Background: To compare structural features of the femoral bone of ovariectomized and non-ovariectomized rats after implantation of porous materials (TANTALUM, CONCELOC, TTM, ATLANT). Methods: Experiments were carried out on 56 white laboratory female rats aged 6 months. Rats were randomly assigned into groups: sham-operated control group (SH) or ovariectomy group (OVX). Four different commercial implant materials (TTM, CONCELOC, TANTALUM, ATLANT) were placed into the defects (diameter 2.5 mm, depth 3.0 mm) in the distal metaphysis of femurs. Rats were sacrificed 45 days after surgery. Histological study was performed and the percentage of the bone area (BA%) around the implant at a distance of 500 μm in the cancellous area was measured. Results: Formation of mature bone tissue of varying degrees around all of the implants was detected. In OVX rats cancellous bone defect zone was characterized by a high density of osteocytes on the surface. In the SH group, no differences in BA% among implant materials were found. In OVX rats, the BA% around ATLANT implants was 1.5time less (p = 0.002) than around TANTALUM. The BA% around the rest of the materials was not statistically different. Conclusions: Bone formation around the studied porous titanium and tantalum materials in the osteoporosis model was lower than in normal bone. There were differences in bone formation around the different materials in the osteoporosis model, while in the normal bone model, these differences were absent.

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Bone tissue engineering strategy involves the 3D scaffolds and appropriate cell types promoting the replacement of the damaged area. In this work, we aimed to develop a fast and reliable clinically relevant protocol for engineering viable bone grafts, using cryopreserved adipose tissue‐derived mesenchymal stromal cells (MSCs) and composite 3D collagen‐nano‐hydroxyapatite (nanoHA) scaffolds. Xeno‐ and DMSO‐free cryopreserved MSCs were perfusion‐seeded into the biomimetic collagen/nanoHA scaffolds manufactured by cryotropic gelation and their osteoregenerative potential was assessed in vitro and in vivo. Cryopreserved MSCs retained the ability to homogenously repopulate the whole volume of the scaffolds during 7 days of post‐thaw culture. Moreover, the scaffold provided a suitable microenvironment for induced osteogenic differentiation of cells, confirmed by alkaline phosphatase activity and mineralization. Implantation of collagen‐nanoHA cryogels with cryopreserved MSCs accelerated woven bone tissue formation, maturation of bone trabeculae, and vascularization of femur defects in immunosuppressed rats compared to cell‐free collagen‐nanoHA scaffolds. The established combination of xeno‐free cell culture and cryopreservation techniques together with an appropriate scaffold design and cell repopulation approach accelerated the generation of viable bone grafts.

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BACKGROUND Today, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads. AIM To compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits. METHODS The study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet's Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred. RESULTS The breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly ( P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM ( P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 ( P = 0.001). CONCLUSION TANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration ( P = 0.001) in healthy and in osteoporotic bone.