There are two general types of stress fractures: fractures induced by
cyclical loading of normal bone with abnormal forces (fatigue fractures) and
those induced by normal forces in abnormal bone (insufficiency
fractures)1-3.
Normal bone remodeling occurs when osteoclastic resorption and osteoblastic
reconstruction are in balance with each other. With increased loading, the
rate of bone remodeling accelerates, initiated by increased bone
resorption4. Under
abnormal stress, the process of resorption becomes dominant and may lead to
microfractures in the
bone5. With
continuing abnormal loading, these microfractures can progress to complete
fractures6,7.
Stress fractures located at the superior surface of the femoral neck are
called tension fractures, and those localized to the inferior surface
are called compression
fractures8,9.
Tension fractures of the femoral neck are at increased risk for displacement,
whereas compression fractures are mechanically
stable10-12.
Most nondisplaced compression fatigue fractures can be treated
nonoperatively12. A
tension fatigue fracture of the femoral neck is a high-risk fracture that can
progress to a complete fracture with displacement, complicated by delayed or
nonunion, osteonecrosis of the femoral head, the need for arthroplasty, and a
risk of permanent
disability9,13,14.
Fatigue fractures of the femoral neck are relatively uncommon during
military service. In large series of military recruits, the incidence of these
fractures was reported to range from 3.5% to 8% of all diagnosed stress
fractures8,15,16.
Displaced fatigue fractures of the femoral neck are even more rare, and most
previous reports have been case
reports8,13,15-32.
The aims of the present study were to examine the incidence, symptoms,
morphologic characteristics, clinical course, and long-term outcome of
displaced fatigue fractures of the femoral neck seen during a twenty-year
period from 1975 to 1994 as well as to evaluate the risk factors predisposing
to displacement of fatigue fractures of the femoral neck. A strategy for the
prevention of such fractures during basic military training was also
analyzed.
During the twenty-year study period, from January 1, 1975, to December 31,
1994, twenty-one consecutive displaced fatigue fractures of the femoral neck
in military recruits were identified in the Finnish nationwide catchment area.
The fractures were first diagnosed at the garrison infirmary, and the patients
were then transported to the nearest hospital providing surgical services. Ten
of the patients were treated operatively at the main military hospital; five,
at a regional central hospital; and three, at a university hospital. In
addition, one patient was treated nonoperatively, with traction, and two were
lost to long-term follow-up. The multiple treatment units had similar policies
regarding operative treatment, but there were some changes over the long
time-period of the study. All of the recruits who had a displaced fatigue
fracture of the femoral neck were identified by a computer search of the
National Hospital Discharge Register, established in 1967. The search was
performed with use of the appropriate diagnostic codes of the Eighth (1969
through 1986) and the Ninth (1987 through 1995) editions of the International
Classification of Diseases (ICD) and by linking them with the codes of the
military hospitals.
In Finland, all men become eligible for compulsory, periodic military
service at the age of eighteen years. During the study period, an average of
34,723 men started their military service annually. At the beginning of their
three-month basic training period, the majority of recruits are nineteen to
twenty years of age. The duration of the service period ranged from 250 to 330
days, depending on the previous education level and the degree of military
training pursued.
Marching and other physical training, such as running, athletics, games,
skiing, and swimming, were actively carried out on a weekly basis throughout
the service period. Since the institution of mandatory military training in
1975, physical fitness programs (separate from marching) continued relatively
unchanged. In 1989, the proportion of military education dedicated to physical
training increased from 6.5% to 7.7% and that of marching, from 7.5% to
7.7%.
The recruits who fulfilled their compulsory military service from 1975 to
1994 formed the population at risk for sustaining a stress fracture of the
femoral neck. The total number of these recruits in the Finnish Defense Forces
was used to calculate the annual incidence of displaced fatigue fractures of
the femoral neck. The total exposure time in person-years was calculated on
the basis of the number of days in service for each year and each
length-of-service category. The total number of recruits was 694,457, and
their exposure time during this twenty-year period was 491,160 service years.
The fracture incidence was calculated in two ways, with use of both service
years and recruits as denominators.
Following the occurrence of five displaced fractures of the femoral neck
within one year, the Finnish military issued permanent orders with detailed
instructions for the diagnosis and treatment of fatigue fractures. These
orders became effective in 1986 and included basic and complementary training
of the medical and military unit personnel to increase awareness of, and
identify, the prodromal symptoms of femoral stress fractures. The program was
designed to also increase the awareness of the recruits themselves and to
provide the most effective diagnostic methods by centralizing the detection of
these fractures to the main military hospital. A fatigue fracture of the
femoral neck was to be suspected in recruits reporting recent pain in the hip,
thigh, or groin region, days or even weeks after marching, running, or combat
training. The physicians and medical officers in charge were further
instructed to deliver information on fatigue fractures to the recruits at
lessons during the basic training period, and the recruits were instructed and
encouraged to seek medical consultation without delay on the appearance of
symptoms. Moreover, the medical personnel were obliged, particularly during
the basic training period, to ensure that the preventive measures were adhered
to and to interfere with training when so indicated. Recruits who reported
that they had, or had recently had, hip or groin pain were to be referred
without delay for bone-scanning or magnetic resonance imaging at the main
military hospital in order to establish an early diagnosis. The impact of the
new regimen was assessed in the present study by calculating the overall
incidence of fatigue fracture of the femoral neck before and after 1986 as
well as the incidence of displaced and nondisplaced fatigue fractures of the
femoral neck during these time-periods.
The original and complete medical records, including radiographs, were
retrieved and reviewed to confirm the accuracy of the diagnoses and to
systematically collect data for the present study. Data on the patients'
health condition and medications, possible prior injuries and operations,
smoking habits, and sports activities were recorded. Furthermore, data on the
level of military training, the duration of prodromal pain or other symptoms
in the lower extremities after the recruit began military training, any
activity or incident preceding the onset of the fracture, the fracture
management, and the clinical course were identified.
The body mass index was calculated by dividing the body weight in kilograms
by the squared body height in meters
(kg/m2)33.
A body mass index of <15 was classified as emaciation; 15 to 18.9,
underweight; 19 to 24.9, normal; 25 to 29.9, overweight; 30 to 39.9, obese;
and =40, morbidly
obese34. The body
mass indexes were compared with those of 223 recruits born in 1958 and
fulfilling their compulsory military service in
197835.
The diagnosis of a displaced femoral neck fracture and its morphologic
features were confirmed on the original, conventional anteroposterior and
frog-leg radiographs. Fracture patterns were determined according to the
Garden36 and
Orthopaedic Trauma
Association37,38
classification systems. Displacement after surgical treatment was assessed by
measuring the neck-shaft angle on the postoperative anteroposterior radiograph
and fracture angulation on the postoperative lateral radiograph. The reduction
was considered acceptable if the neck-shaft angle was >130° and the
fracture angulation was <10°. The time to osseous union of the fracture
after the primary operation was judged clinically and radiographically. Solid
union was defined as the absence of pain on weight-bearing and as mature bone
seen to cross the fracture on the anteroposterior and frog-leg lateral
radiographs. Nonunion was defined as failure of fixation with implant
breakage, a loss of reduction, or persistence of a visible fracture line at a
minimum of six months after the index procedure. Osteonecrosis of the femoral
head was classified radiographically with use of the method of Ficat and
Arlet39.
All patients were asked to participate in a follow-up examination at the
outpatient department of the main military hospital between 2002 and 2004.
Data on treatment after previous visits to the military hospital were
collected, and the medical records and radiographs from those hospital visits
were retrieved for review and analysis. At the final follow-up visit, a
conventional anteroposterior radiograph of the pelvic area was made. The
original diagnosis of a displaced stress fracture was confirmed at the
follow-up examination by evaluating the whole series of radiographic images
for each patient. Shortening of the femoral neck was measured on the latest
supine anteroposterior follow-up radiographs and expressed as a percentage of
the length of the uninjured, contralateral femoral neck in all patients
without a hip endoprosthesis. The radiographic severity of osteoarthritis was
classified according to the criteria of
Tönnis40. All
radiographic results were interpreted by a musculoskeletal radiologist.
A 10-point (0 to 10-cm) visual analogue scale, with a score of 0 denoting
none, was used to determine the degree of pain experienced by the patient one
week before the last follow-up examination.
The chi-square test was used to determine the significance of differences
between two independent groups at the 0.05 level. The t test and Mann-Whitney
exact U test were used to compare independent means. Incidence rate ratios
with 95% confidence intervals were calculated for the fractures sustained from
1975 to 1986 and for those sustained from 1987 to 1994. SPSS 12.0.1 for
Windows software (SPSS, Chicago, Illinois) was used for the statistical
analysis.
Of all male recruits performing their compulsory military service during
the twenty-year period from 1975 to 1994, twenty-one were diagnosed as having
a displaced fatigue fracture of the femoral neck. All were previously healthy,
and their mean age was twenty years (range, eighteen to twenty-seven
years).
The incidence rates were calculated with use of two denominators, recruits
and service years. The incidence of displaced fatigue fractures of the femoral
neck was 3.0/100,000 recruits during the entire study period, with an
incidence of 3.8/100,000 recruits from 1975 to 1986 (prior to the new regimen,
instituted in 1986, for the prevention of fatigue fractures) and an incidence
of 1.6/100,000 recruits from 1987 to 1994. The ratio of the two standardized
ratios was 0.43 (95% confidence interval, 0.12 to 1.09). The incidences of
nondisplaced fatigue fractures of the femoral neck during the above mentioned
time-periods were 7.8/100,000 and 31.0/100,000 recruits, respectively.
As calculated per service years, the incidence of displaced fatigue
fractures of the femoral neck was 5.3/100,000 from 1975 to 1986 and
2.3/100,000 from 1987 to 1994 (ratio of two standardized ratios, 0.43 [95%
confidence interval 0.11 to 1.31]). The incidence of Garden type-IV fractures
decreased from 3.8/100,000 service years in the period from 1975 to 1986 to
0/100,000 service years in the period from 1987 to 1994 (ratio of two
standardized ratios 0 [95% confidence interval, 0 to 0.66]), and the incidence
of nondisplaced symptomatic fatigue fractures of the femoral neck increased
3.4-fold, from 15.5/100,000 to 53.2/100,000 service years between the two
time-periods (ratio of two standardized ratios, 3.44 [95% confidence interval,
2.27 to 5.21]). The total incidence of fatigue fractures of the femoral neck
was 20.8/100,000 service years in the period from 1975 to 1986 and
53.2/100,000 service years in the period from 1987 to 1994 (no displacements
were observed from 1987 to 1990) (ratio of two standardized ratios, 2.56 [95%
confidence interval, 1.71 to 4.04]) which was a 2.6-fold increase (95%
confidence interval, 1.7 to 4.0). After the institution of the new regimen for
the prevention of fatigue fractures in 1986, there was a significant increase
in the total number of observed femoral neck fatigue fractures.
Of the twenty-one patients who had been diagnosed with a displaced fatigue
fracture of the femoral neck and treated at the institution's military
hospitals during the twenty-year period, one patient refused to participate in
the study and one could not be contacted. Thus, long-term follow-up data were
available for nineteen patients (see Appendix). Of those nineteen patients,
sixteen returned for a clinical and radiographic follow-up examination, two
were interviewed over the telephone, and one completed a mailed questionnaire.
The average duration of follow-up for the nineteen patients was eighteen years
(range, eight to twenty-six years).
At the time of the diagnosis of the fracture, the mean height of the
patients was 179.4 cm (range, 171 to 186 cm), the mean weight was 70.3 kg
(range, 50 to 84 kg), and the mean body mass index was 20.7 kg/m2
(range, 16.1 to 26.2 kg/m2). According to the classification system
of Llewellyn-Jones and
Abraham34, four
patients were underweight (body mass index, 15 to 18.9 kg/m2) and
two patients were overweight (body mass index, 25 to 29 kg/m2). The
mean body mass index of the patients was significantly lower (p = 0.013) than
that of the 223 recruits born in 1958 (mean, 22.4 kg/m2; range,
16.9 to 34.3 kg/m2). Eight patients were smokers, and eleven were
nonsmokers.
The displaced fatigue fractures of the femoral neck were diagnosed at a
mean of 3.9 months (range, one to seven months) after the recruit entered the
military service. Eight of the nineteen fractures occurred within the first
three months (i.e., during the period of basic training). Sixteen patients had
experienced prodromal symptoms (hip or groin pain) at an average of 24.1 days
prior to the onset of the fracture. One patient (Case 15; see Appendix) had
had no prodromal pain, and two patients (Cases 14 and 18) had had pain only
one day prior to displacement of the fracture.
Manifestation of the displaced fatigue fracture of the femoral neck was
preceded by marching in twelve recruits, running in four, combat training in
two, and strenuous, long-distance bicycling in one. No triggering event
preceded the displaced fracture in eight patients, whereas eight fractures
were associated with stumbling at ground level; one, with the recruit losing
his footing; and one, with the recruit riding powerfully on a bicycle. In one
recruit (Case 13; see Appendix), who had had prodromal symptoms for two weeks,
the displacement became manifest after he applied automobile brakes. That
patient also displayed an old stress fracture of the pubic arch on the
contralateral side (Figs. 1-A and
1-B).
Of the nineteen patients, twelve had the fracture of the femoral neck on
the right side and seven, on the left side. There were no bilateral fractures.
Eight of the fractures were Garden type III
(Figs. 1-A and 1-B), and eleven
were Garden type IV (Figs. 2-A,
2-B and 2-C,
2-D and 2-E). According to the
classification system of the Orthopaedic Trauma Association, there were
eighteen transcervical (type-31B2) fractures and one subcapital (type-31B1)
fracture.
According to the policy of the orthopaedic department at that time, tibial
traction was applied preoperatively soon after radiographic detection of the
fracture when a delay in surgical treatment was expected. It was used for ten
patients for a mean of 3.8 days (range, two to seven days). The mean delay
between the diagnosis and the surgery for the nineteen patients was 3.4 days
(range, zero to seven days). Internal fixation with a sliding hip screw was
used for fourteen patients, an angled plate was used for four patients, and
one patient (Case 1) was treated with tibial traction for twelve weeks. Closed
reduction without capsular decompression was performed in seventeen patients,
and open reduction was done in the remaining patient. In all but one patient,
the quality of the reduction was acceptable, with a neck-shaft angle of
>130° (mean, 133.5°) and lateral angulation ranging between 0°
and 7° (mean, 2.3°). Only one patient (Case 12) had incomplete
reduction (a neck-shaft angle of 124°) after the index operation. This
resulted in failure of the fixation and necessitated a reoperation to correct
the angulation (Figs. 2-A,
2-B and 2-C,
2-D and 2-E).
Ten patients had early local complications such as deficient bone-healing,
deep infection, heterotopic ossification, or malunion within one year after
the primary operation. The healing of the fracture during the first
postoperative year was uneventful in the remaining nine patients. Delayed
union occurred in three patients and nonunion, in another three. During the
first postoperative year, a reoperation was performed because of a failure of
the fixation in one patient (Case 12), because of deep infection in another
(Case 7), and because of nonunion in two patients (Cases 6 and 9). The one
patient (Case 1) who was treated nonoperatively with tibial traction had
permanent varus angulation. There were two other cases of malunion (Figs.
2-A,
2-B and 2-C,
2-D and 2-E).
During the long-term follow-up period, late, slowly developing
complications such as osteonecrosis of the femoral head and osteoarthritis of
the hip were detected in thirteen patients. Osteonecrosis of the femoral head
developed after the initial surgical treatment in six patients: between the
first and the second postoperative year in three of them (Cases 5, 9, and 10),
at three years in one (Case 12), and at more than five years in two (Cases 4
and 6). Osteoarthritis of the hip developed during the follow-up period in
thirteen patients. According to the Tönnis classification, there were
four Grade-1, one Grade-2, and eight Grade-3 cases of osteoarthritis of the
hip. Grade-2 or 3 osteoarthritis developed without osteonecrosis in three
patients (Cases 1, 7, and 15). Four patients had a reoperations as a result of
these late complications. A vascularized bone graft and valgus osteotomy were
performed in one patient (Case 12) with osteonecrosis of the femoral head, but
severe osteoarthritis still developed (Figs.
2-A,
2-B and 2-C,
2-D and 2-E). Hardware was
routinely removed within two years after the index operation in all patients.
Three patients had undergone a total hip arthroplasty by the time of the final
follow-up examination.
Shortening of the femoral neck (a mean of 32.7% [range, 4% to 100%]
compared with the uninjured, contralateral side) was observed in thirteen
patients at the latest radiographic follow-up examination (see Appendix). No
shortening was evident in six patients. Shortening was significantly greater
(mean, 56.7%) in the six patients with osteonecrosis of the femoral head than
it was in the patients without osteonecrosis (mean, 5.8%) (p = 0.001).
Shortening of the femoral neck also correlated with Garden type-IV fractures
(p = 0.009). Osteonecrosis of the femoral head developed in six of the eleven
patients with a Garden type-IV fracture and in none of the eight with a Garden
type-III fracture (p = 0.018). There was also a correlation between
osteonecrosis of the femoral head and severe (Tönnis grade-2 or 3)
osteoarthritis of the hip (p = 0.020).
At the time of final follow-up, the score for pain intensity was marked on
a visual analogue scale by sixteen patients. The mean score was 23 mm (range,
0 to 61 mm). Two of the three patients with a total hip prosthesis provided a
visual analog score, which was 55 mm for one of them and 50 mm for the other,
reflecting moderate pain.
All of the nineteen patients were exempted from future military service
after the fracture, but at the time of follow-up none were unable to work or
had been compelled to retire as a result of the sequelae of the displaced
femoral neck fatigue fracture. One patient had retired for psychiatric
reasons. Impaired mobility affected the choice of occupation by three
patients. The remaining fifteen patients were employed in various
occupations.
In this study, the overall incidence of displaced fatigue fractures of the
femoral neck in military recruits was 4.3 per 100,000 person-years in military
service. To our knowledge, we are the first to report the true incidence of
these fractures, as the earlier literature dealing with these fractures
consists mainly of case
reports8,13,15-32.
The incidence of displaced fatigue fractures of the femoral neck decreased
during the target period of the present study, from 5.3/100,000 service years
before 1986 to 2.3/100,000 service years after 1986. After 1986, all of the
displaced fatigue fractures were Garden type III, which have a favorable
prognosis. The fracture incidence in the later time-period was slightly higher
than the incidence of displaced stress fractures of the femoral shaft in
Finnish recruits during the twenty years from 1980 to 1999, which was reported
to be 1.5/100,000
person-years41. In
the present study, the incidence of nondisplaced fatigue fractures of the
femoral neck increased from 15.5/100,000 service years before 1986 to
53.2/100,000 service years after 1986. Thus, increased awareness after
introduction of the new regimen in 1986 improved detection of these fatigue
fractures during their early stages, before displacement, despite minor
increases in the physical training programs and marching in 1989.
Osteonecrosis of the femoral head was evident in one-third of our patients.
In a previous series of forty-two military recruits with a displaced fatigue
fracture of the femoral neck, osteonecrosis of the femoral head developed in
ten patients (24%) after a mean of 5.6
years42. Comparison
of these findings with the consequences of surgically treated femoral neck
fractures in elderly patients with osteopenic bone is not relevant because of
the different nature of the fractures. However, high rates of nonunion and
osteonecrosis of the femoral head after all types of traumatic fractures of
the femoral neck have been reported in young
adults43. The
reported incidence of osteonecrosis and nonunion after open reduction of such
fractures in young adults has ranged from 10% to 20%, whereas the rates have
been much higher after closed reduction, ranging from 19% to
86%43. In a recent
study of traumatic fractures of the femoral neck in patients between the ages
of fifteen and fifty years, the rate of nonunion following a displaced
fracture was 9.8% and the rate of osteonecrosis was
27%44.
A delay in treatment and postoperative varus alignment have been considered
to be the major factors contributing to the development of osteonecrosis after
surgical treatment of displaced fatigue fractures of the femoral
neck42. Immediate
anatomic reduction and stable internal fixation have been regarded as the most
important factors preventing osteonecrosis in young
patients45. The
quality of the reduction was acceptable in all of the patients in the present
study except for one in whom a reoperation was performed four weeks after the
primary operation. Because of the retrospective nature of this review, it is
impossible to comment on the influence of timing of the primary fixation on
the outcome. Moreover, gradually developing fatigue fractures of the femoral
neck are different from traumatic high-energy fractures of the femoral neck in
young adults. The actual displacement process and the pain experienced by
patients after displacement might also occur gradually. Furthermore, Upadhyay
et al. noted, in a prospective study of ninety-two adults with an acute
femoral neck fracture, that neither the rate of union nor the development of
osteonecrosis was influenced by whether the surgery had been delayed for more
than forty-eight hours or had been performed within forty-eight hours after
the injury46.
Extensive destruction of the osseous architecture of the femoral neck prior
to displacement as a result of a developing fatigue fracture could well be an
additional predisposing factor for osteonecrosis of the femoral
head47. In this
study, destruction was evident in the form of shortening of the femoral neck,
which had a significant correlation with the development of osteonecrosis.
Other mechanisms leading to osteonecrosis of the femoral head have been
suggested, including the tamponade effect of hemarthrosis and the increased
intracapsular pressure in cases where the joint capsule remains intact or is
not opened during the surgical
treatment48-52.
It is not possible to comment on the effect of decreasing intracapsular
pressure in the present series as the majority of patients were treated with
closed reduction.
Closed and open reduction with internal fixation are the two primary
methods of operative treatment of displaced Garden type-III and IV fatigue
fractures of the femoral neck. Because open reduction was performed in only
one patient in the present series, we could not compare the outcomes of closed
and open methods. However, the closed reductions of displaced Garden type-IV
fractures in the present study resulted in adverse consequences. Supporters of
closed reduction with internal fixation emphasize that it is less invasive and
less time-consuming to
perform53,54,
whereas supporters of open reduction with internal fixation argue that surgery
under direct vision allows a more accurate and anatomic reduction of the
fracture43,55.
As mentioned, the incidences of osteonecrosis and nonunion after open
reduction of acute femoral neck fractures in young adults have ranged from 10%
to 20%, whereas the incidences have been much higher after closed reduction,
ranging from 19% to 86% after a mean of 2.7
years43.
Displacement of the fracture is considered to be a major factor
predisposing to the development of osteonecrosis of the femoral
head48. In the
present series, osteonecrosis of the femoral head occurred in one-third of the
patients and was significantly correlated with Garden type-IV displacement of
the fracture. Radiographic findings have indicated that the development of
osteonecrosis is a slowly progressive
process56,57.
In the present series, osteonecrosis became evident between one and two years
postoperatively in three patients, at three years postoperatively in one, and
not until five years postoperatively in two.
An epidemiologic review revealed numerous risk factors for the development
of stress fractures, including female gender, age, low bone density and bone
strength, low aerobic fitness, low past physical activity levels, cigarette
smoking, and greater amounts of
running58.
Furthermore, Giladi et al. proposed a narrow tibial bone width as a risk
factor for stress fractures in
general59,60.
Pouilles et al. found a correlation between a low femoral bone density and
stress fractures in military
recruits61. Neither
tibial bone width nor femoral bone density was measured in the present
study.
Body weight is positively related to ground reaction forces. This could
increase the likelihood of fatigue fractures in heavy persons, particularly
those with low muscular strength and poor general physical conditioning. On
the other hand, among athletes, neither an increased nor a decreased body mass
index, as compared with a normal body mass index, has been reported to be
associated with a greater risk of stress
fractures62. The
obvious reason for this is that athletes participating in a particular sport
tend to be homogeneous with regard to somatotype. In contrast, all somatotypes
were represented in our study population, and all recruits were required to
participate in the same training programs. The incidence of stress fractures
has also been found to be higher in smaller
persons63,64,
although other studies have indicated no association between the risk of
stress fractures and body size and
composition59,65.
In the present series of young military trainees, a low body mass index was
correlated with fatigue fracture, but the risk factors for a thin body
structure and for stress fractures may be the same.
Displaced fatigue fractures of the femoral neck are uncommon overuse
injuries in military trainees that lead to complications and adverse sequelae,
such as postoperative infection, nonunion, osteonecrosis of the femoral head,
and severe secondary osteoarthritis. A high percentage of major complications
(47%; nine of nineteen) such as osteonecrosis of the femoral head and severe
(Tönnis Grade 2 or 3) osteoarthritis, was detected in the present series.
According to a previous literature review, the rate of failure of surgical
treatment of displaced fatigue fractures of the femoral neck has been
approximately the same (38%) in military trainees and athletes, although it is
noteworthy that the majority of the studies were case
reports8,13,15-32,
with only one extensive
study42. Nearly
half of the patients in our series required at least one additional operative
procedure after the initial surgery, which further reflects the susceptibility
for complications and prolonged morbidity as well as permanent disability
related to these fractures in young men. In the present series, one-sixth of
the patients required professional reeducation, but none had retired on
account of the sequelae of the femoral neck fracture. Previous reports on
displaced fatigue fractures of the femoral neck have not dealt with
occupational disability, to our knowledge.
Severe destruction of the femoral neck and head led to a total hip
replacement, at a relatively young age, in three of our nineteen patients. In
one series, two of ten displaced fatigue fractures of the femoral neck in
athletes led to a total hip
arthroplasty29. In
another series, eight (19%) of forty-two fatigue fractures of the femoral neck
in soldiers led to a total or bipolar hip
replacement42.
Haidukewych et al. reported a similar rate of arthroplasty (18%; thirteen of
seventy-three) in a series of traumatic femoral
fractures44.
The majority of the patients in the present study had had prodromal
symptoms, which if recognized would have permitted the prevention of the
displaced fracture by early intervention and changes in military training. A
correct diagnosis is of utmost importance to prevent the initial microfracture
from propagating to a complete fracture and eventually displacing. The earlier
the diagnosis is made, the more likely it is that displacement of the fracture
can be prevented. The diagnostic evaluation of patients presenting with even
the vaguest hip or groin pain requires a high degree of clinical suspicion.
Early recognition of the prodromal symptoms of a fatigue fracture together
with immediate intervention, as now employed in our institution, are
applicable to other physically active populations, including professional
athletes and other individuals active in physical exercise and sports. There
should be a high degree of suspicion for a fatigue fracture of the femoral
neck in healthy young men reporting hip and/or groin pain during physical
activities.