Initially missed occult fractures of the proximal femur in elderly patients: implications for need of operation and their morbidity.

Abstract

Occult fractures of the proximal femur are not evident on radiographs and the diagnoses are often missed or delayed. We tried to determine whether the delay of diagnosis in elderly patients lead to increased morbidity and increased need for operation.
We identified 26 elderly patients (> or =65 years of age) who were diagnosed as having an occult fracture of the proximal femur over a 3-year period. In 17 patients (17 hips, non-delayed group), the occult fracture was suspected at the first visit and the diagnosis was made on CT and/or MR images (MRI). In the remaining nine patients (9 hips, 34.6% delayed group), the diagnosis was delayed by a mean of 8.4 days (range 4-25 days). We compared the occurrence of fracture displacement, need for operation, change in activity level, and mortality between the non-delayed and delayed groups.
Displacement of fracture occurred in 4 of 9 delayed patients and none of 17 non-delayed patients. Ten non-delayed patients needed operative treatment, whereas eight delayed patients needed operative treatment (p = 0.190). The activity level decreased in 6 of 7 surviving patients of the delayed group, whereas it decreased in 4 of 15 surviving patients of the non-delayed group (p = 0.020).
A delayed diagnosis of occult fracture in elderly patients resulted in increased rate of secondary displacement of the fracture and increased morbidity. In patients suspected of having occult hip fractures, additional studies, such as MRI and/or CT scans should be recommended to confirm the presence of hip fracture.

Full text

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OSTEOPOROTIC FRACTURE MANAGEMENT
Initially missed occult fractures of the proximal femur in elderly
patients: implications for need of operation and their morbidity
Ki-Choul Kim•Yong-Chan Ha•Tae-Young Kim•
Jung-Ah Choi•Kyung-Hoi Koo
Received: 24 April 2009/Published online: 1 May 2010
? Springer-Verlag 2010
Abstract
Introduction
not evident on radiographs and the diagnoses are often
missed or delayed. We tried to determine whether the delay
of diagnosis in elderly patients lead to increased morbidity
and increased need for operation.
Materials and methods
We identified 26 elderly patients
(C65 years of age) who were diagnosed as having an
occult fracture of the proximal femur over a 3-year period.
In 17 patients (17 hips, non-delayed group), the occult
fracture was suspected at the first visit and the diagnosis
was made on CT and/or MR images (MRI). In the
Occult fractures of the proximal femur are
remaining nine patients (9 hips, 34.6% delayed group),
the diagnosis was delayed by a mean of 8.4 days (range
4–25 days). We compared the occurrence of fracture dis-
placement, need for operation, change in activity level, and
mortality between the non-delayed and delayed groups.
Result
Displacement of fracture occurred in 4 of 9
delayed patients and none of 17 non-delayed patients. Ten
non-delayed patients needed operative treatment, whereas
eight delayedpatients needed
(p = 0.190). The activity level decreased in 6 of 7 sur-
viving patients of the delayed group, whereas it decreased
in 4 of 15 surviving patients of the non-delayed group
(p = 0.020).
Conclusion
A delayed diagnosis of occult fracture in
elderly patients resulted in increased rate of secondary
displacement of the fracture and increased morbidity. In
patients suspected of having occult hip fractures, additional
studies, such as MRI and/or CT scans should be recom-
mended to confirm the presence of hip fracture.
operativetreatment
Keywords
Morbidity ? Mortality
Hip ? Proximal femur ? Occult fracture ?
Introduction
Hip fractures in elderly patients are associated with
increased morbidity, mortality and high socio-economic
costs [1–3]. The diagnosis of a displaced hip fracture is
obvious based on the history, physical examination,
and radiographic finding. However, initial radiographs of
undisplaced hip fractures frequently appear normal and
diagnoses are often delayed [4–6]. Previous reports sug-
gested that delayed diagnosis of the so-called occult hip
fractures might lead to considerable increase in morbidity
K.-C. Kim
Department of Orthopaedic Surgery,
Pohang St. Mary’s Hospital, 270-1, Daejam-Dong,
Nam-gu, Pohang 790-825, South Korea
Y.-C. Ha (&)
Department of Orthopaedic Surgery,
Chung-Ang University College of Medicine,
224-1 Heukseok-Dong, Dongjak-ku, Seoul
156-755, South Korea
e-mail: hayongch@naver.com
T.-Y. Kim
Department of Orthopaedic Surgery, Hallym University Sacred
Heart Hospital, 896 Pyeongchon-dong, Dongan-gu,
Anyang 431-070, South Korea
J.-A. Choi
Department of Radiology, Seoul National University Bundang
Hospital, 166 Gumi-ro, Bundang-gu, Seongnam 463-707,
South Korea
K.-H. Koo
Department of Orthopaedic Surgery, Seoul National University
Bundang Hospital, 166 Gumi-ro, Bundang-gu,
Seongnam 463-707, South Korea
123
Arch Orthop Trauma Surg (2010) 130:915–920
DOI 10.1007/s00402-010-1105-4

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[7, 8]. However, these studies evaluated a small number of
cases and had no statistical evidence.
We tried to determine whether a delay in diagnosis of
occult hip fracture is associated with increased morbidity.
Materials and methods
Data base in electronic medical recording was searched for
patients who were diagnosed as having a femoral neck
fracture or intertrochanteric fracture between January 2004
andDecember2006attheauthors’hospitalandtheirmedical
records were reviewed with use of clinical data warehouse.
During the study period, 748 patients were diagnosed as
having a femoral neck or intertrochanteric fracture. The
diagnoses were made on radiographs in 717 patients (723
hips). In the remaining 29 patients (30 hips 4.1%) who had
normal or equivocal findings on radiographs, the diagnoses
were made on additional studies, including CT and/or MRI
(28 hips of 27 patients) or follow-up radiographs (2 hips of
2 patients), which then showed definite evidence of frac-
ture. CT and/or MRI scans were taken within 24 h to
25 days of the initial radiograph.
During the study period, 56 patients who were suspected
to have hip fractures after trauma, but had normal or
equivocal findings on radiographs underwent additional
studies including CT and/or MRI. CT and/or MRI studies
showed no evidence of fracture in 15 patients, insufficiency
fracture of the pubic ramus in 14 patients, femoral neck
fracture or intertrochanteric fracture in 27 patients.
Among 29 patients (30 hips), who were diagnosed as
having femoral neck or intertrochanteric fracture on CT
and/or MRI or follow-up radiographs, 3 patients (4 hips),
who were\65 years and injured in traffic accidents, were
excluded. The remaining 26 patients (26 hips) were
included in this study. Patients who were diagnosed as
having occult fractures at the first visit were categorized
as non-delayed group and those who were not diagnosed at
the first visit as delayed group.
We compared selected baseline characteristics, includ-
ing age, gender, body mass index, cause of injury, type of
fracture, follow-up period, occurrence of fracture dis-
placement, need for operation, change in patient activity,
and mortality within 2 years between the two groups.
Activity levels were defined as follows; I—normal, II—
independent outdoors, but needs help with some outside
activities, III—independent indoors but never goes out
without company, IV—not independent indoors, but can
transfer and walk independently, and V—confined to bed
or chair, not ambulatory. In the analysis, actively levels I
and II cases were also classified as ambulatory outdoors,
whereas activity levels III, IV and V cases were classified
as shut-in patients [9].
CT scans were obtained with a 16-slice multi-detector
CT system (Mx 8000 IDT, Philips, Utrecht, The Nether-
lands) with the standard acquisition protocols as follows;
16 9 1.5 mm beam collimation, gantry angulation at 0?,
field-of-view of 350 mm, and reconstruction with 3.0-mm
slice thickness.
MRI was obtained using a 1.5-T magnet (Gyroscan,
Philips) with the following parameters: axial T1-weighted
images (T1WI) [450-620/7-20 (repetition time msec/echo
time ms (TR/TE)], sagittal T1WIs (400-550/7-20), coronal
T1WIs (400-550/7-20), coronal proton density-weighted
fat-suppressed images (2900-5100/12-20), and axial T2WIs
(4000-6100/100-120). All images were obtained with a 35–
40 cm field-of-view, two excitations, 512 9 512 matrix,
and a slice thickness of 4–5 mm with 0.4 mm gap.
All CT and MR images were reviewed by a single
experienced musculoskeletal radiologist. In CT scans, a
diagnosis of fracture was based on the demonstration of
hypodense fracture lines in the involved cortex [10]. In
MRI scans, a fracture was diagnosed when a linear low-
signal intensity (SI) was surrounded by an intermediate-SI
area on T1WI and the linear low SI was surrounded by high
SI on T2WI.
The change in patient activity and mortality within
2 years were compared between the delayed and non-
delayed group by Fisher’s exact test. For all analyses, we
used SPSS (version 12.0, Chicago, IL). Significance was
defined as p\0.05.
The design and protocol of this retrospective study were
approved by the institutional review board at the authors’
hospital, and all patients were informed that his or her
medical data could be used in a scientific study and pro-
vided consent.
Results
In our study, the incidence of occult fracture was 4.1% (29/
717) in femoral neck and intertrochanteric areas. The
incidence was 5.8% (26/437) in patients older than
65 years.
In 17 patients (17 hips, non-delayed group) occult
fracture of the proximal femur was suspected at the first
visit of patients and the diagnosis was made on CT and/or
MRI; 11 patients on CT, 4 on MRI, and 2 on CT and MRI
(Fig. 1).
In the remaining nine patients (9 hips, delayed group),
the diagnosis was delayed by a mean of 8.4 days (range
4–25 days). Two patients of delayed group refused CT or
MRI scan at the first visit due to costs. One of them
revisited our hospital due to persistent pain and was
diagnosed as having occult fracture on MRI scan 7 days
after the first visit. The other patient suffered severe hip
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pain during walking without trauma 14 days later from
the first visit and revisited our emergency room. The
radiographs at the second visit showed displaced femoral
neck fracture. Even though neither CT nor MRI scans,
which demonstrated occult fracture, was performed, this
patient was included in the delayed group of our study.
One patient was studied with hip radiographs and CT
scans at the first visit of our emergency room which
showed no evidence of fracture. This patient was dis-
charged with analgesics. After 7 days, patient felt severe
pain during walking and revisited our hospital. Radio-
graph revealed displaced femoral neck fracture (Fig. 2).
Six patients of the delayed group had visited other
hospitals and the diagnoses had been missed. These
patients visited our hospital 4–25 days later and the
occult fracture was diagnosed on CT scans and/or MRI
scans.
The 26 patients were followed for 12–48 months (mean
23.2 months) after the diagnosis of occult fractures.
Demographic data of the patients are shown in Table 1.
The age, gender, body mass index, cause of injury, type of
fracture, and follow-up period were not significantly dif-
ferent between the two groups.
Fracture displacement occurred in 4 of 9 delayed
patients between 5 and 14 days after the first visit, while no
fracture displaced in the 17 non-delayed patients.
In the non-delayed group, 7 patients were treated con-
servatively and 10 patients were operated due to intractable
pain using compression hip screws (n = 6) and multiple
pinning (n = 4). In delayed group one patient was treated
conservatively and eight patients were operated due to
fracture displacement (n = 4) and intractable pain (n = 4)
using compression hip screws (n = 3), multiple pinning
(n = 3), and bipolar endoprosthesis (n = 2) (p = 0.190).
In one delayed patient who was operated with multiple
pinning, the operated limb was shortened by 1.5 cm. The
rate of operative treatment was 58.8% (10/17) in the non-
delayed group and 87.5% (7/8) in the delayed group
(p = 0.19).
All of patients were alive at 1 year after the injury.
However, two patients in each group deceased between 24
and 28 months after the injury (p = 0.591). One non-
delayed patient deceased due to metastasis of colon cancer
at 20 months after injury and the other delayed patient due
to cardiac problem at 28 month after injury. Two patients
in the delayed group deceased due to cardiac problem at
posttraumatic 25 and 27 months, respectively (Table 2).
In 4 of 15 surviving patients of the non-delayed group,
the activity level decreased at the final follow-up as com-
pared to the preinjury activity. The activity decreased in six
of sevensurviving patients
(p = 0.020). Two (16.7%) of 12 ambulatory outdoor
patients in the non-delayed group became shut-in patients,
while 3 (60%) of 5 ambulatory outdoor patients in the
delayedgroupbecameshut-in
(Table 3) (Fig. 3).
of the delayedgroup
patients(p = 0.024)
Fig. 1 A 76-year-old woman had left hip pain after a slip down.
There is no abnormal finding on hip anteroposterior radiograph (a).
On T1-weighted MR image, an undisplaced intertrochanteric fracture
appears as a low-signal intensity line (black arrows) with surrounding
patchy low-signal intensity (b)
Fig. 2 A 74-year-old woman
had left hip pain after a slip
down. There is no abnormal
finding on initial hip
anteroposterior radiograph (a)
and CT (b). After 7 days of the
first visit, left hip pain
aggravated. Radiograph shows
displaced fracture of the left
femoral neck (c)
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Discussion
To date, a number of studies have described serious com-
plications due to diagnostic delay of occult hip fracture [7,
8, 11]. The diagnostic delay could lead to disastrous
sequelae, including prolonged incapacity, non-union, and
avascular necrosis [12]. It also increases the risk of mor-
bidity of patients and prolongs the length of hospital stay
[13]. However, these studies were not statistically sup-
ported due to small number of patients.
The reported rate of occult fracture in hip fractures
ranges from 2 to 10% [14–17]. Occult hip fractures are
often missed because findings on plain radiographs are
unremarkable, patients frequently are able to walk and
have a minor traumatic episode. In our study, 29 (4.1%) of
717 femoral neck or intertrochanteric fractures were occult
fractures. In elderly patients older than 65 years, 26 (5.8%)
of 437 were occult fractures and 9 (34.6%) of them were
missed at the first visit to our emergency room or at other
hospitals; 4 of the 9 delayed patients developed displace-
ment of fracture and 2 of them required bipolar hemiar-
throplasty, instead of the simpler internal fixation.
To miss the diagnosis of an occult fracture of the fem-
oral neck may lead to displacement of the fracture and
Table 1 Baseline
characteristics between the non-
delayed group and delayed
group
Non-delayed group (n = 17) Delayed group (n = 9)
p value
Gender (woman/man)14/3 8/11.000
Mean age (range) (years) 78.4 (67–88)76.6 (68–88) 0.523
Mean body mass index (range)21.5 (16.7–27.1) 22.7 (19.1–27.5) 0.319
Cause of injury
Slip down 158 0.556
Fall down21
Type of fracture
Femoral neck74 0.393
Intertrochanteric105
Mean follow-up (range) (months) 22.2 (12–48)25 (13–38) 0.515
Table 2 Fracture displacement,
treatment modality, and
mortality of the two groups
Non-delayed group (n = 17)Delayed group (n = 9)
p value
Displacement of fracture04 Not applicable
Treatment 0.190
Conservative71
Multiple pinning43
Compression hip screw63
Bipolar endoprosthesis02
Number of death22 0.591
Table 3 Change of activity
level of the two groups
Non-delayed group
(n = 15)
Delayed group (n = 7) p value
Preinjury activity0.798
Grade I53
Grade II63
Grade III41
Grade IV00
Activity at the latest follow-up 0.205
Grade I30
Grade II54
Grade III72
Grade IV01
Number of patients with decreased activity 46 0.020
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otherwise unnecessary surgery [11, 18]. In a prospective
study of 90 elderly patients with an acute hip fracture
treated with internal fixation, Tidermark et al. [11] found a
major difference in outcome between undisplaced and
displaced fractures. The rate of fracture healing compli-
cations and reoperations in patients with displaced frac-
tures was high, and even in patients with uneventfully
healed fractures, there was a substantial decrease in the
quality of life. In our study, secondary displacement of the
occult fracture occurred in none of 17 non-delayed patients,
while it occurred in 4 of 9 delayed patients and the activity
level at the final follow-up was significantly different
between the non-delayed group and the delayed group.
CT scan is a useful tool for detecting occult fractures.
However, CT scan has a limitation that it can miss small
impacted fractures or undisplaced fractures that run parallel
to the axial plane [19]. In one of our patients, the occult
fracture was missed on CT scan. Although MRI is more
expensive than CT scan, MRI enables a definitive diagnosis
of occult fractures [4–6, 16]. Lubovsky et al. [4] compared
CT and MRI in diagnosis of occult hip fracture. In six
patients who underwent CT and MRI, four of the CT
images resulted in misdiagnosis due to inaccuracy. In seven
patients, who underwent only MRI, all the results were
accurate and enabled a precise and fast diagnosis. They
pointed out the advantage of immediate MRI imaging in
patients with occult hip fracture enabling a more effective
treatment,a shorterhospitalization
decreased medical costs. Sankey et al. [18] performed an
MRI scan in 98 consecutive patients who presented due to
hip pain after trauma, but had no abnormality on plain
radiographs. Eighty-one patients (83%) had abnormalities
detected on MRI. Their study illustrated a high incidence
of occult hip fractures and showed the accuracy of MRI in
diagnosing occult hip fracture.
There were several limitations in our study. Our study
was a retrospective one performed in a small cohort. In our
study, a protocol for referral to MRI or CT scans could not
be applied in every patient with hip pain after trauma, who
had normal or equivocal findings on conventional radio-
graphs during the study period. Some neglected patients in
whom pain was durable and fracture healed without dis-
placement might not have been detected. Some patients
might have been neglected at our hospital and diagnosed as
having occult fractures at other hospitals. However, it is
barely feasible to conduct a large prospective study of
occult hip facture because the incidence of occult fracture
is low and it is difficult to perform MRI, which infers high
expenses and longer time for scanning, in every consecu-
tive patient who is likely to have an occult hip fracture.
Although the rate of operative treatment in the delayed
group (87.5%) was greater than in the non-delayed group
(58.8%) in our study, the difference was not statistically
significant. It should be noted that the calculated statistical
power was not sufficient to differentiate two groups
because of the small number of patients.
A delayed diagnosis of occult hip fracture might result
in further displacement subsequently leading to increased
morbidity. Patients who present with clinical findings
suggestive of a fracture about the hip, but show negative
findings on initial radiographs, should undergo further
imaging studies, such as CT or MRI, to confirm the pres-
ence of occult fracture.
periodentailing
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