To increase the corrosion prevention of stainless steel implant and fast recovery due to new bone-cell formation at the orthopedic implant site, in the present investigation, a trilayered (with bioceramic interlayer sandwiched between innermost passivated surface and outermost polymer coating) 316L stainless steel (SS) implant was designed and investigated. It was inferred that this new designed implant invokes faster and more bone-cell formation than uncoated commercially available 316L SS implants. Faster bone-cell formation at the coated implant site reduces the initial threat of implant corrosion. The electrochemical corrosion study proved that this model of coated implants is able to prevent corrosion up to 90% better than uncoated commercially available 316L SS. Subsequently, preclinical studies in the rabbit bone defect model (which included histology, radiology, fluorochrome labeling, push-out test, and scanning electron microscopy taken after 45 and 90 days) proved higher rate of new bone tissue formation and better push-out strength between tissue in contact and the coated implant. The toxicological study of vital organs like liver, kidney, and heart also exhibited no abnormality. The outcome of the experimentations indicates suitability of this trilayered 316L SS implant for bone repair and healing.

The bone regeneration and healing effect of formononetin was evaluated in a cortical bone defect model that predominantly heals by intramembranous ossification. For this study, female Balb/c mice were ovariectomised (OVx) and a drill-hole injury was generated in the midfemoral bones of all animals. Treatment with formononetin commenced the day after and continued for 21 d. Parathyroid hormone (PTH1–34) was used as a reference standard. Animals were killed at days 10 and 21. Femur bones were collected at the injury site for histomorphometry studies using microcomputed tomography (μCT) and confocal microscopy. RNA and protein were harvested from the region surrounding the drill-hole injury. For immunohistochemistry, 5 µm sections of decalcified femur bone adjoining the drill-hole site were cut. μCT analysis showed that formononetin promoted bone healing at days 10 and 21 and the healing effect observed was significantly better than in Ovx mice and equal to PTH treatment in many aspects. Formononetin also significantly enhanced bone regeneration as assessed by calcein-labelling studies. In addition, formononetin enhanced the expression of osteogenic markers at the injury site in a manner similar to PTH. Formononetin treatment also led to predominant runt-related transcription factor 2 and osteocalcin localisation at the injury site. These results support the potential of formononetin to be a bone-healing agent and are suggestive of its promising role in the fracture-repair process.

The aim of the present study was to compare dynamics of the bone healing process after different types of osteotomies. In total, 24 Wistar rats were subjected to different types of osteotomy performed with standard steel bur, piezosurgery, contact, and non-contact Erbium:yttrium-aluminum-garnet (Er:YAG) laser ablation. The animals were randomly divided into four groups, to be euthanized immediately after the procedure, or at 1, 2, or 3 weeks after surgery. The obtained bone samples were analyzed by scanning electron microscopy (SEM). Immediately after surgery, there were significant differences in the appearance of the bone defects, with presence of bone fragments and debris after standard steel bur preparation, compared with the clean smooth walls and relatively sharp edges in all other groups. The initial bone formation in defects prepared by piezosurgery was observed to be the most rapid. After 3 weeks, all bone defects were completely restored; although, differences in the healing pattern were noted, with a modest initial delay in healing after laser preparation. The first stage of the bone healing process was delayed when contact and non-contact Er:YAG laser modes were used and accelerated by piezosurgery; however, the results after 3 weeks demonstrated similar restitution of defects in all tested groups.