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INTRODUCCION
•  Hip pain is particularly frequent in both professional
and amateur athletes.
•  There are a significant number of muscle injuries at
this region. Many of them are considered infrequent
and may be overlooked by ultrasonography mainly
because of its depth.
•  The goal of this exhibit is to educate the radiologist
about the complex anatomy of the pelvis in order to
learn to recognize the clinical presentation and
imaging findings of the muscle strains at this level.
MRI protocols
•  Patients should empty their bladders before the
evaluation.
•  Sequences coronal and axial STIR or T2 FS FSE and
coronal T1-weighted SE should be applied while using a
built-in body coil (large FOV).
•  Sagital T2 weighted FS SE and axial oblique T2weighted FS SE sequences should be acquired while
using the same phased-array pelvic coil used for
gynecologic imaging in order to maximize sensitivity for
the detection of muscle injuries.
ILIOPSOAS
•  The psoas major is a large muscle that runs from the
bodies and disc of the L1 to L5 vertebrae, joins with the
iliacus via its tendon and connects to the lesser
trochanter of the femur. The iliacus originates on the iliac
fossa of the ilium.
•  Their injury is considered an occasional cause of athletic
pubalgia and is seen more frequently in football and
rugby players.
Strain of illiopsoas muscle belly.
Axial FS FSE T2-weighted image
and anatomic illustration depict high
signal intensity in the right iliopsoas
muscle (arrow) with sorrounding
fluid and edema. The tendon is not
affected from its insertion onto the
lesser trochanter.
Avulsion tear from the
illiopsoas tendon of the
lesser trochanter.
Coronal and axial STIR
images
GLUTEAL GROUP
•  The gluteus maximus originates primarily on the ilium
and sacrum and inserts on the gluteal tuberosity of the femur as well
as the iliotibial tract. These are often the least common injuries in
this group.
•  The gluteus medius and gluteus minimus originate anterior to the
gluteus maximus on the ilium and both insert on the greater
trochanter of the femur. Their injuries are often due to a sudden
increase in the intensity or duration of training, typically associated
with running.
•  These injuries tend to occur more commonly in the older athlete and
particularly following an inadequate warm-up. The majority of gluteal
strains are grade 2 tears.
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Tear of gluteus medius and minimus
tendons. Axial FS FSE T2-weighted
image and correlate illustration of the
hip show high grade insertional tear of
gluteus medius and minimus tendons
with sorrounding hematoma of both
muscles bellies and trochanteric bursitis
(arrow).
Tear of gluteus medius and minimus
tendons. Axial and coronal STIR
images shows insertional tear of
gluteus medius and minimus tendons
extending to the muscle bellies with
sorrounding hematoma.
Tear of gluteus medius
and maximus muscle
bellies. Axial FS FSE
T2-weighted image and
correlate illustration of
the hip show grade II
tears with sorrounding
hematoma (arrows)
Tear billaterally of both gluteus
maximus muscle bellies. Axial
and coronal STIR images show
grade II tears in an older patient
after a sudden contraction of
these muscles in a position of
stretch.
INFREQUENT MUSCLE STRAINS IN
PELVIS
•  The deep external rotators of the hip include the piriformis,
quadratus femoris, the inferior and superior gemelli, and
external and internal obturators.
•  Many of these muscles have complex origins and sit deep
within the pelvis making them difficult to isolate on a current
MRI examination.
•  These muscles strains are rare and in many cases difficult to
make a correct diagnosis, leading to long periods of inactivity
in the athlete.
•  However, identifying the exact muscle strain of the deep
external rotators with an adequate MRI protocol and a trained
radiologist can appropriately help modify the rehabilitation
program.
PIRIFORMIS
•  The piriformis muscle originates from the anterior part of
the sacrum, the part of the spine in the gluteal region, and from
the superior margin of the greater sciatic notch. It exits the
pelvis through the greater sciatic foramen to insert on the greater
trochanter of the femur.
•  Although this muscle tears are infrequent, there are usually
associated with other pelvic muscles tears. The clinical picture
can result in the "piriformis syndrome" characterized by irritation
of the sciatic nerve as it runs very close to this muscle usually at
the lower edge though it has been described many anatomical
variants.
•  If the piriformis muscle becomes tight it can compress the sciatic
nerve and cause pain which can radiate down the leg.
Tear of Piriformis (internal
arrow) and Gluteus medius
(external arrow) muscles.
Axial FS FSE T2-weighted
image and anatomic
illustration of the hip
demonstrate strain of both
muscle groups with quoted
signs of soft tissue edema.
QUADRATUS FEMORIS
•  Is a quadriteral muscle that arises from the lateral border of
the ischial tuberosity and extends laterally to its insertion on the
posterior side of the head of the femur: the intertrochanteric crest.
•  Injury to the quadratus femoris can radiate distally from the posterior
thigh, presumably by irritation of the sciatic nerve either from
hematoma or edema (similar on clinical grounds to a hamstring
injury).
•  The activities more frequently assocciated with this injury are
running, badminton, lifting and tennis.
•  The rarity of this diagnosis in the imaging literature may be due to
mistaken diagnosis (mostly with hamstrings or obturator externus
muscle tears).
•  Its tear is could be associated with the isquiofemoral impingement
syndrome with narrowing of the space between the lesser trochanter
and the ischial tuberosity.
Ischiofemoral Impingement Syndrome.
Axial fat-suppressed fast spin-echo T2weighted image and correlate illustration
show diffuse edema and increased signal
intensity within the quadratus femoris
muscle on the right hip (arrow). There is a
bilateral narrowing space between the
ischial tuberosity and the lesser
trochanter.
Strain of quadratus femoris. Axial, sagital and
coronal FS FSE T2-weighted image depicts
high signal within this muscle (arrow) in the
isquiofemoral space near the obturator external
and the hamstrings muscles.
EXTERNAL OBTURATOR MUSCLE
•  Covers the outer surface of the pelvis. The muscle is flat and
fan-shaped.
•  It emerges from the margins of the obturator foramen and the
obturator membrane. The fibers course behind the neck of
the femur. It inserts into the trochanteric fossa of the femur, a
depression in the bone’s neck.
•  This injury is seen on soccer and rugby players and may be
mistaken for an injury of the hip adductor or hamstrings
muscles due to the site of the pain reported by the individual.
Strain of obturator
externus. Axial FS FSE T2weighted image and
anatomic illustration depict
high signal within the right
muscle-tendon junction
(arrow) where looking
insertion into the posterior
margin of the greater
trochanter.
INTERNAL OBTURATOR MUSCLE
•  The obturator internus is a fan shaped muscle that
originates on the medial surface of the pubis around the
obturator foramen, runs posterior-lateral and attaches to
the inner surface of the greater trochanter of the femur.
•  Most of the strains involve young athletes and were
associated with quadratus femoris strain, acetabular
fracture or avulsion of the lesser trochanter. Strain of obturator internus.
Axial FS FSE T2-weighted
image and anatomic
illustration depict edema and
increased signal intensity
within the right muscle belly
(arrow) before inserting on the
greater trochanter of the
proximal femur. THE ADDUCTOR GROUP
•  The adductor brevis, adductor longus, adductor
magnus, pectineus, and gracilis make up the adductor group.
The adductors all originate on the pubis and insert on the
medial and posterior surface of the femur, with the exception
of the gracilis which inserts just below the medial condyle of
the tibia.
•  The strains involving the adductor longus and then the
pectineus and adductor brevis are the most frequent as a part
of the athletic pubalgis spectrum.
Pect
Al
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Strain of pectineus and
adductor longus. Axial STIR
image and anatomic
illustration depict edema and
increased signal intensity
within these tendons and
muscle bellies (arrow) at the
level of their insertion at the
upper front of the pubic bone.
Strain of the adductor brevis.
Axial STIR image and
anatomic illustration depict
high signal within the left
muscle and tendon junction
(arrow) prior to its insertion at
the middle front of the pubic
bone.
Strain of gracilis muscle belly.
Axial and sagital FS FSE T2weighted image and anatomic
illustration depict high signal
intensity in the left gracilis muscle
(arrow) with sorrounding fluid and
edema. The muscle's fibers run
vertically downward, ending in a
rounded tendon.
Strain of the adductor magnus.
Coronal obliques, sagital and
axial obliques FS FSE T2weighted images depict high
signal within the right muscle
belly (arrows) prior to its
insertion at the posterior front
of the pubic bone.
It is the most infrequent strain
at the level of the adductor
group.
RECTUS FEMORIS MUSCLE
•  It arises by two tendons: one, the anterior or straight, from
the anterior inferior iliac spine (AIIS); the other, the posterior
or reflected, from a groove above the rim of the acetabulum.
•  The muscle ends in a thick aponeurosis which gradually
becoming narrowed into a tendon inserted into the base of
the patella.
•  Their injuries are frequent, particularly the avulsion of the
anterior tendon from the AIIS or the strain in the upper half
of the muscle belly. The main cause could be related with
overuse through kicking or explosive movements as in
sprint starts.
Avulsion tear from the straight (direct)
head tendon of the rectus femoris from
its insertion at the level of the AIIS.
The reflected (indirect) head tendon is
not affected.
Axial FS FSE T2-weighted images and
anatomic illustration.
VASTUS LATERALIS MUSCLE
•  Is the largest part of the quadriceps femoris. It arises from
several areas of the femur: the intertrochanteric line, the
greater trochanter, the gluteal tuberosity and particularly the
upper half of the linea aspera.
•  The fibers form a strong aponeurosis which becomes
contracted and thickened into a flat tendon inserted into the
lateral border of the patella.
•  Their strains are infrequent taking place in this muscle daily
uses such as cycling or walking up stairs.
Strain of vastus lateralis muscle
belly. Axial FS FSE T2-weighted
image and anatomic illustration
depict high signal intensity in the
left muscle belly (arrow) with
sorrounding fluid and edema.
Sartorius
•  It extends from the anterior superior iliac spine (AAIS), running obliquely
across the upper and anterior part of the thigh. It descends to join the
tendons of the gracilis and semitendinosus muscles which together form
the pes anserinus, finally inserting into the proximal part of the tibia on the
medial surface of its body.
•  Sartorius injuries are seldom mentioned in medical literature and the correct
diagnosis can be challenging.
•  It should be consider in runners as well as football players more frequently
at the level of its proximal insertion in the AAIS. The athlete may be able to
continue playing but the examination often reveals local swelling and
restriction in hip movements.
Strain of sartorius. Axial, sagital and coronal
FS FSE T2-weighted image and anatomic
illustration picture increase signal intensity in
the right muscle belly (arrow) with significant
superficial edema.
Summary
•  There are a significant number of muscle injuries at the level
of the hip. The accurate diagnosis could be challenging for
radiologist due to its depth and the complex muscular
anatomy of this region, especially regarding the deep external
rotators.
•  MRI with a precise protocol provides an adequate anatomic
resolution and multiplanar capability being the method of
choice that identify the precise location of the injury and
establishes its severity.
•  The knowledge of the precise location of a muscle strain helps
the orthopedist to select a correct treatment and provides the
athlete a recovery in the shortest time possible.