Abstract
-
Background
Prodromal symptoms might lead to an early diagnosis of atypical femoral fracture (AFF). However, incomplete AFF can progress to complete fractures because they are often misdiagnosed as degenerative diseases such as lumbar canal stenosis or knee and hip osteoarthritis. The purpose of this study was to examine how many AFFs are misdiagnosed as degenerative diseases and the characteristics of the site of prodromal symptoms in a multicenter study.
-
Methods
We retrospectively analyzed the medical records of patients with AFFs at two institutions. In addition, a survey was sent to affiliated institutions to collect data on prodromal symptoms.
-
Results
Analysis in two institutions revealed 46 AFFs in 35 patients. Seventeen fractures were associated with localized prodromal symptoms in the groin or lateral thigh (conventional type), and 12 fractures had prodromal symptoms not localized to the fracture site, such as widespread lateral thigh, knee, or lateral lower leg (modified type). Eleven fractures were misdiagnosed as degenerative diseases. The survey of 11 affiliated institutions revealed that prodromal pain was reported in 29 of 49 AFFs. Nineteen fractures were associated with modified prodromal pain, and 9 fractures were misdiagnosed as degenerative diseases.
-
Conclusions
Twenty-one percent of AFFs were misdiagnosed with degenerative diseases. All of the misdiagnosed cases were associated with prodromal symptoms. We believe that the prodromal symptoms of AFF are diverse and very similar to those of degenerative diseases, which may have caused the misdiagnosis.
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Key words: Femoral fractures · Missed diagnosis · Multicenter studies as topic · Prodromal symptoms
GRAPHICAL ABSTRACT
INTRODCUTION
Atypical femoral fractures (AFFs) have been associated with severely suppressed bone turnover due to long-term use of bisphosphonates.[
1,
2] AFFs have been shown to carry a high risk of delayed union or nonunion, especially when they progress to complete fracture.[
3,
4] Delayed or missed diagnosis of an AFF in the incomplete fracture stage may adversely impact the patient’s prognosis. Therefore, early diagnosis to prevent progression from incomplete to complete fracture is very important.
Previous reports have shown that 50% to 86% of patients with AFFs have a history of prodromal symptoms. [
1,
5–
9] Because the prevalence of prodromal symptoms is high in patients with AFFs, there may be ample opportunity to diagnose incomplete fractures at an early stage and prevent progression to complete fractures.
However, some reports have described cases in which patients were misdiagnosed with degenerative disorders such as lumbar spinal stenosis or knee and hip osteoarthritis based on prodromal symptoms, resulting in progression of an incomplete AFF to a complete fracture.[
10–
12] We hypothesized that the reasons for delayed or missed diagnosis of AFFs are that (1) the prodromal symptoms are similar to those of the abovementioned degenerative diseases; and (2) the symptoms sometimes occur at sites other than those proposed by the American Society for Bone and Mineral Research (ASBMR). The incidence of AFFs is very low, ranging from 3.0 to 9.8 cases per 100,000 patient-years.[
13,
14] Therefore, it is difficult to perform a detailed single-center investigation of the prodromal symptoms of AFFs. The purpose of this study was to examine how many AFFs are misdiagnosed as degenerative diseases and the characteristics of the site of prodromal symptoms in a multicenter study.
METHODS
This study was approved by the hospital ethics committee of our institution (S201904003) and conducted in accordance with the Declaration of Helsinki.
1. Data collection
The patient and clinical data were collected using the following 2 methods.
2. Two-institution retrospective survey
We retrospectively reviewed data obtained from January 2014 to October 2021 at 2 institutions: Osaka General Medical Center (OGMC) and Sakai City Medical Center (SCMC). The inclusion criteria were diagnosis of AFF as defined by the ASBMR, and clinical observation for ≥12 months. Data collected from medical records included detailed demographic and clinical information such as age at the time of fracture, sex, and history, dosing period, and indication for bisphosphonates or steroids use. We classified the fractures according to site (subtrochanteric or shaft) and pattern (complete or incomplete) with use of radiologic and magnetic resonance imaging analyses. The patients were actively queried about the presence, duration, and location of prodromal symptoms preoperatively and again postoperatively regarding changes after internal fixation. In addition, we assessed data regarding any history of AFFs that were not diagnosed as fractures but instead as a degenerative disease, the name of that degenerative disease, and the presence or absence of radiographic findings consistent with that degenerative disease. For patients with AFFs that were treated at OGMC, we confirmed the presence of local tenderness consistent with the fracture site in all cases who had been diagnosed with an incomplete AFF.
3. Questionnaire survey for related institutions
A multicenter survey involving 11 related institutions was performed. The subjects were patients with AFFs that had been diagnosed according to the ASBMR definition from January 2014 to March 2020. The survey items were the number of patients with prodromal symptoms, the location of the symptoms, and whether AFFs had been diagnosed not as a fracture but rather as a degenerative disease.
4. Definitions
In the present study, we classified the prodromal symptoms that were locally expressed in the groin or thigh as the “conventional type” as proposed by the ASBMR, and widespread lateral thigh pain or ectopic pain in the lateral lower leg or knee as the “modified type.”
5. Statistical analysis
SPSS version 22.0 (IBM Corp., Armonk, NY, USA) was used for all statistical analyses. Continuous variables were expressed as means, whereas categorical variables were expressed as frequencies and proportions. Differences between groups were assessed with the use of the Student’s t-test for continuous data and Fisher’s exact test for categorical variables. The level of statistical significance was set at a P value less than 0.05.
RESULTS
1. Two-institution retrospective survey
A total of 35 patients with 46 AFFs were included in the study. The patients included 2 men and 33 women with a mean age of 69.9 years (range, 47–87 years). With respect to fracture type, 24 fractures were complete and 22 were incomplete. With respect to fracture location, 29 fractures were subtrochanteric and 17 were shaft. Prodromal symptoms were observed in association with 29 of 46 fractures.
Conventional prodromal symptoms, such as localized thigh and groin pain, were found in association with 17 fractures, and modified prodromal symptoms, such as broad thigh pain, lower leg pain, and knee pain, were found in association with 12 fractures.
Thirteen incomplete AFFs were diagnosed with prodromal pain. One patient had bilateral prodromal symptoms in association with bilateral incomplete fractures, and 11 patients had unilateral prodromal symptoms in association with 3 bilateral incomplete fractures and 8 unilateral incomplete fractures.
Two of the 13 patients had progression to complete subtrochanteric fractures while waiting for surgery.
There were no significant differences between the patients with modified and conventional prodromal symptoms with regard to patient age at the time of fracture, the duration of bisphosphonate treatment, or the purpose of bisphosphonate treatment (
Table 1).
Bisphosphonates had been taken by 30 patients. Of these 30 patients, 21 had taken bisphosphonates for ≥3 years, primarily for the treatment of osteoporosis. Eleven patients had taken steroids, with most of those patients having taken them for ≥3 years. Ten patients had taken both steroids and bisphosphonates.
There were no significant differences in the duration and reason of bisphosphonate use between conventional and modified prodromal symptoms (
Table 2).
The duration of prodromal symptoms from onset to diagnosis varied from <1 month to ≥12 months. The duration of conventional and modified prodromal symptoms varied as well. The proportion of each type of prodromal symptoms was examined at both OGMC and SCMC. The number of fractures associated with conventional and modified prodromal symptoms was 10 and 7 at OGMC and 7 and 5 at SCMC, respectively, with no significant difference between 2 institutions in terms of the proportions of each type (
P=0.5) (
Table 3).
Regarding the number of prodromal symptoms by facility, at OGMC, out of 17 fractures, 10 cases were of the conventional type (including 8 cases localized to the thigh and 2 cases in the groin), and 7 cases were of the modified type (including 5 cases extensive to the thigh and 2 cases in the lower leg or knee). At SCMC, out of 12 fractures, 7 cases were of the conventional type (including 6 cases localized to the thigh and 1 case in the groin), and 5 cases were of the modified type (including 3 cases extensive to the thigh and 2 cases in the lower leg or knee).
With regard to the number of prodromal symptoms by fracture site, the number of fractures associated with conventional and modified type prodromal symptoms was 10 and 7 for subtrochanteric fractures and 7 and 5 for shaft fractures, respectively, with no significant difference between the two institutions and the 2 fracture sites in terms of the proportions of 2 types of prodromal symptoms (
P= 0.5) (
Table 4).
Eleven of 46 fractures were misdiagnosed as degenerative diseases, such as lumbar spinal stenosis or hip or knee osteoarthritis. Among these eleven fractures, two progressed to complete AFF during the waiting period for scheduled surgery, despite being diagnosed as incomplete subtrochanteric AFF at our institutions rather than degenerative disease.
Seven of these 11 fractures were diagnosed at OGMC and 4 were diagnosed at SCMC. By fracture site, 6 were subtrochanteric fractures and 5 were shaft; by fracture type, 8 were complete and 3 (2 shaft fractures and 1 subtrochanteric) were incomplete; and by prodromal pain, 4 were associated with the conventional type and 7 were associated with the modified type. There were no significant differences between OGMC and SCMC in terms of the proportion of patients misdiagnosed with degenerative disease, fracture site, fracture type, or type of prodromal symptoms (
Table 5).
The misdiagnosed degenerative diseases included lumbar spinal canal stenosis in 8 fractures (3 of which were associated with conventional symptoms and 5 of which were associated with modified symptoms), osteoarthritis of the hip for 1 fracture (which was associated with conventional symptoms), and osteoarthritis of the knee for 2 fractures (both of which were associated with modified symptoms). Eight fractures had radiographic findings that were consistent with the diagnosis of AFF (
Table 6).
Of the 46 fractures, 44 were treated surgically (43 with intramedullary nails and 1 with a plate) and 2 were treated non-surgically. Five of the fractures progressed to nonunion after the first surgery; of those, 2 were in patients with persistent nonunion who were managed with observation, 2 were in patients who had bone union after reoperation, and 1 was in a patient who had bone union after the third operation (
Table 7).
Of the 29 fractures that were associated with prodromal symptoms, 21 were in patients who had resolution or improvement of the symptoms postoperatively (including 13 patients with conventional symptoms and 8 with modified symptoms).
Two cases involved patients who continued to experience symptoms postoperatively (including one patient with conventional symptoms and 1 with modified symptoms). Six cases were unknown. In cases where prodromal symptoms resolved in less than 2 months, there were 7 cases of the conventional type and 2 cases of the modified type. For cases where symptoms disappeared between more than 2 months and less than 6 months, there were 3 cases and 2 cases, respectively. In cases where symptoms disappeared between more than 7 months and less than 12 months, there were 2 cases and 1 case, respectively.
The time until resolution of prodromal symptoms varied. (
Table 8).
Excluding cases in which the course of prodromal symptoms was unknown, 13 out of 14 fractures associated with conventional type and 8 out of 9 fractures associated with modified type had disappeared or improved in prodromal symptoms.
There was no significant difference in the proportion of cases where prodromal symptoms disappeared or were alleviated after operation, depending on the type of prodromal symptoms (
Table 9).
Local tenderness consistent with the fracture site was identified in all cases of incomplete AFF at OGMC.
2. Questionnaire survey for related institutions
Clinical data were collected from 11 institutions. Of the 49 fractures, 29 were associated with prodromal symptoms. Of these, 19 fractures were associated with prodromal symptoms that were judged to be of the modified type, and 9 fractures were misdiagnosed as degenerative disease according to the prodromal symptoms. In a comparison of the results from the 11 institutions with those from the 2-center survey, no significant differences were found in the proportion of fractures with or without prodromal symptoms, the proportion of the modified type of prodromal symptoms, or the proportion of fractures misdiagnosed as degenerative diseases (
Table 10).
DISCUSSION
The outcomes of this multi-center study indicated that the sites of prodromal symptoms of AFF were diverse, and there were some cases that were misdiagnosed as degenerative diseases, such as lumbar spinal stenosis or hip or knee osteoarthritis, regardless of the institution or AFF site.
AFFs have been shown to have a high risk of delayed union or nonunion, especially when they progress to complete fractures.[
3,
4] Additionally, early internal fixation surgery for the treatment of an incomplete AFF prior to the development of complete AFF has been reported to reduce the duration of hospital stay and the patient’s financial burden.[
15] Therefore, Shane et al. [
1] pointed out the importance of detecting prodromal symptoms as a characteristic finding to prevent progression from incomplete to complete AFF.
However, there are some reports that have described cases in which patients were misdiagnosed with degenerative disorders such as lumbar spinal stenosis or knee and hip osteoarthritis based on prodromal symptoms, resulting in progression of an incomplete AFF to a complete AFF. [
10–
12]
Therefore, a detailed study of prodromal symptoms in AFF is considered highly important. Unfortunately, to our knowledge, the only study that has examined the prodromal symptoms of patients with AFFs in detail is that by Kharazmi et al. [
8], published in 2015. Their validation had been based on a national database and may underestimate rate and the site of onset of prodromal symptoms. This point can be considered a limitation of their research, but they revealed cases with non-conventional prodromal symptoms such as lumbar back pain and knee pain.
Our study showed that both conventional and modified prodromal symptoms occurred in association with both subtrochanteric and shaft fractures. Excluding cases in which the course of prodromal symptoms was unknown, conventional and modified symptoms resolved or improved after internal fixation in most cases. Therefore, we believe that both conventional and modified prodromal symptoms are present in a certain proportion of AFFs. The modified symptoms were thought to be referred pain because it is not uncommon for a femoral lesion to manifest as referred pain in the thigh, knee, or lower leg.[
16]
Eleven fractures in the 2-center survey and nine fractures in the 11-center questionnaire survey were misdiagnosed as degenerative diseases such as lumbar spinal canal stenosis, hip joint disease, and knee arthritis. There was no significant difference between the 11-center questionnaire and the 2-center survey in terms of the proportion of fractures misdiagnosed as degenerative disorders. This finding indicates that not only modified type prodromal symptoms, but also conventional prodromal symptoms may lead to delayed or missed diagnosis. Conventional and especially modified prodromal symptoms are similar to symptoms of degenerative diseases, such as lumbar spinal stenosis and hip and knee arthritis. All of the misdiagnosed cases were associated with prodromal symptoms, so we think that this is the main reason why AFFs are misdiagnosed as degenerative diseases. Similar diagnostic difficulties have been reported only in a few case reports.[
10–
12] To the best of our knowledge, the present report is the first multicenter study on this topic.
We further verified the reasons for such diagnostic difficulties. One systematic review showed that the mean age at onset of AFFs was 70.5 years and that most patients were female.[
17] The prevalence of knee osteoarthritis and lumbar spondylosis in women aged >70 years was 72% to 81% and 75% to 78%, respectively.[
18] The prevalence of hip osteoarthritis in women aged >70 years was 13% to 16%.[
19] Therefore, we believe that the diagnosis of AFF may be further confused by existing imaging findings consistent with degenerative diseases. In fact, 8 of 11 fractures that were misdiagnosed as degenerative disease in 2-center survey were associated with imaging findings consistent with the misdiagnosis. Although we discussed only the possibility of AFF being misdiagnosed as a degenerative disease, the same confusion can also occur in cases in which patients with rheumatoid arthritis have been taking steroids and bisphosphonates for many years. The development of AFF recently has been reported in association with denosumab,[
1] one of the newer osteoporosis drugs. Therefore, the same precautions should be taken for patients with a history of long-term denosumab use.
Other factors that contribute to misdiagnosis are the very low incidence of AFF (3.0 to 9.8 cases per 100,000 patients-years [
13,
14]) and the fact that AFFs are rarely encountered in daily medical practice.
One recent report described the use of dual energy X-ray absorptiometry (DXA) as a screening tool for the early detection of incomplete AFFs.[
20] DXA may be expected to reduce radiation exposure and cost in the treatment of AFFs. Imaging examinations are undoubtedly effective for early diagnosis.
According to the findings from 1 of the institutions (OGMC), all incomplete AFFs with prodromal symptoms, including both the conventional and modified types, were associated with localized tenderness at the fracture site. We believe that the early diagnosis rate of incomplete AFF can be further improved not only by conducting imaging examinations but also by confirming tenderness.
As shown in our study, the prodromal symptoms of AFF are diverse. With this in mind, and with reference to local tenderness, a full-length femoral radiograph should be made for patients with lower extremity or hip pain who have a history of bisphosphonate or steroid use. If abnormal imaging findings are identified, a radiograph of the contralateral femur should be added.
Limitations of this study could be the fact that it is retrospectively undertaken and that the collection of data is based on medical records which may pose the possibility of inaccuracy.
The first case of AFF that prompted us to begin research on prodromal symptoms was a case that was misdiagnosed as lumbar spinal stenosis. The patient's chief complaint is extensive pain in the left thigh, and they have been misdiagnosed with lumbar spinal stenosis. She had been receiving conservative treatment for lumbar spinal stenosis at a nearby clinic for two weeks prior to being referred to OGMC. Unfortunately, on the night of the day the patient was admitted for rest, a complete fracture occurred during weight-bearing, which subsequently required multiple surgeries. After experiencing this case, we became more aware of the importance of prodromal symptoms (
Fig. 1).
Therefore, all patients with AFF who have been managed at OGMC and SCMC have been actively questioned about the prodromal symptoms since the start of this study, and their responses have been recorded in the medical record. We believe that the results of our two-institution survey on prodromal symptoms are very accurate.
We are concerned that the multicenter questionnaire survey might underestimate the frequency of prodromal symptoms. However, there were no significant differences in the incidence of prodromal symptoms, the proportion of modified type, or the proportion of cases misdiagnosed as degenerative diseases compared with the results of our 2-center survey. We believe that the data from the multicenter questionnaire survey was also useful for understanding the characteristics of prodromal symptoms of AFF.
The survey was conducted at medical institutions in a limited region. Further extensive investigations are therefore needed.
Our investigation found that the rate of misdiagnosed cases was 20 out of 95 AFF fractures, which is 21%. All of the misdiagnosed cases were associated with prodromal symptoms, so the misdiagnosis rate among cases with prodromal symptoms was 20 out of 58 fractures, which is 34%. Considering the disadvantages of treating complete AFFs, this was a rate that cannot be overlooked. It is essential for not only orthopedic surgeons but also many healthcare professionals involved in bone metabolism treatment to understand the diversity of the prodromal symptoms of AFF demonstrated in this study.
This report is a secondary publication that added 10 AFFs in 7 additional cases to primary report previously published in Japanese. The content is same as that.
However, I believed it was very important to raise awareness worldwide about the diversity of prodromal symptoms of AFF and the pitfalls of misdiagnosing AFF as degenerative diseases. Therefore, I submitted a secondary publication to English language journal, although the content is the same as the original article.
In conclusion, in this study, the prodromal symptoms of AFF were diverse and similar to those of degenerative diseases such as lumbar spinal stenosis or hip or knee osteoarthritis.
This is considered to be a major factor that can lead to the misdiagnosis of AFFs as degenerative diseases, and such misdiagnosis is not uncommon in our survey. In the diagnosis of lower limb pain in patients taking bisphosphonate, it is advisable to consider not only degenerative diseases but also AFF as one of the differential diagnoses.
DECLARATIONS
-
Funding
The authors received no financial support for this article.
-
Ethics approval and consent to participate
The study protocol conformed to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the hospital ethics committee of our institution (S201904003).
-
Conflicts of Interest
No potential conflict of interest relevant to this article was reported.
Fig. 1A case misdiagnosed as a degenerative disease that resulted in a complete atypical femoral fracture in 49-year-old woman. (A) Radiograph taken on the day of referral to our institution. The arrow shows the localized thickening. (B) Radiograph of a complete atypical femoral fracture that occurred on the night of the day of referral. (C) Radiograph of nail failure after first surgery. (D) Radiograph of nail failure after second surgery. (E, F) Radiograph after third surgery. Bone union was shown.
Table 1Demographic data for patients in 2-institution retrospective survey
Table 1
|
Overall |
Prodromal symptoms |
P-value |
|
|
Conventional |
Modified |
|
No. of patients |
35 |
15 |
12 |
|
|
|
No. of fractures |
46 |
17 |
12 |
|
|
|
Sex (no. of patients) |
|
|
|
|
|
Male |
2 |
1 |
0 |
0.6 |
|
Female |
33 |
14 |
12 |
|
|
|
Age (yr)a)
|
69.9 (47–87) |
72.2 |
69.7 |
0.3 |
|
|
Fracture type (no. of fractures) |
|
|
|
0.2 |
|
Complete |
24 |
11 |
5 |
|
|
Incomplete |
22 |
6 |
7 |
|
|
|
Fracture site (no. of fractures) |
|
|
|
0.6 |
|
Subtrochanteric |
29 |
10 |
7 |
|
|
Shaft |
17 |
7 |
5 |
|
Table 2Duration and reason of bisphosphonate use and duration of steroid use of patients in 2-institution retrospective survey
Table 2
|
Overall |
Prodromal symptoms |
P-value |
|
|
Conventional |
Modified |
|
Duration of bisphosphonate use |
|
<3 yr |
3 |
3 |
0 |
|
|
3–9 yr |
14 |
7 |
5 |
|
|
≥10 yr |
7 |
2 |
3 |
|
|
Unknown |
6 |
3 |
2 |
|
|
Total |
30 |
15 |
10 |
0.3a)
|
|
|
Reason for bisphosphonate use |
|
Osteoporosis treatment |
17 |
9 |
5 |
|
|
Prevention of steroid-induced osteoporosis |
10 |
4 |
3 |
|
|
Bone-modifying agent |
2 |
1 |
1 |
|
|
Unknown |
1 |
1 |
1 |
|
|
Total |
30 |
15 |
10 |
1b)
|
|
|
Duration of steroid use |
|
<3 yr |
1 |
1 |
0 |
|
|
3–9 yr |
3 |
2 |
1 |
|
|
≥10 yr |
6 |
2 |
2 |
|
|
Unknown |
1 |
0 |
0 |
|
|
Total |
11 |
5 |
3 |
|
Table 3Duration of prodromal symptoms in the 2-institution survey
Table 3
|
Duration of prodromal symptoms |
Overall (N=29) |
Prodromal symptoms |
|
Conventional (N=17) |
Modified (N=12) |
|
<1 mon |
6 |
3 |
3 |
|
1–2 mon |
7 |
4 |
3 |
|
3 mon |
3 |
2 |
1 |
|
4–6 mon |
4 |
2 |
2 |
|
7–9 mon |
7 |
5 |
2 |
|
10–11 mon |
1 |
1 |
0 |
|
≥12 mon |
1 |
0 |
1 |
Table 4Types of prodromal symptoms, by facility and fracture site, in the 2-institution survey
Table 4
|
Type of prodromal symptoms |
Facilitya)
|
Fracture siteb)
|
|
|
|
OGMC (N=17) |
SCMC (N=12) |
Subtrochanteric (N=17) |
Shaft (N=12) |
|
Conventional |
10 |
7 |
10 |
7 |
|
Local thigh |
8 |
6 |
7 |
7 |
|
Groin |
2 |
1 |
3 |
0 |
|
|
Modified |
7 |
5 |
7 |
5 |
|
Broad thigh |
5 |
3 |
5 |
3 |
|
Lower leg or knee |
2 |
2 |
2 |
2 |
Table 5Diagnosis of degenerative diseases according to facility, fracture site, fracture type, and prodromal symptoms in the 2-institution survey
Table 5
|
Degenerative disease diagnosis (N=11) |
P-value |
|
Institution |
|
0.6 |
|
OGMC |
7 |
|
|
SCMC |
4 |
|
|
|
Fracture site |
|
0.5 |
|
Subtrochanteric |
6 |
|
|
Shaft |
5 |
|
|
|
Fracture type |
|
0.1 |
|
Complete |
8 |
|
|
Incomplete |
3 |
|
|
|
Prodromal symptomsa)
|
|
0.1 |
|
Conventional |
4 (3:1) |
|
|
Modified |
7 (5:2) |
|
Table 6Degenerative diseases diagnosed in the 2-institution survey
Table 6
|
Degenerative disease diagnosed |
Overall (N=11) |
Prodromal symptoms |
Radiographic findings consistent with diagnosis |
|
Conventional |
Modified |
|
Lumber spinal stenosis |
8 |
3 |
5 |
6 |
|
Hip osteoarthritis |
1 |
1 |
0 |
0 |
|
Knee osteoarthritis |
2 |
0 |
2 |
2 |
Table 7Outcomes of internal fixation
Table 7
|
Value |
|
Internal fixation method |
|
Nail |
43 |
|
Plate |
1 |
|
Outcome of internal fixation |
|
|
Bone union without the need for reoperation |
39 |
|
Bone union after reoperation |
2a)
|
|
Bone union after third operation |
1a)
|
|
Nonunion |
2a)
|
Table 8Progress of prodromal symptoms
Table 8
|
Overall |
Conventional |
Modified |
|
Progress of prodromal symptom after operation |
29 |
18 |
11 |
|
Disappearance |
17 |
12 |
5 |
|
Reduction |
4 |
1 |
3 |
|
Continuation |
2 |
1 |
1 |
|
Unknown |
6 |
4 |
2 |
|
|
Interval until prodromal symptom disappearance |
17 |
12 |
5 |
|
<2 mon |
9 |
7 |
2 |
|
≥2–6 mon |
5 |
3 |
2 |
|
≥7–12 mon |
3 |
2 |
1 |
Table 9Rate of resolution or reduction of prodromal symptoms
Table 9
|
Type of prodromal symptoms |
Rate of resolution or reduction of symptoms (N=21) |
|
Conventional |
93% (13/14) |
|
Modified |
89% (8/9) |
Table 10Comparison of results between the 11-institution and 2-institution surveys
Table 10
|
11-institution questionnaire survey |
OGMC/SCMC 2-institution survey |
P-value |
|
No. of atypical femoral fractures |
49 |
46 |
|
|
No. of fractures associated with prodromal symptoms |
29 |
29 |
0.3 |
|
No. of fractures associated with modified prodromal pain |
19 |
12 |
0.3 |
|
No. of fractures in patients diagnosed with degenerative disease |
9 |
11 |
0.3 |
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, Ikko Ohno2, Nobumasa Matsumura3, Keiichiro Oura4, Yasutaka Nakahori5, Takashi Nishii6
