Bone-implant degradation and mechanical response of bone surrounding Mg-alloy implants.

In the present paper, first results of the influence of the degradation of biodegradable materials on the hardness of the bone are presented in detail. For this purpose, different materials (Mg, Ti and biopolymers) were implanted into the femora of growing rats and bone cross sections were examined for the micro-hardness (MH). The aim of the present paper was to examine the mechanical response of the bone areas surrounding the implant at defined sites and at specified periods after implantation.

Comparative biomechanical and radiological characterization of osseointegration of a biodegradable magnesium alloy pin and a copolymeric control for osteosynthesis.

Magnesium alloys offer great advantages as degradable implant material for pediatric fracture fixation and hold the potential to overcome certain critical shortcomings inherent to currently used degradable (co)polymers. Besides good biocompatibility and appropriate degradation kinetics, sufficient implant anchorage in host bone is critical to prevent implant failure. Bone-implant anchorage of biodegradable magnesium alloys, however, has not yet been related and compared to that of copolymers, their degradable counterparts currently in clinical use.

PHB, crystalline and amorphous magnesium alloys: promising candidates for bioresorbable osteosynthesis implants?

In this study various biodegradable materials were tested for their suitability for use in osteosynthesis implants, in particular as elastically stable intramedullary nails for fracture treatment in paediatric orthopaedics. The materials investigated comprise polyhydroxybutyrate (PHB), which belongs to the polyester family and is produced by microorganisms, with additions of ZrO2 and a bone graft substitute; two crystalline magnesium alloys with significantly different degradation rates ZX50 (MgZnCa, fast) and WZ21 (MgYZnCa, slow); and MgZnCa bulk metallic glasses (BMG). Push-out tests were conducted after various implantation times in rat femur meta-diaphysis to evaluate the shear forces between the implant material and the bone.

Fracture tolerance of reaction wood (yew and spruce wood in the TR crack propagation system).

The fracture properties of spruce and yew were studied by in-situ loading in an environmental scanning microscope (ESEM). Loading was performed with a micro-wedge splitting device in the TR-crack propagation direction. The emphasis was laid on investigating the main mechanisms responsible for a fracture tolerant behavior with a focus on the reaction wood.

Influence of screw diameter and number on reduction loss after plating of distal radius fractures.

Background: The current options for plate-screw combinations in volar locking distal radius plates used for the treatment of distal radius fractures are either plates with a single distal screw row or plates with multiple distal screw rows. Additionally, the screws themselves may have either fixed angle locking or polyaxial locking mechanisms. To date, there is no evidence or consensus regarding the optimal plate-screw combination.

Factors influencing interlocking screw failure in unreamed small diameter nails--a biomechanical study using a distal tibia fracture model.

Background: Unreamed tibia nails with small diameters are increasingly used for fracture fixation. However, little is known about the fatigue strength of proximal and distal interlocking screws in those nails. To date, no data are available reporting on mechanical differences of solid compared to cannulated tibial nails.