Download Chapter 12 Hip Anatomy and Biomechanics

HIP ANATOMY
The Joint
The hip or coxafemoral joint includes the concave acetabulum of the innominate of the
pelvis and the convex head of the femur (1) (Table 12.1). Structurally, the hip is a very stable joint,
supported by one of the strongest ligament systems in the body and a very deep acetabulum.
Further stability is added by the contribution of the fibrocartilaginous acetabular labrum (1), which
deepens the acetabulum for greater congruency. The semi-circular–shaped acetabular labrum is a
fibrocartilaginous rim that attaches to the outer border of the acetabulum, an element that
decreases the friction of the joint surfaces (2). The transverse ligament completes the ‘circle’ of
the labrum and functions as an attachment site for the ligamentum teres. The labrum is much
thicker medially, superiorly, and posteriorly than anteriorly, thus predisposing the anterior labrum
to tears. The joint capsule attaches to the labrum, is integrated with the ligamentous structures,
and has an attachment to the rectus femoris muscle (2).
Table 12.1: General Information Regarding the Hip Region.
Concept
Information
Bones
Composed of 4 bones: 3 from the innominate (the ilium, ischium, and
pubis), which integrates to form the acetabulum and the single femur
Lumbopelvic rhythm
•
•
Femur
•
•
•
•
Ipsilateral lumbopelvic rhythm—the L/S and the pelvis rotate in the
same direction, as in forward bending from the waist
Contralateral lumbopelvic rhythm—the L/S and the pelvis rotate in
opposite directions. The supralumbar trunk (the body above L1)
can remain stationary as the pelvis rotates over the femurs. This
occurs with walking or other activities where the head and eyes
need to be held fixed in space independent of the rotation of the
pelvis
The femur is the longest and strongest bone in the body and has a
slight anterior convexity (bowing) to allow greater loading
The femur has a thick shell of dense, compact bone, which is able
to resist large external loads and a core of cancellous bone that
absorbs external loads
The femoral head forms 2/3 of a perfect sphere and is covered by
articular cartilage, which is thickest anterior and above the fovea.
There is approximately 125° or femoral head inclination and 15° of
normal anteversion
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Acetabulum
The acetabulum has a 20° anterior orientation. There is an acetabular
ring of fibrocartilage. The acetabular cartilage is thickest along the
superior-anterior margin
Theoretical resting
position
Theoretical close-pack
position
Theoretical capsular
pattern
Resting position = 30° flexion, 30° abduction, and slight external
rotation
Close-pack position = extension, internal Rotation, and abduction
Capsular pattern = internal rotation, flexion, abduction, and external
rotation
The hip is unlike the shoulder in the fact that the amount of accessory motion outside of
distraction is minimal (3). Normal arthrokinematic movements such as those associated with glide
and slide are finite, a consequence of structure and function.
Osseous Structures
Four bones make up the coxafemoral joint; 1) the femur, 2) the pubis, 3) the ischium, and
4) the ilium. The innominate bones are composed of the ilium, the pubis, and the ischium. The
ilium is the superior-most osseous structure of the innominate that forms the articulation with the
sacrum and two-fifths of the surface of the acetabulum (4). The pubis is the inferomedial aspect of
the innominate and constitutes one-fifth of the articulation with the acetabulum of the hip. The
ischium is the inferolateral aspect of the innominate that provides the floor of the acetabulum and
the posterior two-fifths of the articular surface of the acetabulum rim. The acetabulum is covered in
hyaline cartilage.
The femur is a very large and stable long bone that is further subdivided into the head,
neck, and trochanteric regions. The spherical head is directed cranially and medially, and slightly
anterior. The surface of the head of the femur is covered with hyaline cartilage for smooth contact
with the acetabulum. The neck of the femur connects the head of the femur with the shaft and is
angled about 125 degrees in an adult. Over time during growth, the angle decreases and varies
greatly among individuals.
The trochanteric region includes the greater and lesser trochanters, attachment sites for
several muscles of the hip region. The greater trochanter is situated lateral and posterior and is
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caudal to the neck of the femur. The tendons of the gluteus medius, and to some extent the
gluteus maximus, insert on the lateral aspect of the greater trochanter, which also serves as the
location for the intertrochanteric bursae. The medial aspect is the attachment site for the tendons
of the obturator externus, the obturator internus, the gemelli, the gluteus minimus, and the
piriformis. The inferior aspect of the medial greater trochanter gives origin to the upper part of the
vastus lateralis. The lesser trochanter serves as the insertion site for the iliacus and the psoas
major (5).
Ligaments and Capsule
There are several major ligaments of the hip, the most prominent being the Y ligament of
Bigelow. The Y ligament of Bigelow provides anterior ligamentous support. The Y ligament of
Bigelow originates from the anterior inferior iliac spine of the pelvis and attaches to the
intertrochanteric line of the femur. The ligament was given the name “Y” because the bifurcation of
the two ligaments looks like an inverted Y. The ligaments support the anterior aspect of the
capsule and provide stabilization against excessive extension-based movements. The Y ligament
of Bigelow is considered the strongest single ligament within the body.
The pubofemoral ligament connects the pubic ramus to the intertrochanteric line and
limits abduction while providing some extension support (6). The ligament extends across the
antero-inferior aspect of the joint to blend with the iliolumbar ligament. Because of the orientation
of the fibers, the ligament also assists in preventing excess abduction (6). This ligament reinforces
the hip capsule and adds to the strength during end-range movements.
The ischiofemoral ligament, the thinnest of the hip ligaments, extends from the posterior
acetabular rim to the inner surface of the greater trochanter of the femur (6). Primarily, the
ligament stabilizes the hip in full extension. Similar to the iliolumbar ligament and the pubofemoral
ligament, the ischiofemoral ligament is tightened during internal rotation and reinforces the hip
capsule.
Cook, Orthopedic Manual Therapy: An Evidence-Based Approach, 2/E
© 2012 by Pearson Education, Inc., Upper Saddle River, NJ
The ligamentum teres is a flat, triangular-shaped ligament that arises from the base of the
transverse acetabular ligament of the acetabulum and inserts into the head of the femur. In
conjunction with the hip capsule, the ligamentum teres limits functional distraction of the hip joint
and may have some stabilizing effect. The ligament is tensioned when the thigh is semi-flexed,
adducted, or externally rotated and is relaxed when the limb is abducted. The teres ligament
provides a conduit for the medial and lateral circumflex arteries and supplies the femur with blood
and nutrients.
Figure 12.1: The Ligaments of the Hip
The hip capsule is fibrous and encloses the hip joint. The anterior attachment sites include
the acetabulum and the neck of the femur at the intertrochanteric line. Posteriorly, the lateral
aspect of the femoral neck is extracapsular and medial. The posterior capsule is attached to the
acetabulum and pubic ramis. The anterior ligament, which arises above the anterior superior iliac
spine (ASIS) and adjacent to the acetabulum, reinforces the capsule with a component of the
iliofemoral ligament and the aforementioned ischiofemoral and pubofemoral ligaments. The
contribution of the ligaments to the capsule often tightens the ligament during extension and
occasionally during internal rotation.
Cook, Orthopedic Manual Therapy: An Evidence-Based Approach, 2/E
© 2012 by Pearson Education, Inc., Upper Saddle River, NJ
Muscles
The largest forces at the hip are a result of muscular contraction (7), specifically those
required during single-leg stance (Table 12.2). Crowninshield and Brand (8) report that an activity
such as the single-leg stance, in which the ipsilateral gluteus medius is forced to contract to
stabilize the pelvis, leads to compression forces three to four times the body weight. Others have
projected the force at six times the person’s body weight (1).
Table 12.2: The Muscles of the Hip.
Location
Anterior
Posterior
Medial
Lateral
Muscle
Sartorius
Rectus femoris
Psoas major
Iliacus
Gluteus maximus
Hamstrings
Gracilis
Hip adductor group
Gluteus medius
Gluteus minimus
Function
Hip flexion, abduction and external rotation
Hip flexion and knee extension
Hip flexion and lumbar compression
Hip flexion
Hip extension
Hip extension and knee flexion
Primarily hip adduction
Hip adduction
Hip abduction and pelvic stabilization during
unilateral stance
Hip abduction
Dividing the muscle into regions more effectively aids in describing the multiple muscles of
the hip. The regions are subdivided into the anterior, medial, lateral, and posterior musculature.
The anterior musculature includes the rectus femoris, sartorius, and the iliopsoas group. Medially,
the musculature consists of the adductor group, including the pectineus and the gracilis.
Numerous muscles comprise the lateral musculature of the hip including the gluteus medius,
tensor fasciae latae (TFL), piriformis, quadratus femoris, obturator internus, obturator externus,
gemellus superior, and gemellus inferior. Lastly, the posterior muscles include the primary muscle
group responsible for hip extension such as the gluteus maximus and hamstrings.
Cook, Orthopedic Manual Therapy: An Evidence-Based Approach, 2/E
© 2012 by Pearson Education, Inc., Upper Saddle River, NJ
Bursae
There are four primary bursae at the hip. Two bursae are of special interest because they
are commonly involved in pathology. The trochanteric bursa is located on the side of the hip near
the posterior aspect of the greater tubercle. The trochanteric bursa normally functions to increase
lubrication of the hip abductors, but when pathological, may cause a dull, burning pain on the
outer hip that is worsened with abduction or squatting. The ischial bursa (not pictured) is located in
the posterior buttock region and lies over the ischial tuberosity. The ischial bursa may cause dull
pain in the buttock region that is most noticeable climbing up hill and is generally worsened during
sitting, specifically in firm-seated chairs (5).
Figure 12.2: Anterior and Lateral Bursae of the Hip
Summary
•
•
•
•
The hip joint consists of the femur, the three bones that make up the innominate, and the
surrounding ligaments and muscles.
The hip joint is a deep-set ball-and-socket joint that sacrifices mobility for stability.
The capsular-ligamentous system of the hip creates the most stable synovial joint system
within the body.
Of the numerous muscles that surround the hip, two primary stabilizers, the gluteus
medius and the gluteus maximus, play a considerable role during gait and function.
Cook, Orthopedic Manual Therapy: An Evidence-Based Approach, 2/E
© 2012 by Pearson Education, Inc., Upper Saddle River, NJ
BIOMECHANICS
Cyriax (11) and Kaltenborn (12) outlined the existence of a capsular pattern during early
stages of osteoarthritis and other forms of hip capsule trauma. Cyriax (11) proposed the loss of
internal rotation typically proceeded flexion, abduction, then extension, and that external rotation
loss was rare. He (11) and Kaltenborn (12), as well as other manual therapy disciplines, have
advocated the use of capsular patterns for both examination and treatment. These theories were
based on clinical experience and ‘perception’ versus experimental analyses.
Recently, two experimental studies (13,14) have refuted the existence of a definable hip
capsular pattern, suggesting that the existence of a single capsular pattern in patients with early or
progressive stages of osteoarthritis does not exist. Others have also reported gross range-ofmotion losses, nonpatterned in external and internal rotation, as well as abduction in osteoarthritis
conditions (15). Based on these findings, examination and treatment based on capsular pattern
could provide inconsistent, unreliable, and subsequently invalid results. Although the use of a
capsular pattern has been documented as helpful in a series of case studies, the use of this
method in examination is excluded as a component of this chapter because it appears highly
variable. Additionally, even though occasional range-of-motion variations (i.e., internal range-ofmotion loss with osteoarthritis) provide some benefit during examination for selected pathologies,
this pattern appears to lack reliability to overlay all like-type disorders.
Using a nationwide database, Roach and Miles (16) reported normative values for the
combined age groups of 25 through 74. The following values of 121 degrees of hip flexion, 19
degrees of hip extension, 42 degrees of hip abduction, 32 degrees of internal rotation, and 32
degrees of external rotation closely reflect those of Hoppenfeld (17) but differ from those of
Kendall et al. (18) and Daniels and Worthingham (19). What was interesting regarding the findings
was that the values associated with all ranges declined with age, although those with hip flexion
declined only minimally.
Along with planar movements, the hip can also move in combined motions of
circumduction, which is a movement combination of variations of plane-based motions (Table
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© 2012 by Pearson Education, Inc., Upper Saddle River, NJ
12.3). The benefit of combined motions during examination and treatment is that the structures
assume a more compromised and tightened position and may provide more discriminatory results.
Specifically, combined movements should be examined if no mechanically based painful findings
are extracted from the initial examination.
Table 12.3: Hip Range-of-Motion Movements and Methods of Limiting Movement.
Motion
Movement
Restricting Elements
Flexion
Abduction
80° with knee extended
120° with knee flexed
20° with knee extended
0° with knee flexed
40°
Adduction
25°
IR
ER
35°
45°
Hamstrings and gracilis
Ischiofemoral ligament and inferior capsule
Iliofemoral ligament and anterior capsule
Rectus femoris
Pubofemoral ligament, inferior capsule, adductor,
and hamstrings
Ischiofemoral ligament, IT band, and abductor
muscles
Ischiofemoral ligament and ER muscles
Iliofemoral ligament, IT band, and IR muscles
Extension
Summary
•
•
Little evidence exists to support Cyriax’s theory of capsular pattern. To date, there are no
studies that have verified a consistent pattern of range-of-motion loss at the hip.
Roach and Miles outlined the following normative values for range of motion at the hip:
121 degrees of hip flexion, 19 degrees of hip extension, 42 degrees of hip abduction, 32
degrees of internal rotation, and 32 degrees of external rotation.
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Cook, Orthopedic Manual Therapy: An Evidence-Based Approach, 2/E
© 2012 by Pearson Education, Inc., Upper Saddle River, NJ