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Physical
Examination
Most fractures cause swelling, deformity, and
pain on attempted movement. Minimally displaced, stress, or impending fractures cause
tenderness on palpation and pain on weight bearing or loading of the involved bone. In
noncommunicative patients, refusal to move an extremity may be the only sign of a fracture
or dislocation. Thorough assessment of the sensory, motor, and circulatory status of the
injured extremity is important before starting therapy. After application of a cast,
splint, or traction or after manipulation of a fractured extremity, the neurovascular
status of the limb should always be reevaluated.
When injury or lack of cooperation makes
physical examination unreliable, x-rays are required to detect a fracture. For instance, a
hip fracture may make examining the contralateral side difficult. Because coexisting
injuries and preexisting abnormal conditions may be present, the physician should obtain
x-rays of both hips and the pelvis in any patient with a femoral or pelvic fracture.
In patients with suspected hemarthrosis, joint
aspiration is useful. Aspiration of fluid suggests acute effusion secondary to gout,
pseudogout, or infection, which can be confirmed by laboratory test. Aspiration of blood
confirms an intra-articular injury (eg, fracture or torn ligament or meniscus). Fat
globules in the blood, which can be seen easily when the aspirate is viewed in an open
container, imply a fracture that allows fat from the marrow cavity to enter the joint.
Diagnostic Tests
X-rays:
Radiographs remain the most important tool for
diagnosing and treating fractures. Routine x-ray evaluation of suspected fractures should
always include both anteroposterior and lateral views. On a single view, the
characteristic displacement, discontinuity in contour, or altered alignment of a fracture
may be hidden because of overlap or projection. When standard views are equivocal, as
sometimes occurs with minimally displaced spiral fractures, oblique views can be helpful.
Fractures may be missed if the x-ray shows too small an area. A patient complaining of
thigh and knee pain, for instance, may actually have a hip fracture causing referred pain;
unless x-rays of the entire femur are taken, the fracture may be missed.
Computed
tomography:
Although not routinely needed, computed
tomography is a useful adjunct to plain x-rays in several circumstances. It allows
visualization of occult fractures, particularly in areas difficult to image with x-rays
because of overlying bony structures (eg, the cervical spine). Computed tomography helps
in determining the extent of articular surface disruption in joint fractures and in
assessing suspected pathologic fractures for bone destruction and soft tissue masses.
Magnetic
resonance imaging:
In special circumstances, magnetic resonance
imaging offers advantages, providing excellent tomography, soft tissue contrast, and
spatial resolution using noninvasive and nonionizing radiation technology. Magnetic
resonance imaging helps in evaluating pathologic fractures and in diagnosing osteonecrosis
and osteomyelitis, both of which can mimic fractures. Often, magnetic resonance imaging
can show occult fractures before an x-ray can detect them. Magnetic resonance imaging
cannot directly show calcification or bone mineral and thus does not visualize bone
structure as well as x-ray or computed tomography.
Bone
scan:
Total-body scanning, using 99mTc-labeled
pyrophosphate or similar radioactive analogs, is performed to detect focal injury to bone
from any cause. Uptake occurs wherever new bone forms, which can occur in response to
infection, arthritis, tumor, or fracture. Occult fractures not yet visible on x-ray can
often be detected on bone scan 3 to 5 days after injury. Patients with suspected
pathologic fractures require bone scans for evaluation of metastatic and metabolic bone
disease, which involve areas other than the fracture site.
Blood
tests:
Fractures, especially those of the hip, can
result in substantial bleeding into soft tissues. The most widely used clinical test for
evaluating blood loss from fractures is hematocrit measurement. A 3 mL/dL drop in
hematocrit corresponds to the loss of roughly 500 mL (1 u.) of blood in a normally
hydrated patient. Patients with acute bleeding or dehydration may initially have
a falsely normal or elevated hematocrit; when intravascular volume is replenished with IV
fluids, hematocrit will fall. Since elderly patients are often at high risk for developing
myocardial ischemia, their RBC volume should not be allowed to drop below a level that
maintains sufficient oxygen-carrying capacity. As a clinical guideline, a hematocrit
< 30 mL/dL usually indicates the need for blood transfusion, especially
preoperatively. In hip fracture patients, the hematocrit should be monitored for at least
4 days after injury or surgery, since a 4- to 8-mL/dL drop can occur because of continued
bleeding or equilibration.
A low or falling hematocrit can also warn of a
serious underlying medical condition with important implications in the fracture patient.
For instance, gastrointestinal bleeding can be exacerbated by anticoagulants routinely
given to immobilized patients for prophylaxis of deep venous thrombosis. Anemia may be the
first sign of multiple myeloma or another malignancy that has led to a pathologic
fracture.
Serum alkaline phosphatase rises when bone
turnover increases. This occurs with normal fracture healing as well as with malignancy
and metabolic abnormality (eg, Paget's disease). Serum calcium rises with some endocrine
disturbances (eg, hyperparathyroidism) and with metastatic disease, especially breast
carcinoma. When patients with Paget's disease are on bed rest, excessively rapid bone
resorption can also elevate the serum calcium level. |