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At the end of this lecture the students shall be able to:
 Describe the joint stability and congruency
 Enumerate capsule biomechanics
 Identify different hip ligaments
 Discus biomechanics of hip ligaments
 The hip joint is considered to be a congruent joint.
 However, there is actually more articular surface
on the head of the femur than on the acetabulum.
 In the neutral or standing position, the articular
surface of the femoral head remains exposed
anteriorly and somewhat superiorly
 The acetabulum does not fully cover the
head superiorly, and the anterior torsion of
the femoral head (angle of torsion) exposes
femoral head’s articular surface anteriorly.
 Articular contact between the femur and the
acetabulum can be increased in the normal nonweight-bearing hip joint by a combination of
flexion, abduction, and slight lateral rotation
 This position (also known as the frog-leg position)
corresponds to that assumed by the hip joint in a
quadruped position and, according to Kapandji, is
the true physiologic position of the hip joint.
 An additional contribution to articular congruence
of joint surfaces may be made by the nonarticular
and non-weight-bearing acetabular fossa.
 The acetabular fossa may be important in setting
up a partial vacuum in the joint so that
atmospheric pressure contributes to stability by
helping maintain contact between the femoral
head and the acetabulum.
 Wingstrand and colleagues concluded that
atmospheric pressure in hip flexion activities
played a stronger role in stabilization than
capsuloligamentous structures.
 It is also true that the head and acetabulum will
remain together in an anesthetized patient even
after the joint capsule has been opened. The
pressure within the joint must be broken before
the hip can be dislocated.
 Unlike the relatively weak articular capsule
of the shoulder, the hip joint capsule is a
substantial contributor to joint stability.
 The articular capsule of the hip joint is an
irregular, dense fibrous structure with
longitudinal and oblique fibers and with
three thickened regions that constitute the
capsular ligaments.
 The capsule is attached proximally to the
entire periphery of the acetabulum beyond
the acetabular labrum.
 Fibers near the proximal attachment are
aligned in a somewhat circumferential
 The capsule itself is thickened anterosuperiorly,
where the predominant stresses occur; it is
posteroinferiorly, with some areas of the capsule
thin enough to be nearly translucent.
 The capsule covers the femoral head and neck like
a cylindrical sleeve and attaches to the base of the
femoral neck.
 The femoral neck is intracapsular, whereas both the
greater and lesser trochanters are extracapsular.
 The synovial membrane lines the inside of the
 Anteriorly, there are longitudinal retinacular fibers
deep in the capsule that travel along the neck
toward the femoral head.
 The retinacular fibers carry blood vessels that are
the major source of nutrition to the femoral head
and neck.
 The ligamentum teres is an intra-articular but
extrasynovial accessory joint structure. The
ligament is a triangular band attached at one end
to both sides of the peripheral edge of the
acetabular notch.
 The ligament then passes under the transverse
acetabular ligament (with which it blends) to
attach at its other end to the fovea of the femur;
thus, it is also called the ligament of the head of
the femur
 The ligamentum teres is encased in a flattened
sleeve of synovial membrane so that it does not
communicate with the synovial cavity of the joint.
The material properties of the ligament of the
head are similar to those of other ligaments, and it
is tensed in semiflexion and adduction.
 However, it does not appear to play a significant
role in joint stabilization regardless of joint
 Rather, the ligamentum teres appears to
function primarily is to supply secondary
blood from the obturator artery and for the
nerves that travel along the ligament to
reach the head of the femur through the
 The hip joint capsule is typically considered to have
three reinforcing capsular ligaments (two anteriorly
and one posteriorly), although some investigators have
further divided or otherwise renamed the ligaments.
 For purposes of understanding hip joint function, the
following three traditional descriptions appear to
 The two anterior ligaments are the iliofemoral
ligament and the pubofemoral ligament.
 The iliofemoral ligament is a fan-shaped ligament that
resembles an inverted letter Y
 It often is referred to as the Y ligament of Bigelow. The apex
of the ligament is attached to the anterior inferior iliac
spine, and the two arms of the Y fan out to attach along the
intertrochanteric line of the femur. The superior band of
the iliofemoral ligament is the strongest and thickest of the
hip joint ligaments.
 The pubofemoral ligament is also anteriorly located,
arising from the anterior aspect of the pubic ramus and
passing to the anterior surface of the intertrochanteric
 The bands of the iliofemoral and the pubofemoral
ligaments form a Z on the anterior capsule, similar to that
of the glenohumeral ligaments. The ischiofemoral
ligament is the posterior capsular ligament.
 The ischiofemoral ligament attaches to the posterior
surface of the acetabular rim and the acetabulum labrum.
 Some of its fibers spiral around the femoral neck and blend
with the fibers of the circumferential fibers of the capsule.
 Other fibers are arranged horizontally and attach to the
inner surface of the greater trochanter.