Afifty-four-year-old, obese woman was bumped by a pedestrian and fell from
a standing position. She was immediately transported to the emergency
department for evaluation. During the interview by the orthopaedic resident on
call, the patient described severe right groin pain and an inability to bear
weight on the right lower extremity. She had no history of pain in the right
hip or groin area. The patient stated that she had a twenty-pack-year history
of smoking. She did not have any history of malignant disease or other medical
problems, and she took no medications. There was no personal or family history
of osteoporosis, and she had had no previous fractures. The range of motion of
the right hip was limited, and the patient was unable to perform a
straight-leg raise. Results of motor, sensory, and vascular testing of the
right lower extremity were normal. Anteroposterior radiographs of the right
hip revealed a Garden
Stage-IV2 subcapital
femoral neck fracture, and a well-defined radiographic lucency in the
superolateral aspect of the femoral head was suggestive of a pathologic
fracture (Fig. 1). Within the
lucency, areas of stippled calcification were observed, raising additional
suspicion of a pathologic process. Cross-table lateral radiographs of
sufficient quality could not be made because of the patient's body habitus.
Radiographs of the contralateral hip revealed normal findings and a grade of
VI on the Singh osteoporosis
index3. Laboratory
studies, including a complete blood-cell count, determination of the
electrolyte level, measurement of prothrombin time and partial thromboplastin
time, liver-function testing, determination of the level of serum alkaline
phosphatase, and serum-protein electrophoresis, revealed values that were
within normal limits. The chest radiograph showed no lesions, and the
electrocardiogram showed no abnormality.
The suspicious appearance of the femoral neck fracture, considered in
conjunction with the relatively low energy of the injury in a nonosteoporotic
individual, led to a presumptive diagnosis of a metastatic lesion of the
femoral neck with a pathologic fracture. A fellowship-trained orthopaedic
oncologist was consulted, and a workup to identify a primary malignant process
was initiated. Extensive physical examination revealed no evidence of primary
malignant disease. The results were negative on guaiac testing of stool. A
plain radiographic bone survey, bone scintigraphy, and computed tomography of
the chest, abdomen, and pelvis were unrevealing. A computed tomographic scan
of the right hip revealed a displaced subcapital femoral neck fracture;
however, the irregularity in the superolateral aspect of the femoral head that
had been seen on the plain radiographs was not evident on the computed
tomographic scan (Fig. 2).
An internist reviewed the laboratory results, electrocardiogram, and chest
radiographs, and the patient received medical clearance for surgical
intervention. After completion of the workup for metastatic disease, a
cemented unipolar hemiarthroplasty was performed. An intraoperative gross
examination of the fracture site revealed a displaced subcapital fracture
without evidence of malignant disease. Intraoperative frozen-section analysis
as well as gross and histopathologic examination of the femoral head revealed
negative findings. The cemented unipolar hemiprosthesis was implanted without
complication. A standard postoperative hemiarthroplasty protocol was
initiated, and the patient was transferred to an inpatient rehabilitation ward
after an uncomplicated hospital course. The patient was discharged to home
after receiving two weeks of rehabilitation therapy. At twelve months after
the fracture, the patient was walking without pain and without assistive
devices.
Traumatic subcapital fractures of the femoral neck are common, with more
than 250,000 occurring in the United States
annually4. Plain
radiographs of subcapital fractures of the femur may simulate a pathologic
appearance5,6.
Few studies on this subject have been published. Pope et al. reported on two
subcapital fractures of the femur for which preoperative radiographs were
suggestive of a pathologic
etiology6. Neither
fracture was neoplastic in origin. They used the term pseudopathologic
fracture to describe a traumatic subcapital fracture of the femur that
resembles a pathologic fracture radiographically, and they attributed this
appearance to fragmentation and rotation of the femoral
head6. Schwappach et
al. performed a radiographic study of cadaveric femora with a displaced
fracture of the femoral neck and retrospectively reviewed their own clinical
experience7. The
cadaver study showed that external rotation of the femoral shaft resulted in
an appearance similar to that of a pathologic fracture and that displacement
of the femoral shaft accentuated this appearance; Schwappach et al. stated
that these changes were independent of fragmentation. These cadaveric findings
were confirmed by their clinical retrospective review in which 32% of all
Garden Stage-III fractures and 24% of all Garden Stage-IV fractures had a
radiographic appearance similar to that of a pathologic fracture. None of the
fractures that appeared to be pathologic were classified as Garden Stage I or
II7.
Subcapital fractures that are truly due to metastatic disease are rare, as
most pathologic fractures occur distal to the subcapital
region8-10.
On the radiographs of our patient, the apparent radiolucency was eccentric in
the superolateral subcapital region, which is different from the central
radiolucency that is usually seen with metastatic pathologic fractures of the
femoral neck7.
In the evaluation of patients with a possible pathologic fracture of the
subcapital region of the femoral neck, the first step is to obtain a complete
history. The circumstances surrounding the current injury and the degree of
trauma can provide information about the strength of the bone. A pathologic
process should be suspected if the degree of energy required to cause the
fracture was unusually low and the radiographic findings are suspicious.
Standard questions regarding general health, including recent weight loss,
fevers, night sweats, and fatigue, are important. Also, the presence of
prefracture pain in the region of an eventual fracture and a history of
diagnosed or treated malignant neoplasms should raise suspicion about a
pathologic process. A history of osteoporosis or of insufficiency fractures
should be sought. Furthermore, it is important to inquire about relevant risk
factors for malignant disease, including smoking, dietary habits, and possible
environmental exposures to carcinogens.
The second step in the evaluation is a thorough physical examination. A
standard examination, with attention given to the distal neurovascular status,
should be performed in all patients. Common primary tumors that metastasize to
bone include those of the breast, lung, prostate, thyroid, kidney, and
gastrointestinal
tract11. Therefore,
a complete examination should be performed to search for evidence of a primary
malignant process in these regions. Special attention should be directed to
the evaluation of a possible soft-tissue mass at the fracture site; to
evidence of primary disease, including lymph-adenopathy, thyroid nodules,
breast masses, prostate nodules, and rectal lesions; and to an examination of
any other painful regions to rule out impending fractures. Guaiac testing of
stool should be performed for all patients.
A complete laboratory assessment should be performed when attempting to
exclude a pathologic lesion. The standard laboratory workup includes a
complete blood-cell count, determination of the electrolyte level, and
measurement of prothrombin time and partial thromboplastin time. In addition,
liver-function tests can be performed to evaluate for metastasis to the liver,
the level of serum alkaline phosphatase can be determined to evaluate for
metastasis to bone, and serum protein electrophoresis can be conducted to
exclude multiple myeloma as a cause of the lytic lesion.
In addition, the plain radiographs must be carefully evaluated when
investigating the possibility of a pathologic process. Recognizing the
radiographic characteristics of fractures that have occurred through a primary
malignant process or a metastatic lesion is crucial for proper diagnosis and
treatment. However, being overly suspicious of the findings on the radiographs
can lead to unnecessary testing and can delay prompt surgical management. With
respect to our patient, the anteroposterior radiograph of the right hip
revealed a Garden Stage-IV subcapital femoral neck fracture with a clearly
defined lucency in the superolateral aspect of the femoral head.
The low-energy mechanism of injury in our patient combined with the
presence of a suspicious lucency on the radiograph of the femoral head led to
many additional laboratory tests and radiographic studies. If the computed
tomographic scan of the affected hip had been performed first, our suspicion
of a pathologic process would have decreased substantially. This would have
enabled us to obtain medical clearance and then move forward with definitive
surgical management.
After reviewing the case of our patient, we concluded that computed
tomography of the affected hip should be the next diagnostic step when plain
radiography reveals a lucency in the superolateral aspect of the femoral head
in a patient who has a potential pathologic fracture of the subcapital region
of the femoral neck but has no history suggestive of malignant disease. If the
computed tomographic scan does not demonstrate any evidence of pathologic bone
destruction, metastatic tumor, or primary tumor, then we recommend proceeding
with operative intervention. The fracture can be inspected at the time of
surgery, and a biopsy can be performed if necessary. The surgeon may obtain an
intraoperative tissue sample for frozen-section analysis if the gross
appearance of the femoral head causes suspicion of malignant disease.
This focused approach to the management of a pseudopathologic fracture of
the neck of the femur helps to avoid a lengthy, costly laboratory and
radiographic workup. It also can help to expedite surgical intervention, which
has been shown to have prognostic importance for patients with hip fractures.
If the computed tomographic scan suggests the presence of a pathologic lesion,
a thorough search for a primary malignant process should proceed.