In this study, we had subjects voluntarily generate various forces in a transverse plane just above their ankles. The contributions of their muscles and soft tissues to the support of the total external knee joint moment were determined by analyzing the experimental data using a biomechanical model of the knee. In this model, muscle forces were estimated using the recorded EMGs. To account for subject variability, various muscle parameters were adjusted using a nonlinear least-squares fit of the model’s estimated flexion and extension joint moments to those recorded externally. Using the estimated muscle forces, the contributions from the muscles and other soft tissues to the total joint moment were obtained. The results showed that muscles were primarily used to support flexion and extension loads at the knee, but in so doing, were able to support some part of the varus or valgus loads. However, soft tissue loading was still required. Soft tissues supported up to an average maximum of 83 percent of the external load in pure varus and valgus. Soft tissue loading in pure varus and valgus was less than 100 percent of the external load as the muscles, on average, were able to support 17 percent of the external load. This muscle support was by virtue of muscle cocontraction and/or specific muscle activation.

1.
Andriacchi
T. P.
,
Andersson
G. B. J.
,
O¨rtengren
R.
, and
Mikosz
R. P.
,
1984
, “
A Study of Factors Influencing Muscle Activity About the Knee Joint
,”
J. Othop. Res.
, Vol.
1
, No.
3
, pp.
266
275
.
2.
Buchanan
T. S.
,
Moniz
M. J.
,
Dewald
J. P. A.
, and
Rymer
W. Z.
,
1993
, “
Estimation of Muscle Forces About the Wrist Joint During Isometric Tasks Using an EMG Coefficient Method
,”
J. Biomech.
, Vol.
4
,
547
560
.
3.
Cantani
S.
,
Hodge
W. A.
, and
Mann
R. W.
,
1988
, “
The Role of Co-Contraction During Human Movement
,”
Trans. Orthop. Res. Soc.
, Vol.
13
, pp.
546
546
.
4.
Cheng, C. K., 1988, “A Mathematical Model for Predicting Bony Contact Forces and Muscle Forces at the Knee During Human Gait,” PhD thesis, University of Iowa, Iowa City, IA.
5.
Cholewicki
J.
, and
McGill
S. M.
,
1994
, “
EMG Assisted Optimization: A Hybrid Approach for Estimating Muscle Forces in an Indeterminate Biomechanical Model
,”
J. Biomech.
, Vol.
27
, pp.
1287
1289
.
6.
Crowninshield
R. D.
,
1978
, “
Use of Optimization Techniques to Predict Muscle Forces
,”
J. Biomech. Eng.
, Vol.
100
, pp.
88
92
.
7.
Crowninshield
R. D.
, and
Brand
R. A.
,
1981
, “
A Physiologically Based Criterion of Muscle Force Prediction in Locomotion
,”
J. Biomech.
, Vol.
14
, pp.
793
801
.
8.
Crowninshield
R. D.
,
Pope
M. H.
,
Johnson
R. J.
,
1976
, “
An Analytical Model of the Knee
,”
J. Biomech.
, Vol.
9
, pp.
397
405
.
9.
Delagi, E. F., Perotto, A., Iazzetti, J., and Morrison, D., 1982, Anatomic Guide for the Electromyographer, Charles C. Thomas, Springfield, IL.
10.
Delp
S. L.
,
Loan
J. P.
,
Hoy
M. G.
,
Zajac
F. E.
,
Topp
E. L.
, and
Rosen
J. M.
,
1990
, “
An Interactive Graphics-Based Model of the Lower Extremity to Study Orthopaedic Surgical Procedures
,”
IEEE Trans. Biomed. Eng.
, Vol.
37
, pp.
757
767
.
11.
Eloranta
V.
,
1989
, “
Coordination of the Thigh Muscles in Static Leg Extension
,”
Electromyogr. Clin. Neuroohysiol.
, Vol.
29
, pp.
227
233
.
12.
Goldfuss
A. J.
,
Morehouse
C. A.
, and
LeVeau
B. F.
,
1973
, “
Effect of Muscular Tension on Knee Stability
,”
Med. Sci. Sports
, Vol.
5
, pp.
267
271
.
13.
Goldspink
D. F.
,
Easton
J.
,
Winterburn
S. K.
,
Williams
P. E.
, and
Goldspink
G. E.
,
1991
, “
The Role of Passive Stretch and Repetitive Electrical Stimulation in Preventing Skeletal Muscle Atrophy while Reprogramming Gene Expression to Improve Fatigue Resistance
,”
J. Cardiac Surg.
, Vol.
6
(
Suppl 1
), pp.
218
24
.
14.
Gordon
A. M.
,
Huxley
A. F.
, and
Julian
F. J.
,
1966
, “
The Variation in Isometric Tension with Sarcomere Length in Vertebrate Muscle Fibres
,”
J. Physiol.
, Vol.
184
, pp.
170
192
.
15.
Hatze
H.
,
1981
, “
Estimation of Myodynamic Parameter Values from Observations on Isometrically Contracting Muscle Groups
,”
Eur. J. Appl. Physiol.
, Vol.
46
, pp.
325
338
.
16.
Hawkins
D. A.
, and
Hull
M. L.
,
1992
, “
An Activation-Recruitment Scheme for Use in Muscle Modeling
,”
J. Biomech.
, Vol.
25
, pp.
1467
1476
.
17.
Hasler
E. M.
,
Denoth
J.
,
Stacoff
A.
, and
Herzog
W.
,
1994
, “
Influence of Hip and Knee Joint Angles on Excitation of Knee Extensor Muscles
,”
Electromyogr. Clin. Neuroohysiol.
, Vol.
34
, pp.
355
361
.
18.
Herzog
W.
, and
Leonard
T. R.
,
1991
, “
Validation of Optimization Models that Estimate the Forces Exerted by Synergistic Muscles
,”
J. Biomech.
, Vol.
24
(
Suppl. 1
), pp.
31
39
.
19.
Herzog
W.
,
Abrahamse
S. K.
, and
Henk
E. D. J. ter Keurs
,
1990
, “
Theoretical Determination of Force-Length Relations of Intact Human Skeletal Muscles Using the Cross-Bridge Model
,”
Eur. J. Physiol.
, Vol.
416
, pp.
113
119
.
20.
Hoy
M. G.
,
Zajac
F. E.
, and
Gordon
M. E.
,
1990
, “
A Musculoskeletal Model of the Human Lower Extremity: The Effect of Muscle, Tendon, and Moment Arm on the Moment-Angle Relationship of Musculotendon Actuators at the Hip, Knee, and Ankle
,”
J. Biomech.
, Vol.
23
, pp.
157
169
.
21.
Hof
A. L.
, and
Van den Berg
J.
,
1977
, “
Linearity Between the Weighted Sum of EMG’s of the Human Triceps Surae and Total Torque
,”
J. Biomech.
, Vol.
10
, pp.
529
539
.
22.
Huijing
P. A.
,
1985
, “
Architecture of the Human Gastrocnemius Muscle and Some Functional Consequences
,”
Acta. Anat.
, Vol.
123
, pp.
101
107
.
23.
Kaufman
S. R.
,
An
K. N.
,
Litchy
W. J.
,
Morrey
B. F.
, and
Chao
E. Y. S.
,
1991
a, “
Dynamic Joint Forces During Knee Isokinetic Exercise
,”
American Journal of Sports Medicine
, Vol.
19
, pp.
305
16
.
24.
Kaufman
K. R.
,
An
K. N.
,
Litchy
W. J.
, and
Chao
E. Y. S.
,
1991
b, “
Physiological Prediction of Muscle Forces—II. Application to Isokinetic Exercise
,”
Neuroscience
, Vol.
40
, pp.
793
804
.
25.
Kendall, F. P., and McCreary, E. K., 1983, Muscles, Testing and Function. Williams and Wilkins, Baltimore, MD.
26.
Kettelkamp
D. B.
,
Hillberry
B. M.
,
Murrish
D. E.
, and
Heck
D. A.
,
1988
, “
Degenerative Arthritis of the Knee Secondary to Fracture Malunion
,”
Clinical Orthopaedics & Related Research
, Vol.
234
, pp.
159
69
.
27.
Komi
P. V.
, and
Viitasalo
J. H. T.
,
1976
, “
Signal Characteristics of EMG at Different Levels of Muscle Tension
,”
Acta. Physiol. Scand.
, Vol.
96
, pp.
267
276
.
28.
Lippold
O. C. J.
,
1952
, “
The Relationship Between Integrated Action Potentials in the Human Muscle and its Isometric Tension
,”
J. Physiol.
, Vol.
177
, pp.
492
499
.
29.
Lloyd, D. G., and Buchanan, T. S., 1994, “Determination of Muscle and Ligament Contributions to the Knee Moments Based on a Biomechanical Model and Experimental Data,” Proceedings of the 2nd World Congress on Biomechanics, Amsterdam, The Netherlands, Vol. II, pp. 152.
30.
McFaull, S., and Lamontagne, M., 1995, “The Passive Elastic Moment about the in vivo Human Knee Joint,” J. Biomech. (submitted).
31.
McGill
S. M.
, and
Norman
R. W.
,
1986
, “
Partitioning of the L4/L5 Dynamic Moment Into Disc, Ligamentous and Muscular Components During Lifting
,”
Spine
, Vol.
11
, pp.
666
678
.
32.
Morgan, D. L., 1994, “Sacromere Non-Uniformities During Lengthening of Active Muscle,” Proceedings of the 2nd World Congress on Biomechanics, Amsterdam, the Netherlands, Vol. II, pp. 93.
33.
Morrison
J. B.
,
1970
, “
The Mechanics of the Knee Joint in Relation to Normal Walking
,”
J. Biomech.
, Vol.
3
, pp.
51
61
.
34.
Noyes
F. R.
,
Schipplein
O. D.
,
Andriacchi
T. P.
,
Saddemi
S. R.
, and
Wise
M.
,
1992
, “
The Anterior Cruciate Ligament-Deficient Knee with Varus Alignment
,”
Am. J. Sports Med.
, Vol.
20
, pp.
707
716
.
35.
O’Connor
J. J.
,
1993
, “
Can Muscle Co-Contraction Protect Knee Ligaments after Injury or Repair?
,”
J. Bone Joint Surg. [Br]
, Vol.
75-B
, pp.
41
48
.
36.
Onley
S. J.
, and
Winter
D. A.
,
1985
, “
Predictions of Knee and Ankle Moments of Force in Walking From EMG and Kinematic Data
,”
J. Biomech.
, Vol.
18
, pp.
9
20
.
37.
Seireg
A.
, and
Arvikar
R. J.
,
1973
, “
The Prediction of Muscular Load Sharing and Joint Forces in the Lower Extremities During Walking
,”
J. Biomech.
, Vol.
8
, pp.
89
102
.
38.
Schipplein
O. D.
, and
Andriacchi
T. P.
,
1991
, “
Interaction Between Active and Passive Knee Stabilizers During Level Walking
,”
J. Orthop. Res.
, Vol.
9
, pp.
113
119
.
39.
Shreeve
D. A.
,
Buchanan
T. S.
,
1993
, “
An Evaluation of Optimization Techniques for Estimation of Muscle Forces Based on EMGs During Static Isometric Tasks
,”
Proceedings of IEEE Engng. Med. Biol.
, Vol.
15
, pp.
1186
1187
.
40.
Thelen
D. G.
,
Schultz
A. B.
,
Fassois
S. D.
, and
Ashton-Miller
J. A.
,
1994
, “
Identification of Dynamic Myoelectric Signal-to-Force Models During Isometric Lumber Muscle Contractions
,”
J. Biomech.
, Vol.
27
, pp.
907
919
.
41.
Van den Bogert, A. J., Janssen, C., and Herzog, W., 1993, “Isometric Properties of Lower Extremity Muscles in Cycfists Determined by Least-Squares Fitting of Muscle Models,” Proceedings of XIVth ISB Conference. Paris, France, pp. 1382–1383.
42.
White
A. A.
, and
Raphael
I. G.
,
1972
, “
The Effect of Quadricep Loads and Knee Position on Strain Measurements of the Tibial Collateral Ligament. An Experimentation Study on Human Amputation Specimens
,”
Acta. Orthop. Scand.
, Vol.
43
, pp.
176
187
.
43.
Williams
P. E.
,
1988
, “
Effect of Intermittent Stretch on Immobilized Muscle
,”
Annals of the Rheumatic Diseases
, Vol.
47
, pp.
1014
1016
.
44.
Winter, D. A., 1990, Biomechanics and Motor Control of Human Movement, 2nd Ed., Wiley, New York, NY.
45.
Zajac, F. E., 1989, “Muscle and Tendon: Properties, Models, Scaling and Application to the Biomechanics of Motor Control,” Critical Reviews in Biomedical Engineering, Bourne J. R., ed., CRC Press, Vol. 17, pp. 359–411.
46.
Zuniga
E. N.
, and
Simons
D. G.
,
1969
, “
Non-Linear Relationship Between Averaged Electromyogram Potential and Muscle Tension in Normal Subjects
,”
Arch. Phys. Med.
, Vol.
50
, pp.
613
620
.
This content is only available via PDF.
You do not currently have access to this content.