Mechanically Assisted Crevice Corrosion Research Articles

Comparison of Pre-Revision Magnetic Resonance Imaging and Operative Findings in Mechanically Assisted Crevice Corrosion in Symptomatic Metal-on-Polyethylene Total Hip Arthroplasties

BackgroundFailed total hip arthroplasty (THA) caused by mechanically assisted crevice corrosion (MACC) has serious consequences—notably, adverse local tissue reactions. Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been used to evaluate failed THA for other reasons but has not been assessed for the analysis of cases of MACC in the setting of metal-on-polyethylene arthroplasties. MethodsWe examined the correlation between preoperative MARS MRI and surgical findings in a cohort of 20 consecutive patients undergoing revision THA for symptomatic MACC without other associated orthopedic diagnoses. Surgical findings included soft tissue and bone evaluation, presence and location of fluid, abductor disruption, composite tissue damage grade, and prosthesis trunnion damage at the time of revision. ResultsMARS MRI complex synovitis, thickened pseudocapsule, and extra-articular fluid extension each strongly correlated with both the soft-tissue damage grade and trunnion damage noted at surgery. Bone marrow edema was also found to strongly correlate with bone necrosis intraoperatively. ConclusionMARS MRI is an excellent diagnostic tool for evaluation of patients with elevated serum Co after metal-on-polyethylene THA. Patients with complex synovitis, a thick pseudocapsule, bone marrow edema, and extra-articular fluid should strongly consider revision surgery.

Elevated Intra-Articular Cobalt and Chromium Levels in Mechanically Assisted Crevice Corrosion in Metal-on-Polyethylene Total Hip Arthroplasty

BackgroundFailed total hip arthroplasty (THA) caused by mechanically assisted crevice corrosion (MACC) has serious consequences such as adverse local tissue reaction (ALTR). Serum cobalt (Co) and chromium (Cr) ion levels have been used to diagnose taper corrosion, but have not been shown to be an accurate measure of the severity of MACC or associated ALTRs. Additionally, elevated serum ions are not specific in patients with multiple artificial joints. MethodsWe examined the relationship between serum and intra-articular (IA) Co and Cr levels in a cohort of 20 patients undergoing revision THA, 16 who had symptomatic MACC. IA Co and Cr levels in MACC patients were compared with demographic, pre-operative, and operative findings. ResultsSerum and IA metal levels were found to be relatively low in THA patients undergoing revision surgery for isolated instability, aseptic loosening, or infection (average serum Co 0.03 ppb [parts per billion], IA Co 1.4 ppb, serum Cr 0.32 ppb, IA Cr 3.3 ppb). In patients with MACC, average IA Co (940 ppb) was significantly higher than serum Co (5.1 ppb) (P = .0003) and IA Cr (491 ppb) was significantly higher than serum Cr (1.3 ppb) (P = .0003). IA Co level was associated with shorter time of hip symptoms to revision surgery (P = .0043). ConclusionSerum levels of Co and Cr correlated with joint levels in the entire cohort, but IA levels of MACC patients were 100 times greater than serum levels. IA Co and Cr levels may be useful in confirming MACC in a specific joint and the striking elevation may explain symptoms and ALTR with relatively low serum values.

Characterization of Femoral Head Taper Corrosion Features Using a 22-Year Retrieval Database.

Modularity in total hip arthroplasty has been used for decades with great success, but new findings regarding corrosion artifacts have caused a resurgence in tapered junction research. Mechanically assisted crevice corrosion (MACC) is thought to be the mechanism by which corrosive attack occurs. Myriad multi-factorial variables are known to influence the susceptibility of a modular taper junction to MACC. Some of these variables are design and manufacture related and others can be controlled by the surgeon. This study was performed to assess a 22-year retrieval database to determine if correlations exist between severity of corrosion artifacts and head size, time in vivo, head offset, or head material. Secondarily, the agreement of visual and semi-quantitative scoring methods was assessed using the retrieved components. A total of 210 femoral head tapers were scored and heads receiving high scores were measured to quantify material loss due to MACC. Increased head size and increased time in vivo did not correlate to higher corrosion scores. Contrarily, there were differences in corrosion scores based on femoral head offset and material. Deviations away from a neutral offset (where neutral is defined as the alignment of femoral head center and stem taper gage point) resulted in higher scores. Cobalt-chromium-molybdenum heads were associated with higher corrosion scores and higher material loss as compared to oxidized zirconium heads. Reducing the moment arm at the head-neck junction and choosing a more inert material appears to provide greater resistance to corrosion.

Corrosion at the head-neck interface of current designs of modular femoral components: essential questions and answers relating to corrosion in modular head-neck junctions.

There is increasing global awareness of adverse reactions to metal debris and elevated serum metal ion concentrations following the use of second generation metal-on-metal total hip arthroplasties. The high incidence of these complications can be largely attributed to corrosion at the head-neck interface. Severe corrosion of the taper is identified most commonly in association with larger diameter femoral heads. However, there is emerging evidence of varying levels of corrosion observed in retrieved components with smaller diameter femoral heads. This same mechanism of galvanic and mechanically-assisted crevice corrosion has been observed in metal-on-polyethylene and ceramic components, suggesting an inherent biomechanical problem with current designs of the head-neck interface. We provide a review of the fundamental questions and answers clinicians and researchers must understand regarding corrosion of the taper, and its relevance to current orthopaedic practice. Cite this article: Bone Joint J 2016;98-B:579-84.

Corrosion at the Head-Neck Junction: Why Is This Happening Now?

While mechanically-assisted crevice corrosion (MACC) at the head/neck junction of modular total hip arthroplasty (THA) femoral components was first described over two decades ago, it is only within the last few years that investigators have observed that adverse local tissue reactions (ALTRs) associated with MACC are an increasingly prevalent mode of failure of contemporary THAs. As yet, the incidence, etiology and pathogenesis of MACC-associated ALTR are not well understood. In this review, possible implant-, patient-, and surgeon-related factors are considered in the context of a small but growing body of evidence from laboratory simulations, implant and tissue retrieval studies and clinical case series. It is likely that MACC-associated ALTR is a multifactorial process and that ongoing research will lead to multiple strategies that will facilitate early diagnosis and ultimately prevention of the adverse clinical sequelae of this phenomenon.

Revision for taper corrosion at the head-neck junction: pearls and pitfalls.

Modular hip replacement components offer numerous advantages, and the modular femoral component has become standard for contemporary total hip implants. Recent reports of mechanically assisted crevice corrosion (MACC) at the head-neck junction, and associated adverse local tissue reactions (ALTRs), have renewed concerns for complications attributed to modularity. This manuscript describes the diagnosis, prognosis, and treatment options for MACC and highlights how appropriate pre-revision evaluation and planning, in conjunction with meticulous surgical technique, should be followed to avoid complications and achieve optimal surgical outcomes. Future directions for research include biomechanical, clinical, and retrieval studies.

A High Prevalence of Corrosion at the Head–Neck Taper with Contemporary Zimmer Non-Cemented Femoral Hip Components

Mechanically assisted crevice corrosion (MACC) occurs at metal/metal modular junctions in which at least one of the components is fabricated from cobalt–chromium alloy and may lead to adverse local tissue reaction (ALTR) in patients with metal-on-polyethylene (MoP) total hip arthroplasty. This type of reaction has been previously described in hips with head/neck modularity, but the prevalence is unknown. We found a prevalence of 1.1 percent in a consecutive series of 1356 contemporary Zimmer non-cemented femoral hip components followed for a minimum of 2years. The average time to presentation was 3.7years (range, 9–105months); delay in treatment led to irreversible soft tissue damage in three patients. We recommend usage of ceramic heads until this problem is further understood.

What Do We Know About Taper Corrosion in Total Hip Arthroplasty?

Mechanically assisted crevice corrosion (MACC) at metal/metal modular junctions in which at least one of the components is fabricated from cobalt-chromium alloy, has reemerged as a potential clinically significant complication in total hip arthroplasty. The clinical manifestation of MACC may include the development of an adverse local tissue reaction (ALTR), similar to what has been described in association with metal-on-metal bearing total hip and resurfacing arthroplasty. The clinical presentation of MACC-associated ALTRs may include pain and possibly late recurrent dislocations. Abnormal metal artifact reduction sequence magnetic resonance images and elevated serum metal levels (cobalt elevations out of proportion to chromium elevations) can be helpful in the diagnosis of these MACC-associated ALTRs.

A multicenter retrieval study of the taper interfaces of modular hip prostheses.

A multicenter retrieval analysis of 231 modular hip implants was done to investigate the effects of material combination, metallurgic condition, flexural rigidity, head and neck moment arm, neck length, and implantation time on corrosion and fretting of modular taper surfaces. Scores for corrosion and fretting were assigned to medial, lateral, anterior, and posterior quadrants of the necks, and proximal and distal regions of the heads. Neck and head corrosion and fretting scores were found to be significantly higher for mixed alloy versus similar alloy couples. Moderate to severe corrosion was observed in 28% of the heads of similar alloy couples and 42% of the heads of mixed alloy couples. Differences in corrosion scores were observed between components made from the same base alloy, but of different metallurgic conditions. Corrosion and fretting scores tended to be higher for heads than necks. Implantation time and flexural rigidity of the neck were predictors of head and neck corrosion and head fretting. The results of this study suggest that in vivo corrosion of modular hip taper interfaces is attributable to a mechanically-assisted crevice corrosion process. Larger diameter necks will increase neck stiffness and may reduce fretting and subsequent corrosion of the taper interface regardless of the alloy used. Increasing neck diameter must be balanced, however, with the resulting loss of range of motion and joint stability.