Orthopaedic metals and their potential toxicity in the arthroplasty patient

Incidence of Metal Hypersensitivity in Orthopedic Surgical Patients Who Self-Report Hypersensitivity History

INTRODUCTION

Metallic implants are integral to the practice of orthopedic surgery. Delayed-onset T-cell-mediated metal hypersensitivity (diagnosed by patch testing) is reported in 10% to 17% of the general population. Inconclusive evidence exists about the role of metal hypersensitivity in persistently painful or aseptic loosening of arthroplasties. Literature suggests that preoperative patch testing may influence surgical practice.

OBJECTIVE

To determine the incidence of metal hypersensitivity in orthopedic surgical patients who self-report hypersensitivity and to characterize which metals are most commonly implicated.

METHODS

A retrospective chart review of patients from a single surgeon's practice was conducted during a 1-year period. All patients were questioned about metal hypersensitivity history; all patients who responded affirmatively were sent for patch testing for specific metals.

RESULTS

Only 41 (4.9%) of 840 patients self-reported any metal hypersensitivity. Of these, 34 (83%) were patch-test positive to 1 or more metals. There were 27 whose test results were positive for nickel, 4 each to cobalt or gold thiosulfate, and 1 each to tin or titanium. Seven patients had positive results to multiple metals, all of whom were also nickel hypersensitive. Six patients had metal orthopedic implants before patch testing, and 4 (67%) tested positively to a metal in their implant.

CONCLUSION

Metal hypersensitivity can be concerning for treating surgeons and patients. Greater awareness of a history to hypersensitivity may prevent patient exposure to implants containing metals that may cause hypersensitivity. Non-metal-containing or nonreactive metal implants are an option for patients in whom metal hypersensitivity is suspected or confirmed.

Improving our understanding of metal implant failures: Multiscale chemical imaging of exogenous metals in ex-vivo biological tissues

Biological exposures to micro- and nano-scale exogenous metal particles generated as a consequence of in-service degradation of orthopaedic prosthetics can result in severe adverse tissues reactions. However, individual reactions are highly variable and are not easily predicted, due to in part a lack of understanding of the speciation of the metal-stimuli which dictates cellular interactions and toxicity. Investigating the chemistry of implant derived metallic particles in biological tissue samples is complicated by small feature sizes, low concentrations and often a heterogeneous speciation and distribution. These challenges were addressed by developing a multi-scale two-dimensional X-ray absorption spectroscopic (XAS) mapping approach to discriminate sub-micron changes in particulate chemistry within ex-vivo tissues associated with failed CoCrMo total hip replacements (THRs). As a result, in the context of THRs, we demonstrate much greater variation in Cr chemistry within tissues compared with previous reports. Cr compounds including phosphate, hydroxide, oxide, metal and organic complexes were observed and correlated with Co and Mo distributions. This variability may help explain the lack of agreement between biological responses observed in experimental exposure models and clinical outcomes. The multi-scale 2D XAS mapping approach presents an essential tool in discriminating the chemistry in dilute biological systems where speciation heterogeneity is expected. SIGNIFICANCE: Metal implants are routinely used in healthcare but may fail following degradation in the body. Although specific implants can be identified as 'high-risk', our analysis of failures is limited by a lack of understanding of the chemistry of implant metals within the peri-prosthetic milieu. A new approach to identify the speciation and variability in speciation at sub-micron resolution, of dilute exogenous metals within biological tissues is reported; applied to understanding the failure of metallic (CoCrMo) total-hip-replacements widely used in orthopedic surgery. Much greater variation in Cr chemistry was observed compared with previous reports and included phosphate, hydroxide, oxide, metal and organic complexes. This variability may explain lack of agreement between biological responses observed in experimental exposure models and clinical outcomes.

Concordance between laboratories in metal ion testing in patients with metal-on-metal hip implants

BACKGROUND

Testing of whole blood or serum metal ion levels has become an important part of assessing and monitoring the performance of metal-on-metal bearings, both in hip resurfacing arthroplasty and in total hip replacement. The aim of this study was to determine the concordance between 2 laboratories testing cobalt and chromium ion levels in patients with metal-on-metal bearings.

METHODS

Serum and whole blood samples from patients who had undergone metal-on-metal resurfacing or large-diameter total hip arthroplasty were tested for cobalt and chromium ions in laboratory A (a recognized laboratory) and laboratory B (tasked with testing clinical specimens). Laboratory A performed cobalt and chromium testing on whole blood, and laboratory B performed cobalt testing on whole blood and chromium testing on serum.

RESULTS

Samples from 104 patients were tested. Laboratory B reported lower whole blood cobalt levels than laboratory A. Furthermore, laboratory A reported that all patients had elevated whole blood cobalt ion levels compared to the normal reference values for the laboratory, whereas laboratory B reported that 46 patients (44.2%) had whole blood cobalt ion levels within the normal reference range for the laboratory.

CONCLUSION

This comparative study highlights the importance of using a single laboratory for metal ion testing, as values generated from different laboratories may not be directly comparable. With recent literature suggesting that whole blood cobalt levels as low as 1 ppb may be a predictor of adverse reactions to metal debris, accurate clinical measurement needs to be increasingly exact.

Study of an Additional Layer of Cement Mantle Hip Joints for Reducing Cracks

Failure of the cement mantle in total hip arthroplasty is not a simple phenomenon. Cracking, which can be caused by crack initiation and repeated loading, can cause loosening of the acetabular liner component. A previous study showed that addition of a metal layer between the liner and acetabular could reduce the stress at the contact surface of the cement mantle. This study elaborates on the performance of the additional layer. Several material properties of the layer were simulated using finite element analysis for maximum performance. A static contact analysis was used to simulate the stresses at the contact surface of the cement mantle. The results show that an additional layer of cobalt chrome produced the best performance.

Analysis of Cellular Activity Short-Term Exposure to Cobalt and Chromium Ions in Mature Human Osteoblasts

In aseptic loosening of endoprosthetic implants, metal particles, as well as their corrosion products, have been shown to elicit a biological response. Due to different metal alloy components, the response may vary depending on the nature of the released corrosion product. Our study aimed to compare the biological effects of different ions released from metal alloys. In order to mimic the corrosion products, different metal salts (CoCl₂, NiCl₂ and CrCl₃ × 6H₂O) were dissolved and allowed to equilibrate. Human osteoblasts were incubated with concentrations of 10 µM to 500 µM metal salt solutions under cell culture conditions, whereas untreated cells served as negative controls. Cells exposed to CoCr28Mo6 particles served as positive controls. The cell activity and expression of osteogenic differentiation and pro-osteolytic mediators were determined. Osteoblastic activity revealed concentration- and material-dependent influences. Collagen 1 synthesis was reduced after treatment with Co(2+) and Ni(2+). Additionally, exposure to these ions (500 µM) resulted in significantly reduced OPG protein synthesis, whereas RANKL as well as IL-6 and IL-8 secretion were increased. TLR4 mRNA was significantly induced by Co(2+) and CoCr28Mo6 particles. The results demonstrate the pro-osteolytic capacity of metal ions in osteoblasts. Compared to CoCr28Mo6 particles, the results indicated that metal ions intervene much earlier in inflammatory processes.

Evaluation of Titanium Serum Levels in Patients After Spine Instrumentation: Comparison Between Posterolateral and 360º Spinal Fusion Surgery

Introduction

The use of orthopedic implants is a cause for concern for the release of its integrating metals and the systemic complications that may occur. Instrumented spine arthrodesis is the recommended treatment for many spine diseases. Different segmental fixation devices, commonly made of titanium and its alloys, are used in these surgeries. The use of this metal for spinal fusion has introduced the possibility of generating microscopic metal particles that are present in the tissues of the surrounding implants (peri-implant environment). In fact, metal debris has been found in the paraspinal soft tissues of patients with posterior lumbar instrumentation and showed to be particularly high in patients undergoing revision procedures of pseudoarthrosis. In addition, part of the metals might also dissolve (either from the released particles or directly from the implant surface) and circulate in the body fluids, accumulating (eventually) in remote organs.

Material and methods

A prospective study was designed with patients who were to be operated by the pathology of the lumbar spine to perform a vertebral arthrodesis composed of a titanium alloy (n=32). Two subgroups were differentiated according to the type of surgery performed: a) Posterolateral arthrodesis (N=5); b) Circumferential arthrodesis intervertebral implant of polyester-ether ketone (PEEK) (N=8) or titanium (N=19). The blood sample was taken before surgery and one year later. The samples were analyzed by mass spectrophotometry with a double focus inductive coupling plasma source (DF-ICP-MS).

Results

Blood titanium levels prior to surgery were similar to those in other publications (0.7449 micrograms per liter^-1 (µgL^-1), Standard Deviation (SD)=0.562). The average titanium concentration levels found after surgery was 2.5406 µgL^-1 (SD=3,69), near 3.5-fold increase. After surgery, there was a significant mean increase in serum titanium levels of 1.7957 µgL^-1 (SD=3.5765, Range=-0.57 µgL^-1; 14.60 µgL^-1). There is a statistically significant increment (p=0.00049) of the titanium concentration in the serum of the patients after surgery. If we analyze the patients in three groups according to the type of implants used (posterolateral, circumferential with PEEK, and circumferential with titanium), there are no differences between those who did not have an intersomatic device implanted and those in which PEEK implants were implanted, but with those in which it was titanium it was p=0.006 and p=0.018, respectively.

Conclusions

Patients undergoing vertebral instrumentation experience a significant increase in serum titanium levels compared to before surgery levels. The use of an intersomatic device did not show differences in titanium release with not using it when it was PEEK. There are significant differences between patients without intersomatic implants or those who had a PEEK implant with those in whom it was titanium, with a significant increase in blood titanium levels.

Adverse reaction to metal debris after small-head diameter metal-on-metal total hip arthroplasty: an increasing concern

INTRODUCTION:

Failures due to adverse reaction to metal debris (ARMD) have become an area of common focus among surgeons performing hip replacements. Several authors have reported data on the prevalence of these masses, in both symptomatic and asymptomatic patients after either large-diameter head metal-on-metal (MoM) total hip arthroplasty (THA) or hip resurfacing arthroplasty, with a large variability of rate. To our knowledge, few data are reported on the association of this lesion with the use of small-head diameter MoM.

METHODS:

15 hips that were revised for ARMD in small-head MoM THA were included in this study. We focused our attention on the difficulties of diagnosis and treatment and also on the histologic aspects of the harvested pathologic tissue.

RESULTS:

The histological examination of our cases showed a presence of lymphocytic infiltrate suggesting a delayed hypersensitivity reaction to the metal of type IV (ALVAL), but different from each other in term of the prevalence of the cellular component. Osteolysis and severe soft tissue damage were also observed. Revision resulted in remission of the lesion and successful implant.

CONCLUSIONS:

Our observation suggests that the evidence of ARMD should be considered even in case of small-head MoM arthroplasty and therefore these patients should be followed scrupulously with 2nd level diagnostic tools such as magnetic resonance imaging with metal artifact reduction sequence (MARS-MRI) and metal ion levels at least once. Further investigations are necessary to establish the real prevalence of this phenomenon in the whole population of small-head MoM THAs.

Osseointegration of ultrafine-grained titanium with a hydrophilic nano-patterned surface: an in vivo examination in miniature pigs

Advances in biomaterials science and implant surface technology have made dental implants more predictable and implant therapy more attractive to patients. Surgical interventions are becoming less invasive, and patients heal faster and suffer less morbidity. In this preclinical in vivo study, we compared a new ultra-fine grained titanium (ufgTi) implant material with a hydrophilic nano-patterned surface to commercially pure titanium (cpTi) in a well-established animal model. CpTi grade 4 was subjected to Equal Channel Angular Pressing (ECAP), followed by a cold drawing process that provided ultra-fine-grained titanium (ufgTi) with a mean grain size of 300 nm. After metallographic assessment, the surface topography was characterized by laser confocal microscopy and atomic force microscopy. UfgTi and cpTi implants were inserted in the mandible and maxilla of miniature pigs that healed for 4 and for 8 weeks. Osseointegration was assessed by biomechanical torque out analysis, histomorphometric evaluation, and micro-CT analysis. The metallographic properties of UfgTi were significantly better than those of cpTi. Their surface topographies had similar hydrophilic nano-patterned characteristics, with no significant differences in the nanometre range. Histomorphometric and biomechanical torque out analysis revealed no significant differences between ufgTi and cpTi in environments of either low (maxilla) or high (mandible) bone density. We obtained high bone-to-implant contact values irrespective of the bony microarchitecture even when the bone mineral density was low. Overall, this investigation suggests that ufgTi forms a hydrophilic nano-patterned surface with superior metallographic properties compared to cpTi and high levels of osseointegration. Thus, ufgTi has therapeutic potential as a future strategy for the development of small diameter implants to enable less invasive treatment concepts, reduce patient morbidity and may also lower the costs of patient care.

Chromium and Nickel Concentrations in Subjects with a Stainless Steel Metal-on-Metal Cervical Disc Arthroplasty: Results from a Prospective Longitudinal Study with 7 Years Follow-Up

Background

Cervical disc arthroplasty (CDA) has emerged as an alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The artificial discs provide intervertebral motion using multicomponent articulation and thus tend to generate particulate debris and soluble metal ions. Limited information is available on the long-term metal concentrations and associated systemic adverse events observed in metal-on-metal CDA. Serum chromium (Cr) and nickel (Ni) concentrations were assessed in patients implanted with ball-in-trough stainless steel-based cervical disc through 7 years.

Methods

A prospective, nonrandomized longitudinal study was conducted that included 25 patients following rigorous exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. Blood serum Cr and Ni concentrations were assayed preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively using high-resolution inductively coupled plasma-mass spectrometry. Longitudinal statistical comparisons were made using the Friedman test with statistical significance at P < .05.

Results

Median serum concentrations determined preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively were 0.074, 0.106, 0.132, 0.170, 0.172, 0.274, 0.192, and 0.203 ng/mL for Cr and 0.085, 0.178, 0.222, 0.175, 0.205, 0.284, 0.181, and 0.194 ng/mL for Ni. The serum Cr concentrations were statistically higher for all postoperative time periods compared to preoperative concentration (Friedman P <.01), whereas serum Ni concentration was statistically higher at the 84-month postoperative time period than the preoperative concentration (Friedman P <.01) and then the concentration at 3, 12, 24, and 60 months postoperatively (Friedman P < .03).

Conclusions

The Cr concentrations detected at all postoperative times were statistically higher than preoperative concentrations, whereas Ni concentration was statistically higher than the preoperative concentration only at 84 months.

The risk of developing cancer following metal-on-metal hip replacement compared with non metal-on-metal hip bearings: Findings from a prospective national registry "The National Joint Registry of England, Wales, Northern Ireland and the Isle of Man"

Background and purpose

Over 1 million metal-on-metal hip replacements were implanted. Even well-functioning implants produce wear debris that can cause tissue damage, disseminate and cause DNA damage. We aimed to establish if there was an association between metal-on-metal hip replacement and the risk of subsequently developing cancer compared with alternative hip replacements.

Methods

We performed a population based prospective longitudinal cohort study using data from the National Joint Registry linked to Hospital Episode Statistics (n = 403,881 patients). We examined the incidence of a new diagnosis of cancer in patients who received a metal-on-metal bearing in comparison with those who received a non metal-on-metal bearing. Kaplan-Meier estimates of time to first cancer diagnosis were used with Cox proportional hazards regression models to assess the effect on the time to cancer diagnosis for all cancer types, haematological, malignant melanoma, urinary tract cancers or prostate cancer in men.

Results

The maximum follow up available was 11.8 years with 25% of patients followed up for more than 6.8 years (mean follow up 4.6 years; median 4.3; IQR 2.1–6.8; range 0.01–11.8). Analyses by gender that adjusted for age at primary and presence or absence of linked Welsh (PEDW) records showed no increase in the risk of developing cancer according to the bearing surface implanted for all cancers, haematological cancers, malignant melanoma, urinary tract cancers or prostate cancer in men. For patients receiving a second hip replacement, there was also no difference.

Conclusion

We have demonstrated that there is currently no evidence of an increase in the risk of cancer following primary hip replacement according to the type of bearing material used. Although the risk of revision in metal-on-metal bearing hip replacements is higher, it is reassuring that the risk of a new diagnosis of cancer is not currently increased. Despite the long term follow up available in this study, the latency period for some cancers is very long and therefore continued monitoring is required to ensure no new patterns emerge that may indicate need for universal screening.

Adipocyte biology: It is time to upgrade to a new model

Globally, the obesity pandemic is profoundly affecting quality of life and economic productivity, but efforts to address this, especially on a pharmacological level, have generally proven unsuccessful to date, serving as a stark demonstration that our understanding of adipocyte biology and pathophysiology is incomplete. To deliver better insight into adipocyte function and obesity, we need improved adipocyte models with a high degree of fidelity in representing the in vivo state and with a diverse range of experimental applications. Adipocyte cell lines, especially 3T3-L1 cells, have been used extensively over many years, but these are limited in terms of relevance and versatility. In this review, I propose that primary adipose-derived stromal/stem cells (ASCs) present a superior model with which to study adipocyte biology ex vivo. In particular, ASCs afford us the opportunity to study adipocytes from different, functionally distinct, adipose depots and to investigate, by means of in vivo/ex vivo studies, the effects of many different physiological and pathophysiological factors, such as age, body weight, hormonal status, diet and nutraceuticals, as well as disease and pharmacological treatments, on the biology of adipocytes and their precursors. This study will give an overview of the characteristics of ASCs and published studies utilizing ASCs, to highlight the areas where our knowledge is lacking. More comprehensive studies in primary ASCs will contribute to an improved understanding of adipose tissue, in healthy and dysfunctional states, which will enhance our efforts to more successfully manage and treat obesity.

Evaluation of Blood Titanium Levels and Total Bone Contact Area of Dental Implants

The purpose of this study was to evaluate the effect of total implant-bone surface contact area of dental implants applied on partial or total edentulous patients on the increase in the level of blood titanium level. Changes of the blood titanium levels were evaluated after placement of the dental implants in 30 patients including 15 females and 15 males. Patients were divided into 3 groups as dental implants were applied on only maxilla, only mandible, or both of them. Taking into the consideration anatomic formation and prosthetic indication, dental implant-bone total contact area was calculated and saved for each patient after dental implants placement. Blood samples of the patients taken preoperatively and postoperatively at 12 weeks were analyzed by ICP-MS device. Blood titanium levels of preoperative and postoperative blood samples were analyzed for each patient and results were evaluated statistically. In the evaluation after analyzing blood titanium level changes, while a statistically significant decrease was observed in Group 1 patients, a statistically significant increase was observed in Group 2 and Group 3 patients to blood titanium level. A statistically significant difference was observed between Group 1 and Group 2 and between Group 1 and Group 3 patients of blood titanium levels. The change of the blood titanium level was not related to total implant-bone surface area, number of the implants, and gender. In our study, no correlation was found between change of blood titanium level and total contact area with bone of dental implants. We believe that more accurate results can be obtained with biopsy of tissues and organs on animal studies.

Revision surgery of metal-on-metal hip arthroplasties for adverse reactions to metal debris

Background and purpose - The initial outcomes following metal-on-metal hip arthroplasty (MoMHA) revision surgery performed for adverse reactions to metal debris (ARMD) were poor. Furthermore, robust thresholds for performing ARMD revision are lacking. This article is the second of 2. The first article considered the various investigative modalities used during MoMHA patient surveillance (Matharu et al. 2018a ). The present article aims to provide a clinical update regarding ARMD revision surgery in MoMHA patients (hip resurfacing and large-diameter MoM total hip arthroplasty), with specific focus on the threshold for performing ARMD revision, the surgical strategy, and the outcomes following revision. Results and interpretation - The outcomes following ARMD revision surgery appear to have improved with time for several reasons, among them the introduction of regular patient surveillance and lowering of the threshold for performing revision. Furthermore, registry data suggest that outcomes following ARMD revision are influenced by modifiable factors (type of revision procedure and bearing surface implanted), meaning surgeons could potentially reduce failure rates. However, additional large multi-center studies are needed to develop robust thresholds for performing ARMD revision surgery, which will guide surgeons' treatment of MoMHA patients. The long-term systemic effects of metal ion exposure in patients with these implants must also be investigated, which will help establish whether there are any systemic reasons to recommend revision of MoMHAs.

Risk of cancer after primary total hip replacement: The influence of bearings, cementation and the material of the stem

Background and purpose - Despite the increasing number of total hip replacements (THRs), their systemic influence is still not known. We have studied the influence of specific features of THRs-the bearing surface, the use of bone cement and the material of the stem-on the cancer incidence. Patients and methods - In a retrospective cohort study we identified 8,343 patients with THRs performed at Valdoltra Hospital from September 1, 1997 to December 31, 2009. Patient data were linked to national cancer and population registries. The standardized incidence ratios (SIR) and Poisson regression relative risks (RR) were calculated for all and specific cancers. Results - General cancer risk in our cohort was comparable to the population risk. Comparing with population, the risk of prostate cancer was statistically significantly higher in patients with metal-on-metal bearings (SIR =1.35); with metal-on-polyethylene bearings (SIR =1.30), with non-cemented THRs (SIR =1.40), and with titanium alloy THRs (SIR =1.41). In these last 3 groups there was a lower risk of hematopoietic tumors (SIR =0.69; 0.66 and 0.66 respectively). Risk of kidney cancer was significantly higher in the non-metal-on-metal, non-cemented, and titanium alloy groups (SIR =1.30; 1.46 and 1.41 respectively). Risk of colorectal and lung cancer was significantly lower in the investigated cohort (SIR =0.82 and 0.83, respectively). Risk for all cancers combined as well as for prostate and skin cancer, shown by Poisson analysis, was higher in the metal-on-metal group compared with non-metal-on-metal group (RR =1.56; 2.02 and 1.92, respectively). Interpretation - Some associations were found between the THRs' features, especially a positive association between metal-on-metal bearings, and specific cancers.

Frank Stinchfield Award: Identification of the At-risk Genotype for Development of Pseudotumors Around Metal-on-metal THAs

BACKGROUND

Once touted as the future of hip arthroplasty, metal-on-metal (MoM) bearing surfaces have fallen sharply from favor with the emergence of a strong body of evidence demonstrating unacceptably high premature implant failure rates. The previously unpredictable development of adverse local tissue reactions (ALTRs) has been a substantive contributor to this. Although the underlying pathophysiology of these so-called "pseudotumors" is now well understood, the fundamental predisposing patient risk factors have remained elusive.

QUESTIONS/PURPOSES

The aim of this research, as a clinical-genotype correlation analysis, was to identify specific alleles (genes) associated with the development of ALTRs in patients with in situ MoM THAs.

METHODS

A case-control study of patients who received a large-head, primary MoM THA between 2005 and 2008 was performed with a minimum followup of 5 years. Twenty-six patients who had undergone revision of a primary MoM THA secondary to symptomatic ALTRs were recruited. The mean timeframe from primary MoM THA to symptomatic revision was 5.5 years (range, 1-10 years). Twenty-eight control subjects were randomly selected asymptomatic patients with no evidence of ALTRs on protocol-specific screening. Baseline demographics and high-resolution genotype (human leukocyte antigen [HLA] Class II) were collected for all patients. Cohorts were similar with respect to age at the time of primary MoM THA (mean, 54.8 versus 54.9 years, p = 0.95) and serum cobalt (mean, 5.5 versus 8.5 μg/L, p = 0.09) and chromium concentrations (mean, 2.9 versus 4.2 μg/L, p = 0.27). The association between genotype and revision surgery secondary to ALTRs was determined with gender as a covariate.

RESULTS

The prevalence of the risk genotype was 30% (16 of 54) among the entire cohort. Adjusting for sex, the odds of revision were 6.1 times greater among patients with the risk genotype present than among patients without (95% confidence interval [CI], 1.5-25.4; p = 0.01). Among females, the specificity of the risk genotype was 1.0 (95% CIexact, 0.5-1.0; pexact = 0.03), and for males, it was 0.8 (95% CIexact, 0.6-0.9; pexact < 0.01).

CONCLUSIONS

The findings of this study suggest that, among patients with a primary MoM THA, allelic variation within the HLA Class II loci may be a strong, independent risk factor associated with the need for subsequent revision surgery secondary to pseudotumor formation.

CLINICAL RELEVANCE

Given the hypothesis-generating nature of this novel undertaking, confirmatory prospective clinical studies are required to further elucidate this correlation and to explore the clinical utility of targeted genetic screening in this specific population. This research may, however, represent a key missing piece in the puzzle that is metal ion-induced pseudotumor formation.

CoCr-enriched medium modulates integrin-based downstream signaling and requires a set of inflammatory genes reprograming in vitro

Significant health concerns have been raised by the high levels of Cr and Co ions into whole blood as resulted of corrosion process released from biomedical implants, but very little is known about their biological behavior in governing cell metabolism. Thus, we prompted to address this issue by exploring the effects of CoCr enriched medium on both fibroblast and preosteoblast (pre-Ob) cells. First, we showed there is a significant difference in Co and Cr releasing dependent on engineered surface, it being even more released in dual acid-etching treating surface (named w/DAE) than the machined surfaces (named wo/DAE). Thereafter, we showed CoCr affects pre-osteoblast and fibroblast metabolism by dynamically modulating integrin-based downstream signaling (FAK, Src, Rac1, and Cofilin). Specifically on this matter, we have shown there is dynamic β1-integrin gene activation up 24 h in both preosteoblast and fibroblast. Our analysis showed also that both pre-Ob and fibroblast are important resource of proinflammatory cytokines when responding to CoCr enriched medium. In addition, survival-related signaling pathway was also affected interfering on survival and proliferating signal, mainly affecting CDK2, mapk-Erk and mapk-p38 phosphorylations, while AKT/PKB-related gene remained active. In addition, during cell adhesion PP2A (an important Ser/Thr phosphatase) was inactive in both cell lineages and it seems be a CoCr's molecular fingerprint, regulating specific metabolic pathways involved with cytoskeleton rearrangement. Altogether, our results showed for the first time CoCr affects cellular performance in vitro by modulating integrin activation-based downstream signaling and requiring a reprograming of inflammatory genes activations in vitro. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 839-849, 2018.

Biological effects of metal degradation in hip arthroplasties

Metals and metal alloys are the most used materials in orthopedic implants. The focus is on total hip arthroplasty (THA) that, though well tolerated, may be associated with local and remote adverse effects in the medium-long term. This review aims to summarize data on the biological consequences of the metal implant degradation that have been attributed predominantly to metal-on-metal (MoM) THA. Local responses to metals consist of a broad clinical spectrum ranging from small asymptomatic tissue lesions to severe destruction of bone and soft tissues, which are designated as metallosis, adverse reactions to metal debris (ARMD), aseptic lymphocytic vasculitis associated lesion (ALVAL), and pseudotumors. In addition, the dissemination of metal particles and ions throughout the body has been associated with systemic adverse effects, including organ toxicity, cancerogenesis, teratogenicity, and immunotoxicity. As proved by the multitude of studies in this field, metal degradation may increase safety issues associated with THA, especially with MoM hip systems. Data collection regarding local, systemic and long-term effects plays an essential role to better define any safety risks and to generate scientifically based recommendations.

Impact of Raised Serum Cobalt Levels From Recalled Articular Surface Replacement Hip Prostheses on the Visual Pathway

BACKGROUND

The articular surface replacement (ASR) was recalled in 2010 because of higher than expected revision rates. Patients reported symptoms of neurologic dysfunction including poor vision. This cohort study, using objective measurements, aimed to establish whether a higher incidence of visual function defects exists in ASR patients.

METHODS

Thirty-three ASR patients and 33 non-ASR controls (control 1) were recruited. Data were compared with normative population data from the visual electrophysiology database (control 2). Patients underwent investigations for serum cobalt levels, psychophysical visual tests, and extensive electrophysiological visual testing.

RESULTS

After excluding 2 subjects with pre-existing eye disease, data from 33 ASR patients were compared with the 2 control cohorts. The median serum cobalt level in the ASR group (median, 52 nmol/L [interquartile range, 14-151 nmol/L]) was significantly higher than that in the control 1 cohort (median, 7 nmol/L [interquartile range, 5-14 nmol/L]; P < .0001). The photoreceptor function of patients with an ASR of the hip showed significantly larger electroretinography mixed rod-cone b-wave amplitudes than both control 1 and control 2 cohorts (P = .0294 and .0410, respectively). Abnormalities in macular function as reflected by multifocal and scotopic electroretinography were more prevalent in control 1 (P = .0445 and .0275, respectively). Optic nerve pathway measurements using visual-evoked potential latency was significantly longer in the ASR group compared with those in the control 2 cohort (P = .0201). There were no statistical differences in visual acuity.

CONCLUSION

A statistically significant disturbance in visual electrophysiology was found in the ASR group when compared with the control groups. These differences did not translate to identifiable clinical visual deficits. Orthopedic surgeons need to be aware of the possibility of visual dysfunction in patients with ASR and other metal-on-metal hip arthroplasties; however, routine visual testing is not recommended.

[Titanium or steel as osteosynthesis material : Systematic literature search for clinical evidence]

BACKGROUND

The selection of the appropriate implant material, stainless steel or titanium, is still the decision of the surgeon and/or the affiliated institution. Additionally, remarkable international differences can be found between the different markets, which cannot really be explained.

OBJECTIVE

A systematic literature search was performed to verify whether there is clinical evidence for the preference of one material over the other.

MATERIAL AND METHODS

The systematic literature search was performed utilizing the internet databases PubMed, Cochrane and Web of Science. Comparative studies were included that reported on adult patients with osteosynthesis of extremities after trauma using either stainless steel or titanium implants. Information was extracted about infection rates, incidence of clinically relevant allergies, problems with implant removal and other complications.

RESULTS

A total of 18 publications were identified to be eligible and 2 referenced articles were added. In summary, there is insufficient clinical evidence that the use of titanium or steel implants has a positive or negative effect on fracture healing, shows different rates of allergies, different rates of infections or mechanical failure. No supporting evidence could be identified for the difficulties with removal of titanium implants reported by surgeons.

CONCLUSION

This systematic literature search did not provide any clinical evidence for material-related differences between titanium or stainless steel implants for fracture fixation. Based on the current clinical evidence both titanium and steel implants can be considered to be of equal value. The reported difficulties with implant removal are not reflected in the published literature.

Off-resonance based assessment of metallic wear debris near total hip arthroplasty

PURPOSE

The presence of metallic debris near total hip arthroplasty can have a significant impact on longitudinal patient management. Methods for magnetic resonance imaging-based quantification of metallic debris near painful total hip replacements are described and applied to cohorts of symptomatic and control subject cases.

METHODS

A combination of metal artifact reduction, off-resonance mapping, off-resonance background removal, and spatial clustering methods are utilized to quantify off-resonance signatures in cases of suspected metallosis. These methods are applied to a cohort of symptomatic hip arthroplasties composed of cobalt-chromium alloys. Magnetostatic simulations and theoretical principles are used to illuminate the potential sources of the measured off-resonance effects. Reported metrics from histological tissue assays extracted during surgical revision procedures are also correlated with the proposed magnetic resonance imaging-based quantification results.

RESULTS

The presented methods identified quantifiable metallosis signatures in more than 70% of the symptomatic and none of the control cases. Preliminary correlations of the MR data with direct histological evaluation of retrieved tissue samples indicate that the observed off-resonance effect may be related to tissue necrosis.

CONCLUSIONS

Magnetostatic simulations, theoretical principles, and preliminary histological trends suggest that disassociated cobalt is the source of the observed off-resonance signature. Magn Reson Med 79:1628-1637, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Corrosion of Harrington rod in idiopathic scoliosis: long-term effects

PURPOSE

Metal implants have been used to treat adolescent idiopathic scoliosis since the 1960s. Only recently, however, it has the issue of metal-bone breakdown secondary to metal corrosion in situ come to light, raising concerns of possible long-term complications from the resulting metallosis and inflammation of spinal tissues. We present a case of a patient with neurological deficit, pain, and disability with Harrington rod in place for over 30 years, to bring attention to the issue of bio-corrosion of metal implants and its effect on human tissue. We call attention to the need for protocols to better diagnose and treat these patients.

METHODS

We provide a complete review of the history and clinical manifestations as well as serum metal, X-ray, and CT/myelogram test results.

RESULTS

A 52-year-old female with spinal fusion and Harrington rod presents with pain, lymphedema, disability, and neurological deficits including thoracic outlet syndrome, hyperreflexia, peripheral muscle weakness and atrophy, hypertonicity, Raynaud's phenomenon, and balance and gait abnormalities. Serum chromium levels were elevated (26.73 nmol). X-rays showed no evidence of rod breakdown. Serial X-rays can demonstrate subtle corrosive changes but were not available. Adhesive arachnoiditis was diagnosed via CT/myelogram.

CONCLUSION

We hypothesize that bio-corrosion is present in this case and that it is associated with intraspinal metallosis. Trauma secondary to a motor vehicle accident, as well as arachnoiditis, and their possible effects on this case are outlined. Challenges in proper diagnosis and management are discussed.

Development of malignant lymphoma after metal-on-metal hip replacement: a case report and review of the literature

A number of previous studies have reported a potential risk of malignancy, particularly hematological malignancy, developing in patients receiving a metal-on-metal (MoM) hip replacement. We report a case of malignant lymphoma that arose in a patient who had an MoM hip arthroplasty complicated by development of a pseudotumour. The tumour was a B cell follicular lymphoma that involved lymph nodes and bone. Metal ions are known to have a genotoxic effect on lymphoid cells. Although epidemiological studies have not established that there is an increased risk of lymphoma associated with MoM implants, only a relatively short time period has elapsed since re-introduction of this type of implant and long-term follow-up of patients with MoM implants is indicated.

In vitro cytotoxicity evaluation of nano-carbon particles with different sp2/sp3 ratios

Graphitization occurs during the long-term service of a diamond-like carbon (DLC) modified artificial joint. Then, DLC wear debris, which are carbon particles with different sp²/sp³ ratios and sizes ranging from the nano- to micro-meter scale produced. In this paper, to promote the application of DLC coating for artificial joint modification, the cytotoxicity of DLC debris (nano-carbon particles, NCs) with different sp²/sp³ ratios was studied. The microstructure and physical characteristics of NCs with different sp²/sp³ ratios were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). Meanwhile, osteoblasts and macrophages were applied to characterize the cytotoxicity of the NCs. In vitro cytotoxicity assay results indicated that cells incubated with NCs of different sp²/sp³ ratios had greater osteogenic capacity, and these particles caused a weaker immune response in comparison with CoCrMo particles. Taken together, the results indicated that NCs with different sp²/sp³ ratios presented a good cytocompatibility than CoCrMo particles. But no significant differences were observed among NCs with different sp²/sp³ ratios. The better cytocompatibility of NCs is mainly attributable to their surface charge.

Effects of cobalt and chromium ions on lymphocyte migration

A T cell-mediated hypersensitivity reaction has been reported in some patients with CoCrMo-based implants. However, the role of cobalt and chromium ions in this reaction remains unclear. The objective of the present study was to analyze the effects of Co²⁺ and Cr³⁺ in culture medium, as well as the effects of culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , on the migration of lymphocytes. The release of cytokines/chemokines by macrophages exposed to Co²⁺ and Cr³⁺ was also analyzed. The migration of murine lymphocytes was quantified using the Boyden chamber assay and flow cytometry, while cytokine/chemokine release by J774A.1 macrophages was measured by ELISA. Results showed an ion concentration-dependent increase in TNF-α and MIP-1α release and a decrease in MCP-1 and RANTES release. Migration analysis showed that the presence of Co²⁺ (8 ppm) and Cr³⁺ (100 ppm) in culture medium increased the migration of T lymphocytes, while it had little or no effect on the migration of B lymphocytes, suggesting that Co²⁺ and Cr³⁺ can stimulate the migration of T but not B lymphocytes. Levels of T lymphocyte migration in culture medium containing Co²⁺ or Cr³⁺ were not statistically different from those in culture supernatants of macrophages exposed to Co²⁺ or Cr³⁺ , suggesting that the effects of the ions and chemokines were not additive, possibly because of ion interference with the chemokines and/or their cognate receptors. Overall, results suggest that Co²⁺ and Cr³⁺ are capable of stimulating the migration of T (but not B) lymphocytes in the absence of cytokines/chemokines, and could thereby contribute to the accumulation of more T than B lymphocytes in periprosthetic tissues of some patients with CoCrMo-based implants. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:916-924, 2017.

Serum Metal Concentrations in Patients With Titanium Ceramic Composite Cervical Disc Replacements

STUDY DESIGN

Prospective longitudinal study.

OBJECTIVE

The serum titanium (Ti) concentrations were examined in patients implanted with a PRESTIGE LP Cervical Disc System (Medtronic, Inc., Memphis, TN). The metal-on-metal disc with ball-in-trough articulation is made of titanium alloy/titanium carbide composite (Ti-6Al-4 V/TiC).

SUMMARY OF BACKGROUND DATA

Cervical disc arthroplasty provides a motion-preserving treatment alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The articulating surfaces have a tendency to generate in vivo wear in the form of insoluble particulates (debris) and soluble metal ions. Not much information is available on the long-term metal concentrations observed in cervical disc arthroplasty and how these compare with the metal concentrations in Ti-based posterior fixation devices and other joint replacement implants.

METHODS

Thirty patients were enrolled after strict exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. High-resolution inductively coupled plasma-mass spectrometry was used to assay blood serum titanium concentrations preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months after surgery. The detection limit for Ti was 0.2 ng/mL. The Friedman test was used to make longitudinal statistical comparisons.

RESULTS

The median serum Ti concentrations determined preoperatively, and at 3, 6, 12, 24, 36, 60, and 84 months were 0.10, 1.22, 1.15, 1.27, 1.21, 1.46, 1.34, and 1.42 ng/mL, respectively. The serum Ti concentrations at all postoperative time points were significantly higher than that at the preoperative time point (Friedman P < 0.01).

CONCLUSION

The long-term postoperative serum Ti concentrations were significantly higher than the preoperative concentrations. The observed serum Ti concentrations in this study are lower than the reported concentrations in patients receiving posterior spinal instrumentation and metal or ceramic-on-polyethylene hip prostheses with Ti-alloy based stems and acetabular components.

LEVEL OF EVIDENCE

3.

Cardiac transplant due to metal toxicity associated with hip arthroplasty

Concerns regarding metal-on-metal (MoM) bearing couples in total hip arthroplasty are well documented in the literature with cobalt (Co) and chromium (Cr) toxicity causing a range of both local and systemic adverse reactions. We describe the case of a patient undergoing cardiac transplantation as a direct result of Co and Cr toxicity following a MoM hip replacement. Poor implant positioning led to catastrophic wear generating abundant wear particles leading to Co and Cr toxicity, metallosis, bony destruction, elevated metal ion levels, and adverse biological responses. Systemic symptoms continued for 3 years following cardiac transplantation with resolution only after revision hip arthroplasty. There was no realization in the initial cardiac assessment and subsequent transplant workup that the hip replacement was the likely cause of the cardiac failure, and the hip replacement was not recognized as the cause until years after the heart transplant. This case highlights the need for clinicians to be aware of systemic MoM complications as well as the importance of positioning when using these prostheses.

601 metal-on-metal total hip replacements with 36 mm heads a 5 minimum year follow up: Levels of ARMD remain low despite a comprehensive screening program

BACKGROUND

We conducted a retrospective study to assess the clinical outcome, failure rate, and reason for failure of a large consecutive series of 36 mm MoM Corail/Pinnacle total hip replacements (THRs).

METHODS

Between 2006 and 2011, 601 consecutive 36 mm MoM THRs were performed (585 patients). Patients were followed according to the UK Medicines and Healthcare Products Regulatory Agency (MHRA) guidelines. All patients were accounted for and 469 patients (78%) were clinically and radiographically assessed. 328 females and 141 males with a median age of 73 (range 36-94 years) and a median follow up of 7.2 years (range 5.2-9.7 years) were followed. Clinical data included blood cobalt and chromium, Oxford Hip Score (OHS), plain radiograph, ultrasound of hip and intra-operative findings in those patients who had revision surgery.

RESULTS

56 patients died of causes unrelated to their hip replacement. The mean survivorship of the implant was 92.8% (range 91.6-94%, 95% CI) at a median time to follow up of 84 months (62-113 months). The functional outcome was good with a median OHS of 38 out of 48 (23-44). The dislocation rate was 0.99%, with all these 6 cases requiring revision. 476 patients had blood tests. 100 patients (21%) had elevated levels of either cobalt above MHRA guidelines of 7 parts per billion (120 and 135 nmol/L respectively for cobalt and chromium). Cobalt was elevated independently of chromium in 75% of the cases (but never vice versa). The mean cup inclination angle was 42°. Each incremental stem size increase resulted in a decrease in cobalt by 11 nmol/L. The most common reason for revision was adverse reaction to metal debris (ARMD) (12 cases).

CONCLUSION

This paper is the largest and longest follow up of 36 mm MoM THRs. Using the MHRA guidelines for follow up, the revision rates of this cohort has remained low compared to other studies, but unacceptably higher than that of other bearing surfaces.

LEVEL OF EVIDENCE

III.

The U.S. Department of Veterans' Affairs depleted uranium exposed cohort at 25 Years: Longitudinal surveillance results

BACKGROUND

A small group of Gulf War I veterans wounded in depleted uranium (DU) friendly-fire incidents have been monitored for health changes in a clinical surveillance program at the Veterans Affairs Medical Center, Baltimore since 1994.

METHODS

During the spring of 2015, an in-patient clinical surveillance protocol was performed on 36 members of the cohort, including exposure monitoring for total and isotopic uranium concentrations in urine and a comprehensive assessment of health outcomes.

RESULTS

On-going mobilization of U from embedded fragments is evidenced by elevated urine U concentrations. The DU isotopic signature is observed principally in participants possessing embedded fragments. Those with only an inhalation exposure have lower urine U concentration and a natural isotopic signature.

CONCLUSIONS

At 25 years since first exposure to DU, an aging cohort of military veterans continues to show no U-related health effects in known target organs of U toxicity. As U body burden continues to accrue from in-situ mobilization from metal fragment depots, and increases with exposure duration, critical tissue-specific U concentration thresholds may be reached, thus recommending on-going surveillance of this veteran cohort.

Detection of incorrect manufacturer labelling of hip components

We describe the case of a 53-year-old man who underwent a left metal-on-metal hip resurfacing in 2015. Component size mismatch (CSM) was suspected because of the patient's immediate post-operative mechanical symptoms and high metal ion levels. Surgical notes indicated the appropriate combinations of implants were used. However, we detected a mismatch using computed tomography. Revision was performed and subsequent measurements of explanted components confirmed the mismatch. To our knowledge, this case is the first report of a CT method being used in a patient to pre-operatively identify CSM.

Granulomatous Lung Disease: A Novel Complication following Metallosis from Hip Arthroplasty

A case of a female patient with local and systemic complications of metallosis, following catastrophic wear of a revised hip arthroplasty, is presented. The patient had a history of a fractured ceramic-on-ceramic implant, exchanged with a metal-on-polyethylene prosthesis. Systemic complications included sarcoidosis-like reactions, presenting as granulomatous lung disease, along with chorioretinitis, erythema nodosum, and cardiomyopathy. High local and circulating cobalt and chromium levels established the diagnosis. The patient underwent extensive debridement and implant revision. One year postoperatively, she had no respiratory symptoms or functional impairment. Local and systemic complications of metallosis after hip arthroplasty should be promptly recognized and treated operatively.

Influence of different grained powders and pellets made of Niobium and Ti-42Nb on human cell viability

Nowadays, biomaterials can be used to maintain or replace several functions of the human body if necessary. Titanium and its alloys, i.e. Ti6Al4V are the most common materials (70 to 80%) used for structural orthopedic implants due to their unique combination of good mechanical properties, corrosion resistance and biocompatibility. Addition of β-stabilizers, e.g. niobium, can improve the mechanical properties of such titanium alloys further, simultaneously offering excellent biocompatibility. In this in vitro study, human osteoblasts and fibroblasts were cultured on different niobium specimens (Nb Amperit, Nb Ampertec), Nb sheets and Ti-42Nb (sintered and 3D-printed by selective laser melting, SLM) and compared with forged Ti6Al4V specimens. Furthermore, human osteoblasts were incubated with particulates of the Nb and Ti-42Nb specimens in three concentrations over four and seven days to imitate influence of wear debris. Thereby, the specimens with the roughest surfaces, i.e. Ti-42Nb and Nb Ampertec, revealed excellent and similar results for both cell types concerning cell viability and collagen synthesis superior to forged Ti6Al4V. Examinations with particulate debris disclosed a dose-dependent influence of all powders with Nb Ampertec showing the highest decrease of cell viability and collagen synthesis. Furthermore, interleukin synthesis was only slightly increased for all powders. In summary, Nb Ampertec (sintered Nb) and Ti-42Nb materials seem to be promising alternatives for medical applications compared to common materials like forged or melted Ti6Al4V.

The Sequelae of Metallosis Resulting in Skin Pigmentation and Tattooing: A Case Presentation and Literature Review

With advancing technologies in orthopedics and increasing demands of the population for orthopedic interventions, younger patients are now receiving joint replacements. One of the potential risks of joint replacement is metallosis, or the local and systemic release of metal ions. Metallosis is caused by the release of metallic debris, secondary to hardware failure. The phenomenon is most commonly associated with failed metal-on-metal hip prostheses and is characterized locally by heavy staining of surrounding soft tissue, metallic synovitis, joint effusion, and gradual loosening of the prosthesis. Additionally, metallic debris can also lead to periarticular superficial skin manifestations. The release of metal ions has further been known to lead to systemic upsets including neurologic deficit (declining vision, hearing, or cognition; headaches), cardiac failure, and hypothyroidism. As the number of patients seeking major orthopedic interventions grows, the incidence of metallosis-related skin tattooing will also increase. The structural components of a failed joint replacement can be revised (improving patients' pain and functioning). However, any skin tattooing secondary to metallosis presents the treating dermatologist with clinical challenge, due to lack of research regarding treatment of this condition. Our aim is to review the published literature on metallosis, including the pathophysiology. After assessing publications on the treatment of traumatic and cosmetic tattooing, we hope to stimulate further research regarding treatment. This article should also serve to remind orthopedic surgeons that with increasing patient concern regarding cosmesis, a multispecialty approach including referral to a dermatologist is valuable.

Availability of Total Knee Arthroplasty Implants for Metal Hypersensitivity Patients

Purpose

To provide information on the type of "hypersensitivity-friendly" components available for primary total knee arthroplasty (TKA) in the current market.

Materials and Methods

Implant manufactures were identified using the 2013 National Joint Registries of the United Kingdom and Sweden and contacted to obtain information about the products they offer for patients with metal hypersensitivity.

Results

Information on 23 TKA systems was provided by 13 implant manufacturers. Of these, 15 systems had options suitable for metal hypersensitivity patients. Two types of "hypersensitivity-friendly" components were identified: 10 implants were cobalt chrome prostheses with a "hypersensitivity-friendly" outer coating and 5 implants were made entirely from non-cobalt chrome alloys.

Conclusions

The results of this study suggest that several hypersensitivity TKA options exist, some of which provide the same designs and surgical techniques as the conventional implants. The information in this study can guide TKA surgeons in making informed choices about implants and identifying implants that could be examined in future controlled studies comparing outcomes between "hypersensitivity-friendly" and conventional implants.

Metallosis in shoulder arthroplasty: an integrative review of literature

Shoulder arthroplasty has gained popularity as an efficient means of achieving pain relief and improved function in a variety of complex shoulder disorders. Despite promising reports, given the increasing number of shoulder arthroplasty procedures, various causes that may contribute to failure of a well-functioning arthroplasty are being increasingly recognized. One such disastrous condition is metallosis, a subject which has not been much talked off with reference to shoulder arthroplasty. This article besides reviewing the existing literature intends to discuss the possible causes that contribute to metallosis and devise a protocol for its timely diagnosis and management.

Early Outcomes Following Metal-on-Metal Reverse Total Shoulder Arthroplasty in Patients Younger Than 50 Years

Reverse total shoulder arthroplasty (TSA) is a useful intervention for older patients with glenohumeral arthritis and a deficient rotator cuff. However, as a semiconstrained prosthesis, conventional reverse TSA implanted in a young patient could fail over time secondary to polyethylene wear and subsequent osteolysis. A metal-on-metal prosthesis may avoid this type of failure. The purpose of this study is to assess the outcomes in an initial cohort of young patients who underwent reverse TSA using a metal-on-metal prosthesis. Surgical indications included age younger than 50 years with a functioning deltoid and significant impairment of shoulder function with irreparable rotator cuff due to tumor resection, arthritis, or revision surgery. Nine patients with an average age of 37 years underwent implantation of a custom metal-on-metal reverse TSA prosthesis. All patients had a minimum 12-month follow-up or a failure of their procedure requiring revision surgery prior to 1 year. American Shoulder and Elbow Surgeons (ASES) scores, Constant scores, and range of motion were recorded and analyzed pre- and postoperatively to assess improvement, and all complications were noted. Average ASES score improved from 47 points preoperatively to 73.4 points postoperatively (P=.013). Average Constant and adjusted Constant scores improved from 20.8 points and 16% preoperatively to 61.8 points and 67.3% postoperatively, respectively (P=.019 and P=.068). Mean postoperative active forward flexion and active external rotation were 119.4° and 10°, respectively. Complications included the following: 3 patients sustained a postoperative dislocation, 1 patient had a glenoid fracture and complete loss of fixation of the baseplate, and 1 patient experienced dissociation of the glenosphere from the base-plate. Although metal-on-metal reverse TSA may appear to be an attractive choice in the treatment of young patients with limited reconstructive options, postoperative outcomes are disappointing, and the complication rate is high. [Orthopedics.2016; 39(5):e957-e961.].

Measurement of titanium in hip-replacement patients by inductively coupled plasma optical emission spectroscopy

Background

Patients with metal-on-metal hip replacements require testing for cobalt and chromium. There may also be a need to test for titanium, which is used in the construction of the femoral stem in total hip replacements. It is not possible to use quadrupole inductively coupled plasma mass spectrometry due to interferences.

Methods

Titanium was measured using inductively coupled plasma optical emission spectroscopy using the emission line at 336.1 nm and Y (internal standard) at 371.0 nm. Internal quality control materials were prepared for blood and serum and concentrations assigned using a sector field-inductively coupled plasma mass spectrometer. A candidate whole blood certified reference material was also evaluated.

Results

The method had detection and quantitation limits of 0.6 and 1.9 µg/L, respectively. The respective bias (%) and measurement uncertainty ( U) (k = 2) were 3.3% and 2.0 µg/L (serum) and − 1.0% and 1.4 µg/L (whole blood). The respective repeatability and intermediate precision (%) were 5.1% and 10.9% (serum) and 2.4% and 8.6% (whole blood). The concentration of titanium was determined in patients’ samples, serum (median = 2.4 µg/L, n = 897) and whole blood (median = 2.4 µg/L, n = 189). Serum is recommended for monitoring titanium in patients, since the concentration is higher than in whole blood and the matrix less problematic. In hip fluid samples, the concentrations were much higher (mean 58.5 µg/L, median 5.1 µg/L, n = 83).

Conclusions

A method based on inductively coupled plasma optical emission spectroscopy was developed and validated for measuring titanium in clinical samples.

An unusual presentation of metastatic melanoma in the shoulder

A 72-year-old lady underwent a Copeland hemiarthoplasty of the shoulder for rotator cuff arthropathy with a good functional outcome. Her past medical history included previous management of a malignant melanoma. Several years following arthroplasty surgery, she acutely developed signs and symptoms of prosthetic joint infection. The present case report describes the metastatic spread of malignant melanoma mimicking that of prosthetic sepsis.

The Inflammatory Phenotype in Failed Metal-On-Metal Hip Arthroplasty Correlates with Blood Metal Concentrations

INTRODUCTION

Hip arthroplasty is the standard treatment of a painful hip destruction. The use of modern metal-on-metal (MOM) bearing surfaces gained popularity in total hip arthroplasties during the last decade. Recently, worrisome failures due to adverse reaction to metal debris (ARMD), including pseudotumor response, have been widely reported. However, the pathogenesis of this reaction remains poorly understood. The aim of the present study was to investigate the ARMD response by flow cytometry approach.

METHODS

Sixteen patients with a failed Articular Surface Replacement (ASR) hip prosthesis were included in the study. Samples of pseudotumor tissues collected during revision surgery were degraded by enzyme digestion and cells were typed by flow cytometry. Whole blood chromium and cobalt concentrations were analyzed with mass spectrometry before revision surgery.

RESULTS

Flow cytometry analysis showed that the peri-implant pseudotumor tissue expressed two principal phenotypes, namely macrophage-dominated and T-lymphocyte-dominated response; the average portions being 54% (macrophages) and 25% (T-lymphocytes) in macrophage-dominated inflammation and 20% (macrophages) and 54% (T-lymphocytes) in T-lymphocyte-dominated response. The percentages of B-lymphocytes and granulocytes were lower in both phenotypes. Interestingly, the levels of blood chromium and cobalt were significantly higher in patients with macrophage-dominated response.

CONCLUSIONS

The results suggest that the adverse tissue reactions induced by MOM wear particles contain heterogeneous pathogeneses and that the metal levels are an important factor in the determination of the inflammatory phenotype. The present results support the hypothesis that higher metal levels cause cytotoxicity and tissue injury and macrophages are recruited to clear the necrotic debris. On the other hand, the adverse response developed in association with lower metal levels is T-lymphocyte-dominated and is likely to reflect hypersensitivity reaction.

Hip Arthroplasty Pseudotumors: Pathogenesis, Imaging, and Clinical Decision Making

Pseudotumors are a complication of hip arthroplasty. The goal of this article is to review the clinical presentation, pathogenesis, histology, and the role of diagnostic imaging in clinical decision making for treatment, and surveillance of pseudotumors. We will discuss the multimodal imaging appearances, differential diagnosis, associated complications, treatment, and prognosis of pseudotumors, as an aid to the assessment of orthopedic prostheses at the hip.

Hexavalent chromium induces chromosome instability in human urothelial cells

Numerous metals are well-known human bladder carcinogens. Despite the significant occupational and public health concern of metals and bladder cancer, the carcinogenic mechanisms remain largely unknown. Chromium, in particular, is a metal of concern as incidences of bladder cancer have been found elevated in chromate workers, and there is an increasing concern for patients with metal hip implants. However, the impact of hexavalent chromium (Cr(VI)) on bladder cells has not been studied. We compared chromate toxicity in two bladder cell lines; primary human urothelial cells and hTERT-immortalized human urothelial cells. Cr(VI) induced a concentration- and time-dependent increase in chromosome damage in both cell lines, with the hTERT-immortalized cells exhibiting more chromosome damage than the primary cells. Chronic exposure to Cr(VI) also induced a concentration-dependent increase in aneuploid metaphases in both cell lines which was not observed after a 24h exposure. Aneuploidy induction was higher in the hTERT-immortalized cells. When we correct for uptake, Cr(VI) induces a similar amount of chromosome damage and aneuploidy suggesting that the differences in Cr(VI) sensitivity between the two cells lines were due to differences in uptake. The increase in chromosome instability after chronic chromate treatment suggests this may be a mechanism for chromate-induced bladder cancer, specifically, and may be a mechanism for metal-induced bladder cancer, in general.

Titanium: a review on exposure, release, penetration, allergy, epidemiology, and clinical reactivity

Exposure to titanium (Ti) from implants and from personal care products as nanoparticles (NPs) is common. This article reviews exposure sources, ion release, skin penetration, allergenic effects, and diagnostic possibilities. We conclude that human exposure to Ti mainly derives from dental and medical implants, personal care products, and foods. Despite being considered to be highly biocompatible relative to other metals, Ti is released in the presence of biological fluids and tissue, especially under certain circumstances, which seem to be more likely with regard to dental implants. Although most of the studies reviewed have important limitations, Ti seems not to penetrate a competent skin barrier, either as pure Ti, alloy, or as Ti oxide NPs. However, there are some indications of Ti penetration through the oral mucosa. We conclude that patch testing with the available Ti preparations for detection of type IV hypersensitivity is currently inadequate for Ti. Although several other methods for contact allergy detection have been suggested, including lymphocyte stimulation tests, none has yet been generally accepted, and the diagnosis of Ti allergy is therefore still based primarily on clinical evaluation. Reports on clinical allergy and adverse events have rarely been published. Whether this is because of unawareness of possible adverse reactions to this specific metal, difficulties in detection methods, or the metal actually being relatively safe to use, is still unresolved.

High revision rates with the metal-on-metal Motec carpometacarpal joint prosthesis

We retrospectively evaluated a consecutive series of 42 Motec thumb carpometacarpal total joint arthroplasties. The primary endpoint was revision with implant removal and trapeziectomy. At follow-up the disability of the arm shoulder and hand (DASH) score, pain on numerical rating scale at rest and with activity and serum chrome and cobalt concentrations were assessed for both unrevised and revised patients. At a mean follow-up of 26 months, 17 patients had been revised. The 2 year cumulative revision rate was 42% (95% CI, 28-60%). The DASH score and pain scores at rest and with activity were comparable between the patients whose thumbs remained unrevised and those revised. Patients with elevated serum chrome and cobalt levels had significantly higher DASH and pain scores, but elevated levels were not associated with revision. The revision rate in this study is unacceptably high. However, pain and DASH scores after revision are acceptable and comparable with patients with non-revised implants.

LEVEL OF EVIDENCE

IV.

New Ti-Alloys and Surface Modifications to Improve the Mechanical Properties and the Biological Response to Orthopedic and Dental Implants: A Review

Titanium implants are widely used in the orthopedic and dentistry fields for many decades, for joint arthroplasties, spinal and maxillofacial reconstructions, and dental prostheses. However, despite the quite satisfactory survival rates failures still exist. New Ti-alloys and surface treatments have been developed, in an attempt to overcome those failures. This review provides information about new Ti-alloys that provide better mechanical properties to the implants, such as superelasticity, mechanical strength, and corrosion resistance. Furthermore, in vitro and in vivo studies, which investigate the biocompatibility and cytotoxicity of these new biomaterials, are introduced. In addition, data regarding the bioactivity of new surface treatments and surface topographies on Ti-implants is provided. The aim of this paper is to discuss the current trends, advantages, and disadvantages of new titanium-based biomaterials, fabricated to enhance the quality of life of many patients around the world.