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Presented byShubham Rao

Knee Joint

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The Knee:

The largest and most complex joint structure Transmit Loads Participate in motion

Aids conservation of momentum Provides a force couple for body activities

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Definitions:

Kinematics is the study of movement withoutreference to forces

Kinetics is the study of movement withreference to forces

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Anatomy of the knee

3 Bones

Tibia, Femur, Patella 3 Compartments Medial, Lateral, Patellofemoral

4 Ligaments MCL, LCL, ACL, PCL 2 Menisci

Articular Cartilage

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The Knee Joint

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Menisci Functions

Deepen the articulation

Increase area of contact Shock absorption a skier lands from a jump

Increase stability Cups the femoral condyle Nutrition of cartilage

Sweeping synovial fluid across joint

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Range of Motion

Three different planes inwhich movements of theknee takes place

1. Sagittal plane2. Frontal plane3. Transverse plane

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Tibia-femoral motion in theTransverse plane Influenced by knee position in Sagittal plane

Ex. If knee is in full extension rotation isrestricted by interlocking of condyles withtibia

Rotation increases as the knee is flexed maximum 90 degree flexion Beyond 90 degree decreases, due to soft tissue restriction

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Tibia-femoral motion in the frontalplane Abduction and Adduction is also affected by the

amount of knee flexion Ex. Full extension precludes motion

Vulgus /Varus

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Types of motion at knee joint

Rolling Motion

Initiates flexion

Gliding Motion

Occurs at end of flexion

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Gliding Motion

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Rolling Motion

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Instantaneous Center of RotationICR "If one rigid body rotates

about another rigid body,

its motion at any instantcan be described by apoint or axis of rotationcalled the instantaneouscenter of rotation.

For normal knees Pathway of ICR is

semicircular Located on the femoral

condyles

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Joint Contact Forces

We would haveequal distributionof forces w/o any

varus or valgusstresses

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Patellar Kinematics

Patella or the knee cap is directly in contact with the femoral

condyles in flexion It is said to be lateral side dominant dominant Greater surface area of contact on the lateralside as opposed to the medial

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