Atypical Femoral Fractures In Patients Research Articles

Bisphosphonate-Related Atypical Femoral Fractures in Patients with Autoimmune Disease Treated with Glucocorticoids: Surgical Results for 20 Limbs.

Glucocorticoids induce osteoporosis, while bisphosphonates treat it, yet both can lead to atypical femoral fractures. Patients on both agents may face challenges in healing from such fractures due to their pathophysiology and pharmacological effects. Intramedullary nail surgery was performed on 20 limbs in 19 patients with atypical femoral fractures and autoimmune diseases, who had received bisphosphonates for GC-induced osteoporosis. The average durations of glucocorticoid and bisphosphonate use were 17 and 9 years (standard deviation: 7.59 and 4.35), respectively, and the mean follow-up period was 66 months. Fifteen and five limbs were fractured at the subtrochanter and diaphysis, respectively. The surgical techniques (type of nail) and additional procedures performed in these cases were examined. The post-operative alignment and reduction status on radiographs were examined to determine their relationship with post-operative outcomes. Cephalomedullary long nails were inserted in nine limbs and antegrade intramedullary nails in 11 limbs. As an additional surgical procedure, open reduction, bone grafting and drilling were carried out on six, two, and five limbs, respectively. Regarding malalignment on radiographs, AP images showed varus in four limbs, and lateral images showed extension in two limbs. Regarding the cortical discontinuity, the distal fragment of the 11th limb shifted posteriorly in the lateral view. Gaps at the fracture sites were observed in 11 limbs. As a result, bone union was confirmed in 13 limbs. Five of the seven nonunion limbs required additional surgery. When comparing union and nonunion, open reduction and drilling were involved in nonunion limbs. The surgical outcomes of atypical femoral fractures in patients with autoimmune disease and on long-term glucocorticoids and bisphosphonates were poor. Although it is not possible to affirm for sure based on these results alone, management with prophylactic surgery before complete fracture is considered to be required to improve outcomes.

FRI680 Atypical Femoral Fracture In Patients With Hypophosphatasia: A Systematic Review

Abstract Disclosure: N. Charoenngam: None. J. Thongpiya: None. P. Yingchoncharoen: None. B. Ponvilawan: None. M.S. Marangoz: None. J. Chenbhanich: None. P. Ungprasert: None. A growing number of case reports and case series have demonstrated that atypical femoral fracture (AFF) can occur in patients with hypophosphatasia (HPP). Due to the lack of summary of the clinical manifestation, risk factors, associated ALPL variants and treatment, we conducted this systematic review with the goal to summarize the characteristics of all reported patients with HPP who sustained AFF. Additionally, we aimed to identify all available evidence to quantify the rate of co-existence between HPP and AFF. Potentially eligible articles were identified from MEDLINE and EMBASE databases from inception to September 2022 using search strategy consisting of terms related to “Hypophosphatasia” and “Atypical femoral fracture”. Eligible articles must report one of the following information: 1.) individual data of patient(s) diagnosed with HPP and AFF, 2.) prevalence of HPP among patients with AFF or 3.) prevalence of AFF among patients of HPP. Characteristics of patients reported in each study were extracted. A total of 148 potentially eligible articles were identified from the databases. After systematic review, 23 articles met the eligibility criteria. A total of 27 patients with AFF and HPP were identified. The mean ± SD age of the reported patients was 53.8 ± 12.7 years and 21 patients (77.8%) were female. Nine patients (33.3%) received antiresorptive medication (bisphosphonate and/or denosumab) and two patients (7.4%) received teriparatide prior to development of AFF. Seven (25.9%) and 17 (63.0%) patients sustained unilateral and bilateral AFF, respectively. Twelve patients (44.4%) had a history of fractures at other sites. Four (14.8%) and six (21.4%) patients received asfotase alfa and teriparatide after sustaining AFF. Two studies that reported the prevalence of AFF among patients with HPP of approximately 10%. One study reported one HPP patient in a cohort of 72 patients with AFF. In summary, based on the limited evidence, AFF occurred in up to 10% of patients with HPP. Based on the 27 case reports, almost two-thirds did not receive antiresorptive treatment, suggesting the HPP itself could potentially be a risk factor for AFF. Presentation: Friday, June 16, 2023

OA07 A case of severe osteoporosis treated with teriparatide following the development of bilateral atypical femoral fractures due to IV zoledronic acid

Abstract Introduction Atypical femoral fractures (AFF) are a rare complication of long-term anti-resorptive therapy. A literature review of 310 cases of AFF did reveal a median duration of bisphosphonate therapy of 7 years. Additionally, simultaneous glucocorticoid use was seen in 34% of the cases and was reported to have a 5-fold increase in one case series. Around 70% of patients do describe a prodrome of thigh pain and around quarter of all cases will have bilateral involvement. Case description A 59-year-old lady with a background diagnosis of Behçet’s disease was referred for continuation of osteoporosis care. History of Fractures 2003- left-sided distal radial fracture; 2017 - refractured again after a fall; left 5th metatarsal fracture a few months later. 2019 - right navicular fracture, left pubic rami fracture and left iliac wing fracture, after a fall from the bus In 2023, she has tripped and fell from the standing height resulting in a left femoral shaft fracture, which had radiological features of an atypical femoral fracture. She denied any prodromal thigh pain. The orthopaedic team did an intramedullary nailing to the left femoral shaft. X-ray of the right femur shaft revealed cortical thickening of right mid femoral shaft. Treatment History In 2009, she was started on oral bisphosphonate therapy and from 2020 to 2022 received 3 doses of IV zoledronic acid at the national Behçet’s centre in Birmingham. She has been on long-term steroid therapy due to the underlying Behçet's disease and was on prednisolone 7mg daily when she was referred to us. Management of AFF The orthopaedic team initially recommended a watch and wait policy for the right side; however, following discussions with the patient and with us, prophylactic nailing of the right femoral shaft was done 2 months later. Investigations DXA scan in 2022: spine T-score of−3.3 (L2 −3.6, L3 −3.9, L4 −3.7); femoral neck T-score of −2.5. Despite treatment with oral and then parenteral bisphosphonates for the last 12 years, there is a significant reduction in BMD with 18.2% decrease in the spine and 7.1% decrease in the femoral neck compared to the last DEXA in 2019. Management plan The next step was to treat her with teriparatide, which she is currently having without any problems. We shall continue it for 24 months. Discussion Atypical femoral fractures are rare. Anti-resorptive medication including bisphosphonates and denosumab are known to cause atypical femoral fractures. Teriparatide, being anabolic agent, is not associated with the increased risk of atypical femoral fractures. While there are no randomised controlled studies about the use of teriparatide in healing atypical femoral fractures, there are some case reports where teriparatide had shown improved fracture healing in AFF. After the 24 months, to ‘lock in the effects’ of teriparatide, an anti-resorptive medication will be required. Because both femoral shafts have received intramedullary nailing, we would consider IV zoledronic acid after the 24 months of teriparatide. This is the approach supported by the European Calcified Tissue Society in their systemic review and recommendations on ‘Medical Management of Patients After Atypical Femur Fractures’ (https://doi.org/10.1210/clinem/dgz295). Key learning points Consider atypical femoral fracture in patients who are on anti-resorptive therapy and complain of thigh/groin pain. Atypical femoral fractures can be bilateral; therefore, evaluate both sides. Teriparatide can be used to treat osteoporosis in patients with atypical femoral fracture, but considerations will have to be made in relation to subsequent therapy.

Atypical tibial fracture in breast cancer patient with bone metastasis receiving denosumab therapy: a case report and review of the literature

BackgroundDenosumab therapy is often used to reduce skeletal-related events in metastatic bone disease. On the other hand, there have been some instances of atypical femoral fracture in patients with metastatic bone disease treated with denosumab. In this case report, we describe a patient with metastatic bone disease due to breast cancer who had been using denosumab for 4 years to prevent skeletal-related events and suffered an atypical tibial fracture.Case presentationWe report here the case of an 82-year-old Japanese woman who had received yearly intravenous denosumab for 4 years and presented with a fracture fulfilling the criteria for an atypical fracture, except for being located at the tibial diaphysis. She was found to have stage 4 breast cancer with multiple bone metastases 4 years prior. She had difficulty walking due to her tibial pain and underwent surgical treatment. Four months after surgery, the tibial fracture site exhibited bone fusion.ConclusionIn patients with long-term use of denosumab to prevent skeletal-related events in metastatic bone disease, it is important to be aware of shin and thigh pain and to examine for signs of atypical tibial fractures to pay attention to atypical femoral fractures.

Multicenter study on atypical femoral fractures in patients with bone metastases taking bone- modifying agents

Bone-modifying agents (BMAs), with bone-resorptive inhibitory effects, such as zoledronic acid and denosumab, are widely used at higher doses for bone-related events caused by bone metastasis of malignant tumors. These drugs have been suggested to be associated with atypical femoral fractures (AFFs), and the relationship between BMAs and AFFs has attracted attention. To investigate the clinical features including bone union time of AFFs in patients administered BMA for bone metastasis, we conducted a retrospective multicenter study. Thirty AFFs from 19 patients were enrolled in this study. Thirteen patients had bilateral AFFs, and nineteen AFFs had prodromal symptoms. Eighteen AFFs underwent surgery after complete fracture, three failed to achieve bone union and required nonunion surgery, and 11 AFFs that achieved bone union had an average period until bone union of 16.2 months, which was much longer than that previously reported for ordinary AFFs. Seven patients discontinued the BMAs, but not due to AFFs. Stopping BMAs in patients with bone metastasis would make it difficult to secure their performance of activities of daily living, and AFF with BMA administration might require a longer time for union. Therefore, it would be important to prevent incomplete AFF from becoming complete AFF via prophylactic internal fixation.

Incidence of Atypical Femoral Fractures in Patients on Osteoporosis Therapy-A Registry-Based Cohort Study.

ABSTRACTAtypical 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.

Risk factors for development of Atypical Femoral Fractures in patients on long-term oral Bisphosphonate therapy

Risk factors for development of Atypical Femoral Fractures in patients on long-term oral Bisphosphonate therapy

Current concepts in the management of bisphosphonate associated atypical femoral fractures.

Bisphosphonates are a class of drugs used as the mainstay of treatment for osteoporosis. Bisphosphonates function by binding to hydroxyapatite, and subsequently targeting osteoclasts by altering their ability to resorb and remodel bone. Whilst aiming to reduce the risk of fragility fractures, bisphosphonates have been associated with atypical insufficiency fractures, specifically in the femur. Atypical femoral fractures occur distal to the lesser trochanter, until the supracondylar flare. There are a number of the differing clinical and radiological features between atypical femoral fractures and osteoporotic femoral fractures, indicating that there is a distinct difference in the respective underlying pathophysiology. At the point of presentation of an atypical femoral fracture, bisphosphonate should be discontinued. This is due to the proposed inhibition of osteoclasts and apoptosis, resulting in impaired callus healing. Conservative management consists primarily of cessation of bisphosphonate therapy and partial weightbearing activity. Nutritional deficiencies should be investigated and appropriately corrected, most notably dietary calcium and vitamin D. Currently there is no established treatment guidelines for either complete or incomplete fractures. There is agreement in the literature that nonoperative management of bisphosphonate-associated femoral fractures conveys poor outcomes. Currently, the favoured methods of surgical fixation are cephalomedullary nailing and plate fixation. Newer techniques advocate the use of both modalities as it gives the plate advantage of best reducing the fracture and compressing the lateral cortex, with the support of the intramedullary nail to stabilise an atypical fracture with increased ability to load-share, and a reduced bending moment across the fracture site. The evidence suggests that cephalomedullary nailing of the fracture has lower revision rates. However, it is important to appreciate that the anatomical location and patient factors may not always allow for this. Although causation between bisphosphonates and atypical fractures is yet to be demonstrated, there is a growing evidence base to suggest a higher incidence to atypical femoral fractures in patients who take bisphosphonates. As we encounter a growing co-morbid elderly population, the prevalence of this fracture-type will likely increase. Therefore, it is imperative clinicians continue to be attentive of atypical femoral fractures and treat them effectively.

Two cases of atypical femoral fracture in cancer patients administered with bone-modifying agents.

Objective: We report two cases of atypical femoral fracture (AFF) in patients with cancer.Patients: Two patients, a 53-year-old woman with breast cancer and a 77-year-old man with prostate cancer, could not walk after being injured in a fall. They used bone-modifying agents (BMA) for the prevention of bone metastasis for three and four years, respectively.Results: Intramedullary nails were placed to fix the femoral fractures in each patient. Neither of them had pathological metastatic femoral fractures based on fracture site specimens; however, severe suppression of bone turnover at the fracture site was suspected. Both patients could ambulate with a T-cane and were free of hip pain after surgery. Radiographs showed no callus formation at the fracture site.Conclusion: Based on the two cases of AFF in patients with cancer related to BMA use, we should consider that the incidence of AFF may be associated with long-term BMA use.

Morphological and Morphometrical Analyses of Fracture-Healing Sites of an Atypical Femoral Fracture in Patients with and without Long-Term Bisphosphonate Treatment for Osteoporosis: A Report of Two Cases

Bisphosphonates have been the first drug of choice for osteoporosis in the recent years because of their known ability to suppress osteoclast activity. The adverse effect of long-term bisphosphonate administration in the fracture-healing process is controversial. The aim of our study was to observe not only morphology but also morphometry of the fracture site of atypical femoral fracture with and without long-term bisphosphonate administration, in a case study of two difficult-to-obtain human samples. The patients with insufficient healing of atypical femoral fracture were treated with valgus wedge osteotomy. Histomorphometrical analysis was performed in bone samples of fracture sites harvested during osteotomy. The thickness of the femoral cortex was measured in the fracture site and the adjacent, non-fracture site. A comparative analysis of the content of hypertrophic osteoclasts in fracture sites, shape and size of osteons, mass, and ratio of the woven bone to the total bone mass was performed, comparing bisphosphonate-treated and untreated samples. In bisphosphonate-treated samples, we observed femoral cortex thickening at the fracture site; the appearance of hypertrophic osteoclasts; decreased bone resorption surface, decreased osteoclast numbers on the bone resorption surface, and increased ratio of multinuclear osteoclasts; osteons were misshapen and thin; and the mass and ratio of the woven bone to the total bone mass were higher. This study demonstrated that long-term bisphosphonate administration can alter the morphological features of the fracture site compared to its physiological state.

Cumulative incidence of femoral localized periosteal thickening (beaking) preceding atypical femoral fractures in patients with rheumatoid arthritis.

Atypical femoral fractures (AFFs) are stress fractures; bisphosphonate (BP) use is a major risk factor for the development of such fractures. Localized periosteal thickening (LPT, also termed beaking) of the lateral cortex often precedes a complete or incomplete AFF. We evaluated the incidence of latent LPT in patients with rheumatoid arthritis (RA), to evaluate LPT progression, and to define LPT risk factors. A total of 254 patients with RA were included; all underwent annual X-ray evaluation, dual-energy X-ray absorptiometry, and analyses of serum and bone metabolic markers for 2-3years. LPT of the lateral cortex was sought in femoral X-rays. The incidence of LPT was 2.4% (6/254). Among patients on both BP and prednisolone (PSL) at enrollment, the incidence was 2.3% (3/131). Two femurs of two patients with LPT developed incomplete AFFs; LPT was extensive and associated with endosteal thickening. One patient had been on BP and PSL and microscopic polyangiitis was comorbidity. The other was on a selective estrogen receptor modulator and PSL. A daily PSL dose >5mg (OR 11.4; 95%CI 2.15-60.2; p = 0.004) and higher-dose methotrexate (OR 1.22; 95%CI 1.01-1.49; p = 0.043) were significant risk factors for LPT. The incidence of latent LPT was not high (2.4%) but incomplete AFFs developed in two RA patients. Higher-dose PSL because of a comorbid disease requiring glucocorticoid treatment other than RA or refractory RA were risk factors for LPT; X-ray screening for latent LPT would usefully prevent complete AFFs.

Atypical femoral neck fracture after prolonged bisphosphonate therapy.

Of the drugs developed to prevent and treat osteoporosis, bisphosphonate has played a very important role in preventing osteoporotic fractures. However, case reports describing atypical femoral fractures in patients using long-term bisphosphonates have emerged. The majority of atypical femur fractures occurs in the lateral aspect of the subtrochanteric or femur diaphysis, which is explained by accumulation of tensile stress in these areas. Although the superior cortex of the femur neck withstands maximum tensile stress, to our knowledge, there have been only two reports (three cases) of atypical femoral neck fracture. In addition, none of those case reports revealed detailed pathology related to suppressed bone turnover rate. We encountered an incomplete femoral neck fracture and diagnosed it as “atypical” on the basis of the patient’s lack of trauma and medication history and pathological findings. For patients with groin pain, minimal or no trauma, and a history of long-term bisphosphonate use, an atypical femoral neck fracture should be considered.

Diabetes and fractures: new evidence of atypical femoral fractures?

Patients with diabetes have an increased risk of femoral fractures, but little is known about the risk of atypical femoral fractures (AFFs). The aim of this study was to identify the risk of subtrochanteric and femoral shaft (ST/FS) fractures and estimate the risk of AFFs in patients with type 1 (T1D) and type 2 diabetes (T2D). From the nationwide Danish National Patient Register, we identified patients with T1D (n = 19,896), T2D (n = 312,188), and sex- and aged-matched controls without diabetes (n = 996,252) from the general population and all ST/FS fractures (n = 7509). Data were analyzed using a Cox proportional-hazards model and the incidence rate and rate ratio of ST/FS fractures were estimated. The incidence rate of ST/FS fractures in T1D was 52.14 events per 100,000 person years and 73.21 per 100,000 person years in T2D. T1D was associated with an increased risk of ST/FS (HR 2.07 (95% CI 1.68-2.56)), whereas T2D was not (HR 0.99 (95% CI 0.94-1.10)). Previous ST/FS fractures were associated with an increased risk of subsequent ST/FS fractures (HR 6.95 (95% CI 6.00-8.05)) and the use of bisphosphonates with an increased risk of ST/FS fractures (HR 1.72 (95% CI 1.54-1.91)). Patients with T1D have a higher risk of ST/FS fractures compared with sex- and age-matched controls. Since a proportion of ST/FS fractures are classified as AFFs, this could point towards the fact that AFFs also are increased in patients with T1D, but not T2D.

Atypical femoral fracture in patients with bone metastasis receiving denosumab therapy: a retrospective study and systematic review

BackgroundWhile denosumab has been shown to prevent skeletal-related events in patients with bone metastasis, there is a concern that it may cause atypical femoral fracture (AFF). While AFF has been reported in patients with osteoporosis receiving denosumab, data are scarce in the context of AFF occurring in patients with bone metastasis receiving monthly denosumab therapy.MethodsTo analyze the incidence of AFF in patients with bone metastasis, we reviewed the medical records of patients who had received monthly denosumab (120 mg) treatment from May 2012 to June 2017 at any of the three participant institutions.ResultsThe study population consisted of 277 patients who had received a median of 10 doses (range, 1–79) of denosumab. Five patients were diagnosed as having AFF or symptomatic atypical femoral stress reaction (AFSR) needing surgical intervention, representing an incidence rate of 1.8% (95% confidence interval, 0.77–4.2). These patients had received 15, 45, 45, 46 or 47 doses of denosumab, respectively. Four of the patients had received prior zoledronic acid treatment. The results of our analysis suggested that long-term use of denosumab, especially for more than 3.5 years, and prior use of zoledronic acid were risk factors for the development of AFF.ConclusionsWe found the AFF events in 5 patients (1.8%) among 277 cancer patients who had received monthly denosumab (120 mg) treatment. Long-term denosumab treatment and prior zoledronic acid treatment were identified as risk factors for the development of AFF.

Natural history of incomplete atypical femoral fractures in patients after a prolonged and variable course of bisphosphonate therapy-a long-term radiological follow-up.

Retrospective study evaluating the natural history of lateral femoral stress fractures (FSF) by serial radiography over a variable period of time in a cohort of patients treated for some time with bisphosphonates for osteoporosis, whilst also identifying the fracture response in cases where bisphosphonates were discontinued. The radiographs of 76 consecutive patients (92 femurs) with 161 FSF were reviewed to document their change over time. Femurs were classified into the following: A-normal, B-focal cortical thickening, C-dreaded black line and D-displaced fracture. Bisphosphonate history was recorded. 66.5% FSF showed group stability between the first and last radiographs: group B (79.1%), group C (45.7%). 28.6% progressed, mostly following an ordered sequence starting from group A, progressing to B, then C, before culminating in D. Progression rate was as follows: A-100% (11/11), B-18.3% (21/115), C-40% (14/35). Regression in FSF was uncommon-5.6% (8/161). 34.8% (32/92) sustained displaced fractures. Kaplan-Meier analysis showed statistically significant difference between the groups; median survival (95% CI): A-4189 (-), B-3383.0 (-), C-1807 (0.0-3788.6) and progression to displaced fracture when bisphosphonate had been stopped for at least 6months. The group without recent bisphosphonates had a lower group progression rate (17.1%, 12/70). Nevertheless, 10.9% (5/46) progressed to displaced fracture. This group also had the highest proportion of stable (77.1%, 54/70) and regressive lesions (5.7%, 4/70). In FSF, there is natural progression from normal bone, to focal cortical thickening, to dreaded black line and eventually to displaced fracture. Most lesions persist, remaining static or progressing, especially if a dreaded black line is present and bisphosphonates are continued. Regression is uncommon and more frequent when bisphosphonates are discontinued. Despite stopping bisphosphonates, there remains a 10.9% risk of progression to displaced fracture.

High bisphosphonate treatment rates and the prevalence of atypical femoral fractures in patients with systematic lupus erythematosus: a single-center retrospective study performed in Japan

Treatment of systemic lupus erythematosus (SLE) often continues with moderate-to-low doses of glucocorticoids for the long term. Bisphosphonates aid in the prevention and management of glucocorticoid-induced osteoporosis (GIOP). However, long-term use of bisphosphonates increases the relative risk of atypical femoral fracture (AFF) and the incidence is typically 16 or 113 per 100,000 person-years in patients treated with bisphosphonates for 5 or 10years, respectively. Here, we explored bisphosphonate prescription rate and prevalence of AFF in patients with SLE. In total, 270 patients with SLE were enrolled. The Japanese Society for Bone and Mineral Research Guideline 2014 for GIOP management and treatment was used. We also explored AFF history through medical records. Most (n = 251) patients were recommended to treat by the GIOP guideline (scores ≥ 3); bisphosphonates, denosumab, teriparatide, or active vitamin D was prescribed for 85.7%. Bisphosphonates were currently used by 66.1% of the patients, and 65% had used them for ≥ 5years. Of all patients, 76.7% had a history of bisphosphonate use, 5 of 270 (1.9%) had histories of AFF. Four of five patients with AFF had taken bisphosphonates for ≥ 3.5years, in addition to moderate doses (≥ 10mg/day) of glucocorticoids. For the SLE patients with a history of bisphosphonate use, the incidence of AFF was calculated to be 278 per 100,000 person-years. Our single-center study found that bisphosphonates were commonly used long term by Japanese patients with SLE. As AFF is not rare, AFF should be cared in patients with SLE.

Bone development and remodeling in metabolic disorders.

There are many metabolic disorders that present with bone phenotypes. In some cases, the pathological bone symptoms are the main features of the disease whereas in others they are a secondary characteristic. In general, the generation of the bone problems in these disorders is not well understood and the therapeutic options for them are scarce. Bone development occurs in the early stages of embryonic development where the bone formation, or osteogenesis, takes place. This osteogenesis can be produced through the direct transformation of the pre-existing mesenchymal cells into bone tissue (intramembranous ossification) or by the replacement of the cartilage by bone (endochondral ossification). In contrast, bone remodeling takes place during the bone's growth, after the bone development, and continues throughout the whole life. The remodeling involves the removal of mineralized bone by osteoclasts followed by the formation of bone matrix by the osteoblasts, which subsequently becomes mineralized. In some metabolic diseases, bone pathological features are associated with bone development problems but in others they are associated with bone remodeling. Here, we describe three examples of impaired bone development or remodeling in metabolic diseases, including work by others and the results from our research. In particular, we will focus on hereditary multiple exostosis (or osteochondromatosis), Gaucher disease, and the susceptibility to atypical femoral fracture in patients treated with bisphosphonates for several years.

Incidence of Mutations in the ALPL, GGPS1, and CYP1A1 Genes in Patients With Atypical Femoral Fractures.

ABSTRACTAtypical femoral fractures (AFFs) are uncommon and often related to prolonged bisphosphonate (BP) treatment. Isolated cases have been linked to mutations of tissue nonspecific alkaline phosphatase (ALPL). Moreover, mutations in the geranylgeranyl pyrophosphate synthase (GGPPS) gene, which can be inhibited by BPs, and in the enzyme of the cytochrome P450 superfamily (CYP1A1), related to the metabolism of several drugs, have also been associated with AFF development. Our aim was to analyze the incidence of ALPL, GGPS1, and CYP1A1 gene mutations in patients with AFFs and their clinical characteristics. Seventeen women with AAFs were included. All patients underwent Sanger sequencing of the ALPL, GGPS1, and CYP1A1 genes, analyzing the presence of mutations and polymorphisms in these genes. The clinical characteristics of the patients, previous treatments, ALP substrates (vitamin B6 and phosphoethanolamine), bone turnover markers, and bone mass were also analyzed. Three of 17 patients (17.6%) presented heterozygous mutations in the ALPL (p.Gly288Ala) or CYP1A1 (p.Arg136His, p.Val409Ile) genes. Only the patient with the ALPL mutation presented increased ALP substrates. Patients with CYP1A1 variants had glucocorticoid‐induced osteoporosis. All patients were previously treated with BPs during 85.5 ± 38 months, and nearly 50% were also treated with glucocorticoids. The AFF was bilateral in 35% of cases. In conclusion, ALPL and CYP1A1 mutations may be related to the development of AFF in patients treated with BPs. The evaluation of ALP substrates in patients with low ALPL levels allows the identification of patients with hypophosphatasia. The role of CYP1A1 mutations in AFF needs further study. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Atypical femoral fracture in patients with malignant bone metastasis receiving denosumab therapy: Retrospective study.

220 Background: While denosumab prevent skeletal-related events in patients with malignant bone metastasis, there are concerns that it may be associated with atypical femoral fracture (AFF). AFF in osteoporotic patients receiving denosumab is reported, but few data have been reported in the context of monthly denosumab therapy for patients with malignant tumor and bone metastasis. Methods: We reviewed the medical records and pharmacy database of patients who received denosumab at 120mg monthly for management of bone metastasis from May 2012 to June 2017 at our institution to analyze the incidence of AFF. To identify the risk factors and optimal management of AFF, we reviewed the clinical features and skeletal images of the patients. Results: We analyzed the data of 204 patients receiving a median of 7 doses (range; 1-60) of denosumab, and 150 (74%) patients received more than three times of denosumab. Four patients were diagnosed as AFF and incidence rate was 2.0%. Five limbs of the 4 patients were diagnosed as AFF and performed intramedullary nail fixation, and 2 limbs of the patients were diagnosed of atypical femoral stress reaction (AFSR) with surgical indication. These patients with AFF received 15, 44, 45 and 45 doses of denosumab, which showed higher doses of denosumab (median: 44.5 doses), compared to the patients without AFF or AFSR (median: 6 doses). Median age of the four patients was 59 (range: 50-66), and primary disease were breast cancer in three patients and non-small lung cell cancer in one patient. Conclusions: We experienced four AFF events among 204 patients receiving denosumab 120mg monthly and incident rate was 2.0%. More data are needed about the occurrence of AFF in these patients.

518P - Retrospective study of atypical femoral fracture in patients with malignant bone metastasis receiving denosumab therapy: Case series

518P - Retrospective study of atypical femoral fracture in patients with malignant bone metastasis receiving denosumab therapy: Case series