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The Knee Complex

The Knee Complex . The Knee Complex. General Structure & Function Structure & Function of Specific Joints Muscular Considerations. General Structure. Joints of the Knee Complex. General Function. Provides very mobile link in an otherwise stable lower extremity

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The Knee Complex

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  1. The Knee Complex

  2. The Knee Complex • General Structure & Function • Structure & Function of Specific Joints • Muscular Considerations

  3. General Structure

  4. Joints of the Knee Complex

  5. General Function • Provides very mobile link in an otherwise stable lower extremity • Transmits loads from tibia/fibula to femur

  6. Knee Complex Movements

  7. Transverse plane • Medial and lateral • rotation • Sagittal plane • Flexion, extension

  8. Knee Complex Movements • Frontal plane • Varus, valgus • Anteroposterior translation • Mediolateral translation

  9. The Knee Complex • General Structure & Function • Structure & Function of Specific Joints • Muscular Considerations

  10. Structure & Function of Specific Joints • Tibiofibular Joint • Patellofemoral Joint • Tibiofemoral Joint

  11. Tibiofibular Joint: Bony Structure Amphiarthrodial membranous syndesmosis joint

  12. Structure & Function of Specific Joints • Tibiofibular Joint • Patellofemoral Joint • Tibiofemoral Joint

  13. Purpose of Patella • Increase leverage of QF • Protect joint during knee flexion • ↓ pressure and distribute forces on femur • Prevent Fcompression on PT in resisted knee flexion • Disadvantage:  ANT shear of QF

  14. Patella Structure • Medial facet • Lateral facet • Odd facet (30%) M L

  15. Largest sesamoid bone Least congruent joint Articular cartilage Vertical ridge Facets M L PF Articular Surfaces

  16. Largest sesamoid bone Least congruent joint Articular cartilage Vertical ridge Facets Angle of femoral sulcus PF Articular Surfaces

  17. INF & SUP Sliding Patellar tilt 11 MT as KN FL Med Lat Patellar Motion

  18. Lateral rotation ACC MR of femur 6 through KN FL Medial rotation ACC LR of femur Patellar Motion

  19. Patellalectomy • ↓ MA of QF (↓ strength 49%) •  Q tendon friction •  compressive stress on groove by Q tendon • Most evident in closed chain EXT • ECC QF in CC • Coupled w/ & assisted by hip & ankle movement • QF not needed in erect posture of CC

  20. Extension Little effect overall

  21. Slight Flexion Noticeable weakness

  22. Extreme Flexion Noticeable weakness

  23. From 0° to 60° of Knee Flexion

  24. 0-60 • Contact area  •  MA of QF;  60 •  ANT shear of QF 0-60 • Facet contact at 20

  25. From 60° to 140° of Knee Flexion

  26. 60-140 •  contact area •  MA of QF • No leverage in full FL

  27. Overall • Medial facet most contact • Odd facet least contact

  28. During Full Extension Full EXT •  MA of QF •  QF length • Patella very unstable

  29. PF JRF • Amount of knee FL • Strength of QF contraction

  30. PF Compressive Forces

  31. Compensatory Mechanisms for Compressive Force Distribution • Contact area  with knee flexion • Medial facet contact from 30-70 • Thickest hyaline cartilage in body

  32. Compensatory Mechanisms for Compressive Force Distribution • Contact area  with knee flexion • Medial facet contact from 30-70 • Thickest hyaline cartilage in body • Largest QF MA 30-70 • QF torque as MA decreases • QF tendon contacts condyles 70-90

  33. Normal Patella Tracking • Maintains maximum congruence • Passive restraints • Active restraints

  34. Abnormal Patella Tracking • ↓ congruence • Stretches capsule & retinacula • ↓ contact area Lateral Medial

  35. Causes of Abnormal Tracking • Skeletal abnormalities • Strength imbalance in QF • Strength imbalance in fibrous tissues • Compensatory movements in knee due to abnormal foot movement

  36. Causes of Abnormal Tracking • Skeletal abnormalities • Strength imbalance in QF • Strength imbalance in fibrous tissues • Compensatory movements in knee due to abnormal foot movement

  37. Skeletal Abnormalities: Q-angle

  38. Skeletal Abnormalities: Genu Varum & Genu Valgum • Q angle  w/ age • Varum common in very young children • Valgum seen in growing children • Menisectomy effects

  39. Skeletal Abnormalities: Patella Alta & Patella Baja • Index of Insall & Salviti • LT/LP • Normal = 1.0 • Patella alta = 0.8 • Patella baja = 1.2 • Women  ratio

  40. Skeletal Abnormalities: Patella Surface Lateral Border • Appositional forces ↓ in full extension • Prominence of lateral border prevents lateral displacement • Underdevelopment common in children as growing

  41. Lateral tracking Skeletal Abnormalities: Femoral & Tibial Torsion

  42. Causes of Abnormal Tracking • Skeletal abnormalities • Strength imbalance in QF • Strength imbalance in fibrous tissues • Compensatory movements in knee due to abnormal foot movement

  43. QF Strength Imbalance

  44. Causes of Abnormal Tracking • Skeletal abnormalities • Strength imbalance in QF • Strength imbalance in fibrous tissues • Compensatory movements in knee due to abnormal foot movement

  45. Fibrous Tissue Strength Imbalance IT

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