what-when-how
In Depth Tutorials and Information
Bone Scintigraphy
Radionuclide bone scanning, although non-specific,
may demonstrate diffuse increased uptake in the femur
head and neck shortly after the onset of symptoms in
the hip and before demineralization is seen on stan-
dard radiographs. Radionuclide uptake may appear in
other involved bones such as the ankle. However, in
the presence of previous injury, as may have occurred
in OI, localized radionuclide uptake may be less help-
ful in establishing a diagnosis. Scintigraphic finds may
be similar in avascular necrosis of the hip. As noted
by Guerra, scintigraphic imaging in avascular necrosis
may show decreased isotope uptake over the antero-
superior area of the femoral head forming a cold spot
which is not seen in transient osteoporosis.
24
of sclerosis which represents compression of subchondral
bone that may precede collapse of the femoral head.
24
Trevian et al. have conducted serial assessments of
spine, hip and whole body bone mass measurements
in three cases of TMO.
16
Systemic osteoporosis, with
involvement of the mainly trabecular bone sites, was
present in each patient, with T-scores below −2.5 in
both the lumbar spine and femoral neck. This suggests
that systemic factors may be altering bone mass in sites
distant from the involved joint.
D
IFFERENTIAL DIAGNOSI
S
The differential diagnoses for localized transient
osteoporosis or TMO is large and includes septic arthri-
tis, osteomyelitis, malignancy, tuberculosis, avascular
Magnetic Resonance Imaging (MRI)
MRI is the diagnostic method of choice for early
diagnosis of TMO. MRI is the most sensitive and use-
ful tool for evaluation of the symptomatic hip when the
results of other imaging methods are inconclusive.
22
The reason is that abnormalities may become apparent
as soon as 48 hours after symptoms begin when stan-
dard radiographs may be negative.
22
Tan reported MRI
findings in a 60-year-old male in whom standard X-rays
remained negative.
25
There is a characteristic appear-
ance of TMO on MRI including a low-signal intensity
on T1-weighted images matched by high-signal inten-
sity on T2-weighted images extending from the femoral
head to the intertrochanteric region.
3
The joint space is
preserved unless this has been previously affected in
the individual with OI (
Figure 39.4
).
7
In differentiating TMO from avascular necrosis, unlike
the diffuse proximal femur osteopenia in TMO, bone loss
in AVN is patchy or mottled (
Figure 39.5
). Typically there
is a mottled radiolucent area that is surrounded by a zone
FIGURE 39.4
MRI of hip bilateral hip involvement in transient
osteoporosis following completion of pregnancy.
FIGURE 39.5
Transient osteoporosis of the knee with surrounding effusion in OI.
