1. Knee

2. Knee Extensor Mechanism (KEM) Quadriceps Patellofemoral Joint Quadriceps Tendon/Ligament Patella Tendon

3. Function of Patella

4. Mechanical Advantage  rotary component of quadriceps force

5. Antatomy of Patella Facets Lateral Medial (7 mm) Odd (most media)

6. Antatomy of Patella

7. Patellofemoral Mechanics Knee Flexion Angle (degrees) Patella Contact 0 Little or no contact 10 - 20 Inferior margin across medial & lateral facets 20 - 90 Moves proximal and lateral 90 - 135 Medial facet  intercondylar notch, odd facet makes contact 135+ Contact via lateral and odd facets only

8. Patellofemoral Mechanics In general, With  flexion, contact migrates from inferior to superior Medial facet receives most consistent contact Odd facet least

9. Patellofemoral Mechanics 25  130 0 knee flexion: 11 0 of medial tilting about a vertical axis (lateral lip) 7 0 of lateral rotation about an anterior- posterior axis

10. Patellofemoral Joint Reaction Forces Gait (10-15 0 flexion) – 50% of BW Stair Climbing (60 0 of flexion) – 3.3 x BW Full Squat (135 0 ) – 7.8 x BW

11. Patellofemoral Joint Reaction Forces

12. Closed-Chain JRF increase from 0 – 90 0 flexion Open-Chain JRF decrease from 0 – 90 0 flexion

13. Patellofemoral Joint Reaction Forces Open-chain safest between 25 – 90 0 of flexion Closed-chain safest between 0 - 45 0 of flexion

14. Meniscus – Vasucular Supply AgeMeniscus Region Birth – 12 months100% *18 months – 18 years 25 – 33 % 50+  25%

15. Meniscus – Vasucular Supply

16. Meniscus – Neural Supply

17. Meniscus Innervation Inner 1/3 – none Outer 2/3 and horns (outer 1/3 > middle 1/3) Nocieptors (pain) Ruffini corpuscles (position) Pacinian corpuscles (acceleration) GTO (at end range)

18. Patella Rupture