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Knee Joint

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Knee Joint ... The knee joint is robust but given the complexity of its ... It is firmly adherent to the deep surface of the tibial collateral ligament. ... – PowerPoint PPT presentation

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Title: Knee Joint


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Knee Joint
  • The knee is primarily a hinge joint allowing
    flexion extension these movements are
    accompanied by gliding rolling in addition to
    rotation about a vertical axis. The knee joint
    is robust but given the complexity of its
    movements which must occur during loading at or
    above body weight its function is often at risk
    particularly when it is hyperextended. Knee
    injuries are consistently the most common cause
    of disabling injuries in the NFL

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Articular surfaces
  • The knee consists of three articulations
  • 1. Two femorotibial articulations (lateral
    medial) between the lateral medial femoral and
    tibial condyles.
  • 2. One intermediate femoropatellar articulation
    between the patella and femur
  • The fibula is not involved in the knee joint.

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  • The stability of the knee joint depends on
  • 1. Strength and actions of surrounding muscles
    and tendons, the most important muscles in
    stabilizing the knee are the quadriceps femoris
    particularly the fibers of the vastus lateralis.
  • 2. Ligaments connecting the femur tibia

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Joint Capsule
  • The joint capsule consists of an external fibrous
    layer and an internal synovial membrane that
    lines the internal surfaces of the articular
    cavity not covered by articular cartilage.
  • The fibrous layer attaches to the femur
    superiorly just proximal to the articular margins
    of the condyles.
  • Posteriorly it encloses the condyles the
    intercondylar fossa.
  • The fibrous layer has an opening posterior to the
    lateral tibial condyle to allow the popliteus
    tendon to pass out of the joint capsule and
    attach to the tibia.
  • Inferiorly the fibrous layer attaches to the
    margins of the articular surface of the tibia
    (tibial plateau).

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  • The quadriceps tendon, patella patellar
    ligament are intimately applied to the fibrous
    capsule anteriorly.

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  • The synovial membrane lines the internal aspects
    of the fibrous capsule and attaches to the
    periphery of the patella and the edges of the
    cartilaginous menisci.
  • The synovial membrane reflects from the posterior
    aspect of the joint anteriorly into the
    intercondylar region, covering the cruciate
    ligaments and the infrapatellar fat pad
    separating them for the articular cavity. This
    creates a median infrapatellar synovial fold, a
    vertical fold of synovial membrane that
    approaches the posterior aspect of the patella
    creating left right femorotibial articular
    cavities.
  • Fat filled lateral medial alar folds cover the
    inner surface of the fat pads that occupy the
    space on each side of the patellar ligament
    internal to the fibrous layer.

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  • Superior to the patella, the knee cavity extends
    deep to the vastus lateralis as the suprapatellar
    bursae.
  • Muscle fibers of the vastus intermedius form the
    articular muscle of the knee which attaches to
    the synovial membrane and retracts the bursa
    during knee extension.

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Ligaments
  • The joint capsule is strengthened by 5
    extracapsular (capsular) ligaments
  • 1. Patellar ligament The distal part of the
    quadriceps tendon, it passes from the apex and
    margins of the patella to the tibial tuberosity.
    Laterally it receives aponeurotic expansions of
    the vastus lateralis (medial lateral
    retinacula) these are important for maintaining
    the alignment of the patella.
  • The collateral ligaments are taut in extension
    but become lax as the knee flexes which allows
    rotation of the knee.
  • 2. Fibular (Lateral) collateral ligament Extends
    inferiorly from the lateral epicondyle of the
    femur to the lateral surface of the head of the
    fibula. The tendon of the popliteus passes deep
    to the FCL separating it from the lateral
    meniscus. The FCL splits the tendon of the
    biceps femoris.

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Ligaments
  • 3. Tibial (Medial) collateral ligament (TCL)
    extends from the medial epicondyles of the femur
    to the medial condyle and superior medial surface
    of the tibia. The deep fibers of the TCL are
    attached to the medial meniscus.
  • 4. Oblique popliteal ligament This is a
    reflected expansion of the tendon of the
    semimembranosus that strengthens the joint
    capsule posteriorly. It arises from the medial
    tibial condyle passes superolaterally to the
    central part of the posterior aspect of the joint
    capsule.
  • 5. Arcuate popliteal ligament strengthens the
    capsule posterolateral. It arises from the
    posterior aspect of the fibular head passes
    supero-medially over the popliteal tendon and
    attaches to the posterior surface of the knee
    joint.

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Intra Articular ligaments (cruciate menisci,
popliteus tendon)
  • Cruciate ligaments These ligaments join the
    femur to the tibia, cris-crossing within the
    joint but outside the articular cavity. These
    ligaments cross each other obliquely. During
    medial rotation of the tibia on the femur the
    cruciate ligaments wind around each other this
    limits the amount of medial rotation to 10. With
    lateral rotation the ligaments unwind thus
    allowing 60 of lateral rotation when the knee
    is flexed at gt90. The cross over point serves
    as an axis for rotatory movements.

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  • 1. Anterior cruciate ligament the weaker of the
    2 ligaments it arises from the anterior
    intercondylar area of the tibia just posterior to
    the attachment of the medial meniscus.
  • It extends superiorly posteriorly and laterally
    to the posterior part of the medial side of the
    lateral condyle of the femur.
  • The ACL limits the posterior rolling of the
    femoral condyles on the tibial plateau during
    flexion converting it into spin.
  • It also prevents posterior displacement of the
    femur on the tibia and hyperextension of the knee
    joint.
  • When the joint is flexed at a right angle the
    tibia cannot be pulled anteriorly because it is
    held by the ACL.

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  • 2. Posterior cruciate ligament (PCL) the stronger
    of the 2 ligaments, it arises from the posterior
    condylar area of the tibia.
  • The PCL passes superiorly and anteriorly on the
    medial side of the ACL to attach to the anterior
    part of the lateral surface of the medial condyle
    of the femur.
  • The PCL limits the anterior rolling of the femur
    on the tibial plateau during extension,
    converting it to spin.
  • It also prevents anterior displacement of the
    femur on the tibia or posterior displacement of
    the tibia on the femur and helps prevent
    hyperflexion of the knee joint.
  • In the weight-bearing flexed knee the PCL is the
    main stabilizing factor for the femur

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  • ACL under tension when knee extended
  • PCL under tension when knee flexed

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Menisci of the knee
  • These are cresentic plates of fibrocartilage on
    the articular surface of the tibia, they serve to
    deepen the joint surface and shock absorption.
  • They are thicker at their outer margins and
    taper to thin inner margins.
  • The menisci are firmly attached at their ends to
    the intercondylar area of the tibia.
  • Their external margins are attached to the
    fibrous joint capsule.
  • The coronary ligaments are capsular fibers that
    attach the margins of the menisci to the tibial
    condyles.
  • The transverse ligament joins the anterior
    margins of the menisci together.

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  • 1. Medial meniscus a C-shaped structure broader
    posteriorly, the anterior horn attaches to the
    anterior intercondylar area anterior to the
    attachment of the ACL. The posterior end
    attaches to the posterior intercondylar area
    anterior to the attachment of the PCL. It is
    firmly adherent to the deep surface of the tibial
    collateral ligament.

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  • 2. Lateral meniscus Nearly circular, smaller and
    more mobile than the medial meniscus. The tendon
    of the popliteus separates the lateral meniscus
    from the fibularr collateral ligament. The
    posterior meniscofemoral ligament joins the
    lateral meniscus to the PCL and the medial
    femoral condyle

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  • Meniscus tears
  • Meniscal repair

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Bursae Around the Knee
  • There are at least 12 bursae around the knee
    joint because most tendons run parallel to the
    bones and pull lengthwise across the joint during
    knee movements. The subcutaneous prepatellar and
    infrapatellar bursae are located at the convex
    surface of the joint allowing the skin to be able
    to move freely during knee movements. Four
    bursae communicate with the articular cavity of
    the knee joint suprapatellar bursa (deep to the
    distal quadriceps), popliteus bursa, anserine
    bursa and gastrocnemius bursa.

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Arterial Supply to the Knee 5-62 63B
  • The arteries supplying the knee joint are the 10
    vessels that form the perigenicular anastomoses
    around the knee the genicular branches of the
    femoral, popliteal and anterior and posterior
    recurrent branches of the anterior tibial
    recurrent and circumflex fibular arteries. The
    middle genicular branches of the popliteal artery
    penetrate the fibrous layer of the joint capsule
    and supply the cruciate ligaments, synovial
    membrane and peripheral margins of the menisci.

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Innervation of the Knee
  • Hiltons law applies the nerves supplying the
    muscles acting on the knee also innervate the
    joint. Articular branches of the femoral nerve
    supply the anterior knee, tibial nerve branches
    go to the posterior knee and the common fibular
    nerve supplies the lateral aspect of the knee.
    The obturator and saphenous nerves also supply
    genicular articular branches.

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Movements of the Knee
  • Flexion extension are the main movements of the
    knee, some rotation can occur when the knee is
    flexed. When the leg is extended with the foot on
    the ground the knee passively locks because of
    medial rotation of the femur on the tibia, this
    allows weight bearing without muscular exertion
    by the leg muscles. To unlock the knee the
    popliteus contracts rotating the femur laterally
    5on the tibial plateau allowing flexion to
    occur.

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