The hip joints bear our entire body’s weight as well as forces exerted by hip and leg muscles. Except for our shoulder joint, it has the widest range of flexibility and motion allowing us to walk, run and jump. No wonder it is considered one of the most important joints in the human body. Replacement of hip joint with an artificial implant is considered one of the top achievements of its generation in the field of orthopedics. Multiple attempts with variety of materials including metal, ceramic and polymeric materials, spread over at least 300 years, allowed this progress. However, revolutionary advances in materials and implant designs starting in the 1960s, due to the efforts of pioneers such as Sir John Charnley, led to the development of the first top hit replacement or arthroplasty implants. Here is a little bit more on the what and how of top hip replacement.
Month: September 2017
The Prozyr Femoral Ball Recall
In 2001, in European and American regulatory agencies recalled millions 
of zirconia ball heads sold under the commercial name Prozyr by Saint Gobain Ceramiques Desmarquest. These heads are one of the important components used in a total hip replacement procedures also known as arthroplasty. This recall happened because the femoral ball heads were fracturing and failing at inordinately high rate after implantation in patients in a relatively short period of time. What followed was an intense international investigation by a panel of experts. The company and regulatory agencies wanted to find out answers to two central questions as soon as possible. What caused these fractures that led to the failure of these implants? What changed that caused this sudden jump in failure rates?
The Map All Biomaterialists Should Understand
We know various material types (e.g., metals, ceramics, polymers) can be used as raw materials to develop an implant or device. We also know composites comprise of more materials. The manufacturing processes shape and assemble the materials into the final product. Heating and cooling techniques are routinely employed during the manufacturing process to shape and deposit the materials. These techniques generate microstructures (typically visible only under a microscope) that play an important role in defining the final product properties. During material’s thermal processing, understanding the nature of phase transformations that give rise to various microstructures is crucial for control of final product properties. Central to this understanding of phase transformation is to have a good grasp of phase diagrams or “maps” for the design of processing methods. So let us delve a little bit more into phase transformation and phase diagrams.
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