Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

Ti/Ta-based composite polysaccharide scaffolds for guided bone regeneration in total hip arthroplasty

Guided bone regeneration can play an important role in orthopedic applications. This work presents the synthesis and characterization of composite scaffolds based on polysaccharides loaded with microparticles of titanium or tantalum as novel materials proposed for composite systems with promising characteristics for guided bone regeneration. Ti/Ta composite scaffolds were synthesized using chitosan and gellan gum as organic substrates and crosslinked with oxidized dextran resulting in stable inorganic-organic composites. Physico-chemical characterization revealed a uniform distribution of metal nanoparticles within the scaffolds that showed a release of metals lower than 5 %. In vitro biological assays demonstrated that Ta composites exhibit a 2 times higher ALP activity than Ti and a higher capacity to support the full differentiation of human mesenchymal stem cells into osteoblasts. These results highlight their potential for bone regeneration applications.

Do mandibular titanium miniplates affect the biomechanical behaviour of the mandible? A preliminary experimental study

INTRODUCTION

Whether to conserve or remove titanium miniplates after rigid internal fixation of mandibular fractures still remains controversial. Miniplates could affect the biomechanical behaviour of the mandible in case of trauma, and therefore cause more complex fractures.

MATERIALS AND METHODS

An experimental study, consisting in simulating a mandibular trauma, was designed in order to compare the fractures caused by an impact on the mandible in the presence or absence of an internal fixation. We simulated an impact on the right parasymphysis region in 10 post-mortem human subjects, according to the Charpy impact test method at an impact speed of 7.4 m/s, using a 5 kg test impactor.

RESULTS

In the control group, the fracture lines were vertical and straight, without comminution. In the miniplate group, the fractures occurred close to the miniplates (4 cases) and under the miniplates (one case). The fracture lines were more complex, even comminuted in 2 cases. Thus, miniplates impacted the biomechanical behavior of the mandible, resulting in more complex fractures.

CONCLUSION

Our experimental study highlighted the impact of the presence of miniplates on the mandible in case of trauma, and the risk of causing more complex fractures. We therefore recommend further investigations to determine if titanium miniplates should be systematically removed after bone healing, in patients with a higher risk of trauma in relation with previous assault injuries, alcohol or substance abuse, the practice of fighting or contact sport/activities, and soldiers.

EXPERIMENTAL STUDY OF BONE DENSITY IN PATIENTS WITH CONGENITAL PSEUDOARTHROSIS OF THE TIBIA BEFORE AND AFTER SURGERY

OBJECTIVE

The aim: Determine the changes in bone density that occur in the cortical layer of the tibia in patients with CPT after surgical treatment due to radiography data.

PATIENTS AND METHODS

Materials and methods: The study was performed on X-rays of the tibia of three patients with CPT, aged 5 to 7 years. X-rays were taken before surgery and 1 year after surgery. The optical density of the cortical layer of both tibia bones was determined, for which they were conditionally divided into 7 zones.

RESULTS

Results: In all patients with CPT before treatment, there is significant decrease in the optical density of cortical bone tissue of the damaged tibia compared with contralateral. One year after surgery, there was an increase in the optical density of the cortical layer of both tibia of the studied patients. The increase in the density of the nonoperated tibia can be attributed to the active growth of patients. On the operated limb, the increase in the density of the cortical layer became statistically significant in all studied areas, which can be attributed not only to the growth of patients, but also to the possibility of active loading of the operated limb.

CONCLUSION

Conclusions: In all patients with CPT before treatment, a statistically significant decrease in the density of cortical bone tissue of the damaged tibia was observed. As a result of the treatment there is an approximation of the bone density of the operated limb to the indicators of intact contralateral bone.