problems in Children: Normal Values to Guide Management.
    Journal of Bone and Joint Surgery, 67-A (1); 39-47.

    Stedman's Concise Medical Dictionary Illustrated (1994). Second
    Edited by James T. McDonough, Jr. Williams and Wilkins, Philadelphia.

    Stewart, S.F. and Karshner, R.G. (1926). Congenital Dislocation of the
    Hip: A Method of Determining the Degree of Antetorsion of the Femoral
    Neck. American Journal of Roentgenology Radium Therapy Nuclear
    15; 258-260.

    Sullivan, J.A., Vanhoutte, J.J., and Remondino, B. (1982). Femoral Neck
    Anteversion in Perspective. Clinical Orthopaedics and Related Research,
    163; 185-191.

    Terjesen, T. and Anda, S. (1987). Femoral Anteversion in Children
    by Ultrasound. Acta Orthopaedica Scandinavica, 58; 403-407.

    Terjesen, T. and Anda, S., and Svenningsen, S. (1990). Femoral
    in Adolescents and Adults Measured by Ultrasound. Clinical Orthopaedics
    and Related Research, 256; 274-279.

    Terjesen, T., Anda, S., and Ronningen, H. (1993). Ultrasound
    for Measurement of Femoral Anteversion in Children. Skeletal Radiology,
    22; 33-36.

    Tylkowski, C.M., Simon, S.R., and Mansour J.M. (1982). Internal
    Gait in Spastic Cerebral Palsy. The Hip: Proceedings of the Tenth Open
    Meeting of the Hip Society 10 pp. 89-125.

    Upadhyay, S.S., O'Neil, T., Burwell, R.G., and Moulton, A. (1987). A
    Method Using Ultrasound for Measuring Femoral Anteversion (Torsion):
    Technique and Reliability. The British Journal of Radiology, 60 (714);

    Vanhoutte, J.J. and Raeside, D.E. (1978). A Generalization of Chevrot's
    Method for Determining Anteversion and Cervico-Diaphyseal Angles.
    Radiology, 128; 251-252.

    Vaughan, C.L., Davis, B.L., O'Connor, J.C. (1992). Dynamics of Human
    Gait. Human Kinetics Publishers, Champaign, Illinois.

    Wadsworth, C.T. (1988). Manual Examination and Treatment of the Spine
    Extremities. Williams and Wilkins, Baltimore.

    Walmsley, T. (1933). The Vertical Axes of the Femur and Their
    A Contribution to the Study of the Erect Position. Journal of Anatomy,

    Weiner, D.S., Cook, A.J., Hoyt, W.A., and Oravec, C.E. (1978). Computed
    Tomography in the Measurement of Femoral Anteversion. Orthopedics, 1

    Weiner, D.S. and Cook, A.J. (1980). Practical Considerations in the Use
    Computed Tomography in the Measurement of Femoral Anteversion. Israel
    Journal of Medical Science, 16 (4); 288-294.

    Winter, D.A. (1991). The Biomechanics and Motor Control of Human Gait:
    Normal, Elderly and Pathological. (Second Edition) University of

    Woltring, H.J., Huiskes, R., and De Lange, A. (1985). Finite Centroid
    Helical Axis Estimation From Noisy Landmark Measurements in the Study of
    Human Joint Kinematics. Journal of Biomechanics, 18 (5); 379-389.

    Yoshioka, Y. and Cooke, T. D. V. (1987). Femoral Anteversion:
    Based on Function Axes. Journal of Orthopaedic Research, 5; 86-91.

    Yoshioka, Y., Siu, D., and Cooke, T. D. V. (1987) The Anatomy and
    Functional Axes of the Femur. Journal of Bone and Joint Surgery, 69-A

    Christoph Roth of the Orthopaedic Research Institute, Inc. (E-mail: suggested the following references:

    Reikeras O: Patellofemoral characteristics in patients with increased
    femoral anteversion. Skeletal Radiology (1992) 21:311-313

    Eckhoff DG, Montgomery WK, Kilcoyne RF, Stamm ER: Femoral morphometry
    anterior knee pain. Clinical Orthopaedics and Related Research (1994)

    Mesgarzadeh M, Revesz G, Bonakdarpour A: Femoral neck torsion angle
    measurement by computed tomography. Journal of Computer Assisted
    (1987) 11:799-803