Roughness ,lubrication and friction of normal and diseased knee joint has been introduced . Various surface roughness of articular cartilage have been determined during the gait cycle ( stance phase- swing phase) using squeeze film characteristics in knee joint, this paper aims to study the effects friction and roughness on stride length for male and female during daily activities. The mathematical model depended on the basis of the Stokes micro continuum theory as well as we used lubricant (Newtonian - non Newtonian) in case non Newtonian (micro-macro) roughness effect has been studied and we compared

2. Introduction
Roughness ,lubrication and friction of normal and
diseased knee joint has been introduced . Various
surface roughness of articular cartilage have been
determined during the gait cycle ( stance phase- swing
phase) using squeeze film characteristics in knee joint,
this paper aims to study the effects friction and
roughness on stride length for male and female during
daily activities. The mathematical model depended on
the basis of the Stokes micro continuum theory as
well as we used lubricant (Newtonian - non
Newtonian) in case non Newtonian (micro-macro)
roughness effect has been studied and we compared

3. Study through Squeeze
film characteristics in
the young and elderly
people for each sexes
pressure
film
load carry
capacity
Friction
force

4. Gait Cycle of normal Walk
•Describes important events occurring between two
successive heel contacts of same limb Gait cycle is
described as occurring between 0% and 100% and
includes 2 primary phases, the stance phase and
swing phase

5. Stance phase
Toe-off
Mid-stance
Terminal
Stance
Initial
contact
Loading
Response
Gait Cycle Division
Swing phase
Mid-swing
Terminal
swing
Initial swing

7. Gait parameters
2. Stride Length: the distance between successive points of
heel contact of the same foot
1.Cycle time: The time required in seconds to complete
one walking cycle
Figure (2) Methods for measuring step length and stride length

8. Table (1) shows the stride length for male and female at normal walking speed

9. Figure (3) shows the method measure gait cycle

10. Analysis
• Based upon Reynolds equation ,effects of macro- roughness on
the squeeze film characteristics between articular cartilage
surface is analyzed .Comparing with the micro- roughness case.
So we can calculated the Pressure in synovial film .
• In equation (1) the first and two terms of the are the Poiseuille
flow expresses the relationship between the rate of flow of a
lubricant in a film thickness and the Pressure gradient in the
film. The three and four terms physical wedge and squeeze film
effect are the two major Pressure -generating devices in
hydrodynamic or self-acting fluid film bearings . For
hydrodynamic lubrication the motion is pure sliding ,so that V is
zero, applying the assumptions hydrodynamic lubrication theory
equation (1) becomes
(1)  
     effectfilm
1221
33
)(12
)(
)(6).().(
Squeeze
wedgePhyical
a
Poieuille
VV
x
h
UUR
y
ph
yx
ph
x

















11. (2)
This equation can be integrated with respect to x to give
(3)
In order to solve the Reynolds equation , the integral constants
must be determined ,based on dimensionless Pressure boundary
conditions .Natural boundary condition is:
.
(4)
x
h
UR
x
ph
x
a






 )(
6).(
3

Where 21 UUU 
𝑑𝑃
𝑑𝑥
= 0 𝑎𝑡 𝑥 = 𝑥 𝑜 , ℎ = ℎ 𝑜
∴ 𝑍 = −6𝑈𝑅 𝑎ℎ 𝑜

12. Substituting this into equation (3) gives
(5)
Where ℎ 𝑜 = minimum film thickness when 𝑑𝑝 𝑑𝑥 = 0
ℎ = ℎ 𝑜 +
𝑥2
2𝑅
(6)
Figure (4) Shape film

13. Now substitute equation (6) in equation (5)
(7)
(8)
Substituting equation (8) in equation (6)
(9)
(10)
Now derivative
(11)

14. Film Dim. Pressure of the roughness journal bearing representing
the knee joint
Introducing the following non- dimensional quantities of the
governing equation of pressure
Applying the above dimensionless equations in equation (7) .Thus
the final dimensionless from of the modified Reynolds becomes :
(13)
(14)
(16)
The Dim. Pressure equation become
(15)

15. Applying the boundary conditions 𝑃 = 0 , 𝛽 = 1.5 on equations
(1.13) hence it was obtained the
integration constant 𝐾 = +
6.614
ℎ0
∗
3
2
𝑅 𝑎 + 0.58 𝑆𝑒𝑐2 𝛽 .Substituting
for K into the equation (9) to get general form:
𝑃∗
=
8.4𝑅 𝑎
(ℎ0
∗
)3/2
[
𝛽
2
+
𝑆𝑖𝑛 2𝛽
4
+ 𝑆𝑒𝑐2 𝛽
3𝛽
8
+
𝑆𝑖𝑛 2𝛽
4
+
𝑆𝑖𝑛 4𝛽
32
+
6.614
ℎ0
∗
3
2
𝑅 𝑎 + 0.58 𝑆𝑒𝑐2 𝛽 (17)

16. 2.2 The load carrying capacity
The load carrying capacity of the porous partial articular cartilage
is evaluated by integrating the Dim. Pressure film action on knee
joint :
𝑊 = 2𝜋
0
𝑅
𝑃𝑟𝑑𝑟
Introduce the non-dimensional load carrying capacity in
consideration to roughness porosity cartilage
𝑊∗ =
𝑊 𝐻 𝑜
𝜇. 𝑈. 𝑅2
Substituted equation (18) into (19), and we integrate dimensional
Pressure with respect to the dimensional radial and thus we obtain
(18)
(19)

17. (20)
(21)
2.3 Frication force
Frication friction between surface cylinder and surface plane is a
very important factor in synovial knee joint ,to find frication
force depended on shear stress action on the ball surface.

18. (22)
The frictional force is given by :
(23)
(24)
Substitute Dim. Pressure (p*) from equation (17) in equation (24)
to obtain the final dimensionless friction force in the synovial fluid
pass through the synovial knee joint.
Hitting the two parties by the formula above to convert the equation
(14) to the following formula:
(25)

19. Result and discussion :
On the basis of Reynolds equations , this paper examines the effective of
roughness on synovial human knee joint in case (normal -disease ) joint during
normal walk .To take into account the friction force effects due to the number
stride length for male and female during cycle time
Fig.5.Variation of Dim. Pressure film with stride length for different values of
cycle time
1. Squeeze film Pressure

20. Stride length in young Stride length in older
Film
thickness
Time(s) Dim.
Pressure
film
Film
thickness
Time(s) Dim .Pressure
Film
0.72 1.2 2.6 0.72 1.2 3.3
0.50 2.4 2.3 0.50 2.4 2.09
0.41 3.6 2.2 0.41 3.6 1.98
0.35 4.8 2.1 0.35 4.8 1.90
0.32 6 2.09 0.32 6 1.86
0.29 7.2 2.05 0.29 7.2 1.82
0.27 8.4 2.02 0.27 8.4 1.80
0.25 9.6 1.99 0.25 9.6 1.77
Table (2) Relation between. Dim. Pressure film and
film thickness

21. Fig.6.Variation of Dim. .Pressure film with stride length for different values of micro-
roughness and macro- roughness

22. Table(3).Relation between Dim. Pressure film and roughness
parameter during daily active
Fig.7.Variation of Dim. Pressure film with film thickness for different
values of stride length

23. 2. Load carrying capacity
Fig.8.Variation of dim. load carrying capacity with Stride length for different values of
micro- roughness and macro-roughness
Fig.9.Variation of load carrying capacity with
surface roughness parameter for different
values of Stride length

24. Table (4) Relation between Dim .load carrying capacity and type
lubrication with different stride length parameter during daily
active

25. 3.Friction force
Fig.(10.) Variation of Dim. friction force with Stride length for different values
(a) micro roughness parameter (b) macro roughness parameter
(b)(a)

26. Fig.11. Variation of Dim. friction force
with roughness parameter for different
values of Dim. Stride length
Fig.12 Comparison of effective Dim.
Friction force for male female.

27. Conclusion
1. The use of squeeze film lubrication for knee joint during gait cycle led to
higher level pressure film between articular cartilage that is clearly in swing
phase compared with stance phase where low surface roughness.
2. roughness in (one- two -three) cycle very little a result, we find that level
pressure film between articular cartilage is higher due to flow lubricant
after ten cycle roughness increasing as well as loads on the joint this
correlates inversely with pressure film.
3.In older person become stride length very small since diseases joint
(osteoarthritis- arthritis) and increase in weight this led to movement
obstruction, therefore bone of the knee joint become weaken and pressure
film reduce compare as health joint.
•
4. since stress is less on the joint in swing phase where the roughness of
articular is micro making load carrying capacity with different minimal film
thickness in (one- two-three) cycle time is less as compared to stance phase
that increase weight so load carrying capacity.

28. • 5. The big stride of young led to double the weight and increase in motion
resulting from it increase in load carrying capacity this correlates inversely
with stride length for elderly
• 6. The friction increases in the surface macro -roughness more than micro-
roughness for all stride length in healthy and diseases .
•
• 7. The higher value of friction is attributed to the higher value of surface
roughness in stance phase .
• 8. Stride length is different between male and female from young to
elderly during the gait cycle thus the friction force be more increase with
respect to female from male.
•
• 9. In the elderly the length of the stride less thus it increases friction and
wear on the one- cycle to reach the highest level after ten cycles where
less pressure and increase friction and roughness. When the young where
the joint is normal and durability is high, resulting in a decrease in friction.