HIP

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HIP

• Dr. Michael P. Gillespie

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OSTEOLOGY

• Each innominate is the union of three bones the
  ilium, pubis, and ischium.
• The right and left innominates connect with each
  other anteriorly at the pubic symphysis and
  posteriorly at the sacrum.
• An osteoligamentous ring known as the pelvis
  (Latin basin or bowel) is formed.
• Functions of the pelvis
• Attachment point for many muscles of the lower
  extremity and trunk.
• Transmits the weight of the upper body and trunk
  to the ischial tuberosities during sitting and to
  the lower extremities during standing or walking.
• Supports the organs of the bowel, bladder, and
  reproductive system.

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INNOMINATE

• Ilium
• Pubis
• Ischium
• Acetabulum

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EXTERNAL SURFACE OF THE PELVIS

• Wing (ala) the large fan-shaped wing of the
  ilium forms the superior half of the innominate.
• Acetabulum a deep, cup-shaped cavity below the
  wing.
• Obturator-foramen the largest foramen in the
  body. Covered by the obturator membrane.

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OSTEOLOGIC FEATURES OF THE ILIUM

• External Surface
• Posterior, anterior, and inferior gluteal lines
• Anterior-superior iliac spine
• Anterior-inferior iliac spine
• Iliac crest
• Posterior-superior iliac spine
• Posterior-inferior iliac spine
• Greater sciatic notch
• Greater sciatic foramen
• Sacrotuberous and sacrospinous ligaments

• Internal Surface
• Iliac fossa
• Auricular surface
• Iliac tuberosity

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OSTEOLOGIC FEATURES OF THE PUBIS

• Superior pubic ramus
• Body
• Crest
• Pectineal line
• Pubic tubercle
• Pubic symphysis joint and disc
• Inferior pubic ramus

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OSTEOLOGIC FEATURES OF THE ISCHIUM

• Ischial spine
• Lesser sciatic notch
• Lesser sciatic foramen
• Ischial tuberosity
• Ischial ramus

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ANTERIOR ASPECT PELVIS, SACRUM, RIGHT PROXIMAL
FEMUR
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LATERAL VIEW RIGHT INNOMINATE BONE
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POSTERIOR ASPECT OF PELVIS, SACRUM, PROXIMAL
FEMUR
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FEMUR

• The longest and strongest bone in the human body.
• The femoral head projects medially and slightly
  anterior to articulate with the acetabulum.
• The femoral neck connects the head with the
  shaft.
• The neck displaces the proximal shaft of the
  femur laterally away from the joint, thereby
  reducing the likelihood of bony impingement.
• Distal to the neck, the shaft of the femur
  courses slightly medially, placing the knees and
  feet closer to the midline of the body.
• The femur bows slightly when subjected to the
  weight of the body. Stress along the bone is
  dissipated through compression along the
  posterior shaft and through tension along the
  anterior shaft.

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OSTEOLOGIC FEATURES OF THE FEMUR

• Femoral Head
• Femoral Neck
• Intertrochanteric Line
• Greater trochanter
• Trochanteric fossa
• Intertrochanteric crest
• Quadrate tubercle

• Lesser trochanter
• Linea aspera
• Pectineal (spiral) line
• Gluteal tuberosity
• Lateral and medial supracondylar lines
• Adductor tubercle

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ANTERIOR ASPECT RIGHT FEMUR
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MEDIAL POSTERIOR SURFACES RIGHT FEMUR
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ANGLE OF INCLINATION

• The angle of inclination of the proximal femur
  describes the angle within the frontal plane
  between the femoral neck and the medial side of
  the femoral shaft.
• At birth this angle is about 140 150 degrees
  however, the loading across the femoral neck
  during walking usually decreases this to the
  normal adult value of about 125 degrees.
• Coxa hip, vara to bend inward, valga to
  bend outward
• Coxa vara an angle of inclination markedly less
  than 125 degrees.
• Coxa valga an angle of inclination markedly
  greater than 125 degrees.
• Abnormal angles can lead to dislocation or
  stress-induced degeneration of the joint.

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ANGLE OF INCLINATION
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FEMORAL TORSION

• Femoral torsion describes the relative rotation
  (twist) between the bones shaft and neck.
• Normally, as viewed from above, the femoral neck
  projects about 15 degrees anterior to a
  mid-lateral axis through the femoral condyles
  (normal anteversion).
• Femoral torsion significantly different than 15
  degrees is considered abnormal.
• Excessive anteversion significantly greater
  than 15 degrees
• Retroversion approaching 0 degrees
• Healthy infants are born with about 40 degrees of
  femoral anteversion

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EXCESSIVE FEMORAL ANTEVERSION

• Excessive anterversion that persists into
  adulthood can increase the likelihood of hip
  dislocation, articular incongruence, increase
  joint contact force, and increased wear on the
  cartilage.
• This can lead to secondary osteoarthritis of the
  hip.
• It may be associated with an abnormal gait
  pattern called in-toeing, a walking pattern
  with exaggerated posturing of hip internal
  rotation.
• The amount of in-toeing is generally related to
  the amount of femoral anteversion.
• It is a compensatory mechanism used to guide the
  excessively anteverted femoral head more directly
  into the acetabulum.
• Over time, shortening of the internal rotator
  muscles and ligaments occurs, thereby reducing
  external rotation.
• Most children with in-toeing eventually walk
  normally.
• Excessive femoral anteversion is common in
  persons with cerebral palsy. It typically does
  not resolve in this population.

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NORMAL ANTEVERSION
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EXCESSIVE ANTEVERSION
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RETROVERSION
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INTERNAL ROTATION IMPROVING JOINT CONGRUITY
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IN-TOEING
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FUNCTIONAL ANATOMY OF THE HIP JOINT

• The hip is a classic ball-and-socket joint
  secured within the acetabulum by an extensive set
  of connective tissues and muscles.
• Articular cartilage, muscle, and cancellous bone
  in the proximal femur help dampen the large
  forces that cross the hip.

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FEMORAL HEAD

• The head of the femur forms about two-thirds of a
  nearly perfect sphere.
• The entire surface of the femoral head is covered
  by articular cartilage except for the region of
  the fovea, which is slightly posterior to the
  center of the head.
• The fovea is a prominent pit that serves as the
  attachment point for the ligamentum teres.
• The ligamentum teres is a tubular sheath that
  runs between the transverse acetabular ligament
  and the fovea of the femoral head. It is a
  sheath that contains the acetabular artery.

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ACETABULUM

• The acetabulum (Latin vinegar cup) is a deep,
  hemispheric cuplike socket that accepts the
  femoral head.
• The femoral head contacts the acetabulum along
  the horseshoe-shaped lunate surface, which is
  covered with thick articular cartilage.
• During walking, hip forces fluctuate from 13 of
  body weight to over 300 of body weight during
  the mid-stance phase.
• During stance phase, the lunate surface flattens
  slightly as the acetabular notch widens. This
  serves as a dampening mechanism to reduce peak
  pressure.
• The acetabular fossa is a depression located deep
  within the floor of the acetabulum. It does not
  normally come into contact with the femoral head.

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HIP JOINT COMPRESSION AS A PERCENT OF GAIT CYCLE
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ANATOMIC FEATURES OF THE HIP JOINT

• Femoral Head
• Fovea
• Ligamentum teres
• Acetabulum
• Acetabular notch
• Lunate surface
• Acetabular fossa
• Labrum
• Transverse acetabular ligament

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INTERNAL ANATOMY OF HIP JOINT
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ACETABULAR LABRUM

• The acetabular labrum is a flexible ring of
  fibrocartilage that surrounds the outer
  circumference (rim) of the acetabulum.
• The acetabular labrum projects about 5 mm toward
  the femoral head.
• It provides significant stability to the hip by
  gripping the femoral head and deepening the
  volume of the socket by approximately 30.
• The seal formed by the labrum maintains a
  negative intra-articular pressure, thereby
  creating a modest suction that resists
  distraction of the joint surfaces.
• It also helps to hold synovial fluid within the
  joint space.
• It decreases the contact stress (force / area) by
  increasing the surface area of the acetabulum.
• Poor blood supply limited ability to heal
• Well supplied with afferent nerves
  proprioceptive feedback / pain

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ACETABULAR ALIGNMENT

• In the anatomic position, the acetabulum
  typically projects laterally from the pelvis with
  a varying amount of inferior and anterior tilt.
• Congenital or developmental conditions can result
  in an abnormally shaped acetabulum.
• A dysplastic acetabulum that does not adequately
  cover the femoral head can lead to chronic
  dislocation and increased stress, which can lead
  to osteoarthritis.
• Two measurements are used to describe the extent
  to which the acetabulum naturally covers and
  helps to secure the femoral head
• Center-edge angle
• Acetabular anteversion angle

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CENTER-EDGE ANGLE

• The center-edge angle varies widely, but on
  average measures about 35 degrees in adults.
• A significantly lower center-edge angle reduces
  the acetabular coverage of the femoral head.
  This increases the risk of dislocation and
  reduces contact area within the joint.
• During the single-limb-support phase of walking,
  this reduced surface area would increase joint
  pressure (force / area) by about 50.
• This increased joint pressure can lead to
  premature osteoarthritis.

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CENTER-EDGE ANGLE
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ACETABULAR ANTEVERSION ANGLE

• The acetabular anteversion angle measures the
  extent to which the acetabulum projects
  anteriorly within the horizontal plane, relative
  to the pelvis.
• Observed from above, the normal acetabular
  anteversion angle is about 20 degrees, which
  exposes part of the anterior side of the femoral
  head.
• A hip with excessive acetabular anteversion is
  more exposed anteriorly.
• When anteversion is severe, the hip is more prone
  to anterior dislocation and associated lesions of
  the labrum.

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ACETABULAR ANTEVERSION ANGLE
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CAPSULE AND LIGAMENTS OF THE HIP

• A synovial membrane lines the internal surface of
  the hip joint capsule.
• The iliofemoral, pubofemoral, and ischiofemoral
  ligaments reinforce the external surface of the
  capsule.
• Passive tension in the stretched ligaments, the
  adjacent capsule, and the surrounding muscles
  help to define end-range movements of the hip.
• Increasing the flexibility of parts of the
  capsule is an important component of manual
  physical therapy for restricted movement of the
  hip.

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ANTERIOR CAPSULE LIGAMENTS
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POSTERIOR CAPSULE LIGAMENTS
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PARAPLEGIC WITH SUPPORT BRACES
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TISSUES THAT BECOME TAUT AT THE END-RANGES OF
PASSIVE HIP MOTION
End-Range Position Taut Tissue
Hip flexion (knee extended) Hamstrings
Hip flexion (knee flexed) Inferior and posterior capsule gluteus maximus
Hip extension (knee extended) Primarily iliofemoral ligament, some fibers of the pubofemoral and ischiofemoral ligaments psoas major
Hip extension (knee flexed) Rectus femoris
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TISSUES THAT BECOME TAUT AT THE END-RANGES OF
PASSIVE HIP MOTION
End-Range Position Taut Tissue
Abduction Pubofemoral ligament adductor muscles
Adduction Superior fibers of ischiofemoral ligament iliotibial band and abductor muscles such as the tensor fascia latae and gluteus maximus
Internal rotation Ischiofemoral ligament external rotator muscles, such as the piroformis or gluteus maximus
External rotation Iliofemoral and pubofemoral ligaments internal rotator muscles, such as the tensor fascia latae or gluteus minimus
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CLOSE-PACKED POSITION OF THE HIP

• Full extension of the hip (about 20 degrees
  beyond neutral) in conjunction with slight
  internal rotation and slight abduction twists or
  spirals the fibers of the capsular ligaments to
  their most taut position.
• This is considered the close-packed position of
  the hip.
• The passive tension leads to stability of the
  joint and reduces joint play.
• The hip joint is one of the few joints in the
  body where the close-packed position is NOT also
  the position of maximal joint congruency. They
  fit most congruently in about 90 degrees of
  flexion, moderate abduction, and external
  rotation.

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NEUTRAL AND CLOSED PACKED POSITIONS
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OSTEOKINEMATICS

• Reduced hip motion may be an early indicator of
  disease or trauma.
• Limited hip motion can impose functional
  limitations on activities such as walking,
  standing upright, or picking up objects on the
  floor.
• Femoral-on-pelvic hip osteokinematics rotation
  of the femur about a relatively fixed pelvis.
• Pelvic-on-femoral hip osteokinematics rotation
  of the pelvis, and often the superimposed trunk,
  over relatively fixed femurs.
• Movements
• flexion extension in the sagittal plane,
  abduction adduction in the frontal plane, and
  internal and external rotation in the horizontal
  plane.
• The anatomic position is the 0-degree or neutral
  reference point.

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FEMORAL-ON-PELVIC OSTEOKINEMATICS

• Rotation of the Femur in the Sagittal Plane
• Hip flexion to 120 degrees
• Full knee extension limits hip flexion to 70 80
  degrees due to increased tension in the
  hamstrings
• Hip extension to 20 degrees
• Full knee flexion reduces hip extension due to
  tension in rectus femoris
• Rotation of the Femur in the Frontal Plane
• Hip abduction to 40 degrees
• Limited by pubofemoral ligament and adductors
• Hip adduction to 25 degrees
• Limited by interference with contralateral limb,
  passive tension in hip abductors, iliotibial
  band, and ischiofemoral ligament
• Rotation of the Femur in the Horizontal Plane
• Internal rotation to 35 degrees
• Produces tension in piriformis and ischiofemoral
  ligament
• External rotation to 45 degrees
• Produces tension in internal rotators and
  iliofemoral ligament

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SAGITTAL PLANE ROTATIONS
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FRONTAL PLANE ROTATIONS
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HORIZONTAL PLANE ROTATIONS
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FEMORAL-ON-PELVIC (HIP) MOTION
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PELVIC-ON-FEMORAL OSTEOKINEMATICS

• Pelvic rotation in the Sagittal Plane
• Pelvic rotation in the Frontal Plane
• Pelvic Rotation in the Horizontal Plane

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LUMBOPELVIC RHYTHM

• The caudal end of the axial skeleton is firmly
  attached to the pelvis by way of the sacroiliac
  joints.
• Rotation of the pelvis over the femoral heads
  typically changes the configuration of the lumbar
  spine.
• This is referred to as lumbopelvic rhythm.
• Ipsidirectional lumbopelvic rhythm.
• The pelvis and lumbar spine rotate in the same
  direction.
• Contradirectional lumbopelvic rhythm.
• The pelvis and lumbar spine rotate in opposite
  directions.

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LUMBOPELVIC RHYTHMS
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PELVIC ROTATION IN THE SAGITTAL PLANE ANTERIOR
AND POSTERIOR PELVIC TILTING

• Pelvic Tilt a short-arc, sagittal rotation of
  the pelvis relative to stationary femurs.
• Anterior Pelvic Tilt
• Increase in lumbar curvature offsets the tendency
  of the supralumbar trunk to follow the forward
  rotation
• 30 degrees
• Posterior Pelvic Tilt
• Decrease in lumbar curvature
• 15 degrees

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PELVIC ROTATION IN THE FRONTAL PLANE

• Pelvic-on-femoral rotation in the frontal and
  horizontal planes is best described assuming a
  person is standing on one limb. The weight
  bearing extremity is referred to as the support
  hip.
• Abduction of the support hip occurs by raising or
  hiking the iliac crest on the side of the
  nonsupport hip.
• The lumbar spine must bend in the direction
  opposite the rotating pelvis.
• Slight lateral convexity within the lumbar region
  toward the side of the abducting hip.
• 30 degrees of abduction
• Adduction of the support hip occurs by a lowering
  of the iliac crest on the side of the nonsupport
  hip.
• Slight lateral concavity within the lumbar region
  of the side of the adducted hip.

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PELVIC ROTATION IN THE HORIZONTAL PLANE

• Pelvic-on-femoral rotation in the frontal and
  horizontal planes is best described assuming a
  person is standing on one limb. The weight
  bearing extremity is referred to as the support
  hip.
• Internal rotation of the support hip occurs as
  the iliac crest on the side of the nonsupport hip
  rotates forward in the horizontal plane.
• External rotation of the support hip occurs as
  the iliac crest on the side of the nonsupport hip
  rotates backward in the horizontal plane.

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PELVIC-ON-FEMORAL (HIP) MOTION
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ARTHROKINEMATICS

• During hip motion, the nearly spherical femoral
  head normally remains snugly seated within the
  confines of the acetabulum.
• Hip arthrokinematics are based upon traditional
  convex-on-concave or concave-on-convex principles.

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MOTOR INNERVATION

• Lumbar Plexus
• Femoral nerve (L2-L4)
• Obturator nerve (L2-L4)
• Sacral Plexus
• Nerve to piriformis (S1-S2)
• Nerve to obturator internus and gemullus superior
  (L5-S2)
• Nerve to quadratus femoris and gemullus inferior
  (L4-S1)
• Superior gluteal nerve (L4-S1)
• Inferior gluteal nerve (L5-S2)
• Sciatic nerve (L4-S3), including tibial and
  common fibular (peroneal) portions

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SENSORY INNERVATION

• As a general rule, the hip capsule, ligaments,
  and parts of the labrum receive sensory
  innervation through the same nerve roots that
  supply the overlying muscles.
• The anterior part of the capsule of the hip
  receives sensory fibers from the femoral nerve.
• The posterior capsule receives sensory fibers
  from all nerve roots originating from the sacral
  plexus.
• The connective tissues of the medial aspects of
  the hip and knee joints receive sensory fibers
  from the obturator nerve (Inflammation of the hip
  may be perceived as pain in the medial knee
  region).

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OBTURATOR NERVE
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SCIATIC NERVE
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MUSCULAR FUNCTION AT THE HIP
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MUSCLES OF THE HIP, ORGANIZED ACCORDING TO
PRIMARY OR SECONDARY ACTIONS
Flexors Adductors Internal Rotators Extensors Abductors External Rotators
Primary Iliopsoas Sartorius TFL Rectus femoris Adductor longus Pectineus Pectineus Adductor longus Gracilis Adductor brevis Adductor magnus Not applicable Gluteus maximus Biceps femoris (long head) Semitendinosus Semimembranosus Adductor magnus (posterior head) Gluteus medius Gluteus minimus TFL Gluteus maximus Piriformis Obturator internus Gemellus superior Gemellus inferior Quadratus femoris
Secondary Adductor brevis Gracilis Gluteus minimus (anterior fibers) Biceps femoris (long head) Gluteus maximus (lower fibers) Quadratus femoris Gluteus minimus (anterior fibers) Gluteus medius (anterior fibers) TFL Adductor longus Adductor brevis Pectineus Gluteus medius (posterior fibers) Adductor magnus (anterior head) Piriformis Sartorius Gluteus medius (posterior fibers) Gluteus minimus (posterior fibers) Obturator externus Sartorius Biceps femoris (long head)
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MUSCLES OF THE ANTERIOR HIP
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HIP FLEXOR MUSCLES

• The primary hip flexors are the iliopsoas,
  sartorius, tensor fascia latae, rectus femoris,
  adductor longus, and pectineus.
• Secondary hip flexors are adductor brevis,
  gracilis, and anterior fibers of the gluteus
  minimus.

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PELVIC-ON-FEMORAL HIP FLEXION ANTERIOR PELVIC
TILT

• The anterior pelvic tilt is performed by a
  force-couple between the hip flexor and low back
  extensor muscles.

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FORCE COUPLE FOR ANTERIOR PELVIC TILT
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FEMORAL-ON-PELVIC HIP FLEXION

• Femoral-on-pelvic hip flexion often occurs
  simultaneously with knee flexion as a means to
  shorten the functional length of the lower
  extremity during the swing phase of walking or
  running.
• Moderate to high power hip flexion requires
  coactivation of the hip flexor and abdominal
  muscles.
• Rectus abdominus must create a strong posterior
  pelvic tilt to neutralize the strong anterior
  pelvic tilt potential of the hip flexors.

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STABILIZING ROLE OF ABDOMINALS WITH UNILATERAL
LEG RAISING
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HIP ADDUCTOR MUSCLES

• The primary adductors of the hip are the
  pectineus, adductor longus, gracilis, adductor
  brevis, and adductor magnus.
• Secondary adductors are the biceps femoris (long
  head), the gluteus maximus (especially lower
  fibers) and the quadratus femoris.

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HIP ADDUCTORS
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BILATERAL COOPERATIVE ACTION OF ADDUCTORS
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DUAL ACTION OF ADDUCTOR LONGUS
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HIP INTERNAL ROTATORS OVERALL FUNCTION

• There are no primary internal rotators of the hip
  because no muscle is oriented close to the
  horizontal plane.
• Secondary internal rotators are the anterior
  fibers of the gluteus minimus and gluteus medius,
  tensor fasciae latae, adductor longus, adductor
  brevis, and pectineus.

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HORIZONTAL PLANE LINES OF FORCE OF SEVERAL
MUSCLES THAT CROSS THE HIP
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ADDUCTORS AS INTERNAL ROTATORS
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HIP EXTENSOR MUSCLES

• The primary hip extensors are the gluteus
  maximus, the hamstrings (long head of the biceps
  femoris, semitendinosus, semimembranosus), and
  the posterior head of the adductor magnus.
• Secondary extensors are the posterior fibers of
  the gluteus medius and the anterior fibers of the
  adductor magnus.

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POSTERIOR MUSCLES OF THE HIP
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PELVIC-ON-FEMORAL HIP EXTENSIONPERFORMING A
POSTERIOR PELVIC TILT

• Hip extensors performing a posterior pelvic tilt.
• The hip extensors and the abdominal muscles act
  as a force couple to posteriorly tilt the pelvis.
• Hip extensors controlling a forward lean of the
  body.
• The muscular support for this activity is
  primarily the responsibility of the hamstrings.

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FORCE COUPLE FOR POSTERIOR PELVIC TILT
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HIP EXTENSORS CONTROLLING A FORWARD LEAN OF THE
BODY
82
FEMORAL-ON-PELVIC HIP EXTENSION

• Hip extensor muscles are required to produce
  large and powerful femoral-on-pelvic hip
  extension torque to accelerate the body forward
  and upward (i.e. climbing a hill).

83
HIP EXTENSOR ENGAGEMENT WHILE CLIMBING
84
FULLY EXTENDABLE HIP
85
EFFECTS OF HIP FLEXION CONTRACTURE ON THE
BIOMECHANICS OF STANDING
86
HIP ABDUCTOR MUSCLES

• The primary hip abductor muscles are the gluteus
  medius, gluteus minimus, and tensor fasciae
  latae.
• Secondary abductors are the piriformis and
  sartorius.

87
DEEP MUSCLES OF POSTERIOR LATERAL HIP
88
ABDUCTOR CONTROL OF FRONTAL PLANE STABILITY OF
THE PELVIS WHILE WALKING

• The abduction torque produced by the hip abductor
  muscles is essential to the control of the
  frontal plane pelvic-on-femoral kinematics during
  walking.
• The abduction torque produced by hip abductor
  muscles is particularly important during the
  single-limb-support phase of gait.
• The abduction torque on the stance limb prevents
  the pelvis and trunk from dropping uncontrollably
  toward the side of the swinging limb.

89
ABDUCTOR ROLE IN THE PRODUCTION OF COMPRESSION
FORCE AT THE HIP

• During single-limb support, the hip abductor
  muscles (esp. gluteus medius) produce most of the
  compression force across the hip.
• The hip abductor muscles must produce a force
  that is twice that of body weight in order to
  achieve stability during single-limb support.

90
GREATER TROCHANTERIC PAIN SYNDROME

• Excessive or repetitive action of the gluteus
  medius and minimus can cause point tenderness
  adjacent to the greater trochanter (the primary
  distal attachment of these muscles).
• This painful response suggests inflammation
  within the hip abductor mechanism.
• Pain associated with activation of the hip
  abductor mechanism can be disabling considering
  the frequent and relatively large demands placed
  upon these muscles during the single-limb-support
  phase of the gait cycle.
• Pain can be due to inflammation of the bursa
  associated with the distal attachments or with
  tears of the distal tendons.
• The term greater trochanteric pain syndrome
  describes this condition.

91
HIP ABDUCTOR MUSCLE WEAKNESS

• Several conditions are associated with weakness
  of the hip abductor muscles.
• Muscular dystrophy, Guillian-Barre syndrome,
  spinal cord injury, greater trochanteric pain
  syndrome, hip osteoarthritis or rheumatoid
  arthritis, poliomyelitis, and undefined hip pain
  or weakness.
• The classic indicator of hip abductor weakness is
  the positive Trendelenburg sign.
• The patient is asked to stand in single-limb
  support over the weak hip.
• A positive sign occurs if the pelvis drops to the
  side of the unsupported limb. The weak hip
  falls into pelvic-on-femoral adduction.

92
HIP EXTERNAL ROTATOR MUSCLES

• The primary external rotator muscles of the hip
  are the gluteus maximus and five of the six
  short external rotators.
• Secondary external rotators are the posterior
  fibers of gluteus medius and minimus, obturator
  externus, sartorius, and long head of biceps
  femoris.

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OBTURATOR INTERNUS
94
FUNCTIONAL ANATOMY OF THE SHORT EXTERNAL
ROTATORS

• The six short external rotators of the hip are
  the piriformis, obturator internus, gemellus
  superior, gemellus inferior, quadratus femoris,
  and obturator externus.

95
EXTERNAL ROTATORS OVERALL FUNCTION

• The functional potential of the external rotators
  is most evident during pelvic-on-femoral
  rotation.
• The action of planting a foot and cutting to
  the opposite side is the natural way to abruptly
  change direction while running.

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EXTERNAL ROTATOR ACTION
97
FRACTURE OF THE HIP

• Fracture of the hip (i.e. proximal femur) is a
  major health and economic problem in the United
  States.
• About 95 of all fractures of the hip are the
  result of falls.
• It is the 2nd leading cause of hospitalization in
  the elderly.
• Age related osteoporosis and a higher incidence
  of falling are reasons for a higher incidence of
  hip fracture in the elderly.
• Mortality is surprisingly high after hip
  fracture studies report 12 to 25 of persons
  die within 1 year of fracturing a hip.
• Only about 40 of persons are able to
  independently perform their basic functional
  activities 6 to 12 months after hip fracture.
• About half of those persons continue to require
  an assistive device to aid their walking.

98
OSTEOARTHRITIS OF THE HIP

• Hip osteoarthritis is a disease manifested by
  deterioration of the joints articular cartilage,
  loss of joint space, sclerosis of subchondral
  bone, and the presence of osteophytes.

99
EFFECTS OF COXA VARA COXA VALGA