Biomechanics unit 3

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Biomechanics unit 3
2011-11-11 15:34:53
unit LE gait

Knee, Gait
Show Answers:

  1. What type of joint is the Tibiofemoral Joint?
  2. Whta provides the limits to the motions of the Tibiofemoral joint?
    • Limitation to motion
    • No bony stops
    • 1st line of defense: Surface shape of meniscus
    • 2nd line of defense: Ligamentous tissue
    • 3rd line of defense: Musculature
  3. Femur projects laterally from vertical creating an angle on the lateral side of the knee this is it normal position what help resist change to the angle?
    Changes to normal are resisted by joint restraints -specificly

    Primary Line: of defense: Surface shape of meniscus

    Seondary Line: of defense: Ligamentous tissue
  4. What is Genu valgum?
    Genu valgum, commonly called "knock-knee", is a condition where the knees angle in and touch one another when the legs are straightened. Women have a wider pelvis than men and a relatively shorter length of the thigh bone, and as a result, have a greater static genu valgum than men. Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs. The term originates from the Latin genu, "knee", and valgus which actually means bent outwards, but in this case, it is used to describe the distal portion of the knee joint which bends outwards and thus the proximal portion seems to be bent inwards. For citation and more information on uses of the words Valgus and Varus, please visit the internal link to -varus. Mild genu valgum can be seen in children from ages 2 to 5, and is often corrected naturally as children grow. However, the condition may continue or worsen with age, particularly when it is the result of a disease, such as rickets or obesity. Idiopathic is the term used to describe genu valgum that is congenital or has no known cause.
  5. What tissues resist excessive valgus and what catagory of tissues are they?
    • Primary Valgus restraints
    • Medial collateral ligament (MCL)

    • Secondary valgus restraints
    • Medial capsule
    • Semimembranosus tendon
    • Anterior cruciate ligament (ACL)
    • posterior cruciate ligament (PCL)
    • Compression of lateral meniscus
    • Pes anserine tendons
    • Medial head of gastrocnemius
  6. What tissues resist excessive Genu Varum?
    Primary tissues - LCL

    • Secondary varus restraints
    • IT band
    • Popliteus tendon
    • Biceps femoris tendon
    • Compression of medial meniscus
    • ACL and PCL
    • Lateral head of gastrocnemius
    • Lateral capsule
  7. What is Genu recurvatum?
    Genu recurvatum is a deformity in the knee joint, so that the knee bends backwards. In this deformity, excessive extension occurs in the tibiofemoral joint. Genu recurvatum is also called knee hyperextension and back knee. This deformity is more common in women[citation needed] and people with familial ligamentous laxity. Hyperextension of the knee may be mild, moderate, or severe Normal range of motion (ROM) of the knee joint is from 0 to 135 degrees in an adult. Full knee extension should be 0 degrees. In genu recurvatum (back knee), normal extension is increased. The development of genu recurvatum, may lead to knee pain and knee osteoarthritis.
  8. What are the osteokinamatic motions and planes of the knee and the arthrokinamatic motions of the knee?
    • Flexion / Extension
    • Plane Sagittal
    • Arthrokinematics Roll/glide same (open chain)
    • Internal rotation / External rotation
  9. What are the Stabilizing Tissue of the capsule of the knee joint? and what do they resist?
    • Anterior - capsule
    • Patellar retinacular fibers
    • Patellar ligament
    • Quadriceps muscle

    Medial capsule - Resists extreme valgus movement

    Posterior capsule - Resists extreme hyperextension

    Lateral capsule - Resists extreme varus movement
  10. How the cruciate ligaments named and what do they resist?
    • Cruciate ligaments
    • Named according to their attachment on tibia
    • ACL is on the anterior tibia
    • PCL is on the posterior tibia
    • Resist anterior/posterior shear forces between tibia and femur
  11. How does the ACL attach and were?
    • Attachment
    • Femur:Posterior, medial side of lateral femoral condyle
    • Tibia:Anterior intercondylar area
  12. What are the functions of the ACL?
    • Limits extremes of all movements
    • Limits tibia on femur anterior translation
    • Femur on tibia posterior translation

    • At near extension the quadriceps can induce anterior tibial translation
    • The hamstrings can reduce anterior tibial translation throughout knee fleixon ROM
    • The soleus can reduce anterior tibial translation with a closed-chain contraction

    • Most fibers are taut with full extension
    • Limits both medial and lateral rotation of tibia/femur
    • May be dependent on other forces acting on knee
  13. What does the PCL do?
    • Limits the extremes of all movements
    • Limits tibia on femur posterior translation
    • Femur on tibia anterior translation
    • Popliteus can minimize posterior tibial translation on the femur
    • Most fibers are taut at full flexion
    • Limits both medial and lateral rotation of tibia/femur
    • May be dependent on other forces acting on knee
  14. List the functions of the MCL?
    • Limits valgus movement – primary restraint
    • Is best from 0 – 30° knee flexion; then becomes lax
    • Limits extremes of knee extension – assists when ACL is gone
    • Limits lateral rotation of tibia
  15. What are the functions of the LCL?
    • Limits varus movement – best in extension when ligament is taut
    • Limits extremes of knee extension
    • Limits lateral rotation of tibia
  16. What happens to the IT band in flexion and extension of the knee?
    As the knee is extended the IT band moves anterior to the mediolateral axis As the knee is flexed the IT band moves posterior to the mediolateral axis

    Can help limit anterior tibial translation when the knee is partially flexed
  17. What muscles help stabilize the menisci during knee movements?
    • Semimembranosus
    • Popliteus
  18. What are the functions of the menisci of the knee?
    • Shock Absorber
    • Triple area of joint contact
    • Supports 50-70% of the total load across the human knee
    • Stabilize joint during motion
    • Reduce friction
    • Guide knee arthrokinematics
    • Limit anterior and posterior translation
  19. What does the medial meniscus attach to? and why does this matter?
    • Attached to deep portion of MCL
    • Attached to semimembranosus
    • Attached to the ACL and PCL at the horns

    Immobility (due to attachments above) may lead to more frequent injuries
  20. What does the lateral meniscus attach to?
    • Attached to PCL via posterior meniscofemoral ligament
    • Attached to popliteus