music by ted nugent -stanglehold. photos i have taken over last year some good some personal let me know what you think.
Hip replacements have a limited life before they too need replacing. This is called revision surgery and it is a cause of much pain and inconvenience for the patient. Revision surgery is most often because the underlying bone has deteriorated. Bone needs stress to grow and remain strong, yet current hip replacement implants are too stiff – they constrain the affixed bone, preventing it from stretching. The bone around the implant deteriorates and the bond between bone and implant fails. Titanium is used in orthopaedic implants because it is strong, lightweight and biocompatible. Titanium transforms at temperatures above 883°C as the atoms rearrange from a densely-packed crystalline structure (called the alpha phase) to the loosely-packed beta phase. Both alpha and beta phases are strong, but the beta phase is half as stiff and has elastic properties closer to that of bone. By adding elements such as tin, niobium and zirconium, our titanium alloy keeps its flexible beta structure at room temperature. If the alloy is then gently re-heated to 450°C, some alpha phase re-emerges, complicating the microstructure. This makes it more difficult for cracks to progress through the metal, making it less susceptible to fatigue failure. If the amount of alpha phase is controlled, a metal with good fatigue properties and low-stiffness is made. To further reduce the stiffness of the implant and match it to that of bone, we use flexible scaffold structures. The porous scaffold also allows …