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Previous subgroup analyses from the ACTIVE trial in women with postmenopausal osteoporosis (NCT01343004) using three‐dimensional (3D)‐processing of dual X‐ray absorptiometry (DXA) scans indicated greater increases in total hip cortical volumetric bone mineral density (Ct.vBMD) and estimated indices of hip strength following 18 months of abaloparatide (ABL) versus placebo or teriparatide. The current post hoc analyses describe hip 3D‐DXA data for ACTIVExtend (NCT01657162), in which 18 months of ABL followed by 24 months of alendronate (ABL/ALN) increased hip and spine areal BMD (aBMD) and reduced fracture risk versus placebo (PBO) followed by ALN (PBO/ALN). In an ACTIVExtend subgroup (ABL/ALN, n = 204; PBO/ALN, n = 202), hip DXA scans retrospectively underwent 3D modeling via 3D‐Shaper software. Changes from baseline in cortical and trabecular compartments were calculated for total hip and hip subregions (femoral neck, trochanter, and shaft). Estimated strength indices comprising cross‐sectional moment of inertia, section modulus, and buckling ratio were calculated for each hip subregion. Correlations between bone turnover marker levels at the time of alendronate initiation and subsequent BMD gains with alendronate were also investigated within each group. Total hip trabecular and cortical 3D‐DXA parameters increased from baseline in both groups (all p < 0.001), with greater average increases for ABL/ALN versus PBO/ALN (trabecular vBMD: 10.87% versus 4.3%; cortical thickness: 2.32% versus 1.14%; Ct.vBMD: 3.41% versus 1.86%; cortical surface BMD: 5.82% versus 3.0%; all p < 0.001). Strength indices in the ABL/ALN group improved in all subregions versus baseline (all p < 0.0001) and versus PBO/ALN (all p < 0.02). In the ABL/ALN group, collagen type I N‐terminal propeptide (P1NP) levels at the time of alendronate initiation correlated with subsequent percent changes in all 3D‐DXA parameters with 24 months of alendronate therapy. In conclusion, sequential ABL/ALN or PBO/ALN treatment improves trabecular and cortical 3D‐DXA parameters at the hip, as well as strength indices of hip subregions, with greater increases with ABL/ALN versus PBO/ALN. © 2022 Radius Health, Inc. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. [ABSTRACT FROM AUTHOR]

Purpose: New repair techniques for fragility fractures such as those of the distal radius require biomechanical justification. This study was conducted to investigate a technique using an expanding polymer bone cement to provide strength to a fracture repair. Methods: Distal and proximal ends were isolated from 6 pairs of human radii (mean age 65). Transverse osteotomies were made near the head of each specimen. Paired specimens were repaired using 2 materials of differing polymer chemistries: polyurethane versus polymethylmethacrylate. Repaired specimens were subjected to failure tests in a cantilever beam configuration (distal, n = 6 per treatment) or pure tension (proximal, n = 5 per treatment). Cement penetration tests were conducted using a uniform open-cell model of cancellous bone. Baseline mechanical properties of the polyurethane cement were determined according to ASTM standards. Results: Distal radii repaired with polyurethane bone cement withstood average shear stress 2.9 times as high as polymethylmethacrylate (0.91 vs 0.31 MPa). Peak tensile bending stress was 2.5 times as high in polyurethane (2.57 vs 1.02 MPa). Under pure tension, polyurethane-repaired samples failed at 0.83 MPa versus 0.74 MPa for polymethylmethacrylate. The polyurethane cement expanded to penetrate 49% farther into the trabeculae. The polyurethane cement had mean compressive yield stress of 20.3 MPa, compressive modulus of 754 MPa, ultimate tensile stress of 18.5 MPa, and tensile elastic modulus of 723 MPa. Conclusions: The biomechanical strength data indicate the potential of an expanding bone cement as a candidate strategy for fracture repair. Further evaluation might provide evidence for such an alternative repair strategy for fragility fractures, including those of the distal radius. Clinical relevance: An approach that couples the benefits of closed reduction and internal fixation might prove an attractive paradigm for treatment of distal radius fractures. [ABSTRACT FROM AUTHOR]

The article presents a medical research on an in vivo model of reduced nucleus pulposus glycosaminoglycan content in lumbar intervertebral disc in rats. It established an in vivo model in the rat lumbar spine, simulating reduced glycosaminoglycan content as observed in early degeneration. Reduced nucleus glycosaminoglycan resulted in alterations in disc mechanics. It revealed that the model will be useful in understanding the role of glycosaminoglycan reduction in degeneration.

Purpose: Development of alternatives to autologous bone has been served by many hypotheses and developments. Favorable properties of synthetic materials used currently in bone grafting support tissue differentiation without shielding capacity for integrated modeling. Ideally, new materials provide tissue compatibility and minimize patient morbidity and are attractive because of potential for in situ delivery, isothermal polymerization, porous structure, and nontoxic chemistry. For application in cranial bone, ability for materials to be laid adjacent to brain and offer postsurgical protection without neural risk is a critical asset., Methods: Kryptonite Bone Cement (KBC) meets the property criteria for cranial bone repair with regard to adhesive, conductive, and biologic transparency and US Food and Drug Administration approval for cranial bone void repair. To better delineate the morphology effective in cranial bone repair, a comparison was made between KBC and BoneSource, another material approved for the same indication. After Institutional Animal Care and Use Committee approval, the study assessed 24 rabbits, each with 2 separate cranial implants, to evaluate integration and absorption of the biomaterial at defined time points of 12, 18, 24, and 36 weeks., Results: The 36-week assessment demonstrated near-complete resorption/integration of the BoneSource graft material. Bone was present within the biomaterial as well as independent of contact. The KBC was similarly integrated throughout the mass of the material, and new bone was in contact with the grafting material and also seen as separate islands of new bone. The bone demonstrated lamellar bone architecture with clear trabecular morphology. At higher magnification, the bone architecture can be clearly delineated, and comparison between the graft fillers is not obvious relative to the bone that has formed. Despite microscopic similarities, the most striking difference was maintenance of scaffold anatomy during bone regeneration., Conclusions: Kryptonite Bone Cement meets the criteria described in the introduction; properties of biologic transparency, osteoconductivity, and ergonomic utility offer other potential uses in bone repair. Key tenets of bone tissue regeneration observed in this analysis included adequate cell differentiation and tissue support. Bone that formed demonstrated lamellar rather than woven bone to suggest response to loading strain rather than merely biochemical precipitation. Over the 36-week study, the graft showed progressive bioabsorbable potential with calibrated replacement.