Download Lateral Shift of the Pelvis

Lecture-4
BIO-MECHANICS OF HIP
JOINT
Objectives
At the end of this lecture the student shall be
able to:
• Enumerate the kinematics of hip complex
• Describe the movement of the femur on
pelvis..
• Describe the movement of the pelvis on
femur.
• Describe the lumbo-pelvis rhythm.
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Kinematics of hip joint
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Motion of the Femur on the
Acetabulum
The motions of the hip joint are easiest to
visualize as movement of the convex femoral
head within the concavity of the acetabulum as
the femur moves through its three degrees of
freedom:
flexion/extension,
abduction/adduction, and
medial/lateral rotation.
The femoral head will glide within the
acetabulum in a direction opposite to motion of
the distal end of the femur.
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• Flexion and extension of the femur occur from a
neutral position as an almost pure spin of the
femoral head around a coronal axis through the
head and neck of the femur.
• The head spins posteriorly in flexion and
anteriorly in extension.
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• The motions of abduction/adduction and
medial/lateral rotation must include both
spinning and gliding of the femoral head within
the acetabulum, but the intra-articular motion
again occurs in a direction opposite to motion of
the distal end of the femur.
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• Flexion of the hip is generally about 90° with the
knee extended and 120 ° when the knee is
flexed and when passive tension in the two-joint
hamstrings muscle group is released. Hip
extension is considered to have a range of 10 °
to 30°.
• Hip extension ROM appears to diminish
somewhat with age, whereas flexion remains
relatively unchanged.
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• When hip extension is combined with knee
flexion, passive tension in the two-joint rectus
femoris muscle may limit the movement. The
femur can be abducted 45° to 50° and adducted
20° to 30°.
• Abduction can be limited by the two-joint gracilis
muscle and adduction limited by the tensor
fascia lata (TFL) muscle and its associated
iliotibial (IT) band.
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• Medial and lateral rotation of the hip are
usually measured with the hip joint in 90°
of flexion; the typical range is 42° to 50°.
• Femoral anteversion is correlated with
decreased range of lateral rotation and
less strongly with increased range of
medial rotation.
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• When the femoral head is torsioned anteriorly
more than normal lateral rotation of the femur
turns the head out even more, both risking
subluxation and encountering
capsuloligamentous and muscular restrictions
on the anterior aspect of the joint as the head
presses forward.
• Hip joint rotation can similarly be affected by
retroversion of the femur, as well as by
acetabular anteversion and laxity of the joint
capsule.
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• Normal gait on level ground requires at least the
following hip joint ranges:
• 30° flexion,
• 10° hyperextension,
• 5° of both abduction and adduction, and
• 5° of both medial and lateral rotation.
• Walking on uneven terrain or stairs will increase
the need for joint range beyond that required for
level ground, as will activities such as sitting in a
chair or sitting cross-legged.
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Motion of the Pelvis on the Femur
• Whenever the hip joint is weight-bearing, the
femur is relatively fixed, and, in fact, motion of
the hip joint is produced by movement of the
pelvis on the femur.
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Anterior and Posterior Pelvic Tilt
• Anterior and posterior pelvic tilt are motions of
the entire pelvic ring in the sagittal plane.
• In the normally aligned pelvis, the anterosuperior iliac spines (ASISs) of the pelvis lie on a
horizontal line with the posterior superior iliac
spines.
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• Anterior and posterior tilting of the pelvis on the
fixed femur produce hip flexion and extension,
respectively.
• Hip joint extension through posterior tilting of the
pelvis brings the symphysis pubis up and the
sacrum of the pelvis closer to the femur, rather
than moving the femur posteriorly on the pelvis
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• Hip flexion through anterior tilting of the pelvis
moves the ASISs anteriorly and inferiorly; the
inferior sacrum moves farther from the femur,
rather than moving the femur away from the
sacrum
• Anterior and posterior tilting will result in flexion
and extension of both hip joints simultaneously
in bilateral stance or can occur at the stance hip
joint alone if the opposite limb is non-weightbearing.
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Lateral Pelvic Tilt
• Lateral pelvic tilt is a frontal plane motion of the
entire pelvis around an antero-posterior axis. In
the normally aligned pelvis, a line through the
ASISs is horizontal.
• Left pelvic tilt ;is when the right side of the
pelvis is elevated higher than the left side.
• Right pelvic tilt ;is when the left side of the
pelvis is elevated higher than the right side.
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Lateral Shift of the Pelvis
• Lateral pelvic tilt can also occur in bilateral
stance. If both feet are on the ground and the
hip and knee of one limb are flexed, the
opposite limb is largely the weight-bearing
limb and the terminology is the same as for
unilateral stance.
• However, if both limbs are weight-bearing,
lateral tilt of the pelvis will cause the pelvis to
shift to one side or the other.
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• If the pelvis is shifted to the right in
bilateral stance, the left side of the pelvis
will drop, the right hip joint will be
adducted, and the left hip joint will be
abducted.
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Anterior and Posterior Pelvic
Rotation
• Pelvic rotation is motion of the entire pelvic
ring in the transverse plane around a vertical
axis.
• Although rotation can occur around a vertical
axis through the middle of the pelvis in
bilateral stance, it most commonly and more
importantly occurs in single-limb support
around the axis of the supporting hip joint.
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Forward Rotation
• Forward rotation of the pelvis occurs in
unilateral stance when the side of the
pelvis opposite to the supporting hip joint
moves anteriorly .
• Forward rotation of the pelvis produces
medial rotation of the supporting hip joint.
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Backward Rotation
• Backward rotation of the pelvis occurs
when the side of the pelvis opposite the
supporting hip moves posteriorly.
• Backward rotation of the pelvis produces
lateral rotation of the supporting hip joint.
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Bilateral Pelvic Rotation
• Pelvic rotation can occur in bilateral stance as
well as unilateral stance, as is true for lateral
pelvic tilt.
• If both feet are bearing weight and the axis of
motion occurs around a vertical axis through the
center of the pelvis, the terms forward rotation
and backward rotation must be used by
referencing a side (e.g., forward rotation on the
right and backward rotation on the left).
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Coordinated Motions of the Femur,
Pelvis, and Lumbar Spine
• When the pelvis moves on a relatively fixed
femur, there are two possible outcomes to
consider.
• Either the head and trunk will follow the motion
of the pelvis or the head will continue to remain
relatively upright and vertical despite the pelvic
motions.
• These are open- and closed-chain responses,
respectively.
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Pelvifemoral Motion
• When the femur, pelvis, and spine move in
a coordinated manner to produce a larger
ROM than is available to one segment
alone, the hip joint is participating in what
will predominantly be an open-chain
motion termed pelvifemoral motion.
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• Table presents the compensatory motions
of the lumbar spine that accompany given
motions of the pelvis and hip joint.
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Muscles Work in
AT & PT
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