Potential bone fragility of mid-shaft atypical femoral fracture: Biomechanical analysis by a CT-based nonlinear finite element method

Tano, Atsuhiro; Oh, Yoto; Fukushima, Kazuyuki; Kurosa, Yoshiro; Wakabayashi, Y.; Fujita, Koji; Yoshii, Toshitaka; Okawa, Atsushi

doi:10.1016/j.injury.2019.09.004

Cited by 24 publications

(18 citation statements)

References 30 publications

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“…The distal condyle was constrained, and a load equal to the patient's weight was applied to the center of the femoral head. According to the method of Oh et al, we analyzed the distribution of tensile stresses, and maximum and mean values of maximum principal stress (MPS) by data extraction from a 70 mm section in the middle of the femoral diaphysis ( Oh et al, 2014 ; Oh et al, 2017 ; Tano et al, 2019 ), we analyzed the distribution of tensile stresses for the medial and lateral cortex of the femur, and compared this to bone histomorphometric findings.…”

Section: Methodsmentioning

confidence: 99%

Disturbance of osteonal bone remodeling and high tensile stresses on the lateral cortex in atypical femoral fracture after long-term treatment with Risedronate and Alfacalcidol for osteoporosis

et al. 2021

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An 83 year-old Japanese woman complained of left lateral thigh pain following a low-energy fall 4 months prior to admission. She had been treated for osteoporosis with Risedronate and Alfacalcidol for the previous five years. She was diagnosed with an atypical femoral fracture (AFF) according to the American Society for Bone and Mineral Research (ASBMR) Task Force revised criteria. Radiographs revealed cortical thickening and a transverse radiolucent fracture line in the lateral cortex of the shaft. MRI showed a high intensity signal on the T2WI image 1 cm long in the lateral cortex. The patient had normal levels of bone resorption and formation biomarkers except for low 25(OH) Vitamin D. Double fluorescent labeling was done preoperatively. Due to significant bowing, a corrective osteotomy and intramedullary nailing were performed, and the resected bone wedge was analyzed by bone histomorphometry. Three ground sections of the lateral cortex at the fracture site showed many and large pores, with or without tetracycline labeling. Histomorphometric assessment was done on intracortical pores, classified by a novel criteria, only to assess size of the pores to know prolonged osteoclastic activity and its characteristics of inner surfaces to assess whether bone formation has been occurring or not in labeling period in remodeling cycle, and coalition of multi-pores. Increased size with widespread variation of pores suggested prolonged osteoclastic activity in the reversal/resorptive phase. Bone labeling showed lamellar bone on the endocortical surface. We hypothesize that the case had developed from a regional disturbance of osteonal remodeling in the lateral cortex, in which accumulated microcracks might have initiated a resorption process resulting in resorption cavities, i.e., pores, which became larger due to prolonged activity of secondary osteoclasts. Various sized pores could form lamellar bone, still forming at the time of biopsy, some had formed lamellar bone, but stopped to form before labeling and not to start to form at all, probably due to incomplete coupling. Endocortical lamellar bone might had started to resorbed to smooth off endocortical surface, followed by formation of lamellar bone. The endocortical bone formation was assessed and its formation period is about 2.7 years. A finite element analysis using preoperative CT data revealed high tensile stresses on the lateral aspect of the femur. Histomorphometric results suggest that there might be more pores in the tensile area than the compressive area. These findings may subsequently connect accumulation of microcracks, an increase of size and number of pores and coalition and subsequent fracture in the lateral cortex.

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Section: Methodsmentioning

confidence: 99%

Disturbance of osteonal bone remodeling and high tensile stresses on the lateral cortex in atypical femoral fracture after long-term treatment with Risedronate and Alfacalcidol for osteoporosis

et al. 2021

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“…4 – 6 , 12 , 23 – 27 Other factors potentially involved in the pathogenesis of AFF include ethnicity, 4 body mass index, 20 loading stress in daily life, 7 – 10 femoral morphology, 6 – 8 , 11 , 12 , 14 , 28 , 29 and bone density, quality, and strength. 12 – 14 Mild mechanical stress during daily activities is undoubtedly involved in the onset of AFF. 4 , 6 – 10 Mechanical studies using finite-element methods by our research group and Haider et al have demonstrated that the distribution of tensile stress in the femoral shaft as a result of everyday loading stress is affected by femoral morphology (e.g.…”

Section: Atypical Fracturesmentioning

confidence: 99%

“…This type of fracture was recently defined as an SBF. 7 , 8 , 11 – 13 Figure 3 shows a representative X-ray image of SBF in a 73-year-old woman with no history of exposure to specific drugs (e.g. bisphosphonates, denosumab, glucocorticoids, or proton pump inhibitors).…”

Section: Classification Of Aff Subtypesmentioning

confidence: 99%

“…osteomalacia, rickets, and hypophosphatasia) would essentially be classified as insufficiency fractures, which generally have sufficient biological activity for fracture healing despite fulfilling the current diagnostic criteria for AFF. 6 , 13 Figure 4 shows representative imaging findings for a 70-year-old woman with an incomplete subtrochanteric AFF who had vitamin D deficiency osteomalacia but adequate biological activity for bone healing. However, there is no bone fragility and no biological activity in cases of “typical” AFF, which frequently develops in the subtrochanteric region.…”

Section: New Classification Of Stress Fracturesmentioning

confidence: 99%

“… 11 , 12 Although the pathology of SBF fits with the concept of an insufficiency fracture, bone in patients with AFF is not necessarily fragile or weak. 12 – 14 In this article, we propose addition of a fourth category in the classification of stress fractures to cover this particular type of fracture.…”

Section: Introductionmentioning

confidence: 99%

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Current concept of stress fractures with an additional category of atypical fractures: a perspective review with representative images

Yamamoto

Yoshii

et al. 2021

Therapeutic Advances in Endocrinology

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Stress fractures have traditionally been classified into three categories: fatigue fractures due to overuse of bone with normal elastic resistance; insufficiency fractures due to everyday physiological stress on fragile bone with poor elastic resistance; and pathologic fractures due to bone weakness involving tumors. The concept of atypical fractures has emerged and is considered a type of stress fracture. However, there has been some inconsistency in interpretation when using the traditional classification of stress fractures, and atypical femoral fractures (AFFs) can potentially be classified into subtypes: “typical” AFFs involving bone turnover suppression due to specific drugs (e.g. bisphosphonates) and fragility fractures of the bowed femoral shaft. In this article, the classification of stress fractures is redefined with the addition of atypical fractures as a fourth category, in which biological activity for fracture healing is absent, to promote consistent understanding and interpretation of clinical conditions involving stress fractures.

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Towards understanding how bisphosphonate‐dependent alterations to nutrient canal integrity can contribute to risk for atypical femoral fractures: Biomechanical considerations and potential relationship to a real‐world analogy

Hart

2023

BioEssays

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Bisphosphonates are a class of drugs which have shown good efficacy in the treatment of post‐menopausal osteoporosis, as well as a good safety profile. However, side‐effects such as risk for atypical femoral fractures (AFF) have appeared, leading to a decline in use of the drugs by many patients who would benefit from the treatment. While patient characteristics have contributed to improved understanding of risk factors, the mechanisms involved that explain AFF risk have not appeared. Recently, the possibility that the mechanism(s) involved drug‐induced modification of cells of the nutrient canals of the femur and subsequent compromise in the bone matrix has been published. The present Hypothesis article builds on the concept presented earlier and expands into biomechanical considerations. An analogy of the mechanisms involved to a real‐life scenario is also presented. While this analogy has limitations, consideration of the biomechanical implications of progressive alterations to defects presented by compromised nutrient canal‐bone matrix also presents potential relationships with AFF risk.

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Potential bone fragility of mid-shaft atypical femoral fracture: Biomechanical analysis by a CT-based nonlinear finite element method

Cited by 24 publications

References 30 publications

Disturbance of osteonal bone remodeling and high tensile stresses on the lateral cortex in atypical femoral fracture after long-term treatment with Risedronate and Alfacalcidol for osteoporosis

Disturbance of osteonal bone remodeling and high tensile stresses on the lateral cortex in atypical femoral fracture after long-term treatment with Risedronate and Alfacalcidol for osteoporosis

Current concept of stress fractures with an additional category of atypical fractures: a perspective review with representative images

Towards understanding how bisphosphonate‐dependent alterations to nutrient canal integrity can contribute to risk for atypical femoral fractures: Biomechanical considerations and potential relationship to a real‐world analogy

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