the normally well-defined, hypointense, triangular
acetabular labrum.
•Cartilage-sensitive pulse sequences are necessary to
adequately evaluate for subtle areas of chondromala-
cia over the femoral head.
•A large field-of-view water sensitive pulse sequence
(fast inversion recovery) should be performed to eval-
uate for other possible causes of hip pain: degenera-
tive disc disease, sacroiliac joint pathology, possible
sacral or pubic ramus insufficiency fracture, or bursi-
tis.
- In addition to the hip joint proper, MR imaging of the
hip can evaluate the regional muscles and tendons.
With the adductor insertion avulsion syndrome
(“thigh splints”), patients have mid thigh pain that is
activity-related; MR imaging demonstrates hyperin-
tensity and periosteal reaction along the mid femur.
Findings are thought to be related to traction injury of
the adductor longus and brevis tendons (Anderson,
Kaplan, and Dussault, 2001). - Subchondral insuffiency fractures, transient osteo-
porosis, and avascular necrosis of the femoral may all
have similar clinical presentation. In the acute stage,
MR findings may only include edema in the femoral
head and neck; a discrete subchondral fracture line or
a zone of demarcation in the setting of avascular
necrosis may not be visible on large field-of-view
images. Small field of view and dedicated surface
coils of the hip are necessary to visualize subtle frac-
ture lines and early avascular necrosis.- MR is of value in imaging the hip after a dislocation,
to evaluate the soft tissue envelope as well as for eval-
uating for any osteochondral injuries and possible
intra-articular chondral fragments.
•Tendinosis of the tendons about the hip is seen as
thickening, hyperintensity, and ill-definition of the
normally uniformly hypointense (dark) tendon.
KNEE- In general three planes of imaging should be per-
formed in addition to at least one fat suppression
sequence to evaluate for bone marrow edema. High
resolution imaging of the menisci is also suggested. - Normal ligaments and tendons about the knee are uni-
formly hypointense (Fig. 56-2 and 56-3). In general,
the sagittal sequence is best for evaluating the cruciate
ligaments and the coronal sequence for evaluating the
collateral ligamentous complexes. The cruciate liga-
ments, however, have an oblique course; and areas of
potential signal abnormality should be confirmed in
two planes, as some of the signal may be fictitious due
to volume average with the ligament passing out of
the plane of imaging. - Cartilage sensitive pulse sequences are suggested for
routine imaging of the knee. Cartilage should nor-
mally be intermediate signal intensity and of uniform
thickness. Occasionally, the laminar microstructure of
330 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE
FIG. 56-1 Sagittal fast spin echo image of the hip demonstrat-
ing a tear of the anterior labrum (arrow).
FIG. 56-2 Sagittal fast spin echo image demonstrating a
normal hypointense anterior cruciate ligament (arrow).