Orthopedic implants—a clinical and metallurgical analysis

Abstract

SummaryA study of metallic implants consecutively removed from 133 patients at the Hospital for Special Surgery during a 2-year period was conducted to evaluate their performance. They had been implanted for 2 weeks to over fifteen years. The implants studied consisted of prostheses and internal fixation devices used for open reduction of fractures or immobilization of osteotomies. The implants had been fabricated from either stainless steel or cobalt-chromium alloys.Case histories and roentgenograms were reviewed. A detailed inspection of each implant was performed including failure analysis when required. Crevice or fretting corrosion was noted on all but one stainless steel implant of the plate and screw type, and to a lesser extent with the cobalt-chromium alloy implants. Extreme wear was noted on contact areas of articulating prosthetic components made of cobalt chromium alloy. Complete mechanical failures of internal fixation devices were attributable to fatigue, design deficiencies or misuse of the implant. These findings are discussed in light of the clinical results.

The tribological difference between biomedical steels and CoCrMo-alloys

“…In orthopedic surgery several self-mating metal couples are used for different applications such as screws, bone plates (Vadiraj and Kamaraj, 2006; Weinstein et al, 1973), total disc and hip arthroplasty (THA) (Bono and Garfin, 2004; Jacobs et al, 1994; Scales and Lowe, 1972; Stanton and Eck, 2010; Valdevit and Errico, 2004) as well as surface replacements (SR). For the hip, stainless steel couples were already tested 70 years ago by Wiles (Wiles, 1949; Wiles, 1958) and the Judet brothers (Sherk, 2003), however, these bearings failed for various reasons.…”

Glass and Medicine: The Larry Hench Story

“…Sir John Charnley introduced the use of methyl methacrylate cement as a way of better achieving fixation of these implants . While these dramatic advances in the treatment of orthopedic defects improved patient outcomes, there were still a significant number of failures of these implants related to the reaction of the body to the materials, mechanical design, or a combination of the two factors . These failures accelerated the rate of research focused on the interactions of biomaterials with living tissue.…”

“…The matrix of materials with different compositions and different fixation methods was large and ranged from cements, to porous materials, to direct fixation using pins, screws, and other hardware . It was recognized that even high strength metallic implants were subject to corrosion and to a limited lifetime in the body and even to complete failure …”

“…2 While these dramatic advances in the treatment of orthopedic defects improved patient outcomes, there were still a significant number of failures of these implants related to the reaction of the body to the materials, mechanical design, or a combination of the two factors. 3 These failures accelerated the rate of research focused on the interactions of biomaterials with living tissue. During this period of time, the biomaterials community was generally hard at work trying to make more highly compatible and, more importantly, less reactive materials (more inert) for implantable medical devices.…”

Friction and Wear of Polymers, Ceramics and Composites in Biomedical Applications

“…There were, however, persistent problems associated with stainless steel implants due to their susceptibility to corrosion in body fluids [51], and these materials have now been replaced by more suitable cobalt and titanium alloys in many prosthetic designs. ASTM specification F 138) were the main metallic alloys used for femoral components.…”