THE KNEE

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THE KNEE

• H L, pg 182 193
• T F, Chpt 8, pg 144

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KNEE JOINT STRUCTURE

• Bony
• Femur
• Tibia
• Fibula
• A non-weight bearing bone
• Patella (largest sesamoid bone in the body)
• Bone that forms in the middle of a tendon

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Articulations

• Tibiofemoral - (modified hinge) largest joint in
  the body
• Tibiofibular (Superior) fibula attaches to
  tibia
• Patellofemoral - patella acts as a pulley to
  improve the force capability of the quadriceps
  muscle in knee extension

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Menisci

• Two menisci
• Medial
• Lateral
• FUNCTIONS
• deepen the articulating depressions of the tibial
  plateaus
• absorb forces
• retard wear and tear on bony surfaces
• limit slipping of femoral condyle on the tibial
  plateau

• Menisci are circular rims of fibrocartilage
• Lateral is an incomplete circle
• Medial C shaped
• Thick peripheral borders taper to a thin inner
  edge

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LIGAMENTS

• Patellar ligament - connects lower margin
  of patella with tibial tuberosity
• Often referred to as the patellar tendon

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LIGAMENTS

• Medial (Tibial) Collateral Ligament (MCL)
• Checks extension
• Prevents lateral motion of the tibia (valgus
  stress)
• Medial meniscus is attached to MCL

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LIGAMENTS

• Lateral (Fibular) Collateral Ligament
• Checks extension
• Prevents medial motion of tibia (varus stress)

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LIGAMENTS

• Anterior Cruciate ligament - to cross
• Intracapsular - lies inside the joint capsule
• Limits extension and rotation
• Checks backward sliding of femur on tibia when
  weight bearing

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LIGAMENTS

• Posterior Cruciate Ligament - to cross
• Limits extension and rotation
• Checks forward sliding of femur on tibia during
  weight bearing

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LATERAL STABILIZER

• Iliotibial Tract (IT Band) - acts like a ligament
  in its ability to laterally stabilize the knee.
• Perhaps more than LCL
• Biceps Femoris Tendon - also acts to stabilize
  lateral knee

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MOTIONS

• Flexion
• Extension
• Internal/external rotation
• only occur when knee is flexed non-wt. bearing

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SCREW HOME MECHANISM

• Allows knee to achieve the most stable
  "closed-packed" position.
• Close-packed point where the most contact
  occurs between articulating surfaces
• Most stable
• Weight bearing Involves extension and internal
  rotation of the femur
• Non-weight bearing Involves extension and
  externally rotation of the tibia

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ANTERIOR LINE OF PULL
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Quadriceps Muscle Group

• Proximal attachment
• Rectus Femoris Anterior Inferior Iliac Spine
  (AIIS) - only quad muscle that acts on hip joint
• Vastus Lateralis lateral femur
• Vastus Medialis medial femur
• Vastus Intermedius - anterior femur
• Distal attachment tibial tuberosity
• Movement extension

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Posterior/Medial Line of Pull

• Flexion, Internal Rotation

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Semimembranosus Hamstring

• Proximal attachment ischial tuberosity
• 2 joint muscle of the hip and knee
• Distal attachment posterior tibia

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Semitendinosus Hamstring

• Also a muscle of the Pesanserine group
• Semitendinosus, gracilis, sartorius
• Proximal attachment ischial tuberosity
• 2 joint muscle of the hip and knee
• Distal attachment proximal medial tibia

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Sartorius

• Muscle of the Pesanserine group
• Proximal attachment Anterior Superior Iliac
  Spine (ASIS)
• 2 joint muscle of the hip and knee
• Distal attachment proximal medial tibia

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Gracilis

• Muscle of the Pesanserine group
• Proximal attachment pubic bone
• 2 joint muscle of the hip and knee
• Distal attachment proximal medial tibia

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Popliteus

• Proximal attachment lateral femoral condyle
• Distal attachment posterior tibia
• Movements flexion and internal rotation
• Initiates flexion, internal rotation of tibia to
  unscrew the knee

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Posterior/Lateral Line of Pull

• Flexion, External Rotation

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Biceps Femoris Hamstring

• Proximal attachment
• long head ischial tuberosity (2 jt. muscle)
• short head posterior femur
• Distal attachment head of fibula

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Iliotibial Band (IT band)

• Connective tissue aponeurosis that arises from
  the tensor fascia latae, and gluteal muscles of
  the hip
• Distal attachment Gerdys tubercle of the
  proximal lateral tibia
• Movements acts to both flex and extend knee
  depending upon position

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Posterior Line of Pull

• Flexion

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Gastrocnemius

• 2 jt. muscle of knee and ankle
• Proximal attachment
• medial head posterior medial femoral condyle
• lateral head posterior lateral femoral condyle
• Distal attachment calcaneus apophysis
• Movements flexion of knee, plantar flexion of
  ankle

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Plantaris

• Small muscle without much functional significance
• Proximal attachment posterior lateral condyle of
  femur
• 2 jt. muscle of knee and ankle
• Distal attachment calcaneus apophysis
• Movements knee flexion, ankle plantar flexion

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