Epidemiology, radiology and histology of atypical femoral fractures

Atypical Subtrochanteric Femur Fracture and Hip Osteoarthritis Treated with a Revision Monoblock Stem and Strut Allograft: A Case Report

CASE

A 73-year-old woman was diagnosed with a nondisplaced incomplete atypical bisphosphonate-related subtrochanteric femur fracture and ipsilateral hip osteoarthritis. She was treated with a total hip arthroplasty using a monoblock revision stem and a strut allograft to provide adjunctive mechanical and biological support. At the final follow-up, the patient had no pain, the stem was well fixed, and the allograft strut had incorporated; however, a persistent fracture line was noted.

CONCLUSION

When an atypical femur fracture coexists with hip osteoarthritis, total hip arthroplasty may be a reasonable treatment option to address the fracture and concomitant hip osteoarthritis with a single surgical intervention. However, consideration should be given to using a stem with distal fixation and augmenting the construct with a strut allograft.

Antiresorptive-associated spontaneous fractures of both tibiae, followed by an atypical femur fracture during the sequential treatment with alendronate, denosumab then teriparatide

A 35-year-old man with juvenile idiopathic arthritis since childhood presented with bilateral atypical tibial fractures, followed by a later, single atypical fracture of the femur. The fractures were associated with 6 years of oral alendronate treatment immediately followed by subcutaneous denosumab therapy and later teriparatide therapy for osteoporosis. Atypical fractures are known to occur in the femur following bisphosphonate therapy; however, there are only a few documented cases of atypical fractures in the tibia. Our case highlights a rare but serious complication of a commonly prescribed antiresorptive agent. It also shows that teriparatide, while helpful in increasing bone mass, does not fully prevent the development of atypical fractures. Careful investigation should be considered in patients on long-term antiresorptive therapy presenting with bony tenderness to exclude an atypical fracture.

Atypical diaphyseal femoral fractures: Considerations on surgical technique

In the last two decades bisphosphonates (BP) has become the mainstream therapy for osteoporosis and the benefit in reducing the incidence of fractures has been well demonstrated in several studies, together with the drug long term (5-10 years) efficacy and safety. A complication of the long-term use of bisphosphonates is a low-energy stress fractures located in the sub-trochanteric region and the femoral shaft called atypical femur fracture (AFF). These stress fractures can be seen on plain radiographs as simple transverse patterns, with unicortical beaking and hypertrophy of the diaphyseal lateral cortex. Usually a localized thigh pain in the prodromal phase may precede the fracture by months. The current surgical treatment of choice for AFFs is intramedullary nailing (IMN). However, the treatment of AFFs is associated with a higher rate of intra-operative and post-surgical complications. This is related to anatomical e biomechanical reasons. Iatrogenic fractures, deformities, medial gap opening, eccentric position of the distal nail tip with anterior cortex perforation, delayed or non-union are frequent complications of this procedure and healing rate of AFFs. The average healing time of almost 8 months for AFFs appeared to be longer than that for typical femoral fractures, which heal at an average of 3-6 months. The purpose of this study is to analyze the different surgical devices and techniques and to advance some considerations that can be useful to diminish the rate of failure and/or complications in the treatment of AFFs in both oncologic and osteoporotic patients.

Chronic anterior tibial stress fractures in athletes: No crack but intense remodeling

PURPOSE

Delayed healing of anterior tibial stress fractures in athletes is related to high tensional forces acting across a putative fracture gap. These forces lead to crack propagation and create strains that exceed tissue differentiation thresholds for new bone to form in the gap. The "dreaded black line" is a radiographic hallmark sign of stress fractures considered to represent a transverse fracture gap. However, whether a fracture gap truly exists at the microscopic level remains unclear. The aim of this study was to describe the area of the "dreaded black line" microscopically and to identify signs of delayed healing.

METHODS

Between 2011 and 2016, we included seven athletes with chronic anterior mid-shaft tibial stress fractures. The fracture site was excised as a cylindrical biopsy. The biopsy was evaluated with micro-CT and histology. The formation of new bone in the defect was evaluated radiographically.

RESULTS

The "dreaded black line" seen on pre-operative radiographs in all patients could not be seen on the microscopic level. Instead, the area of the putative crack showed widened resorption cavities, lined with active osteoblasts, and surrounded by immature bone. This area of intense remodeling seemed to create a false impression of a fracture line on radiographs. Complete cortical continuity was restored at the biopsy site at median 8 months (range 6-13 months).

CONCLUSION

Tibial stress fractures in athletes normally show no fracture defect, but a region of increased remodeling. The healing process is already ongoing but seems mechanically insufficient.

Selected life quality variables of women treated surgically due to intertrochanteric femur fractures in the aspect of nursing and rehabilitation standards

Introduction: The aim of presented study was to evaluate selected quality of life indicators for women treated surgically due to intertrochanteric femur fractures in terms of implementation of physiotherapeutic and nursing standards. Clinical Hospital in Krakow (5WSK) within the period from January 2015 to December 2016. At that time, 145 women with intertrochanteric femur fracture were admitted to the hospital. The age of the patients ranged between 58 and 92 years, with an average of 83.6 years. The following questionnaires and score scales were used to assess the quality of life: Short Pfeiffer Mental Status Questionnaire (SPMSQ), Instrumental Activities of Daily Living (IADL) scale, SF-36 Quality of Life Questionnaire, Barthel scale, HOOS scale, Geriatric Depression Scale (GDS) by Yesavage, the author’s questionnaire on rehabilitation care problems related to urinary tract infections, bed sores, pneumonia, gastrointestinal disorders, gastrointestinal infections and thromboembolic complications as well as survival rate. Results and conclusions: 1. The quality of life of women operated because of intertrochanteric femoral fractures using an intramedullary Gamma nail had deteriorated in both short and long-term observation. 2. Maintenance and individualization of nursing standards and rehabilitation in women treated surgically due to intertrochanteric femoral fractures had a positive effect on the overall process of their treatment. 3.The level of physical activity declared by women operated due to intertrochanteric femur fracture prior to the occurrence of these fractures, has a signifi cant effect on their functional results in short and long-term observation. The higher the level of physical activity of these patients before the fracture, the more favourable was the functional outcome. 4. The level of mood and self-acceptance of the disease in women treated surgically for this fracture had signifi cant impact on the process of their nursing as well as rehabilitation, and on functional status in short and long-term follow-up. The higher the level of mood and self-acceptance of the disease in these women, the better the process of their nursing, rehabilitation and the functional outcome.

Histological study of atraumatic periprosthetic fractures: does atypical periprosthetic fracture exist?

Purpose

Is it possible a correlation between some periprosthetic femoral fractures and atypical fractures?

Case

We present a case of a 77-year-old woman with atypical periprosthetic femoral fracture. The patient had a history of long-term bisphosphonate use. We performed an open reduction, a synthesis of the fracture and a histological exam. The patient stopped the bisphosphonate (BF) therapy. Three months later, before starting the teriparatide treatment, the patient had a re-fracture so we did a second osteosynthesis and began a teriparatide therapy. After six months, the radiography showed a bone healing at the fracture site.

Result

The histological examination confirmed the diagnosis of atypical femoral fracture.

Conclusion

At first, the fracture showed a delayed union which led to a new surgery, as often happens in BF-related atypical fractures. Appropriate treatment (BF suspension and teriparatide beginning) permitted fracture healing. The atypical characteristic of the fracture was confirmed by histological exam.Some periprosthetic femoral fractures in patients treated with BF, especially in long time therapies, should be suspected as atypical fractures and a specific medical treatment should be performed, as well as a correct surgical treatment.

T-Score Discordance of Bone Mineral Density in Patients with Atypical Femoral Fracture

BACKGROUND

Although atypical femoral fracture (AFF) occurs more frequently in patients taking bisphosphonates and longer treatment is associated with higher risk, the causal relationship between AFF and bisphosphonates has not been established. Most patients with AFF have osteoporosis that is being treated with bisphosphonates, but we are not aware of any reports regarding the areal bone mineral density (aBMD) and discordance between the T-scores of the femur and spine in such patients. We investigated the prevalence of aBMD discordance and the characteristics of patients with AFF.

METHODS

Medical records for 63 consecutive patients treated for AFF were retrospectively evaluated, and 48 patients, all female, were eligible for the study. The average age at the time of fracture was 73.0 years, the average duration of bisphosphonate use was 68.5 months, and the average presumed age at bisphosphonate initiation was 67.2 years. We evaluated the prevalence of discordance, defined as a difference between the T-score categories of the femur and spine in the same individual as well as demographic differences between the discordance and concordance groups. We also compared the prevalence of discordance in patients with AFF with that in 114 female patients with intertrochanteric femoral fracture (ITFF).

RESULTS

T-score concordance, minor discordance, and major discordance were seen in 14 (29%), 32 (67%), and 2 (4%) of the patients with AFF, respectively. The prevalence of discordance was significantly higher in those with AFF (71%) than in those with ITFF (23%) (p < 0.001). The average age at bisphosphonate initiation in the AFF group was lower in the discordance group (65.7 years) than in the concordance group (70.7 years) (p = 0.04).

CONCLUSIONS

The prevalence of T-score discordance between the hip and lumbar spine was relatively high in patients with AFF, and the presumed age at the initiation of bisphosphonate therapy was younger in patients with discordant T-scores in this study.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Surgical outcome of intramedullary nailing in patients with complete atypical femoral fracture: A multicenter retrospective study

BACKGROUND

Management of atypical femoral fracture on bisphosphonate therapy still remains controversy and is reported high rate of complications. The aim of this study was to evaluate the outcome of intramedullary nailing in patients with atypical femoral fracture who took bisphosphonate more than one year through the multicenter retrospective study.

METHODS

We gathered 75 atypical femoral fractures from seven institutions between 2009 and 2014. Among them 46 atypical femoral fractures which met the inclusion criteria was evaluated in this study. The average age was 70.1 years (53-80) and the average duration of bisphosphonate use was 5.1 years (1-15 years). Medical records and radiographs were reviewed to determine time to union, union rate, need for revision surgery, restoration of ambulatory function, and complications.

RESULTS

Twenty-nine (63%) fractures healed within 6 months without complications. The average time to union except two non-union was 24.9 weeks (11-48 weeks). Two patients (4.3%) underwent revision surgery for non-union and there was no implant failure. Thirty-seven (80.4%) patients achieved their pre-fracture ambulatory function at the final follow up.

CONCLUSIONS

Although the incidence of delayed bone healing is high in atypical femoral fracture on bisphosphonate therapy even treated with intramedullary nailing, the incidence of revision surgery and implant failure was relatively lower than those of extramedullary devices.

Strains caused by daily loading might be responsible for delayed healing of an incomplete atypical femoral fracture

Atypical femoral fractures are insufficiency fractures in the lateral femoral diaphysis or subtrochanteric region that mainly affect older patients on bisphosphonate therapy. Delayed healing is often seen in patients with incomplete fractures (cracks), and histology of bone biopsies shows mainly necrotic material inside the crack. We hypothesized that the magnitude of the strains produced in the soft tissue inside the crack during normal walk exceeds the limit for new bone formation, and thereby inhibit healing. A patient specific finite element model was developed, based on clinical CT images and high resolution μCT images of a biopsy from the crack site. Strain distributions in the femur and inside the crack were calculated for load cases representing normal walk. The models predicted large strains inside the crack, with strain levels above 10% in more than three quarters of the crack volume. According to two different tissue differentiation theories, bone would only form in less than 1-5% of the crack volume. This can explain the impaired healing generally seen in incomplete atypical fractures. Furthermore, the microgeometry of the crack highly influenced the strain distributions. Hence, a realistic microgeometry needs to be considered when modeling the crack. Histology of the biopsy showed signs of remodeling in the bone tissue adjacent to the fracture line, while the crack itself contained mainly necrotic material and signs of healing only in portions that seemed to have been widened by resorption. In conclusion, the poor healing capacity of incomplete atypical femoral fractures can be explained by biomechanical factors, and daily low impact activities are enough to cause strain magnitudes that prohibit bone formation.

Healing Time and Complications in Operatively Treated Atypical Femur Fractures Associated With Bisphosphonate Use: A Multicenter Retrospective Cohort

OBJECTIVES

The purpose of this study was to characterize demographics, healing time, and complications of a large series of operatively treated atypical femur fractures.

DESIGN

Retrospective multicenter review.

SETTING

Seventeen academic medical centers.

PATIENTS

Bisphosphonate-related fractures as defined by American Society of Bone and Mineral Research. Fractures had to be followed for at least 6 months or to union or revision.

INTERVENTION

Operative treatment of bisphosphonate-related fracture.

MAIN OUTCOME MEASUREMENTS

Union time and complications of treatment, as well as information about the contralateral limb.

RESULTS

There were 179 patients, average age 72, average body mass index 27.2. Average follow-up was 17 months. Twenty-one percent had a previous history of fragility fracture; 34% had prodromal pain. Most (88%) lived independently before injury. Thirty-one percent had radiographic changes suggesting stress reaction. Surgical fixation was with cephalomedullary nail (51%), IM nail (48%), or plate (1%). Complications included death (4), PE (3), and wound infection (6). Twenty (12%) patients underwent revision at an average of 11 months. Excluding revisions, average union time was 5.2 months. For revisions, union occurred at an average of 10.2 months after intervention. No association was identified between discontinuation of bisphosphonates and union time (P = 0.5) or need for revision (P = 0.7). Twenty-one percent sustained contralateral femur fractures; 32% of these had pain and 59% had stress reaction before contralateral fracture.

CONCLUSIONS

In this series, surgery had a 12% failure rate and delayed average time to union. Twenty-one percent developed contralateral femur fractures within 2 years, underscoring the need to evaluate the contralateral extremity.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Atypical fractures, a biased perspective

When stress fractures started to show up in the femurs of elderly ladies, it was soon evident that bisphosphonate use lay behind, and the absolute risk increase due to bisphosphonate use was reasonably well estimated already in 2008. Thereafter followed a period of confusion: the term atypical fracture was introduced, with a definition so vague that the true stress fractures tended to disappear in a cloud of ambiguity. This cast doubt on the association with bisphosphonates. The association was then re-established by large epidemiological studies based on radiographic adjudication. Atypical fractures are largely caused by bisphosphonates. With a correct indication, bisphosphonates prevent many more fractures than they cause, at least during the first years of use. With an incorrect indication they are likely to cause more harm than good.

High revision rate but good healing capacity of atypical femoral fractures. A comparison with common shaft fractures

INTRODUCTION

Healing of complete, atypical femoral fractures is thought to be impaired, but the evidence is weak and appears to be based on the delayed healing observed in patients with incomplete atypical fractures. Time until fracture healing is difficult to assess, therefore we compared the reoperation rates between women with complete atypical femoral fractures and common femoral shaft fractures.

METHODS

We searched the orthopaedic surgical registry in Östergötland County for patients with subtrochanteric and femoral shaft fractures (ICD-10 diagnosis codes S72.2, S72.3 and M84.3F) between January 1st 2007 and December 31st 2013. Out of 895 patients with surgically treated femoral shaft fractures, 511 were women 50 years of age or older. Among these we identified 24 women with atypical femoral shaft fractures, and 71 with common shaft fractures.

RESULTS

Reoperations were performed in 6 and 5 patients, respectively, odds ratio 4.4 (95% CI 1.2 to 16.1). However, 5 reoperations in the atypical fracture group could not be ascribed to poor healing. In 3 patients the reoperation was due to a new fracture proximal to a standard intramedullary nail. In 2 patients the distal locking screws were removed due to callus formation that was deemed incomplete 5 months post-operatively. The one patient with poor healing showed faint callus formation at 5 months when the fracture was dynamised and callus remained sparse at 11 months. Among patients with common shaft fractures, 2 reoperations were performed to remove loose screws, 2 because of peri-implant fractures and 1 reoperation due to infection.

DISCUSSION

Reoperation rates in patients with complete atypical femoral fractures are higher than in patients with common shaft fractures. The main reason for failure was peri-implant fragility fractures which might be prevented with the use of cephalomedullary nails at the index surgery. Fracture healing however, seems generally good. A watchful waiting approach is advocated in patients with fractures that appear to heal slowly.

Atypical femoral fracture due to chronic use of bisphosphonates: case report

The causal relationship between chronic use of bisphosphonates and occurrences of atypical femoral fractures has not yet been established. Nonetheless, it is known that their chronic use is more related to fractures with a pattern differing from that of classical osteoporotic fractures. Atypical fractures are still rare events and the benefit from using bisphosphonates remains greater for prevention and treatment of osteoporosis. There are few studies guiding the diagnosis and management of these fractures, thus making it difficult to achieve better results. In this report, we present the case of an elderly patient with an atypical femoral fracture that was managed in accordance with guidance from the American Society for Bone and Mineral Research.

Risk of atypical femoral fracture during and after bisphosphonate use

BACKGROUND AND PURPOSE

Use of bisphosphonates in women is associated with higher risk of atypical femoral fractures. The risk in terms of timing of use and type of bisphosphonate, and in men, remains unclear.

PATIENTS AND METHODS

We reviewed radiographs of 5,342 Swedish women and men aged 55 years or more who had had a fracture of the femoral shaft in the 3-year period 2008-2010 (97% of those eligible), and found 172 patients with atypical fractures (93% of them women). We obtained data on medication and comorbidity. The risk of atypical fracture associated with bisphosphonate use was estimated in a nationwide cohort analysis. In addition, we performed a case-control analysis with comparison to 952 patients with ordinary shaft fractures. A short report of the findings has recently been presented (Schilcher et al. 2014a). Here we provide full details.

RESULTS

The age-adjusted relative risk (RR) of atypical fracture associated with bisphosphonate use was 55 (95% CI: 39-79) in women and 54 (CI: 15-192) in men. In bisphosphonate users, women had a 3-fold higher risk than men (RR = 3.1, CI: 1.1-8.4). Alendronate users had higher risk than risedronate users (RR = 1.9, CI: 1.1-3.3). The RR after 4 years or more of use reached 126 (CI: 55-288), with a corresponding absolute risk of 11 (CI: 7-14) fractures per 10,000 person-years of use. The risk decreased by 70% per year since last use.

INTERPRETATION

Women have a higher risk of atypical femoral fracture than men. The type of bisphosphonate used may affect risk estimates and the risk decreases rapidly after cessation.

Atypical femoral fractures, bisphosphonates, and mechanical stress

Atypical fractures are stress fractures occurring in the femoral shaft and closely related to bisphosphonate use. We here discuss their radiographic definition and different putative etiologies, apart from mechanical stress. Long time reduction of skeletal remodeling because of bisphosphonate use is thought to allow time for the bone to deteriorate mechanically, resulting in reduced toughness. However, the risk of atypical fracture diminishes rapidly after cessation of treatment, which suggests more acute effects of bisphosphonate use. Microdamage normally accumulates at areas of high stress. Possibly, ongoing bisphosphonate use reduces the ability to resorb and replace areas of microdamage by targeted remodeling. This could lead to crack propagation beyond a point of no return, ending in macroscopic stress fracture.