Regional differences in cortical porosity in the fractured femoral neck

Bell, Karen L.; Loveridge, N.; Power, Jonathan; Garrahan, NJ; Meggitt, B. F.; Reeve, J.

doi:10.1016/s8756-3282(98)00143-4

Cited by 239 publications

(195 citation statements)

References 38 publications

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“…that most humerus fractures sustained above the age of 50 years were associated with minimal trauma (60.2%), with the incidence being higher in women than in men, and localization at the proximal humerus accounting for some 85% of the fractures. We observed a significant and negative relationship between the Ct.Th of the humerus and age, consistent with age-induced bone loss, (27)(28)(29)(30) indicating that our population was representative of elderly patients with humeral fractures. Shaft fractures accounted for 10% of low-energy humeral fractures, and occurred more frequently in women than in men.…”

Section: Discussionsupporting

confidence: 65%

Low-energy fractures of the humeral shaft and bisphosphonate use

Yavropoulou

Giusti

Ramautar

et al. 2012

Journal of Bone and Mineral Research

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Atypical fractures of the femur have been reported to occur in patients on long-term treatment with bisphosphonates; however, causality has not been proven, and it is not known whether similar fractures may occur in other long bones. We addressed this issue by examining the relationship between humeral shaft fractures and bisphosphonate use. We identified all patients aged !50 years consecutively admitted to a single center with a new fracture of the humerus. All individual radiographs were examined and fracture site was classified. A case-control study was undertaken in patients with humeral shaft fractures, and controls were sex-and age-matched patients with proximal humeral fractures in a 1:4 ratio. Patients with shaft fractures and radiographic characteristics similar to those of atypical femoral fractures were compared with those with ordinary shaft fractures. The association between ''atypical'' fractures and bisphosphonate or glucocorticoid use was examined. A total of 198 patients had a low-energy fracture of the humerus; 20 of these patients had a shaft fracture (10%). These 20 patients (cases) were matched with 80 patients with proximal fractures (controls). Bisphosphonates were used by 5% of cases and by 6.3% of controls (odds ratio [OR], 0.80; 95% confidence interval [CI], 0.09-6.85); glucocorticoids were used by 10% of cases and 8.8% of controls (OR, 1.15; 95% CI, 0.23-5.83). There was no difference in cortical thickness between cases and controls and bisphosphonate or glucocorticoid users and nonusers. Four of the 20 patients with shaft fractures had ''atypical'' radiographic features, with significantly increased cortical thickness, but none of these had ever been treated with bisphosphonates or glucocorticoids. Our results show that low-energy fractures of the humeral shaft with ''atypical'' radiographic characteristics are infrequent and are not associated with the use of bisphosphonates or glucocorticoids. ß

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Section: Discussionsupporting

confidence: 65%

Low-energy fractures of the humeral shaft and bisphosphonate use

Yavropoulou

Giusti

Ramautar

et al. 2012

Journal of Bone and Mineral Research

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“…We have previously demonstrated the importance of giant canals (diameter Ͼ385 m) in the porosity of the femoral neck cortex of female fracture cases (Bell et al, 1999b) and have shown a positive association between the presence of giant canals and remodeling clusters in an aged population . The osteonal popu- lation was not uniform but had a population of systems that we termed composite osteons, 90% of which had canal diameters greater than 172 m .…”

Section: Discussionmentioning

confidence: 92%

Super‐osteons (remodeling clusters) in the cortex of the femoral shaft: Influence of age and gender

et al. 2001

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Previous studies of cortical remodeling in the fractured femoral neck indicated that the merging of spatially clustered remodeling osteons could result in the formation of deleteriously large cavities associated with femoral neck fracture. This study aimed to identify whether remodeling osteons in the femoral shaft were also clustered and to assess the influence of age and gender. Microradiographic images of femoral mid-shaft cross-sections from 66 subjects over 21 years of age were analyzed to determine the number, size and location of all Haversian canals. Those most recently remodeled were identified using an edge-detection algorithm highlighting the most marked differential gradients in grey levels. Cluster analysis (JMP software) of these osteons identified the proportion of recently remodeled osteons that were within 0.75mm clusters. As in the femoral neck, remodeling osteons were significantly more clustered than could occur by chance (real, 59.4%; random, 39.4%; P Ͻ 0.0001). The density of these clusters (number/mm 2 ) was not significantly associated with subject age or gender but was greatest near the periosteum and decreased toward the marrow cavity (periosteal 0.043 Ϯ 0.004; mid-cortex 0.028 Ϯ 0.003; endosteal 0.017 Ϯ 0.002). Cortical porosity increased with age. The presence of giant canals (diameter Ͼ385 m) was inversely related to the presence of clusters (R 2 ϭ 0.237, P Ͻ 0.0001). This data suggest that remodeling osteons tend to be spatially colocalized in the shaft as they are in the neck of the femur and their presence is independent of age or gender. We propose that these remodeling clusters be termed super-osteons. The negative relationship between super-osteons and giant canals raises the intriguing possibility that loss of the control of remodeling depth results in the merging of osteonal systems to form deleteriously large cortical cavities with a marked reduction in bone strength. Anat Rec 264: 378 -386, 2001.

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“…We hypothesized that reduced and/or delayed expression of sclerostin may be associated with the increased bone formation seen in hOA. In FNF, we tested the hypothesis that the adverse (negative) remodeling balance (34) leading to increased porosity (35) may be attributable to increased or premature sclerostin expression by young osteocytes. We hypothesized that local sclerostin production by osteocytes would be an independent determinant of whether the canal was actively forming bone, as evidenced by alkaline phosphatase activity.…”

Section: Introductionmentioning

confidence: 99%

Sclerostin and the regulation of bone formation: Effects in hip osteoarthritis and femoral neck fracture

Power

Poole

Bezooijen

et al. 2010

Journal of Bone and Mineral Research

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Remodeling imbalance in the elderly femoral neck can result in thin cortices and porosity predisposing to hip fracture. Hip osteoarthritis protects against intracapsular hip fracture. By secreting sclerostin, osteocytes may inhibit Wnt signaling and reduce bone formation by osteoblasts. We hypothesised that differences in osteocytic sclerostin expression might account for differences in osteonal boneformation activity between controls and subjects with hip fracture or hip osteoarthritis. Using specific antibody staining, we determined the osteocytic expression of sclerostin within osteons of the femoral neck cortex in bone removed from subjects undergoing surgery for hip osteoarthritis (hOA: 5 males, 5 females, 49 to 92 years of age) or hip fracture fixation (FNF: 5 males, 5 females, 73 to 87 years of age) and controls (C: 5 males, 6 females, 61 to 90 years of age). Sclerostin expression and distances of each osteocyte to the canal surface and cement line were assessed for all osteonal osteocytes in 636 unremodeled osteons chosen from fields ($0.5 mm in diameter) with at least one canal staining for alkaline phosphatase (ALP), a marker of bone formation. In adjacent sections, ALP staining was used to classify basic multicellular unit (BMUs) as quiescent or actively forming bone (ALP þ ). The areal densities of scl À and scl þ osteocytes (number of cells per unit area) in the BMU were inversely correlated and were strong determinants of ALP status in the BMU. In controls and hip fracture patients only, sclerostin-negative osteocytes were closer to osteonal surfaces than positively stained cells. Osteon maturity (progress to closure) was strongly associated with the proportion of osteonal osteocytes expressing sclerostin, and sclerostin expression was the chief determinant of ALP status. hOA patients had 18% fewer osteocytes per unit bone area than controls, fewer osteocytes expressed sclerostin on average than in controls, but wide variation was seen between subjects. Thus, in most hOA patients, there was increased osteonal ALP staining and reduced sclerostin staining of osteocytes. In FNF patients, newly forming osteons were similar in this respect to hOA osteons, but with closure, there was a much sharper reduction in ALP staining that was only partly accounted for by the increased proportions of osteonal osteocytes staining positive for sclerostin. There was no evidence for a greater effect on ALP expression by osteocytes near the osteonal canal. In line with data from blocking antibody experiments, osteonal sclerostin appears to be a strong determinant of whether osteoblasts actively produce bone. In hOA, reduced sclerostin expression likely mediates increased osteoblastic activity in the intracapsular cortex. In FNF, full osteonal closure is postponed, with increased porosity, in part because the proportion of osteocytes expressing sclerostin increases sharply with osteonal maturation. ß

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Regional differences in cortical porosity in the fractured femoral neck

Cited by 239 publications

References 38 publications

Low-energy fractures of the humeral shaft and bisphosphonate use

Low-energy fractures of the humeral shaft and bisphosphonate use

Super‐osteons (remodeling clusters) in the cortex of the femoral shaft: Influence of age and gender

Sclerostin and the regulation of bone formation: Effects in hip osteoarthritis and femoral neck fracture

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