MP₃₅N: A corrosion resistant, high strength alloy for orthopedic surgical impants: Bio‐assay results

Abstract

A cobalt based alloy, MP35N, with excellent mechanical properties has been recently introduced as a material for surgical orthopedic implants. A study was made of local and systemic host response to this material in two different mammal species. The implantation time ranged from one to 12 months. The result of this study indicated: MP35N produces a degree of local tissue response comparable to that of 316L stainless steel. No systemic side effects were observed during the implantation times included in this study.

Tissue reaction to implants of different metals: A study using guide wires in cannulated screws

“…These metals were also considered among the best in terms of being biologically tolerated metals. Experimental data correlated ion migration with fibrous reaction around the implants and showed this effect to be minimal around CoCr-Mo, Co-Cr-Ni and Co-Cr-Ni-Mo in experimental animal implantation and suggested that Co-Cr alloys were well suited as skeletal implants from a biocompatibility point of view (Escalas et al, 1975). Younkin (1974) also found that the tissue from rabbits containing MP35N implants had a lower incidence of inflammatory changes than the tissue implanted with 304 stainless steel.…”

“…A Cobalt-Nickel-Chromium-Tungsten based alloy, L605, has similar properties to MP35N (Poncin et al, 2004). Both these alloys are generally recommended for applications where a combination of high strength, high modulus and good corrosion resistance are required (Escalas et al, 1975;Williams, 1981;Marti, 2000;Hanawa, 2002;Poncin et al, 2004 The purpose of this study was to determine the biological response to these mechanically superior metals (MP35N and L605), when the material is coupled with stainless steel in a non-loaded situation. This would simulate a situation where the guide wire bends and breaks and cannot be removed leaving a condition of contact between the L605 and MP35N alloys and a stainless steel cannulated screw in vivo.…”

Metal is not inert: Role of metal ions released by biocorrosion in aseptic loosening—Current concepts

“…However, despite the great progress in providing corrosion resistant metallic biomaterials, in a physiological environment corrosion remains a slow and continuous process, which leads to the release of significant amounts of metal ions and other corrosion products. For instance, the corrosion of a stainless steel implant releases Fe, Cr, and Ni ions; corrosion of titanium and titanium alloys release titanium (mostly at the Ti(IV) oxidation state), vanadium and aluminum ions 38–50. Dissolved metal ions can accumulate in the tissue, surrounding metal implants or can be released into the systemic blood circulation and transported to distal organs 18–21.…”

An In Vitro Biomechanical Investigation of an MP35N Intramedullary Interlocking Nail System for Repair of Third Metacarpal Fractures in Adult Horses

“…MP35N is a nonmagnetic, nickel‐cobalt‐chromium‐molybdenum–based, ultra–high‐strength, corrosion‐resistant, biocompatible metal alloy 29,30 . MP35N is primarily composed of 33% to 37% Ni, 33% Co, 19% to 21% Cr, and 9% to 10.5% Mo.…”