Download Tendon and Ligament

Tendon and Ligament
Roles of Ligaments and
Joint Capsules
 Assist
in Stabilization of Joint
 Restrict
Movement
 Prevent
Excessive Motion
Roles of Tendons
 Attach
muscle to bone
 Transmit
 Position
tensile loads
of muscle relative to joint
Mechanical Behavior of
Tendons and Ligaments
 Both
are viscoelastic tissues
 Visco - a small amount of load results in
quite a bit of deformation (relative)
 Elastic - refers to Elastic Region
 Importance of viscoelastic qualities?
Properties of Tendon
 can
sustain high tensile loads
 flexible
to allow changes in direction of
muscle pull
Properties of Ligament
 guides
movement
 resists
applied force
Mechanical Properties
of Tendon and Ligament
 Strength
 Stiffness
Damage to Tendon and
Ligament
 When
load is great enough to cause
injury, damage is dependent on:
 rate
and
 amount of load
Load-Deformation Curve
for Tendon and Ligament
 (0,0)
- A: Toe Region
 A - B: Elastic Region
 B: Yield Point
 B - C: Plastic Region
 C: Ultimate Failure Point
Comparison of Bone to
Tendon and Ligament
 Identify
similarities and differences
between these tissue types.
Mechanical Properties of
Tendon and Ligament
 Strength
 Stiffness
Injury Mechanisms
 Injury
occurs when tissue is loaded
beyond its physiological range.
 Microfailure occurs before the yield
point is reached.
Injury Mechanisms cont.
 When
yield point is exceeded, the
ligament begins to undergo gross
failure.
 Results
in abnormal joint displacement
 Displacement
results in...
3 Clinical Categories of
Ligament Injury
 Negligible
Clinical Symptoms (Grade 1)
 no
joint instability can be detected
clinically
 Severe
 joint
Pain (Grade 2)
instability can be detected clinically
 strength and stiffness decreases by 50%
 instability can be masked by muscle
involvement
3 Clinical Categories of
Ligament Injury cont.
 Severe
Pain (Grade 3)
 severe
pain experienced during the injury
with less pain after the injury
 joint is completely unstable
 most collagen fibers have ruptured
Noyes Study (1977)
 Rhesus
monkeys
 8 wks immobilization
 returned to mobilization
 at 12 mo. mechanical properties were
comparable to non-immobilized
ligaments.
 Drumroll?
Additional Factors Important
in Tendon Injury
 Amount
of force produced by muscle
 Stress comparison between tendon and
muscle
 Loading Rates
Factors Affecting Biomechanical
Properties of Tendon and Ligament
 Aging
 Pregnancy
 Mobilization
 NSAIDs
vs. Immobilization
Osteoarthritis
 Researchers
suggest that a deficiency in
mechanisms that minimize peak forces
may cause osteoarthritis.