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  1. Joint capsule reinforcements - anteriorly
    • CT: patellar retinacular fibers (medial and lateral)
    • Muscular: quadriceps (quadriceps tendon & patellar tendon)
  2. Joint capsule reinforcements - laterally
    • CT: lateral collateral ligament (not a part of capsule), lateral patellar retinaculum, and iliotibial band
    • Muscular: biceps femoris and popliteus
  3. Joint capsule reinforcements - posteriorly
    • CT: oblique popliteal and arcuate popliteal
    • Muscular: gastrocnemius, hamstrings, and popliteus
  4. Joint capsule reinforcements - medially
    • CT: medial patellar retinaculum & medial collateral ligament (part of capsule)
    • Muscular: pes anserine group
  5. Mensici
    • Composition: fibrocartilage
    • Convert flat tibial plateaus to slight concave sockets
    • Anchored to tibia by: anterior/posterior meniscal horns & coronary ligaments (meniscotibial)
    • Transverse ligament links anterior horns
    • Attachments: [muscles] quadriceps (both), semimembranosus (both), and popliteus (lateral) & posterior meniscofemoral ligament
  6. Medial meniscus
    • C shaped
    • Attachments: deep MCL, Semimembranosus, quadriceps
    • Less mobile than the lateral mensicus: MCL attachemnt
  7. Lateral meniscus
    • O-shaped
    • Attachments: popliteus, semimembranosus, and quadriceps
    • No LCL attachment
    • Greater mobility than MCL
  8. Meniscal Functions
    • Cotnribute to joint stability
    • Lubication
    • Guiding knee motion
    • Distribute load in weight bearing (shock absorption)
  9. Medial collateral ligament
    • Flat, board ligament
    • Components: superifical and deep
  10. Medial Collateral ligament - superifical
    • origin at medial epicondyle
    • 10 cm long
    • attach posteiro to pes anserine
  11. Medial collateral ligament - deep
    • 6-7 cm
    • oblique
    • attached to medial meniscus and capsule
  12. Medial collateral ligament functions
    • Primary: resists valgus force
    • Secondary: tightens with knee extension
    • Secondary: resists extremes of medial and lateral tibial rotation when knee flexed
  13. Structures that resists valgus force
    • MCL
    • capsule
    • medial muscles
    • ACL
  14. Lateral Collateral ligament
    • extra-articular
    • cordlike
    • no attachment to lateral mensicus
    • Attachments: lateral epicondyle (femur) & fibular head (fibula)
  15. Lateral collateral ligament functions
    • Primary: resists varus stress
    • Secondary: tightens with knee extension
    • Secondary: resists extremes of medial & lateral tibial rotation when knee flexed
  16. Structures that resist varus forces
    • LCL
    • capsule
    • ITB
    • ACL
  17. Cruicate ligaments functions
    • important in control of arthrokinematics
    • mechanoreceptors present in ACL/PCL: sensory structures
  18. Anterior Cruciate ligament
    • Anatomy: anterior tibial spine to medial aspect of lateral femoral condyle
    • ACL tension changes through ROM
  19. ACL resists
    • Anterior translation of tibia on femur
    • Posterior translation of femur on tibia
    • End range extension
    • Extremes of varus, valgus, and rotation
  20. Anterior cruciate ligament - portions
    • posterolateral: main component & tightest in extension
    • anteromedial: tightest in flexion
  21. Posterior cruciate ligament
    • Shorter and stronger than ACL
    • Posterior tibia below plateau to lateral aspect of medial femoral condyle
  22. Posterior cruciate ligament - portions
    • anteriolateral: larger bundle, more taut in flexion
    • posteromedial: more taut in extension
  23. Posterior cruicate ligament resists
    • Anterior translation of femur on tibia
    • Posterior translation of tibia on femur
    • End range flexion
    • Extremes of varus, valgus, rotation
  24. Tibiofemoral osteokinematics - sagittal plane axis of rotation
    • Medial-lateral
    • Not fixed: migrates wiht ROM
    • Migrating axis changes the moment arm length
    • Influenced by contour of condyles
  25. Tibiofemoral osteokinematics - sagittal plane motion
    • 130-140 flexion
    • 5-10 hyperextension
  26. Function motion requirements at the knee
    • Gait: 60-70 degrees
    • Stair-climbing: 80-85 degrees
    • Standing from seated position: 100-115 degrees
  27. Voluntary rotation of the knee
    • Vertical axis through tibial intercondylar region
    • Effect of sagittal plane knee position on rotation range: amount of axial motion increases as knee flexes with greatest motion at 90 flexion- 40-45 & decreases toward flexion and full extension
    • Controlled by posterior musculature (horse reins)
    • Resisted by capsuloligamentous tension
  28. Automatic rotation at the knee
    • AKA "screw-home" mechanism
    • Mechanically involuntary coupled rotation that occurs in final 15 degrees of extension
    • Caused by: asymmetry of femoral articular surfaces & tension in ACL and PCL
    • "Locks" the knee in full extension
    • To flex the knee from a fully extended position, the knee has to be "unlocked"
    • Popliteus functions to initiate flexion by: medially rotating the tibia in OKC and laterally rotating the femur in CKC
  29. Automatic rotation of the knee - OKC
    • Motion of the lateral TF compartment stops before motion of the medial TF compartment
    • Tibia laterally rotates on the femur as knee fully extend
    • Ligaments and capsule tighten "screwing home" or "locking" the knee
  30. Automatic rotation of the knee - CKC
    Femur medial rotates on tibia as knee fully extends
  31. Active OKC extension - knee
    • Tibia rolls anterior and glides anterior
    • Tibia laterally rotates on femur
  32. Active CKC extension - knee
    • Femur rolls anterior and glides posterior
    • Femur medially rotates on tibia at terminal extension (locking)
  33. Active OKC flexion (from full extension) - knee
    • Tibia medially rotates on femur (unlocking)
    • Tibia rolls and glides posterior on femur
  34. Active CKC flexion (from full extension) - knee
    • Femur laterally rotates on tibia (unlocking)
    • Femur rolls posterior on tibia and glides anteriorly
  35. Knee positions
    • Close packed position: full extension, lateral rotation of tibia on femur (or medial rotation of emur on tibia in CKC)
    • Loose packed position: 25-30 degrees of flexion
  36. Alignment effect - genu varum
    if lateral tibiofemoral angle = 190, medial compartment loading is increased by 50%
  37. Alignment effect - genu valgum
    if lateral tibiofemoral angle = 165, lateral compartment loading is increased
  38. Genu Recurvatum
    • Excessive (>10) knee hypertension
    • Resisted by passive tension in posterior capsule
    • May be a result of: neuromuscular disease & postural habit
Card Set:
2011-12-04 16:55:13

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