A C T A MECHANICA SINICA, Vol. 2, No. 2, June, 1986 Science Press, Beijing, China
BIOMECHANICAL III. A N E X P E R I M E N T A L ON THE F E M U R ' S OF KNEE
178
RESEARCH OF JOINT BIOMECHANICAL R E S E A R C H ARTICULAR S U R F A C E OF P O N G I D A E
Zhang Renxiang, Lan Zuyun and Qu Wenji (Beijing University of Iron And Steel Technology)
A B S T R A C T : In this paper, moir6 contour fringes is applied to study the femur's articular surface of the knee of Pongidae. The preliminary division of the femur's articular surface of knee into three types is proposed. The moir6 contour fringes ofthe medial condyle is taken as a mark according to the references. Owing to the fact that the moir$ contour fringes obtained from experiments after the 2nd order of fringe basically follow a certain rule, an investigation is made on the distribution of the angle a which is defined as the angle of the major axis of the 2nd order's near-oval shaped moir6 contour fringe on the medial condyle with the horizontal axis. Preliminary distribution graphs are given in the paper. KEY WORDS:
biomechanies, Pongidae, Primates, moir6 topography, knee, condyle.
I. I N T R O D U C T I O N The movement style of the joint has a direct relationship with the shape of the contact surface of the joint. Therefore it is necessary to make a special investigation on the contact surface of the joint of the animal, particularly on the knee joint which is especially important. This paper continues the study of the knee joint of primates I1-3l. The results may be an useful reference in the study of biomechanics and primates. The molt6 contour fringes have been applied by many investigaters to determine the deformation of solid bodies [4's] and to examine the human body16'7]. Moreover, we have used it to show the articular surface of vertebrates [3].
II. M A T E R I A L S A N D M E T H O D 1. E x p e r i m e n t a l m a t e r i a l s All of the 26 pieces of intact and damageless specimens of 17 animals of Pongidae are borrowed from The Institute of Vertebrate Palaeontology and Palaesanthropology of The Chinese Academy of Sciences and The Animal Lab. of Biology Department of Peking University. 2. E x p e r i m e n t a l m e t h o d The grating irradiation of molt6 topography method was used in our experiments. The principle of the method is shown in Figure 1.
Received 25 April 1984.
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Fig. 1 Diagram of the principle of the grating irradiation type of moir6 topography. Place the femur to be examined on the horizontal board in the natural position. The grating is fixed on the front surface of the femur, perpendicular to the horizontal board. Both light source and the focus of camera are at the same plane which is behind and parallel with the grating plane. The perpendicular distance between the observational point and grating is e. Due to the interference of the light passing through the grating, on the surface of femur the moir6 contour fringes of black alternating with white can be seen. In our experiment, the pitch of grating is p = 0.25 mm, the distance between the observation point and light source is os = 200 ram, and the distance e = 510 ram. The center of the lens of the camera must be focused on the center of the examined subject. Shifting either up and down or right and left will affect the result of the measurement. In experimenting, the grating plane must be perpendicular to the horizontal board, or else there will be influence on the result of the measurement. With all other conditions fixed, a comparison is made of the moir6 fringes between the grating slanting 15.9 ~ and in normal position at an arbitrary section A - A as shown in figure 2. Photo 1 is the moir6 picture when the grating is perpendicular to the horizontal board, and photo 2 is the picture when the grating is inward 15.9 ~ slanting with the base.
Photo 1 The grating in normal position.
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Photo 2 The grating inward slanting 15.9".
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/ is~
p
:
//
J'
]., :
t
! t / N
0
10
20
30
40
50
70
80 x~,,
A--A
Fig. 2 The comparisonof the results betweenthe gratingin normal positionand inward slanting15.9~at an arbitrary cross section A - A . • ...... • The grating is in normal position. ...... The grating is slanted 15.9~, The grating plane must be the tangent or at the same distance of both femur condyles. W h e n all other conditions are fixed, Figure 3 compares the moir6 fringes between the one condyle of femur tangent with the grating, but the other condyle is 3 m m away from the grating and the grating is the tangent of both condyles. Photo 3 is the picture when the grating is tangent to both femur condyles. Photo 4 is the picture when one condyle of femur is tangent with the grating and the other condyle is 3 m m away from the grating.
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Photo 3 The grating is the tangent plane of two condyles.
Photo 4 The one condyle tangent with the gra~ing aod the other is 3ram away.
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~
60
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The comparison of moir6 contour fringes between tile tangent of both condyles and the one condyle tangent with
the grating, the other condyle is 3 m m away from the grating at an arbitrary cross section C-C. • ...... •
The one condyle tangent with the grating and the other is 3ram away.
......
The grating is the tangent plane of two condyles.
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ACTA MECHANICA SINICA
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The distance between the moir6 contour fringes and grating plane is h, as shown below (fig.l):
h. =
Kep
(1)
f sinO - K p
Using the notation: K is the order of moir6 contour fringe. p is the pitch of the grating. f is the distance between the light source and the observational point. e is the distance between the grating plane and observational point. 0 is the angle between the connecting line of the observational point and light source and the line of grating.
III. R E S U L T A N D D I S C U S S I O N S 1. Since the curved surface of femur's articular surface of knee is irregular, and for the purpose of comparison with each other, we must pay attention to the position of the femur's articular surface of knee relative to the grating, because it will influence the result of analysis. 2. From the experiment of 26 pieces of femur's articular surface of knee of 17 animals of Pongidae we know that the moir6 contour fringes of both condyles of femur's articular surface of knee are approximately ellipsis. According to the position of the fringes in the coordinate system, they can fall roughly into categories, approximately long oval shape, approximately oval at an arbitrary position and approximately oblate oval. 3. Under the experimental condition, the shape of moi% contour fringes of two condyles after the 2nd order is relatively stable. We define c~ as the angle of the major axis of 2rid order of moir6 contour fringes on the medial condyle with the horizontal plane. The a values of 26 pieces on the medial condyle of the femu's articular surface of knee are shown in table 1. When the medial condyle is at the second quadrant, value 7 is taken from the horizontal plane counter-clockwise, when the medial condyle is at the first quadrant value a is taken clockwise from the horizontal plane. Table 1 The ~ values on the medial condyle of the femur's articular surface of knee of Pongidae. No.
Specimen No.
Sex
Limb
Angle ~~
Remarks
1
318
male
left
60~
Gorilla
2
318
male
right
70~
Gorilla
3
319
male
left
175~
Gorilla
4
319
male
right
175~
Gorilla
5
322
male
left
60~
Gorilla
6
322
male
right
70~
Gorilla
7
324
female
right
170~
Gorilla
8
325
male
left
55~
Gorilla
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Zhang Renxiang et al: Biomechanical Research of Joint
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183
No.
Specimen No.
Sex
Limb
Remarks
9
325
male
right
55~
Gorilla
10
326
male
right
170~
Gorilla
11
327
r-role
right
170~
Gorilla
12
327
male
left
165~
Gorilla
13
328
female
left
65~
Gorilla
14
328
female
right
70~
Gorilla
15
333
male
left
60~
Gorilla
16
333
male
right
60~
Gorilla
17
391
female
left
55~
Gorilla
18
331
male
right
50~
Gorilla
19
800
right
55~
Gorilla
20
KS 5825
male
left
700
21
KS 5825
male
fight
70~
22
425
female
right
55~
Orang-utan
23
801
male
left
65~
Chimpanzee
24
801
male
right
50~
Chimpanzee
25
388.
left
40~
Chimpanzee (larva)
26
P.U.
right
165~
From table 1 we know that the value ~ on the medial condyle of Gorilla (Gorilla gorilla) are distributed in two areas, one is the 50~ ~ the other is 165~ ~ Also, a part of major axis of moir6 contour fringes of medial condyle of Gorilla belongs to approximately horizontal oblate oval shape, and the other part has major axis slanting in an arbitrary position. Therefore the Gorillas are divided into two categories depending on the moir$ contour fringes. Because of the limited n u m b e r of the specimens under test and vague type, the classication of the moir6 contour fringes in relation with the types of Gorilla remains to be further solved. 4. From experiment of the moir6 contour fringes of femur's articular surface of knee of Chimpanzee (Anthropopithecus troglodytes), we find that the 2nd order fringe of the medial condyle has major axis of the near-oval slanting. The value 0t on the medial condyle concentrates only in one area, it is near to the lower value of Gorilla. From the limited specimens which we borrowed the average value of ~ is just a little lower than Gorilla. Owing to the limit of the specimens, the present discossion is only preliminary. 5. According to table 1 distribution graph of 9 on the medial condyle of femur's articular surface of knee is shown in figure 4.
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.2/
Y 0
Fig. 4 The distributional graph of ~ on the medial condyle of femur's articular surface of knee of Pongidae.
The major axis of moir6 contour fringes on the lateral condyle of femur's articular surface of knee of Pongidae is approximately perpendicular to the horizontal board. ~' is the angle of major axis of molt6 contour fringes on the lateral condyle of femur's articular surface of knee with the horizontal board, value ~' is near 90 ~ But the medial condyle plays a leading role for working while standing straight. hank is due to The Institute of Vertebrate Palaeontology and Palaesanthropology of The Chinese ~cademy of Sciences and The Animal Lab. of Biology Department of Peking University for upplying the specimens. REFERENCES [1] Zhang, R.X., Experimental research of the human knee joint, Peking Institute of Iron And Steel Technology, (1979) (In Chinese). [2] Zhang, R. X., Lan, Z. Y., Zhang, X. Z. and Lu, M., Acta Machanica Sinica, I4, 3(1982), 308-310. (In Chinese). [3] Zhang, R. X., Lan, Z. Y. and Zhang, X. Z., SPIE Proc. 398(1983), 159. [4"] Guild, J., The Interference Systems of Crossed Diffraction Grating, Oxford (1956). [5] Meadows, D. M., Johnson; W. O. and Allen, J. B., Appl. Opt., 9, 4(1970), 942-947. [6"] Takasaki, H., Appl. Opt., 9, 6(1970), 1467-1472. [7] Zhang, R. X., Lu, M., Lan, Z. Y. and ~Zbang, X. Z., SPIE, 361(1982), 284-286.
