LOWER EXTREMITY

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The Lower Extremity Functional Consequences of
Bipedality Form Follows Function
(From J.G. Fleagles Primate Adaptation
Evolution, 1988)
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Bipedal Locomotion ONLY in humans!!!
(From R.M. Alexanders The Human Machine, 1992)
Why are we so unique? MUST STAND UPRIGHT!
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4 Design Considerations for Bipedal Gait and
Upright Posture 1) Stability in Upright
Posture 2) Ability to Raise Control Trunk Over
Hindlimbs 3) Ability to Balance on One Leg 4)
Walk with Feet Underneath Body
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Stability lower extremities larger heavier
than upper extremities
Weebles wobble but they dont fall down!
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Ability to Raise Control Trunk Over Hindlimbs
Gluteus Maximus
sacral attachment
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Ability to Balance on One Leg
Well-developed Hip Abductors gluteus medius
gluteus minimus
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ANGLE OF FEMUR 14-15 degrees moves CM more
directly over base of support DONT HAVE TO
SHIFT LATERALLY WHEN YOU WALK!
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greater trochanter
ANTERIOR VIEW
POSTERIOR VIEW
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Comparison to Shoulder

• the hip is a weight bearing joint
• both are ball-and-socket joints
• acetabulum much deeper than glenoid fossa
• both have a labrum to increase depth of the
  socket
• hip has more bony support than shoulder
• left and right shoulder girdles are more
  independent than the corresponding portions of
  the pelvis/femur

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Gender

• Females have pelvic girdles that are lighter,
  thinner and wider than their male counterparts.
• The female pelvis flares out more laterally in
  the front and the sacrum is wider in the back,
  creating a broader pelvic cavity than males.

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Pelvic movement

• Concomitant movement of the pelvic girdle and the
  thigh at the hip joint are necessary for
  efficient joint actions.
• Movements of the pelvis are described by
  monitoring the ilium - specifically the anterior
  superior iliac spine.

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Anterior Tilt

• forward tilting and downward movement of the
  pelvis
• occurs when the hip extends

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Posterior Tilt

• tilting of the pelvis posteriorly
• occurs when the hip flexes

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Lateral Tilt

• tilting of the pelvis from neutral position to
  the right or left
• lateral tilt tends to occur naturally when you
  support your weight on your leg
• this allows you raise your opposite leg enough to
  swing through during gait

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Pelvic Rotation

• rotation of the pelvis defined by the direction
  in which the anterior aspect of the pelvis moves
• occurs naturally during unilateral leg movements
  (walking)
• as the right leg swings forward during gait the
  pelvis rotates left

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Hip Joint
capitis femoris ligament (round ligament)
acetabular labrum

• The femoral head and acetabulum have large
  amounts of spongy, trabecular bone to help
  attenuate forces.
• Approximately 70 of the head of the femur
  articulates with the acetabulum.

sagittal view of right hip
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Hip Ligaments
anterior view of right hip
iliofemoral (Y-shaped)
Resists extension, internal rotation and some
external rotation.
pubofemoral ligament
Resists abduction and some external rotation.
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Hip Ligaments
ischiofemoral ligament
Resists adduction and internal rotation.
Note none of these ligaments restrict flexion.
posterior view of right hip
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Femoral Neck

• The neck holds the femur away from the pelvis.
• It is formed by cancellous trabecular bone and
  reinforced with cortical bone, particularly on
  the inferior portion.
• The angle of inclination is measured in the
  frontal plane and typically ranges from 90 to 135
  degrees.

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Coxa Vara

• If the angle of inclination is less than 125
  degrees it is termed coxa vara.
• This shortens the limb, increases the
  effectiveness of the abductors, reduces the load
  on the femoral head and increases the load on the
  femoral neck.

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Coxa Valga

• If the angle of inclination is greater than 125
  degrees it is termed coxa valga.
• This lengthens the limb, reduces the
  effectiveness of the abductors, increases the
  load on the femoral head and reduces the load on
  the femoral neck.

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Angle of Anteversion

• The angle of the femoral neck in the transverse
  plane is termed the angle of anteversion.
• Normally the femoral neck is rotated anteriorly
  12 to 14 degrees with respect to the femur.

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Excessive Anteversion

• Excessive anteversion beyond 14 degrees causes
  the head of the femur become uncovered.
• In order to keep the head of the femur within the
  acetabulum a person must internally rotate the
  femur.

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Retroversion

• If the angle of anteversion is reversed so that
  it moves posteriorly, it is termed retroversion.
• This condition causes the person to externally
  rotate the femur.

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Hip Range of Motion
Movement Range flexion 70-140o hyperextension 4-15
o adduction 20o abduction 30o internal
rotation 70o external rotation 90o
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Primary Hip Flexors psoas major iliacus (aka
iliopsoas)
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Assisting Hip Flexors pectineus rectus
femoris sartorius tensor fascia latae
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Assisting Hip Flexors pectineus tensor
fascia latae sartorius rectus femoris
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Hip Extensors Gluteus maximus Hamstrings
biceps femoris semitendinosus
semimembranosus
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semimembranosus
semitendinosus
biceps femoris
B
T
M
lateral
medial
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long head
short head
Biceps Femoris
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Hip Extensor
Hip Abductors
gluteus maximus
gluteus medius minimus
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Hip Adductors
pectineus
adductor brevis
adductor longus
adductor magnus
anterior view
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Hip Adductors
gracilis
posterior view
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Medial Rotation of the Hip

• due primarily to the gluteus medius and minimus
• extension of hip tends to laterally rotate femur
  so medial rotators needed to neutralize this
  effect
• not usually performed against resistance, thus
  not a lot of muscular support
• medial much weaker than lateral rotation

Assisting Muscles semimembranosus,
semitendinosus, tensor fascia latae, and hip
adductors
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Lateral Rotation of the Hip

• lateral rotation - 5 muscles
• lateral rotation is a natural movement in human
  gait to accommodate pelvic rotation

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Phases of Walking
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Muscle Activity During Walking
Muscle Footstrike Midsupport Toe-off Swing Decel.
Dorsiflexors
Intrinsic Foot Gluteus Maximus
Gluteus Medius
Gluteus Minimus
Hamstrings
Iliopsoas Plantar Flexors
Quadriceps
Sartorius Tensor Fascia Latae
Thigh Adductors

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Hip Fractures

• occurs in neck of femur
• usually due to a decreased bone mineral density
• 87 are 65 or older
• current annual cost is more than 9.8 billion
• accounts for more hospital days, by far, than any
  other musculoskeletal injury
• results in increased mortality, reduced
  mobility, and, for many, the inability to live
  independently
• American Academy of Orthopaedic Surgeons

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Hamstring Injuries

• few activities require simultaneous hip flexion
  and knee extension
• usually little hamstring stretch except for
  specific exercises
• hamstrings susceptible to strain due to this poor
  extensibility
• injuries most often occur during sprinting -
  particularly when muscle is fatigued

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Hamstring Injuries - Theories

• overstretching of muscle
• for example during overstriding
• development of maximal tension when muscle is
  fully elongated
• development of max tension necessary to act
  antagonistically to quads which are stronger

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Which side of the body do you use a cane on when
your hip is hurt?