Bisphosphonate-associated atypical sub-trochanteric femur fractures: paired bone biopsy quantitative histomorphometry before and after teriparatide administration

Teriparatide Does not Have Beneficial Effects on Bone Healing in Complete Atypical Femur Fractures

Teriparatide is an anabolic drug sometimes administered to patients who have atypical femoral fracture (AFF). However, whether teriparatide has beneficial effects on bone healing remains uncertain. The present study aimed to analyze the association between teriparatide and bone healing in complete AFF. A total of 59 consecutive cases (58 patients) who underwent intramedullary nailing for complete AFF were categorized based on postoperative use of teriparatide into the non-teriparatide (non-TPTD, n = 34) and teriparatide groups (TPTD, n = 25). Time-to-bone union was evaluated and compared between the two groups. Additionally, multiple regression analysis was performed to evaluate factors affecting time-to-bone union. All participants were women, with a mean age of 77.6 years (range: 62-92). No significant difference in time-to-bone union was found between the non-TPTD and TPTD groups (5.5 months vs. 5.8 months, p = 0.359). Two patients in the non-TPTD group underwent reoperation (p = 0.503) due to failure caused by inadequate fixation, and both achieved bone healing after additional fixation with blocking screws. Multiple regression analysis revealed that the anterior gap of the fracture site postoperatively was a factor affecting time-to-bone union (p = 0.014). The beneficial effect of teriparatide on bone healing in complete AFF could not be confirmed. Additional randomized controlled trials are required. Nonetheless, appropriate techniques, including efforts to reduce the gap on the tensile side during the surgery, are important for reliable bone healing.

Utility of iliac crest tetracycline-labelled bone biopsy in osteoporosis and metabolic bone disease: An evaluation of 95 cases over a period of 25 years

Background

Metabolic bone diseases (MBD) are typically diagnosed by non-invasive imaging and clinical biomarkers. However, imaging does not provide structural information, and biomarkers can be transiently affected by many systemic factors. Bone biopsy and pathologic evaluation is the gold standard for diagnosis of MBD, however, it is rarely utilized. We describe our technique for iliac crest tetracycline-labelled bone using a cannulated drill and assess the utility of bone biopsies to provide diagnostic and therapeutic guidance.

Methods

In the 25-year period between March 1998 and January 2023, a total of 95 bone biopsies were performed on 94 patients for an osteological indication at Vanderbilt University Medical Center (VUMC). Patient demographics, bone biopsy indications, complications, diagnostic utility, and subsequent therapeutic guidance were retrospectively reviewed and analyzed.

Results

The procedure had minimal complications and was well tolerated by patients. This technique provided good quality specimens for pathology, which helped establish a diagnosis and treatment change in most patients. Patients that had biopsy-guided treatment alterations showed significant increases in Dual-Energy X-ray Absorptiometry (DEXA) bone mineral density (BMD) scores post-biopsy and subsequent treatment.

Conclusion

Despite scientific and technological progress in non-invasive diagnostic imaging, clinical biomarkers, and procedures for MBD, there remains a small but significant subset of patients who may benefit from inclusion of tetracycline-labelled bone biopsy into the diagnostic and therapeutic picture. Future prospective comparison studies are warranted.

Mini abstract

Tetracycline-labelled bone biopsies are under-utilized. Biopsy led to a histological diagnosis and ensuing treatment alteration in most patients with significant increases in bone mineral density. The biopsy procedure used herein provided good specimens with low pain/adverse events. Bone biopsy remains a valuable tool in a small, though significant, subset of patients.

Effect of photobiomodulation therapy with different wavelengths on bone mineral density in osteoporotic rats

Osteoporosis is associated with severe pain, bone deformity, fracture, and bone loss. It is important to find strategies to prevent bone resorption and treat osteoporosis. This study sought to assess the effect of photobiomodulation therapy (PBMT) with different wavelengths on bone mineral density (BMD) in osteoporotic rats. This animal study evaluated 63 adult female rats. The rats underwent ovariectomy to induce osteoporosis. Ovariectomized rats were randomly divided into 9 groups of control (OC), treatment with zoledronic acid alone (0.02 mg/kg), and treatment with 660 nm, 810 nm, and 940 nm PBMT alone (3 times a week for 6 weeks, energy density of 4 J/cm2), and combined with zoledronic acid. The healthy control group (HC) only underwent sham surgery. The rats underwent cone-beam computed tomography (CBCT) 52 days after the first treatment session to measure their BMD according to the gray value (GV) of images. To assess the biomechanical properties of bone, the resected bones were subjected to 3-point bending test (3-PBT). The experimental groups had significant differences with the OC group regarding radiographic and biomechanical properties of bone (P < 0.05), indicating a healing course. No significant difference was noted between the experimental groups treated with different laser wavelengths and those treated with zoledronic acid (P > 0.05). In the condition of this study, it was found that PBMT at a constant energy density of 4 J/cm2 with 660-, 810-, and 940-nm wavelengths is effective for enhancement of bone mineral density and biomechanical properties. No significant difference was noted between different wavelengths of diode laser regarding radiographic and biomechanical properties of bone.

A brief review and clinical evidences of teriparatide therapy for atypical femoral fractures associated with long-term bisphosphonate treatment

The risk of bisphosphonate (BP)-associated atypical femur fracture (AFF) has markedly increased over recent decades due to suppression of bone turnover, accumulation of structural micro-damage and reduction of bone remodeling consequent to long-term BP treatment. These medications further delay bone union and result in challenging clinical management. Teriparatide (TPTD), a synthetic human parathyroid hormone, exhibits unique anabolic effects and can increase bone remodeling and improve bone microarchitecture, further promoting fracture healing and reducing the rate of bone non-union. In this study, we briefly define AFF as well as the effects of BPs on AFFs, detailed the role of TPTD in AFF management and the latest clinical therapeutic findings. We have confirmed that TPTD positively promotes the healing of AFFs by reducing the time to bone union and likelihood of non-union. Thus, teriparatide therapy could be considered as an alternative treatment for AFFs, however, further research is required for the establishment of effective clinical guidelines of TPTD use in the management of AFF.

Effects of bisphosphonates on appendicular fracture repair in rodents

The balance between osteoclastic bone resorption and osteoblastic bone formation is ultimately responsible for maintaining a structural and functional skeleton. Despite their strength, bones do break and the main cause of fractures are trauma and decreased bone mineral density as a result of aging and/or pathology that weakens the bone's microarchitecture and subsequently, its material properties. Osteoporosis is a disease marked by increased osteoclast activity and decreased osteoblastic activity tipping the remodeling balance in favor of bone resorption and can be caused by aging, glucocorticoids, disuse and estrogen-deficiency. Ultimately, this leads to brittle and weaker bones which become more prone to trauma or stress-induced fractures. The current treatment for preventing and treating osteoporotic fractures is the use of antiresorptive drugs such as bisphosphonates (BPs) and denosumab, but unfortunately, their long-term use, especially with alendronate and ibandronate, has been associated with increased risk of atypical femoral fractures (AFFs); femoral diaphyseal fractures distal to the lesser trochanter but proximal to the supracondylar flare. The purpose of this review is to examine the information that exists in the literature examining the effects of BPs on fracture repair of long bones in rodent (rat and mouse) models. The focus on rodents stems from the scientific community's unresolved need to develop small animal models to examine the molecular, cellular, tissue and biomechanical mechanisms responsible for the development of AFFs and how best they can be treated.

Dynamic Effects of the Third Generation Bisphosphonate of Risedronate on Rat Osteoporotic Fractures for Clinical Usage Guidance

OBJECTIVE

To better understand the risks of bisphosphonates in order to develop guidance for appropriate clinical usage, to compared femoral fracture healing at different time points and to explore the effects of Residronate on fracture healing.

METHODS

Osteoporosis model was achieved by ovariectomy surgery, followed by surgical incision of left femoral shaft 4 weeks after ovariectomy surgery. Three days after fracture surgery, risedronateor saline was fed by intragastric administration. X ray examination was used to check the callus formation, Bone Mineral Density (BMD), Bone Mineral Content (BMC), biomechanical, imaging and micromorphological of bone tissue as well as the trabecular bone parameters were all examined. The femoral pathology tissue of each rat was used to analyze trabecular bone parameters, including trabecular bone volume/tissue volume (Tb. BV/TV), bone surface to tissue volume ratio (BS/TV), trabecular bone mineral density (Tb. BMD), trabecular bone number (Tb. N), trabecular bone thickness (Tb. Th) and small bone Trabecular bone space (Tb. Sp).

RESULTS

Via X-ray and pathologically, risedronate treatment promoted the callus forming at the fracture site during the following 6 weeks after osteoporotic fracture by X-ray (P < 0.01), increased the local bone mineral density (P < 0.01), and accelerated the fracture healing during the first 3 weeks (P <0.01), but delayed facture healing in the later 3 weeks (P < 0.01). Risedronate increased the bone continuity of fracture at 7th week, but this phenomenon was not found at the 10th week (P < 0.01). Delayed fracture healing occurred locally at the fracture site. At 7th week, Risedronate may promote cartilage cells proliferating at fracture site, increase the dense of bone trabeculae and the connection of bone trabeculae, thicken the bone cortex showing better fracture healing than OPF-Saline groups (P < 0.01). However, these parameter did not continue during the 7th and 10th weeks. Comparing the first and the later 3 weeks, the rats in group Osteoporotic Fracture-Risedronate (OPF-RD) accelerated the local fracture healing in the first 3 weeks but not in the last 3 weeks, which is consistent for the BMD and BMC among each group (P < 0.05). Through evaluation of bone mineral density and bone mineral content, risedronate dramatically increased the BMD at the fracture site and resulted in reduction of BMC by risedronate at the fracture site (P < 0.05) among each group still exist, indicating dramatic (P < 0.05). Through load testing, Risedronate increased the structural strength and mechanical indexes of the new callus (P < 0.01).

CONCLUSION

Risedronate can improve the structural strength and mechanical index of newborn callus. Longer than 7 weeks usage of third generation bisphosphonate of risedronate does not contribute to osteoporotic fracture.

Evaluation and management of atypical femoral fractures: an update of current knowledge

Atypical femoral fractures are often attributed to the use of anti-resorptive medications such as bisphosphonates (BP). Whilst they have proven effects on fragility fracture prevention, clinical and laboratory evidence is evolving linking BP-related suppression of bone remodelling to the development of atypical stress-related sub-trochanteric fractures (Shane et al. in JBMR 29:1-23, 2014; Odvina et al. in JCEM 90:1294-301, 2005; Durchschlag et al. in JBMR 21(10):1581-1590, 2006; Donnelly et al. in JBMR 27:672-678, 2012; Mashiba et al. in Bone 28(5):524-531, 2001; Dell et al. in JBMR 27(12):2544-2550, 2012; Black et al. in Lancet 348:1535-1541, 1996; Black et al. in NEJM 356:1809-1822, 2007; Black et al. in JAMA 296:2927-2938, 2006; Schwartz et al. in JBMR 25:976-82, 2010). Injuries may present asymptomatically or with prodromal thigh pain and most can be successfully managed with cephalomedullary nailing and discontinuation of BP therapy. Such injuries exhibit a prolonged time to fracture union with high rates of non-union and metal-work failure when compared to typical subtrochanteric osteoporotic femoral fractures. Despite emerging literature on AFFs, their management continues to pose a challenge to the orthopaedic and extended multi-disciplinary team. The purpose of this review includes evaluation of the current evidence supporting the management of AFFs, clinical and radiological features associated with their presentation and a review of reported surgical strategies to treat and prevent these devastating injures.

Intermittent Parathyroid Hormone Accelerates Stress Fracture Healing More Effectively Following Cessation of Bisphosphonate Treatment

Parathyroid hormone (PTH) and bisphosphonates (BPs), including alendronate (ALN), have opposing effects on bone dynamics. The extent to which PTH remains effective in the treatment of stress fracture (SFx) in the presence of an ongoing BP treatment has not been tested. SFx was induced in 150 female Wistar rats, divided into five equal groups (n = 30). All rats were pretreated with ALN (1 μg/kg^-1/day^-1) for 14 days prior to SFx induction, followed by ALN cessation or continuation for the duration of the experiment; this was combined with daily PTH (8 μg/100 g^-1/day^-1) on SFx induction for 14 days, followed by cessation or continuation of ALN after SFx induction or an equivalent vehicle as a control. Ulnas were examined 2 weeks or 6 weeks following SFx. Two toluidine blue- and two tartrate-resistant acid phosphatase-stained sections were examined for histomorphometric analysis using Osteomeasure software. There was a significant interaction between the effects of time and treatment type on the woven bone width and apposition rate, as well as an improvement in the woven bone architecture. However, woven bone variables remained unaffected by the cessation or continuation of ALN. Cessation of ALN increased osteoclast number when compared with the ALN-PTH continuation group (p = 0.006), and vehicle (p = 0.024) after 2 weeks. There was a significant interaction between the effects of time and treatment type on the number of osteoclasts per unit BMU area and length. The number of osteoclasts per unit BMU area and length was significantly greater in ALN cessation groups. It was concluded that intermittent short-duration iPTH treatment effectively increased remodeling of SFx with a concurrent BP treatment, provided that BP was ceased at the time of SFx. Our results could help develop shorter iPTH treatment protocols for the clinical management of SFxs and guide clinical decision-making to cease BP treatment in cases of SFx. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Bisphosphonate-related atypical femoral fractures: A novel strategy to improve patient outcomes

Background:

Atypical femoral fracture (AFF) is a serious adverse event associated with bisphosphonate therapy and prone to complications and delayed union. We propose a technique and management strategy to maximise bone healing and outcomes.

Methods:

We report on a cohort of patients with AFF using our novel technique of preparing the intramedullary canal and rigid fixation with cephalomedullary nailing. Patients were admitted under a multidisciplinary team with rehabilitation goals of early mobilisation and teriparatide initiation. Clinical and radiographic data were retrospectively reviewed.

Results:

Twenty-eight AFFs were treated with a mean follow-up of 58.5 weeks and a mean age of 75.2 years old. All cases achieved radiological union by a mean of 6 months and post-operative thigh pain experienced up to 8.7 weeks. No cases underwent revision or experienced intraoperative complication.

Conclusion:

Our surgical technique and multidisciplinary management are reproducible with excellent results in patients with this rare yet challenging injury.

Medical Management of Patients After Atypical Femur Fractures: a Systematic Review and Recommendations From the European Calcified Tissue Society

CONTEXT

Atypical femur fractures (AFFs) are serious adverse events associated with bisphosphonates and often show poor healing.

EVIDENCE ACQUISITION

We performed a systematic review to evaluate effects of teriparatide, raloxifene, and denosumab on healing and occurrence of AFF.

EVIDENCE SYNTHESIS

We retrieved 910 references and reviewed 67 papers, including 31 case reports, 9 retrospective and 3 prospective studies on teriparatide. There were no RCTs. We pooled data on fracture union (n = 98 AFFs on teriparatide) and found that radiological healing occurred within 6 months of teriparatide in 13 of 30 (43%) conservatively managed incomplete AFFs, 9 of 10 (90%) incomplete AFFs with surgical intervention, and 44 of 58 (75%) complete AFFs. In 9 of 30 (30%) nonoperated incomplete AFFs, no union was achieved after 12 months and 4 (13%) fractures became complete on teriparatide. Eight patients had new AFFs during or after teriparatide. AFF on denosumab was reported in 22 patients, including 11 patients treated for bone metastases and 8 without bisphosphonate exposure. Denosumab after AFF was associated with recurrent incomplete AFFs in 1 patient and 2 patients of contralateral complete AFF. Eight patients had used raloxifene before AFF occurred, including 1 bisphosphonate-naïve patient.

CONCLUSIONS

There is no evidence-based indication in patients with AFF for teriparatide apart from reducing the risk of typical fragility fractures, although observational data suggest that teriparatide might result in faster healing of surgically treated AFFs. Awaiting further evidence, we formulate recommendations for treatment after an AFF based on expert opinion.

Nonunions of Bisphosphonate Fractures of the Femur: Presentation, Etiopathogenesis, Diagnosis, and Operative Treatment

Patients presenting with femoral fractures and long-term use of bisphosphonate treatment are at risk of developing a delayed union and/or nonunion as a result of the atypical metabolic activity prevailing at the fracture edges of the affected extremity. The treatment of these nonunions poses a serious challenge to orthopaedic surgeons worldwide and necessitates specialized techniques and materials to design a construct that will last a long period (greater than 6 months), while still allowing weight-bearing in this elderly population. Treatment options, timing of intervention, selection of implant, and the option of bone grafting are discussed to assist the clinician to make the right decisions in these complex clinical cases.

A retrospective bicenter comparative study of surgical outcomes of atypical femoral fracture: Potential effect of teriparatide on fracture healing and callus formation

BACKGROUND

The main purpose of the present study was to assess the radiologic effect of teriparatide on fracture healing, including union rate, union time, and callus formation, by quantitative measurements using serial follow-up X-ray imaging examinations in patients with complete atypical femoral fractures (AFFs) treated using closed intramedullary nailing.

METHODS

From January 2010 to October 2017, 58 consecutive patients with complete AFF who were treated with intramedullary nailing at two institutions were enrolled. Patients were classified into two groups: those who received teriparatide therapy (group A) and those who did not (group B). Teriparatide (Forsteo®; Eli Lily Co., Indianapolis, IN, USA) at a once-daily 20 μg dose was prescribed as continuous treatment of osteoporosis or with the expectation of better bone healing. Surgical outcomes, including union rate, union time, modified radiologic union score (mRUS), and callus formation at 3, 6, and 12 months postoperatively, were assessed to evaluate the effect of teriparatide on fracture healing. Quantitative measurement of callus formation was performed using the region of interest (ROI) tool in the picture archiving communication system (PACS).

RESULTS

Non-union was not observed in group A, whereas two patients had non-union in group B. Union time was 18.3 ± 4.8 (range, 12-28) weeks in group A and 23.6 ± 9.5 (range, 12-64) weeks in group B and was significantly shorter in group A than group B (p = 0.010). The average mRUSs during periods A (3-4 months postoperatively), B (6-8 months postoperatively), and C (12-14 months postoperatively) were 10.0, 13.9, and 15.9 in group A, and 8.7, 12.0, and 14.9 in group B, respectively. The average mRUSs during periods A and B were significantly different (p = 0.027 and 0.011, respectively). The medial, posterior, and total callus areas during periods A and B were also significantly greater in group A than in group B. No difference was observed in the union rate between the two groups (p = 0.492).

CONCLUSION

Teriparatide may improve callus formation and shorten union time in patients with complete diaphyseal AFF who underwent closed intramedullary nailing.

LEVEL OF EVIDENCE

Level III retrospective comparative study.

Atypical femoral fracture associated with delayed union for which the cessation of alendronate and daily administration of teriparatide contributed to fracture healing: histopathological evidence of the enhancement in bone formation parameters

A female patient with systemic lupus erythematosus developed an atypical femoral fracture of the left femur after 5 years of glucocorticoid and alendronate therapy. We performed intramedullary nailing. However, 1 week later, we performed a revision surgery using a locking plate and an iliac bone graft because of displacement at the fracture site. At this stage, alendronate was discontinued and daily teriparatide was introduced and continued for 24 months. Twenty months after the revision surgery, a re-revision surgery was performed with an iliac bone graft because of breakage of the locking plate and fracture non-union. Fracture healing was eventually obtained 15 months after the re-revision surgery. Biopsies of the ilium before the treatment and 20 months after daily teriparatide treatment were evaluated. The histology revealed that proliferating osteoid and cuboidal osteoblasts were detected around the osteoid tissue after teriparatide treatment. Bone histomorphometry findings showed that bone volume parameters and osteoid parameters prominently increased with the teriparatide treatment, but not bone resorption parameters. Laboratory findings revealed the elevation of bone-specific alkaline phosphatase (24 U/L at 7 months) compared to its pre-teriparatide level (8.1 U/L) and increased bone mineral density of the hip (from -0.2 to 0.0 in T-score). These data indicated that the discontinuation of alendronate and initiation of teriparatide treatment activated bone-forming ability in our patient and may have contributed to fracture healing.

Alendronate improves bone density and type I collagen accumulation but increases the amount of pentosidine in the healing dental alveolus of ovariectomized rabbits

BACKGROUND

It has been shown that the oral aminobisphosphonate sodium alendronate (ALN) therapy reduces the risk of main fractures in osteoporotic women, but its effect on the jaw bones is poorly known. Here, we hypothesized that ALN affects the newly formed alveolar bone, particularly the quality of the type I collagen cross-linking.

METHODS

Osteoporosis was induced by ovariectomy (OVX) in 6-month old rabbits. Six weeks following surgery, eight animals were treated by oral gavage with ALN (OVX + ALN) and ten received placebo (OVX + Pbo). Another six rabbits which were sham operated also received placebo (SHAM + Pbo). One month following the beginning of treatment, the upper and lower left first premolars were removed. Six weeks later, the upper and the lower right first premolars were also extracted. One month after the second extraction, biopsies were collected from the maxillary extraction sites and collagen crosslinks were analyzed in the newly formed bone tissue by HPLC. Also, at this time, mandibular bone segments were subjected to μCT.

RESULTS

Animals treated with ALN achieved a roughly 2-time greater bone volume fraction value at a late healing period than animals in the other groups (p < 0.05). Collagen mean results were 2- to 4-times superior in the OVX + ALN group than in the control groups (p < 0.05). ALN-treated animals presented higher amounts of the non-enzymatic collagen cross-link pentosidine (PEN) than the sham-operated rabbits (p < 0.05), whereas the OVX + Pbo group presented the highest amount of PEN (p < 0.05).

CONCLUSION

Alendronate increases bone volume and collagen accumulation, but does not fully rescue the non-osteoporotic alveolar tissue quality as is evident from the increased quantity of pentosidine.

The effects of teriparatide on acceleration of bone healing following atypical femoral fracture: comparison between daily and weekly administration

We compared the effectiveness of promoting bone healing between two teriparatide preparations for atypical femoral fracture (AFF). A total of 45 AFFs were included in this study, and we compared the duration of bone union. Teriparatide administered by daily injection enhanced bone union more than weekly administration in complete AFFs.

INTRODUCTION

The efficacy of teriparatide for atypical femoral fracture (AFF) has been recently reported. Although two different teriparatide preparations can be used to treat osteoporosis in Japan, daily or weekly injection, all previous reports on the effectiveness of teriparatide for AFF only examined daily injection formulations. Therefore, we compared the promotion of bone healing between the two teriparatide preparations for AFF.

METHODS

A total of 45 consecutive AFFs in 43 Japanese patients were included in this study. They received either a daily 20-μg teriparatide injection (daily group; n = 32) or a once-a-week 56.5-μg teriparatide injection (weekly group; n = 13). We compared the clinical background and duration of bone union between these two groups.

RESULTS

When all patents were included, the fracture healing time was not significantly different between the two groups. Only patients with complete AFFs had significantly fewer daily bisphosphonate or denosumab injections than the weekly group (P < 0.05). The fracture healing time in the daily group (6.1 ± 4.1 months) was significantly shorter than that in the weekly group (10.1 ± 4.2 months) (P < 0.05). Even if the influence of bisphosphonate or denosumab usage was excluded, a similar significant difference was observed in the fracture healing time (P < 0.05). There was no significant difference between the two groups among patients with incomplete AFFs.

CONCLUSIONS

Daily teriparatide injections enhance bone union more than weekly injections in complete AFF patients.

Anabolic agents: what is beyond osteoporosis?

Osteoporosis is a common skeletal disorder characterized by low bone mass, which leads to reduced bone strength and an increased risk of fractures. Anabolic agents have been shown to improve bone mass and decrease fracture risk in osteoporosis patients by directly stimulating osteoblasts to produce new bone. Currently, two anabolic agents are available in the USA: recombinantly produced teriparatide (TPTD), which is the fully active (1-34) amino active sequence of human parathyroid hormone (PTH), and abaloparatide (APTD), a synthetic analog of parathyroid hormone-related peptide (PTHrP). At present, both agents are approved only for treatment of patients with osteoporosis at high risk of fracture. Nonetheless, their anabolic properties have led to off-label application in additional settings which include spine fusion, osteonecrosis of the jaw, arthroplasty, and fracture healing. In this article, we summarize available scientific literature regarding the efficacy, effectiveness, and safety of TPTD in these off-label settings.

Coupling factors and exosomal packaging microRNAs involved in the regulation of bone remodelling

Bone remodelling is a continuous process by which bone resorption by osteoclasts is followed by bone formation by osteoblasts to maintain skeletal homeostasis. These two forces must be tightly coordinated not only quantitatively, but also in time and space, and its malfunction leads to diseases such as osteoporosis. Recent research focusing on the cross-talk and coupling mechanisms associated with the sequential recruitment of osteoblasts to areas where osteoclasts have removed bone matrix have identified a number of osteogenic factors produced by the osteoclasts themselves. Osteoclast-derived factors and exosomal-containing microRNA (miRNA) can either enhance or inhibit osteoblast differentiation through paracrine and juxtacrine mechanisms, and therefore may have a central coupling role in bone formation. Entwined with angiocrine factors released by vessel-specific endothelial cells and perivascular cells or pericytes, these factors play a critical role in angiogenesis-osteogenesis coupling essential in bone remodelling.

Responses to Treatment With Teriparatide in Patients With Atypical Femur Fractures Previously Treated With Bisphosphonates

If oversuppression of bone turnover explained the association between bisphosphonate use and atypical subtrochanteric femur fractures (AFF), this could be reversed with anabolic treatment such as teriparatide. We conducted a prospective, open-label study in patients previously treated with bisphosphonates who sustained AFF, examining the response to 24-month treatment with teriparatide on bone mineral density (BMD), trabecular bone score (TBS), bone turnover markers (BTM), and fracture healing as well as quantitative histomorphometry. We studied 14 patients. Baseline BMD, BTM, and TBS varied widely. On initial bone biopsies, 12 of 14 patients showed tetracycline labels, but mineralizing surface/bone surface was below published normal values in all but 2. Lumbar spine BMD increased significantly at month 24 (6.1% ± 4.3%, p < 0.05 versus baseline), whereas total hip BMD and TBS did not change significantly. Changes in BTM occurred as reported previously for patients without AFF treated with teriparatide after prior bisphosphonate treatment. At month 24, fractures were healed in 6 patients, showed partial healing in 3, were unchanged in 2, and showed nonunion in 1. In a patient with two fractures, the fracture that occurred before teriparatide treatment was reported as healed, but the fracture that occurred while on treatment showed only partial healing. Bisphosphonate-treated patients who sustain AFF show heterogeneity of bone turnover. Treatment with teriparatide resulted in increases in BTM and lumbar spine BMD, as has been reported for patients without AFF. There was no significant effect of teriparatide on hip BMD, mineralizing surface to bone surface (MS/BS), or TBS and no consistent effect on fracture healing. In the context of a patient who has experienced an AFF after receiving bisphosphonate treatment, therapy with teriparatide for 24 months would be expected to increase BMD and BTM (and probably reduce the risk of fractures resulting from osteoporosis) but should not be relied on to aid in healing of the AFF. © 2017 American Society for Bone and Mineral Research.

Bone Structure and Turnover Status in Postmenopausal Women with Atypical Femur Fracture After Prolonged Bisphosphonate Therapy

Atypical femur fracture (AFF), a serious complication of long-term bisphosphonate therapy, is usually preceded by an incomplete fracture appearing on the lateral femur. AFF is most likely the result of severely suppressed bone turnover (SSBT). However, the differences in bone structure and turnover between patients with incomplete and complete AFF remain unknown. We examined trans-iliac bone biopsies from 12 white postmenopausal women with AFF (incomplete = 5; complete = 7) on BP therapy of >5 years and 43 healthy white premenopausal women. Histomorphometric measurements were performed separately in cancellous, intracortical and endosteal envelopes. Of the 43 histomorphometric measurements on 3 difference bone surfaces (cancellous, intracortical and endosteal), only 2 bone resorption variables (Oc.S/BS and Oc.S/NOS) on the endosteal surface were significantly lower in patients with complete AFF than those with incomplete AFF. Compared to healthy premenopausal women, the trabecular bone volume, thickness and number were all significantly lower in patients with AFF. The dynamic bone formation variables in patients with AFF were significantly reduced on all bone surfaces. The likelihood of a biopsy with no tetracycline labeling was significantly higher in AFF patients than in healthy premenopausal women. Based on these results, we conclude that there are no significant differences in bone turnover between patients with incomplete and complete AFF, suggesting that the suppression of bone turnover had already existed in the femur with incomplete AFF. Compared to healthy premenopausal women, bone turnover is similarly suppressed in patients with either type of AFF.

Bisphosphonates and atypical femoral fractures

PURPOSE OF REVIEW

Bisphosphonates are used widely for the treatment of osteoporosis and prevention of fractures. Although generally well tolerated and effective, bisphosphonates (and denosumab, a newer antiresorptive agent) have been associated with unusual fractures of the femoral shaft.

RECENT FINDINGS

New information about the incidence, pathophysiology, and management of atypical femoral fractures (AFFs) are reviewed. Histomorphometric studies have shown variable amounts of bone turnover suppression, but new studies suggest that healing near bone cracks may not occur in patients with AFF. Some studies suggest that hip and femur geometry make certain people more at risk for AFF. In some but not all studies, the risk of AFF appears to be related to duration of treatment. Thus, the benefit/risk ratio needs to be reassessed as bisphosphonate therapy is prolonged.

SUMMARY

If we can better understand the pathogenesis of AFF, it may be possible to identify those patients at highest risk. In the meantime, clinicians must periodically assess risk for osteoporotic fracture versus risk for AFF in managing patients with osteoporosis.

Atypical Femur Fractures in Patients Treated with Bisphosphonates: Identification, Management, and Prevention

Osteoporosis is a common condition with significant health care costs. First-line therapy is with bisphosphonates, which have proven anti-fracture efficacy. Around 10 years after the introduction of bisphosphonates reports began to be published of atypical femoral fractures (AFFs) that may be associated with this therapy. These fractures are associated with significant morbidity although lower mortality than the more common osteoporotic neck-of-femur fractures. A case definition has been described to allow identification of this class of fracture. Further work has established a high relative risk of AFFs in patients treated with bisphosphonates, but a low absolute risk in comparison to that of osteoporotic fractures. Proposed pathological mechanisms include low bone turnover states leading to stress/insufficiency fractures. Clinicians should be aware of the risk of AFFs and in particular the high rate of prodromal thigh/groin pain that warrants investigation in a patient receiving a bisphosphonate. If an incomplete fracture is diagnosed then bisphosphonate therapy needs to be stopped and prophylactic surgery may be considered. Due to these rare side effects patients on bisphosphonates require regular review, and this is particularly advised after 5 years of oral or 3 years of intravenous therapy.

[Pertrochanteric femoral fractures in the elderly]

Pertrochanteric fractures are one of the most common injuries in the elderly and due to the demographic changes the incidence and importance of this fracture entity will even increase in the future. The dynamic hip screw (DHS) has been used as the gold standard implant in the treatment of pertrochanteric femoral fractures for many years but recent studies have shown that cephalomedullary nails have some advantages. Due to the high incidence, operative treatment of these fractures is part of the standard repertoire of trauma surgeons and this article therefore provides an overview of existing knowledge and new trends in the treatment of pertrochanteric femoral fractures.

Recurrence of bilateral atypical femoral fractures associated with the sequential use of teriparatide and denosumab: a case report

We report that a postmenopausal woman with osteoporosis developed bilateral incomplete atypical femoral fractures (AFFs) after seven years of bisphosphonate therapy. Cessation of the bisphosphonate and treatment with teriparatide was associated with near complete radiological resolution of the AFFs. After 12 months without treatment, denosumab was commenced to prevent structural deterioration. Six months later she developed recurrent bilateral AFFs. This case highlights the management dilemma in patients with ongoing bone loss but prone to stress fractures associated with antiresorptive therapy. Stopping the antiresorptive is recommended but structural decay will recur predisposing to fragility fractures. If the antiresorptive is continued, bone material composition will be further compromised predisposing to atypical fractures. Teriparatide may assist healing of stress fractures and improvement in bone matrix composition. Later antiresosrptive therapy to preserve bone microstructure may compromise material composition.

Effect of Teriparatide on Healing of Atypical Femoral Fractures: A Systemic Review

BACKGROUND

Bisphosphonates (BPs) are the most commonly used anti-osteoporotic drugs, which have been proven to reduce the risk of osteoporotic fractures. However, use of BPs, particularly for long periods of time, is associated with an increased risk of atypical femoral fracture (AFF). Healing of BP-associated AFF is usually delayed because of suppressed bone turnover. Teriparatide (TPTD), a recombinant form of parathyroid hormone (PTH), enhances bone healing in patients with delayed healing or non-union.

METHODS

In this study, we summarized and performed a systemic review of the published literature on treatment of AFF using TPTD.

RESULTS

Although there is a lack of level 1 studies on the evidence of TPTD in promoting bone union in AFFs, this systemic review of the available literature revealed that TPTD works positively in AFFs, and we put together the evidence that TPTD is a viable treatment option for enhancing fracture healing in AFFs.

CONCLUSIONS

While anecdotal evidence of beneficial effects of TPTD on fracture healing offer limited guidance for clinical decision making, a better understanding of the role of TPTD in fracture healing may be elucidated with future prospective trials.

Co-administration of aspirin and allogeneic adipose-derived stromal cells attenuates bone loss in ovariectomized rats through the anti-inflammatory and chemotactic abilities of aspirin

Introduction

Osteoporosis is a syndrome of excessive skeletal fragility characterized by the loss of mass and deterioration of microarchitecture in bone. Single use of aspirin or adipose-derived stromal cells (ASCs) has been recognized recently to be effective against osteoporosis. The goal of the study was to evaluate the osteogenic effects of the co-administration of aspirin and allogeneic rat adipose-derived stromal cells (rASCs) on ovariectomized (OVX)-induced bone loss in rats. The underlying mechanisms were investigated in vitro and in vivo.

Methods

Firstly, allogeneic rASCs were isolated and cultured, and the conditioned medium (CM) from the maintenance of rASCs was collected. Secondly, the OVX rats were administrated CM, rASCs, aspirin (ASP) or rASCs + ASP, respectively. Twelve weeks later, the anti-inflammatory and osteogenic effects were assessed by micro-CT, undecalcified histological sections, dynamic histomorphometric analyses and serologic assays for biochemical markers. Finally, a Transwell migration assay in vitro and cell-trafficking analyses in vivo were used to explore the effects of aspirin on rASC migration.

Results

Systemic administration of aspirin and rASCs attenuated OVX-induced bone loss better than single use of aspirin or ASCs (p < 0.05, respectively). Next, we analyzed the underlying mechanisms of the anti-inflammatory and chemotactic abilities of aspirin. Aspirin suppressed serum levels of the pro-inflammatory cytokines on tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), and the anti-inflammatory ability was positively associated with bone morphometry. Also, aspirin exhibited excellent chemotactic effects in vitro and accelerated the homing of allogeneic rASCs into bone marrow during early in vivo stages.

Conclusions

Co-administered aspirin and allogeneic ASCs can partially reverse OVX-induced bone loss in rats. This effect appears to be mediated by the anti-inflammatory and chemotactic abilities of aspirin.

Chronic kidney disease and the skeleton

Fractures across the stages of chronic kidney disease (CKD) could be due to osteoporosis, some form of renal osteodystrophy defined by specific quantitative histomorphometry or chronic kidney disease-mineral and bone disorder (CKD-MBD). CKD-MBD is a systemic disease that links disorders of mineral and bone metabolism due to CKD to either one or all of the following: abnormalities of calcium, phosphorus, parathyroid hormone or vitamin D metabolism; abnormalities in bone turnover, mineralization, volume, linear growth or strength; or vascular or other soft-tissue calcification. Osteoporosis, as defined by the National Institutes of Health, may coexist with renal osteodystrophy or CKD-MBD. Differentiation among these disorders is required to manage correctly the correct disorder to reduce the risk of fractures. While the World Health Organization (WHO) bone mineral density (BMD) criteria for osteoporosis can be used in patients with stages 1-3 CKD, the disorders of bone turnover become so aberrant by stages 4 and 5 CKD that neither the WHO criteria nor the occurrence of a fragility fracture can be used for the diagnosis of osteoporosis. The diagnosis of osteoporosis in stages 4 and 5 CKD is one of the exclusion-excluding either renal osteodystrophy or CKD-MBD as the cause of low BMD or fragility fractures. Differentiations among the disorders of renal osteodystrophy, CKD-MBD or osteoporosis are dependent on the measurement of specific biochemical markers, including serum parathyroid hormone (PTH) and/or quantitative bone histomorphometry. Management of fractures in stages 1-3 CKD does not differ in persons with or without CKD with osteoporosis assuming that there is no evidence for CKD-MBD, clinically suspected by elevated PTH, hyperphosphatemia or fibroblast growth factor 23 due to CKD. Treatment of fractures in persons with osteoporosis and stages 4 and 5 CKD is not evidence-based, with the exception of post-hoc analysis suggesting efficacy and safety of specific osteoporosis therapies (alendronate, risedronate and denosumab) in stage 4 CKD. This review also discusses how to diagnose and manage fragility fractures across the five stages of CKD.