The Long Bone Deformity of Osteogenesis Imperfecta III: Analysis of Structural Changes Carried Out with Scanning Electron Microscopic Morphometry

Abstract

The wedges of the mid-diaphyseal osteotomies carried out to correct the femoral and/or tibial native deformity in type III osteogenesis imperfecta (OI III) were used to study the remodeling patterns and lamellar organization at the level of the major deformity. Histology and scanning electron microscopy (SEM) morphology showed abnormal cortical remodeling characterized by the failure to form a cylinder of compact bone with a regular marrow canal. Atypical, flattened, and large resorption lacunae with a wide resorption front on one side and systems of parallel lamellae on the opposite side were observed, resembling those formerly reported as drifting osteons. SEM morphometry documented a higher percentage of nonossified vascular/resorption area (44.3 %) in OI than in controls (13.6 %), a lower density of secondary osteons, and lower values for the parameters expressing the individual osteon size. The mean osteon total area, the mean central canal area, and the mean osteon bone area of two selected, randomized populations of secondary osteons were significantly higher (p < 0.001, p = 0.028, and p < 0.001, respectively) in control bones than in OI. The mean ossified matrix area was not significantly different, but the mean secondary osteon number and mean density were higher in controls (both p < 0.001). Osteon wedges were carried out to correct the native deformity of OI III and morphologic analysis suggested that the abnormal remodeling pattern (with "drifting osteons") may result from the altered load and tensile stresses on the deformed tubular bones.

Reduced diaphyseal strength associated with high intracortical vascular porosity within long bones of children with osteogenesis imperfecta

“…Further investigation by high-resolution computed tomography confirmed the presence of unusually high vascular porosity, on average 21%, within long bone diaphyseal cortex of children with OI, when compared with control specimens from children with no known musculoskeletal disease, for which the average porosity was 3% [39]. A similar finding was since then reported by another group in a scanning electron microscopy study of mid-diaphyseal osteotomy specimens from children with OI type III, which described the presence of “flattened and elongated lacunar spaces” within regions of bone “normally taken up by compact cortex” [40]. The current study builds upon our group’s recent work, and offers an in-depth analysis of relationships between cortical tissue architecture, including vascular porosity, and the mechanical properties of diaphyseal bone in children with OI.…”

“…Low bone mass is a characteristic clinical feature of OI, and evidence of a discontinuous and porous cortical bone structure within the iliac crest and long bone diaphyses can be found in other reports [12, 13, 40, 43]. In a recent study, elevated cortex porosity observed within long bone diaphyses of children with OI was attributed to abnormal secondary remodeling, resulting in a combination of regular concentric osteons and large, flattened resorption spaces formed by drifting osteons [40]. …”

“…For the current study, an accepted masking procedure was used during segmentation to label all vascular pores [43, 44], and a lower size restriction of 2000 µm 3 was imposed to minimize the inclusion of any artifacts or spuriously labelled lacunae (which are typically smaller than 500 µm 3 in volume) [44, 48–50]. Low bone mass is a characteristic clinical feature of OI, and evidence of a discontinuous and porous cortical bone structure within the iliac crest and long bone diaphyses can be found in other reports [12, 13, 40, 43]. In a recent study, elevated cortex porosity observed within long bone diaphyses of children with OI was attributed to abnormal secondary remodeling, resulting in a combination of regular concentric osteons and large, flattened resorption spaces formed by drifting osteons [40].…”

Transdermal Delivery of Functional Collagen Via Polyvinylpyrrolidone Microneedles

“…Deficits of C1 can lead to numerous negative outcomes, from cosmetic blemishes such as wrinkles and decreased ability of wound healing, to life altering and debilitating diseases, such as Osteogenesis Imperfecta and Ehler– Danlos Syndrome. 6,23,33 These deficits can be caused by congenital defects, infection, autoimmune diseases, nutrient deficiency, sun damage, or old age. 4,20,26 Aging alone can reduce the collagen content of adult human skin to 1% per unit area per year.…”

The ever-expanding conundrum of primary osteoporosis: aetiopathogenesis, diagnosis, and treatment

“…Type III ( OMIM #259420 ) is a severe form with obvious bony deformities and reduced BMD [17]. Whereas type I OI patients have a reduced amount of type I collagen, patients with types II, III and IV ( OMIM #166220 ) have lower quality type I collagen [9,18]. Some children with OI do not fall clearly into one of these four types.…”