- In the setting of a patellar dislocation and subsequent
relocation, bone marrow edema pattern is typically
localized in the anterolateral aspect of the femur and
inferomedial aspect of the patella. MR imaging is rec-
ommended in cases of patellar dislocations to look for
possible chondral or osteochondral fragments. - Proximal patellar tendinosis is diagnosed on MR as
focal thickening and hyperintensity of the proximal
patellar tendon fibers (Fig. 56-7). Occasionally, reactive
edema in the inferior pole of the patella or edema in the
infrapatellar fat can also be seen.
•Tears of the extensor mechanism or patellar tendon
are seen as focal areas of tendinous discontinuity,
often replaced with heterogenous fluid, usually a
hematoma (Fig. 56-8).
•Redundancy and laxity of the quadriceps mechanism
and patella alta is often seen in cases of full thickness
patellar tendon tears due to the unopposed pull of the
quadriceps.FOOT AND ANKLE- At least one water sensitive pulse sequence should be
used to evaluate for bone marrow edema in the ankle.
Fast inversion recovery is suggested as opposed to fat
suppression as the ankle is a peripheral joint and is
more susceptible to regional field inhomogeneities. - Stress fractures and insufficiency fractures can be seen
earlier on MR than with conventional radiographs. - Ankle sprains can result in a variety of osseous
injuries than can often be overlooked on conventional
radiographs. These include the fractures of the malle-
oli, the talus, the navicular, the anterior process of the
calcaneus, and the base of the cuboid. - MR is useful in evaluating chronic pain after an ankle
sprain as causes of this pain are varied and can include
osteochondral injuries, unrecognized fractures, and
ligamentous injuries. - Nondisplaced fractures can be overlooked on conven-
tional radiographs, such as talar insufficiency frac-
tures (Umans and Pavlov, 1995).
334 SECTION 4 • MUSCULOSKELETAL PROBLEMS IN THE ATHLETE
FIG. 56-8 Sagittal fat suppression (left) and fast spin echo (right) image of the knee demonstrat-
ing complete tear of the proximal patellar tendon (arrow).
FIG. 56-7 Sagittal fat suppression MR image of the knee
demonstrating moderate proximal patellar tendinosis (arrow)
with hyperintensity and thickening of the proximal patellar
tendon and reactive edema in the inferior pole of the patella.