Prentice14e Ppt Ch20 3

Chapter 20: The Knee and
Related Structures

© 2011 McGraw-Hill Higher Education. All rights

• Complex joint that endures great amounts of trauma due to extreme amounts of stress that are regularly applied • Hinge joint w/ a rotational component
• Stability is due primarily to ligaments, joint capsule and muscles surrounding the joint
• Designed for stability w/ weight bearing and mobility in locomotion

© 2011 McGraw-Hill Higher Education. All rights

Figure 20-1
© 2011 McGraw-Hill Higher Education. All rights

Figure 20-2

© 2011 McGraw-Hill Higher Education. All rights

Figure 20-3 A-B

© 2011 McGraw-Hill Higher Education. All rights

Figure 20-3 C

© 2011 McGraw-Hill Higher Education. All rights

Figure 20-4
© 2011 McGraw-Hill Higher Education. All rights

Figure 20-5 A & B
© 2011 McGraw-Hill Higher Education. All rights

Figure 20-5C
© 2011 McGraw-Hill Higher Education. All rights

Figure 20-6

© 2011 McGraw-Hill Higher Education. All rights

Figure 20-7

© 2011 McGraw-Hill Higher Education. All rights

Functional Anatomy
• Movement of the knee requires flexion, extension, rotation and the arthrokinematic motions of rolling and gliding • Rotational component involves the
“screw home mechanism”
– As the knee extends it externally rotates because the medial femoral condyle is larger than the lateral
– Provides increased stability to the knee
– Popliteus “unlocks” knee allowing knee to flex © 2011 McGraw-Hill Higher Education. All rights

• Capsular ligaments are taut during full extension and relaxed w/ flexion
– Allows rotation to occur
• Deeper capsular ligaments remain taut to keep rotation in check
• PCL prevents excessive internal rotation, limits anterior translation and posterior translation when tibia is fixed and non-weight bearing, respectively
• ACL stops excessive internal rotation, stabilizes the knee in full extension and prevents hyperextension
© 2011 McGraw-Hill Higher Education. All rights

• Range of motion includes 140 degrees of