Characterization and Modification of Surface Topography by Sequential Laser Peening Biodegradable Magnesium-Calcium Alloy

The development of biodegradable implants has had a beneficial effect on in-vivo treatment of patients with various bone ailments. Currently, biodegradable implants are mainly made of polymers, such as PLA or PMMA. However, these polymer based implants usually have unsatisfactory mechanical strength and are prone to considerable amounts of wear [1]. An alternative to polymers is a biodegradable magnesium-calcium (Mg-Ca) alloy which has the ability to gradually dissolve and absorb into the human body after implantation. The similar properties of Mg to bone indicate it is an ideal implant material to minimize the damaging effects of stress shielding. The critical issue that hinders the application of Mg implants is poor corrosion resistance to human body fluids. Sequential laser shock peening (LSP) of a biodegradable Mg-Ca alloy was initiated to create a superior surface integrity for improving implant performance. LSP is an innovative surface treatment method to impart deep compressive residual stresses across a broad area of an implant. The high compressive residual stress has great potential to slow corrosion rates and improve wear and fatigue performance. Also, LSP produces a unique surface topography. Structural surface modifications are an effective way to alter the implant/tissue interface in order to improve biocompatibility.