BIOMECHANICS
OF HIP JOINT
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TYPE
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VARIETY
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THE MAJOR FUNCTION OF HIP JOINT
IS STABILITY
IT SUPPORTS THE BODY WEIGHT
TRANSMIT FORCES FROM PELVIS TO
LEGS AND FROM LEGS TO PELVIS
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SYNOVIAL JOINT
BALL & SOCKET JOINT
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Cup like concave structure on the hip
bone called ACETABULUM ,articulates
with a spherical shaped HEAD OF
FEMUR
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The acetabulum is deepened by
peripheral ring called as ACETABULUM
LABRUM.It helps to hold the head of
Femur in the socket
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IN FRONTAL PLANE
The axis of Femoral neck and Femoral
shaft forms an angle
Normal angle is 120 degree
Increase in the angle is called COXA
VALGA
Decrease in the angle is called COXA
VARA
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In TRANSVERSE PLANE:
The angle formed by the head and
neck of femur with the axis of Femoral
condyles
Normal angle is 8-25 degrees
The increase in the Angle of Torsion is
called as ANTEVERSION
The decrease in the Angle of Torsion is
called as RETROVERSION
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The Trabecular lines of stress found in
Femur and Pelvis to meet the stress
requirements
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1.Medial Trabecular system
2.Lateral Trabecular system
3.Medial accessory system
4.Lateral accessory system
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It arises from Medial cortex to upper
Femoral shaft and radiates outwards to
cortical bone of superior aspect of
Femoral head.
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It helps to resist the Joint reaction
forces during Single Limb Support.
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It arises from Lateral cortex of Upper
Femoral Shaft after crossing the Medial
system and end on Inferior aspect of
head of Femur.
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It is developed in response to force
created by contraction of abductor
Muscle
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Medial Accessory system crosses lateral
and fans out into region of Greater
Trochanter
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Lateral Accessory system runs parallel
to Greater Trochanter.
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The areas where the Trabecular system
cross each other in right angles are
areas of strength
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The areas where Trabeculae does not
cross at Right angles are area of
Weakness
The Zone of Weakness is the Femoral
neck
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The articular capsule of Hip is very
strong and dense
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The capsule extends the periphery of
acetabulum to Femoral neck
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The anterior capsule is stronger than
the Posterior capsule because of two
ligaments
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ILIO FEMORAL LIGAMENT---Strongest
ligament of hip,Y shaped attached to
ASIS and INTERTROCHANTERIC LINE.
It checks HIP HYPEREXTENSION
PUBO FEMORAL LIGAMENT--- it arises
from anterior aspect of Pubic ramus
and passess to anterior surface of
Intertrochanteric fossa
It checks Hip Abduction and Extension
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ISCHIO FEMORAL LIGAMENT
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Attached to posterior surface of
Acetabulum Labrum to Femoral neck
and inner surface of Greater Trochanter
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Checks Hip Hyperextension
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THREE DEGREE OF FREEDOM
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FLEXION –EXTENSION
Saggital plane----Medio lateral axis
ABDUCTION-ADDUCTION
Coronal plane------ Anterio Posterio axis
MEDIAL LATERAL ROTATION
Transverse plane---- Vertical axis
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FLEXORS: Ilio Psoas , Pectenius, Tensor
fasciae lata,Rectus femoris, Sartorius
EXTENSORS: Gluteus Maximus
Posterior fibers of Gluteus
Medius,Piriformis
TWO JOINT EXTENSORS: Long head of
BICEPS,Semimembranosus,
Semitendosus
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Adductor Magnus
Adductor Longus
Adductor Brevis
The Adductors are stronger than the
Abductors.
▪ Gluteus Medius is a powerful
Abductor
▪ The Abductors able to generate
maximum Isometric Torque in the
Supine position when they are in
Lengthened position
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Gluteus Medius, Gluteus Minimus, they
have fibers lie anterior to axis of motion
of Hip and are Medial Rotators
Adductor Longus and Magnus are also
active in Medial Rotation
LATERAL ROTATORS, Obturator
internus & externus
,Piriformis,Gemellus
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Anterior –Posterior Pelvic tilting--------Saggital plane
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Lateral pelvic tilting--------coronal plane
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Pelvic rotation----------Transverse plane
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Anterior pelvic tilting causes Symphysis
pubis to move inferiorly, anterior
surface of pelvis moves closer to
anterior surface of Femur
Causes Hyper extension of Lumbar
spine
Increase the Lumbar anterior convexity
Hip Flexors work with Trunk Extensors
as a force couple
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Posterior tilting brings the posterior
aspect of pelvis closer to posterior
surface of Femur
It causes Flexion of Lumbar spine
It decreases the Lumbar anterior
convexity
Hip extensors works with Trunk flexors
as a force couple to produce Posterior
tilting
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It refers to specific type of coordinated
activity in which anterior pelvic tilting
occurs with flexion of Lumbar spine
and posterior tilt occurs with Extension
of Lumbar Spine
It helps to gain more range of motion
during trunk bending
Pelvis tilt Inferiorly or Superiorly
It causes lateral flexion and rotation of
spine and abduction or adduction of Hip.
 Hip Hiking is produced by Quadratus
Lumborum muscle
 Pelvic drop is controlled by Gluteus
Medius of opposite side
 Excessive tilting due to Abductor
weakness is called TRENDELENBURG
SIGN
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Forward and Backward rotation of
Pelvis
If the right side pelvis is forwardly
rotating on the side of Swinging
extremity,left hip serves as a axis for
motion
Lateral rotation takes place in right hip
due to posterior movement of Right
acetabulum over Right head of Femur
This figure provides a posterior view of the pelvis, might have of a person as he or she
walks and bears weight momentarily on the right lower limb.
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Because the stance phase of walking
occurs in a closed kinetic chain, we
analyze right (stance) hip movement by
considering the mass superincumbent to
the joint as the moving part.
By placing the gravity vector on the
approximate center of gravity of the
moving part, we determine that its force,
the weight of the mass superincumbent to
the hip joint, produces adduction of the
right hip.
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When people walk, their pelvises don't
drop dramatically on the non-stance
side because gravity's adductor
moment is balanced by an equal and
opposite abductor moment. "A major
function of the hip abductors is in
closed-chain motion to maintain a level
pelvis in unilateral stance" (Smith,
Weiss, & Lehmkuhl, 1996, p.294)
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Because hip abductor activity is
necessary to stabilize the hip in the
frontal plane during unilateral stance,
including the stance phase of walking,
people with hip abductor weakness
(note the relatively short vector M in
the figure below) have a problem.
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We might see the pelvis drop on the
unsupported side if we ask a person to
stand briefly on the limb whose hip
abductors are weak. The, inability to
maintain a level pelvis in unilateral
stance is called a positive
Trendelenburg sign.
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The most direct way to reorient the line of
application of the gravity vector (note
how vector W has shifted to the right),
and so to shorten its moment arm with
respect to the hip joint, is to lean the
trunk toward the side of the hip whose
abductor muscles are weak. This
characteristic way of walking, in which
the person leans laterally during stance, is
sometimes called a Trendelenburg gait
pattern or a gluteus medius limp
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WEIGHT SHIFTING:
When body weight is shifted totally to
supporting leg then the resultant force
acting on the Femur is reduced
(If the line of gravity is shifted directly
to the axis of Hip joint then the clock
wise gravitational moment is
eliminated and need for abductor
muscle activity is reduced)
USE OF CANE:
To reduce the force acting at the
supporting hip is by use of cane on
unsupported side of pelvis
 The gravitational moment acting at the
Right hip tends to produce a drop of
pelvis on Left unsupported side. The
ground reaction force created as a result
of downward thrust of body weight on
cane will counterbalance moment in
opposite direction.
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The secret in using an assistive device, like a
cane, is to create an additional force that keeps
the pelvis level in the face of gravity's tendency
to adduct the hip during unilateral stance. The
cane's force must substitute for the hip
abductors.
 A force that levels the pelvis efficiently,
because its moment arm is relatively long, is
directed upward from a point of application on
the pelvis (vector C). The force originates on
the side opposite the hip whose abductor
muscles (vector M) are weak .
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To produce a force like vector C with a cane, one
must push the cane firmly into the ground in a
vertical direction. Doing so generates an upward
reaction force (vector R) whose magnitude equals
the downward force one exerts on the cane.
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Additionally, the person needs adequate strength
in the muscles of the wrist, elbow, shoulder girdle,
and trunk, whose effect is symbolized by the
dashed line that connects vectors R and C. If not,
he or she cannot efficiently transfer the cane's
vertical reaction force (vector R) to the top of the
pelvis (vector C) where it is needed.
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COXA VARA,COXA VALGA
ANTEVERSION ,RETROVERSION
ANTEVERSION causes anterior
dislocation of Head of Femur ,intoeing,
RETROVERSION causes Lateral
rotation gives more stability to Hipjoint
Fracture Neck Of FEMUR