Localization of Atypical Femoral Fracture on Straight and Bowed Femurs

Effect of Severe Bowing in Bisphosphonate-Related Atypical Femoral Fracture

Backgroud

Long-term use of bisphosphonate is a risk factor for atypical femoral fractures (AFFs). Femoral bowing is known to be associated with AFFs. However, whether femoral bowing quickens the occurrence of AFF is unknown. The purpose of this study was to determine whether AFF occurs earlier in patients with severe femoral bowing than in those without severe bowing.

Methods

One hundred and sixty-four patients (186 AFFs) from January 2006 to December 2022 were included in this study. According to severity of femoral bowing, patients were divided into 2 groups: severe bowing group (26 femurs) and minimal to moderate bowing group (160 femurs). Age, sex, and completeness and location of AFF were compared between the 2 groups. We compared the time of AFF occurrence after bisphosphonate therapy using cumulative percentage between the 2 groups.

Results

Age and sex were similar between the 2 groups, while body mass index (BMI) was lower (22.5 ± 3.0 kg/m2 vs. 24.5 ± 3.5 kg/m2, p = 0.003) in the severe bowing group. The duration of bisphosphonate use was shorter in the severe bowing group than in the minimal to moderate bowing group (3.3 ± 3.8 years vs. 5.0 ± 4.0 years, p = 0.048). In the severe bowing group, 85% of AFFs were diaphyseal in contrast to the 46% in the minimal to moderate bowing group (p < 0.001). Cumulative percentage plot of AFFs in the severe bowing group was left-shifted compared to the minimal to moderate bowing group.

Conclusions

At the time of AFF diagnosis, the severe bowing group exhibited shorter duration of bisphosphonate use, lower BMI, and a higher incidence of diaphyseal location. Shortening the duration of bisphosphonate therapy may be advisable in patients with severe femoral bowing.

Atypical Tibial Fracture Following Chronic Bisphosphonate Use: A Case Report and Review of the Literature

Atypical fractures are diagnosed when an otherwise normal force causes a fracture in a patient using bisphosphonates chronically. These occur most commonly in the subtrochanteric region of the femur. Yet, the literature on atypical tibial shaft fractures is scarce. We describe a case of a 60-year-old Hispanic female who presented with an atypical open tibial fracture with a seven-year history of bisphosphonate use, successfully managed with intramedullary nailing.

Treatment of Osteoporosis after Hip Fracture: Survey of the Korean Hip Society

Purpose

To assess current practice in the treatment of osteoporosis in patients who underwent treatment for hip fracture in South Korea.

Materials and Methods

A survey of 97 members of the Korean Hip Society, orthopedic hip surgeons who administer treatment for hip fractures in South Korea, was conducted. The survey was conducted for assessment of demographic data and perceptions regarding the management of osteoporosis in patients who have undergone treatment for hip fracture. Analysis of the data was performed using descriptive statistical methods.

Results

The majority of participants were between the age of 41 and 50 years, and 74% were practicing in tertiary hospitals. Testing for serum vitamin D levels (82%) was the most commonly performed laboratory test. Calcium and vitamin D were prescribed for more than 80% of patients by 47% and 52% of participants, respectively. Denosumab was the most commonly used first-line treatment option for osteoporosis in hip fracture patients. Bisphosphonate was most often perceived as the cause of atypical femoral fractures, and the most appropriate time for reoperation was postoperative 12 months. Teriparatide was most preferred after cessation of bisphosphonate and only prescribing calcium and vitamin D was most common in high-risk patients for prevention of atypical femoral fracture.

Conclusion

The results of this study that surveyed orthopedic hip surgeons showed that most participants followed the current strategy for management of osteoporosis. Because the end result of osteoporosis is a bone fracture, active involvement of orthopedic surgeons is important in treating this condition.

Incidence of Atypical Femoral Fractures in Patients on Osteoporosis Therapy – a Registry‐based Cohort Study

Atypical femoral fractures (AFFs) have been reported in patients taking bisphosphonates (BPs) for osteoporosis therapy but also in patients with no exposure to these drugs. In contrast, less is known about the incidence of AFFs in patients taking denosumab. This registry‐based cohort study analyzed the incidence of AFFs in patients with suspected or confirmed osteoporosis who were included in the osteoporosis register of the Swiss Society of Rheumatology between January 2015 and September 2019. Statistical analyses included incidence rates, rate ratios, and hazard ratios for AFFs, and considered sequential therapies and drug holidays as time‐dependent covariates. Among the 9956 subjects in the cohort, 53 had subtrochanteric or femoral shaft fractures. Ten fractures occurred under BP or denosumab treatment and two under teriparatide therapy. Five fractures were classified as AFFs based on the revised American Society of Bone and Mineral Research case definition of AFFs from 2014. Three AFFs occurred in women being treated with denosumab at the time of diagnosis, all with prior BP use (10, 7, and 1 years, respectively). One AFF developed in a woman receiving ibandronate and one arose in a woman receiving glucocorticoids rather than antiresorptive therapy. The incidence of AFFs per 10,000 observed patient‐years was 7.1 in patients receiving denosumab and 0.9 in patients with BP‐associated AFFs, yielding a rate ratio of 7.9 (95% confidence interval [CI] 0.63–413), p = 0.073. The risk of AFFs was not significantly higher in patients receiving denosumab therapy compared with BP therapy (hazard ratio = 7.07, 95% CI 0.74–68.01, p = 0.090). We conclude that the risk of AFFs is low in patients taking BPs, denosumab, or both sequentially. All three patients with AFFs under denosumab therapy had undergone prior BP therapy. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Straight nail insertion through a laterally shifted entry for diaphyseal atypical femoral fractures with bowing: good indications and limitations of this technique

PURPOSE

Inserting a straight (piriformis fossa entry) nail through the tip of the greater trochanter has been used for treating atypical femoral fractures (AFFs) with bowing. This study aimed to determine what degree of bowing can be successfully treated using a laterally shifted entry technique.

METHODS

Twenty-three complete and six incomplete diaphyseal AFFs treated using the shifted entry technique were retrospectively analysed. Radiologic parameters and complications were evaluated. The complete AFFs were divided into two groups based on the severity of preoperative bowing: grade 0-II bowing and < 20° lateral bowing (minimal/moderate) and grade III bowing or ≥ 20° lateral bowing (severe). Comparison according to postoperative malalignment, a change of lateral or anterior bowing ≥ 5° was also performed.

RESULTS

Three complete AFFs in the minimal/moderate group showed malalignment, as did all in the severe group (p < 0.001). The change of bowing was greater for the severe group in lateral and anterior bowing (p = 0.004 and 0.001, respectively). A greater fracture gap was found on AP and lateral radiographs in the severe group (p = 0.044 and 0.026, respectively). In the comparison according to postoperative malalignment, a significant difference was found for the percentage of severe deformity (p < 0.001). All incomplete AFFs were united without complication.

CONCLUSION

Diaphyseal AFFs with grade 0-II bowing and < 20° anterior bowing were treated successfully by the shifted entry technique. However, postoperative malalignment was found in all cases of AFFs with severe bowing. Therefore, other techniques should be considered for AFFs with grade III bowing or ≥ 20° anterior bowing.

Differences in subtrochanteric and diaphyseal atypical femoral fractures in a super-aging prefectural area: YamaCAFe Study

INTRODUCTION

Atypical femoral fractures (AFFs) have been correlated with long-term use of bisphosphonates (BPs), glucocorticoids (GCs), and femoral geometry. We investigated the incidence and characteristics of subtrochanteric (ST) and diaphyseal (DP) AFFs in all institutes in a super-aging prefectural area.

MATERIALS AND METHODS

We performed a blinded analysis of radiographic data in 87 patients with 98 AFFs in all institutes in Yamagata prefectural area from 2009 to 2014. Among the 98 AFFs, 57 AFFs comprising 11 ST fractures in 9 patients and 46 DP fractures in 41 patients with adequate medical records and X-rays were surveyed for time to bone healing and geometry.

RESULTS

Of the 87 patients, 67 received BPs/denosumab (77%) and 10 received GCs (11%). Surgery was performed in 94 AFFs. Among 4 AFFs with conservative therapy, 3 required additional surgery. In univariate regression analyses for ST group versus DP group, male-to-female ratio was 2/7 versus 1/40, mean age at fracture was 58.2 (37-75) versus 78 (60-89) years, rheumatic diseases affected 55.5% (5/9) versus 4.9% (2/41), femoral lateral bowing angle was 1.7 (0-6) versus 11.8 (0.8-24)°, GC usage was 67% (6/9) versus 4.9% (2/41), and bone healing time was 12.1 (6-20) versus 8.1 (3-38) months (p < 0.05). In multivariate analyses, higher male-to-female ratio, younger age, greater proportion affected by rheumatic diseases, and higher GC usage remained significant (p < 0.05).

CONCLUSIONS

The incidence of AFFs in our prefectural area was 1.43 cases/100,000 persons/year. This study suggests that the onset of ST AFFs have greater correlation with the worse bone quality, vice versa, the onset of DP AFFs correlated with the bone geometry. The developmental mechanisms of AFFs may differ significantly between ST and DP fractures.

Stress Fracture of the Femoral Shaft in Paget's Disease of Bone: A Case Report

Paget’s disease of bone (PDB) is a progressive bone disorder characterized by increased osteoclast-mediated bone resorption and abnormal bone formation. Incomplete atypical femoral fracture, appearing radiographically as a stress fracture at the lateral aspect of the femur, is an uncommon low-trauma fracture frequently seen in association with long-term bisphosphonate therapy. We describe the case of a 61-year-old female patient with PDB who developed a stress fracture at the lateral femoral cortex after 5 doses of intravenous bisphosphonate. The conservative treatment plan included discontinuation of bisphosphonate, a continuation of calcium and vitamin D supplementation, and limited weight-bearing for 3 months. The patient’s pain level gradually improved after switching to the new treatment plan. At the latest follow-up, approximately 5 years after the initiation of conservative treatment, the patient remained pain-free, and her PDB was well-controlled. However, the fracture line was still visible on the most recent radiograph. Although it remains unclear whether a stress fracture at the lateral femoral cortex occurred due to bisphosphonate therapy or PDB, this case highlights the importance of careful evaluation of any lesion that appears in PDB patients receiving bisphosphonate therapy.

Morphological divergence in the curvature of human femoral diaphyses: Tracing the central mass distributions of cross-sections

The diaphysis of the human femoral bone has a physiological anterior curvature; additionally, there is a curvature to the medial side or lateral side. In addition to compression stress from gravity during standing, walking, and running, these bones are continuously exposed to complex stresses from the traction forces of the various strong muscles attached to them. The femoral diaphysis is subjected to these mechanical stresses, and the direction and size of its curvature are defined according to Wolff's law and the mechanostat theory of Frost. The purpose of this study was to quantitatively evaluate the curvature of the femoral diaphysis in Japanese skeletons by determining the curve connecting the central mass distributions (CMD) of cross-sectional images. A total of 90 right femora (46 males and 44 females) were randomly selected from modern Japanese skeletal specimens. Full-length images of these bones were acquired using a clinical computed tomography scanner. The range between the lower end of the lesser trochanter and the adductor tubercle of each femur was divided at regular intervals to obtain ten planes, and nine levels were analyzed. The CMD curve was determined by connecting the CMDs of each of the nine cross-sections. First, the CMD of a cross-section in each of the nine slices was calculated, and the nine trajectories were superimposed from above. Then, by converting the shape of the entire CMD curve to superimpose the coordinates of the endpoint on the starting point, a closed arc representing the curvature of the femur was determined. For both males and females, the patterns varied from mostly medial to largely lateral curvature. The size of the curvature also varied for individuals. By analyzing only the coordinates of the vertex of the CMD curve of each femoral bone, the outlines of the diaphyseal curvatures could be recognized. The femora were thereby divided into two groups: medial bending and lateral bending. Considering males and females together, the number in the lateral-curvature group (n = 51) was larger than that in the medial-curvature group (n = 39). Moreover, the average age of the lateral-curvature group was significantly higher than that of the medial-curvature group (p < 0.05). In males, with an increase in the cortical bone proportion of the cross-sectional area, the anterior vertex of diaphyseal bending tended to be more prominent. This cortical proportion was significantly higher in the medial-curvature groups than in the lateral-curvature group (p < 0.01). The phenomena observed in this study may be related to pathophysiologies such as atypical fractures of the femur and osteoarthritis of the knee joints.

Incidence of nonunion after surgery of distal femoral fractures using contemporary fixation device: a meta-analysis

PURPOSE

Nonunion is the most frequent cause of reoperation and is associated with high morbidity after distal femur fracture (DFF). We examined the rates of nonunion requiring reoperation after fixation for DFF using a locking compression plate (LCP) or retrograde intramedullary nail (RIMN).

METHODS

We included four studies comparing LCP and RIMN and 38 single-cohort studies reporting LCP or RIMN. In total, 2156 femurs were included and 166 non-unions were detected. We conducted a pair-wise meta-analysis (with a fixed-effects model) on the four comparative studies and a proportional meta-analysis on the 38 articles to estimate the nonunion rate. We performed sensitivity analysis by comparing studies using LCP with less invasive surgical systems (LISS) with those that used RIMN.

RESULTS

The pairwise meta-analysis showed a similar nonunion rate between the groups [odds ratio: 1.02; 95% confidence interval (CI) 0.94-1.11, p = 0.633]. According to proportional meta-analysis, the pooled prevalence of nonunion was 5% (95% CI 4-7) totally, 6% (95% CI 4-8) in the LCP group, and 4% (95% CI 2-6) in the RIMN group (heterogeneity: p = 0.105). According to the sensitivity analysis, there was no difference in the union rate. The pooled prevalence of nonunion from sensitivity analysis was 4 % (95% CI, 3-5); it was 4% (95% CI, 3-6) in LCP with LISS and was 4% (95% CI, 2-6) in RIMN group (heterogeneity: p = 0.941).

CONCLUSION

Approximately 5% of patients who underwent LCP or RIMN fixation developed nonunion. Therefore, LCP and RIMN are effective DFF techniques and mastering one of them is essential.

Evaluation of the Nature and Etiologies of Risk Factors for Diaphyseal Atypical Femoral Fractures

OBJECTIVES

Differences in mechanisms of subtrochanteric and diaphyseal atypical femoral fractures (AFFs) are speculated in studies that analyzed differences in the patients' background. However, the etiologies of each type of AFF have not been studied in detail. This study aimed to investigate the nature and etiologies of the risk factors for diaphyseal AFFs.

MATERIALS AND METHODS

Eighty consecutive Japanese patients with 91 diaphyseal AFFs (AFF group) and 110 age-matched women with osteoporosis (non-AFF control group) were included. Their clinical data were compared; factors affecting AFFs were investigated, and the etiologies of the risk factors for diaphyseal AFFs were examined.

RESULTS

Multivariate analysis revealed that femoral serrated changes, bisphosphonate or denosumab usage, and lateral and anterior femoral curvatures were risk factors for diaphyseal AFFs (p < 0.0011, p = 0.0137, and p < 0.0001, respectively). Multivariate analyses revealed that serrated changes and low serum 25(OH)D levels affected the lateral curvature (p = 0.0088 and 0.0205, respectively), while serrated changes affected the anterior curvature (p = 0.0006), each significantly affected the femoral curvature. High serum calcium (Ca) levels, lateral femoral curvature, and anterior femoral curvature were predictors of serrated changes (p = 0.0146, 0.0002, and 0.0098, respectively).

CONCLUSION

Risk factors for diaphyseal AFFs were bone resorption inhibitor usage, a strong femoral curvature, and serrated changes. Low serum 25(OH)D levels and serrated changes are risk factors for lateral curvature, while a high serum Ca level is a risk factor for serrated changes.

Factors related to femoral bowing among Korean female farmers: a cross-sectional study

Background

Female farmers have a high prevalence of knee osteoarthritis (KOA) in South Korea. Femoral bowing has been reported to be related to KOA by increasing load on the mechanical axis. This study aimed to investigate factors related to femoral bowing in Korean female farmers.

Methods

We analyzed the legs of 264 female farmers registered with the Korea farmers' knee cohort of Jeonnam Center for Farmers' Safety and Health. A structured questionnaire was used to determine sociodemographic variables, agricultural career, cumulative squatting working time (CSWT), and cumulative heavy lifting working time. Femoral bone density was measured and Kellgren-Lawrence (KL) grades were obtained from the knee radiographs. Mechanical axis angle (MAA), femoral bowing angle (FBA), anatomical lateral distal femoral angle (aLDFA), anatomical medial proximal tibial angle (aMPTA), and condylar-plateau angle (CPA) were measured. We examined the relationship between the FBA and related factors by using multiple linear regression.

Results

The proportion of individuals with radiographic KOA (≥ KL grade 2) in this study was 37.9%. As KL grades increased, MAA, FBA, and CPA increased, whereas aLDFA and aMPTA decreased. FBA increased with age. Multiple linear regression analyses using FBA as a dependent variable showed relationship with higher age, lower height, higher BMI, lower bone mineral density, longer CSWT, and longer agricultural careers.

Conclusions

The results of this study suggest that external factors related to agricultural work in female farmers was associated with femoral bowing, in addition to internal factors such as age, bone density, height, and obesity.

Biological activity is not suppressed in mid-shaft stress fracture of the bowed femoral shaft unlike in "typical" atypical subtrochanteric femoral fracture: A proposed theory of atypical femoral fracture subtypes

BACKGROUND

We have investigated mid-shaft stress fractures of the bowed femoral shaft (SBFs), well before the first report of an association between suppression of bone turnover and atypical femoral fractures (AFFs). Although all cases of SBF meet the criteria for AFF, SBFs can also occur in patients with no exposure to bone turnover suppression-related drugs (e.g., bisphosphonates). Using bone morphometry and biomechanical analyses, we devised a theory of AFF subtypes, dividing AFFs into fragility SBFs in the mid-shaft and "typical" subtrochanteric AFFs caused by suppressed bone turnover. The aim of this multicenter prospective study was to provide evidence for this novel concept in terms of biological activity.

METHODS

The study was conducted at 12 hospitals in Japan from 2015 through 2019. Thirty-seven elderly women with AFF were included and classified according to location of the fracture into a mid-shaft AFF group (n = 18) and a subtrochanteric AFF group (n = 19). Patient demographics and clinical characteristics were investigated to compare the two groups. The main focus was on histological analysis of the fracture site, and bone metabolism markers were evaluated to specifically estimate biological activity.

RESULTS

All patients in the subtrochanteric AFF group had a history of long-term (>3 years) exposure to specific drugs that have been reported to cause AFF, but 5 of the 18 patients in the mid-shaft AFF group had no history of exposure to such drugs. Femoral bowing was significantly greater in the mid-shaft AFF group (p < 0.001). In the histological analysis, active bone remodeling or endochondral ossification was observed in the mid-shaft AFF group, whereas no fracture repair-related biological activity was observed in the majority of patients in the subtrochanteric AFF group. Levels of tartrate-resistant acid phosphatase-5b and undercaroxylated osteocalcin were significantly lower in the subtrochanteric AFF group (p < 0.05).

CONCLUSION

The possibility of our devised AFF subtype theory was demonstrated. Biological activity tends not to be suppressed in mid-shaft SBFs unlike in "typical" subtrochanteric AFFs involving bone turnover suppression. Although validation of the proposed theory in other populations is needed, we suggest that the pathology and treatment of AFFs be reconsidered based on its subtype.