Pelvis, Hips, and Thighs

FIGURE 4-1 Common minor fractures of the pelvis. (A)
Anterior superior iliac spine (1), anterior inferior iliac spine (2),
ischial tuberosity (3), and iliac wing (4). One to three are avulsion
injuries with muscles labeled. (B) Transverse sacral fracture (5), isolated pubic rami fractures (6 and 7).

FIGURE 4-2 (A) AP radiograph of the hip demonstrating an ischial avulsion fracture. (B) CT image of an old ischial avulsion fracture.

FIGURE 4-3 AP radiograph demonstrating an iliac wing fracture (arrow).

FIGURE 4-4 Anterior Judet view demonstrating pubic rami fractures (arrowheads) resulting in a single break in the pelvic ring.

FIGURE 4-5 Lateral compression injuries. (A) Type I: force applied posterolaterally (arrow)
resulting in a crush injury to the sacrum, ilium, and sacroiliac joint
(1) and oblique or horizontal pubic rami fractures (2). (B) Type II: force directed anterolaterally (arrow)
resulting in diastasis of the sacroiliac joint (1 and 3) (Type IIA) or
iliac wing fracture (Type IIB) plus oblique or horizontal pubic rami
fractures (2). (C) Type III: force applied anterolaterally (arrow)
with oblique or horizontal pubic rami fractures (2) and involvement of
both sacroiliac joints and ligaments (1, 3, and 4) (Type IIIA) or
sacroiliac joints and ipsilateral iliac wing fracture (Type IIIB).

FIGURE 4-6 AP compression injuries. (A) Type I: force applied anteriorly (arrow) resulting in diastasis of the pubic symphysis or vertical pubic rami fractures. (B)
Type II: wider diastasis of the pubic symphysis or vertical pubic rami
fractures with disruption of the anterior sacroiliac ligaments. (C)
Type III: wider diastasis of the pubic symphysis or displaced vertical
pubic rami fractures with disruption of both the anterior and posterior
sacroiliac ligaments. (D) AP compression
injury with vertical pubic rami fractures. Sacroiliac joints are
normal. Note the elevated bladder resulting from a large pelvic
hematoma. Type I. (E) Type III AP compression injury with wide diastasis of the pubic symphysis, displaced iliac wing fracture (white arrow), widening of the right sacroiliac joint (black arrow), and multiple avulsion fractures (arrowheads).

FIGURE 4-7 Vertical shearing injury. (A) Force is applied vertically (arrow)
with vertical pubic rami fractures (3) or step-off at the pubic
symphysis and disruption of the anterior and posterior sacroiliac
ligaments (1 and 2). (B) Widening and step-off of the right sacroiliac joint (open arrow) and symphysis (arrow). Suprapubic tube in the bladder because of associated urethral injury.

FIGURE 4-8 (A) Judet view of the hip demonstrating and undisplaced central acetabular fracture (curved arrow). (B) CT image demonstrating an uncomplicated central acetabular fracture (arrow).

FIGURE 4-9 (A) Acetabular margins and the anterior (iliopectineal) and posterior (ilioischial) columns. Three-dimensional CT images (B,C) demonstrating the anterior and posterior columns.

FIGURE 4-10 Fracture patterns (AO classification). (A)
Type A: A1, posterior wall fracture; A2, posterior column fracture;
A3-1, anterior wall fracture; A3-2, anterior column fracture. (B)
Type B1-1, transverse fracture; Type B1-2, transverse with posterior
wall fracture; Type B2-T, fracture; Type B3, anterior column with
posterior transverse fracture. (C) Type
C1, both columns with fracture extending to the iliac crest; Type C2,
both columns extending to anterior inferior iliac spine; Type C3, both
columns with extension to sacroiliac joint. Types A1, B1-1, B1-2, B-2,
and C1 are the most common.

FIGURE 4-11 Complex acetabular fractures. (A)
AP radiograph shows a displaced central acetabular fracture with the
femoral head and fragments extending into the pelvis. Note the
coccygeal dislocation (arrow). Three-dimensional reconstructions (B,C) of a complex acetabular fracture (arrows).

FIGURE 4-12 AP radiographs of posterior (A) and anterior (B) dislocations. Note the displaced femoral head fragment (arrow) in (A).

FIGURE 4-13 (A) CT image of a posterior dislocation. Direction of the force (line with arrowhead). Small posterior rim fracture (open arrow). (B) CT image after reduction of an anterior dislocation with fractures of the femoral neck and anterior acetabulum (arrows).

FIGURE 4-14 Impacted femoral neck fracture (arrows) with cortical disruption and trabecular compression laterally (curved arrow). The hip was pinned.

FIGURE 4-15 (A) Displaced femoral neck fracture (arrow). (B) Treated with bipolar endoprosthesis.

FIGURE 4-16 Coronal fast spin-echo T2-weighted image demonstrates edema with a central linear low-intensity line (arrow) caused by femoral neck stress fracture.

FIGURE 4-17 Sites for avulsion fractures in the pelvis and hips with muscle origins labeled.

FIGURE 4-18 AP radiograph of a comminuted intertrochanteric fracture. Trochanters (arrows) and angular deformity (lines).

FIGURE 4-19 AP radiograph of a subtrochanteric fracture with overriding and slight angulation of the fragments.

FIGURE 4-20 Radiographs of insufficiency fractures. (A) Radiograph demonstrates subtle bone condensation in the sacrum (arrow) caused by an insufficiency fracture. (B) AP radiograph of the pelvis with linear condensation in the left acetabulum (arrow) caused by an acetabular insufficiency fracture.

FIGURE 4-21 MRI of insufficiency fractures. Coronal T1- (A) and fast spin-echo T2- (B)
weighted images show abnormal signal intensity in the acetabulum on the
right caused by insufficiency fracture. There is also marrow edema in
the femoral head and neck caused by early AVN. (C) Axial fast spin-echo T2-weighted image of the sacrum with and insufficiency fracture and fluid (arrow) in the fracture line.

FIGURE 4-22 Axial (A) and sagittal (B) T2-weighted images of a Grade 1–2 strain of the hamstring muscles (arrows).

FIGURE 4-23 Coronal (A) and axial (B) T2-weighted images of an adductor muscle tear (arrows) with a central hematoma.

FIGURE 4-24 Hip arthrogram/injection with filling of the iliopsoas bursa (arrows).

FIGURE 4-25 Coronal fast spin-echo T2-weighted image demonstrating an enlarged iliopsoas bursa (arrows) with low signal intensity filling defects because of chronic synovitis.

FIGURE 4-26 Axial fast spin-echo T2-weighted image of an inflamed trochanteric bursa (arrow).

FIGURE 4-27 (A) Coronal T1-weighted image shows gluteus minimus atrophy (arrows). (B) Fast spin-echo T2-weighted image shows high signal intensity because of a high-grade tear in the minimus tendon (arrow).

FIGURE 4-28 Coronal MR arthrogram image demonstrating the normal triangular shape of the superior labrum (arrow) and the transverse ligament inferiorly (open arrow).

FIGURE 4-29 Coronal MR arthrogram image demonstrating a superior labral tear (arrow).

FIGURE 4-30 Coronal MR arthrogram image with superior labral tear and paralabral cyst (arrows).

FIGURE 4-31 Axial (A) and sagittal (B) MR arthrogram images demonstrate a bony prominence at the head–neck junction (arrow) causing impingement.

FIGURE 4-32 Routine radiograph was normal. (A) Radionuclide scan shows increased signal intensity in the right femoral head and neck. (B) Spin-echo T1-weighted image shows a femoral neck fracture (arrow), low-intensity edema pattern, and AVN (open arrow).

FIGURE 4-33 MRI of AVN. (A) Coronal T1-weighted image of bilateral AVN with greater articular involvement on the left (lines). (B) Sagittal T1-weighted image demonstrating articular surface involvement. (C) Fat-suppressed T1-weighted postcontrast image shows enhancement at the margin of the necrotic bone (arrows) caused by revascularization. (D) Coronal T1-weighted image demonstrating a simple method to calculate the weight-bearing surface involvement. Angle A (thick black lines)
is formed by lines from the center of the femoral head to the
weight-bearing margins. Angle N is formed by lines from the necrotic
margins to the center of the femoral head. N/A × 100% = % of
weight-bearing involvement. In this case 43/94 = 46% indicating a
poorer prognosis.

FIGURE 4-34 Coronal T1-weighted MRI showing AVN of both femoral heads and infarcts (arrows) in the trochanteric regions.

FIGURE 4-35 Coronal (A) and sagittal (B) T1-weighted images showing low signal intensity in the right femoral head and neck caused by transient marrow edema.

FIGURE 4-36 Coronal T1- (A) and T2- (B)
weighted images demonstrate abnormal signal intensity in the left
femoral head and neck in a patient with hip pain. Radiographs in a
different patient showing osteopenia in the right hip during the
symptomatic phase (C) and return to normal (D) 6 months later.

FIGURE 4-37 Osteoid osteoma. (A) Routine radiographs demonstrating medial joint space widening (arrow) caused by soft tissue reaction. (B) Axial T2-weighted MR image showing focal increased signal along the femoral neck (arrow). (C) CT clearly demonstrating osteoid osteoma (arrow). Note the anterior soft tissue thickening (open arrow).

FIGURE 4-38 Low-grade liposarcoma. Sagittal T1- (A) and T2- (B)
weighted images demonstrate a large fatty tumor with areas of
low-signal intensity on T1- and high-signal intensity on T2-weighted
sequences (arrows).

FIGURE 4-39 Normal AP view of the hip with joint spaces marked (black lines). Narrowing may occur medially (M), axially (A), or superolaterally (SL).

FIGURE 4-40 Degenerative arthritis. AP radiograph of the right hip shows superolateral joint space narrowing, marginal osteophytes (arrows), and subchondral geodes (open arrows). There is bone sclerosis in the femoral head.

FIGURE 4-41 Degenerative arthritis. AP arthrogram shows superolateral joint space narrowing with a large communicating iliopsoas bursa (arrow).

FIGURE 4-42 Pigmented villonodular synovitis. Coronal T1-weighted image demonstrates erosion (arrow) of the head–neck junction with lobulated low signal intensity in the capsule.

FIGURE 4-43
Synovial chondromatosis. Axial T2-weighted image demonstrates a
high-signal intensity joint effusion with small low-signal intensity
structures throughout the joint (arrowheads).

FIGURE 4-44 (A) Normal sacroiliac joints. (B) Bilateral sacroiliac ankylosis and spine changes of ankylosing spondylitis.

FIGURE 4-45 Greater trochanteric abscess. (A) Oblique radiograph shows a lucent area in the greater trochanter (arrows). (B)
Coronal fat-suppressed T1-weighted image after gadolinium enhancement
demonstrates an irregular lesion with peripheral enhancement.

FIGURE 4-46 Legg-Calvé-Perthes Disease. (A)
Radiograph shows the right capital epiphysis is 100% involved
(Catterall group IV) with greater than 50% loss of height (Herring
group C). (B) Several years later the epiphysis is still flat and irregular. Fat planes (arrows) are displaced because of a joint effusion. (C) Four years later the physis is closed with flattening and widening of the femoral head and neck on the right.

FIGURE 4-47 Coronal T1- (A) and T2- (B)
weighted images in an older child with Legg-Calvé-Perthes Disease on
the right. There is an effusion on the right and central necrosis of
the epiphysis. Note the uncovered femoral head by the labrum on the
right compared with the left (white lines).

FIGURE 4-48 AP radiographs (A,B) demonstrating developmental dysplasia on the right. The acetabular angle (line
along acetabulum to Hilgenreiner line [H]) is increased and the hip is
displaced superolaterally with interruption of Shenton line (S) (broken white lines).
The femoral head should lie in the inferomedial (im) quadrant. Four
quadrants (im, inferomedial; il, inferolateral; sl, superolateral; sm,
superomedial) are formed by a line (Perkins line) at the acetabular margin perpendicular to Hilgenreiner line. The femoral head is out of the im quadrant in (B).

FIGURE 4-49 MR image in the frog-leg position shows dislocation of the left hip (arrow).

FIGURE 4-50 Coronal T2-weighted image with developmental hip dysplasia on the right. The medial joint space is widened (open arrow). The labrum is well demonstrated (arrow), and the femoral head is less well covered compared with the left hip.

FIGURE 4-51 AP (A) and oblique frog-leg views (B,C) of a slipped capital femoral epiphysis on the left. AP view (A) shows osteopenia and widening of the physis (arrows). Note the line along the lateral neck does not intersect the ossified epiphysis. The right hip (B) is normal. The displacement of the capital epiphysis on the metaphysis (lines) is obvious on the frog-leg oblique view (C).

FIGURE 4-52 Coronal T1-weighted image of a slipped capital femoral epiphysis on the left (arrow).

FIGURE 4-53 Normal femoral neck angle (lines) seen on AP radiograph.

FIGURE 4-54
Coxa vara. AP view of the hips in a patient with healed slipped capital
femoral epiphyses showing a decreased femoral neck angle (lines).

FIGURE 4-55 Coxa valga. Child with thalassemia and increased femoral neck angle (lines).

FIGURE 4-56 Femoral anteversion measurement. (A) Coronal MR image demonstrating oblique angle for axial images (lines). (B) Axial image of the hips with line through the plane of the neck and horizontal line forming the angle. (C)
Axial image of the knee. A line is drawn along the posterior condyles
and the angle formed by the horizontal line. If the knee is externally
rotated, as in this case, the knee angle is subtracted from the axial
femoral angle. If the knee is internally rotated, the angle is added to
the femoral angle to measure the degree of anteversion.