I believe ceramic-on-polyethylene should be used in all patients undergoing THA. I believe the issues that one must look at include wear and osteolysis, bearing fracture and in 2018 corrosion/adverse local tissue reaction (ALTR). If one looks at these aspects it is clear ceramic-on-polyethylene is the bearing of choice. In the literature, there is a paucity of studies comparing metal-on-polyethylene with ceramic-on-polyethylene total hips. The data suggests no real difference in survivorship but less wear. However, most studies are not comparative studies and are underpowered to see these differences. The only data that is powered to see these differences is registry data. In first decade survivorship of metal-on- polyethylene is similar to ceramic-on-polyethylene. However, in the second decade the advantage is clearly with ceramic-on-polyethylene. However, in 2018, the major issue is corrosion and subsequent ALTR. While corrosion at the femoral head and stem taper has been seen for many years, in 2012 an article by Cooper et al. highlighted that this corrosion may lead to ALTR. They reported on 10 cases with variable presentation and no specific factor was found in their study or any study to date that will lead to corrosion and ALTR. More recently, a study from our center highlighted that dislocation may be the first presentation of ALTR. In this study, 10 cases of dislocation presented at an mean of 8 months with their first dislocation. Components were well positioned and it was concluded that the ALTR was the cause for the dislocation. Today any patient with new onset pain, stiffness or instability with a metal-on-polyethylene THA should be worked up for ALTR. The question of why this is happening now is important to answer. Numerous theories have been proposed, most likely it is a combination of these factors: change in trunnion dimension/surface, increasing head size, trunnion preparation and impaction force. It also appears to be stem dependent. In a study by McGrory et al. they found a 1% prevalence of ALTR in just over 1300 cases with one particular femoral stem. At present, however, we cannot predict at all which patient will develop ALTR and therefore we have gone to ceramic-on-polyethylene in all our THAs. In summary, the ideal bearing has low wear, low corrosion potential, generalizable, easy to revise, versatile, biocompatible and safe. In 2018, ceramic-on-polyethylene as a bearing fulfills all these criteria and should be the bearing of choice in total hip replacement

Background. Adverse local tissue reactions (ALTR) in metal-on-polyethylene (MoP) total hip arthroplasty (THA) with head-neck taper corrosion is likely to be multifactorial involving implant and patient factors. However, there is a paucity of clinical data on implant parameters as predisposing factors in MoP head-neck taper corrosion. The aim of this study was to identify any potential implant factors associated with failed MoP THA due to head-neck taper corrosion. Methods. A total of 67 MoP THA patients in two groups was investigated: 1) ALTR (n=38) on MARS MRI and 2) non-ALTR (n=29) on MARS MRI. All patients had highly cross-linked polyethylene liners with cobalt-chromium femoral heads with a single head-neck modularity. Parameters compared between groups included: acetabular component orientation, femoral neck shaft angle, radiographic measurement of medial and vertical femoral offsets, limb length discrepancy, component size, femoral head offset, implant type, femoral stem alloy and taper design. Results. The occurrence of ALTR was associated with increased femoral head offset (non-ALTR vs. ALTR, 0.5 ± 3.7 vs. 4.1 ± 3.6, p = 0.008), increased radiographic femoral stem offset (35.9 ± 7.4 mm vs 40.7 ± 7.1mm, p = 0.018), and the use of TMZF alloy stems (p = 0.051). The presence of ALTR was significantly associated with higher cobalt (9.1 µg/L vs. 0.4µg/L, p=0.001) and chromium (2.6µg/L vs. 0.4µg/L). A significant correlation was identified between the serum cobalt level and the femoral stem offset (R=0.375, p=0.009). Conclusions. Although the occurrence of head-neck taper corrosion in MoP THA is likely to be an interplay between implant and patient factors, the results of this study identified increased femoral head and stem offset and the use of TMZF alloy stems as risk factors associated with clinically relevant ALTR due to head-neck taper corrosion in MoP THA patients. The study provides evidenced-based information in risk stratification of symptomatic MoP THA patients for head-neck taper corrosion. For any tables or figures, please contact the authors directly

High failure rates have been associated with large diameter metal-on-metal total hip replacements (MoM THR). However there is limited literature describing the outcomes following the revision of MoM THR for adverse local tissue reaction (ALTR). A total of 98 large diameter MoM THRs underwent revision for ALTR at our institution. The data was obtained from the clinical records and included the demographics, intra-operative findings of ALTR and post-operative complications. Any subsequent procedures and re-revision for any reason was analysed in detail. The clinical outcome was measured using functional outcome scores using the Oxford hip score (OHS), Western Ontario and McMaster Universities osteo-arthritis index (WOMAC) score and Short Form (SF12). The mean age of the patients at the time of revision was 58.2 yrs. At a mean follow-up of 3.9 years (1.0 to 8.6) from revision for ALTR, there were 15 hips (15.3 %) with post-operative complications and 8 hips (8 %) requiring re-revision. The Kaplan–Meier five-year survival rate for ALTR revision was 91 % (95% confidence interval 78.9 to 98.0). There were no statistically significant predictors of re-revision. The rate of postoperative dislocation following revision was 9.2% (9 hips). The post-operative functional outcome depends on the intra-operative findings of tissue destruction secondary to ALTR. The short term results following revision of large diameter MoM THR for ALTR are comparable with other reports in the literature. The use of constrained liners reduces the incidence of post-operative dislocation. There is an increased risk of postoperative instability following revision THR for ALTR. Early identification and intervention seems to be the logical approach in the management of patients with ALTR

Introduction. Modular dual-mobility constructs reduce the risk of dislocation after total hip arthroplasty (THA). However, questions about metal ions from the cobalt-chrome (CoCr) liner persist, and are particularly germane to patients being revised for adverse local tissue reactions (ALTR) to metal. We determined the mid-term serum Co and Cr levels after modular dual-mobilities used in revision and complex primary THAs, and specifically included patients revised for ALTR. Methods. Serum Co and Cr levels were measured prospectively in 22 patients with a modular dual-mobility construct and a ceramic femoral head. Patients with CoCr heads or contralateral THAs with CoCr heads were excluded. Mean age 64 years with 50% female. The mean follow-up was 4 years. Indications for modular dual-mobility were: periprosthetic joint infection treated with 2-stage exchange and subsequent reimplantation (n=8), ALTR revision (n=7), complex primary THA (n=6), and periprosthetic femoral fracture (n=1). Mean preoperative Co and Cr in patients revised for an ALTR were 29.7 µg/L and 21.5 µg/L, respectively. Results. Mean Co and Cr levels were 0.26 µg/L and 0.82 µg/L, respectively, at most recent follow-up. No patients had a cobalt level ≥1 µg/L. Only one patient had a chromium level ≥1 µg/L. That patient's chromium level was 12 µg/L at 57 months after revision THA for ALTR (and decreased 10-fold from a preoperative Cr of 113 µg/L). Conclusion. At a mean of 4 years, no patient with a modular dual-mobility construct and ceramic femoral head had elevated cobalt levels, including seven patients revised specifically for ALTR. While further studies are required, we support selective use of a modular dual-mobility construct in revision and complex primary THAs for patients at high risk for instability. Summary. At a mean of 4 years after revision or complex primary THAs with a modular dual-mobility construct and a ceramic head, none of 22 patients had serum cobalt levels that measured ≥1 µg/L

Introduction. Failure of metal on metal (MOM) total hip arthroplasty (THA) and resurfacing arthroplasty (HRA) due to development of adverse local tissue reaction (ALTRs) is a significant problem. The prevalence of ALTRs in asymptomatic MOM arthroplasty patients is highly variable. The purpose of this prospective, longitudinal study was to: 1) determine MRI ALTR prevalence in patients with HRA; 2) determine if patients with HRA have a greater rate of MRI ALTRs compared to control patients with ceramic on poly (COP) THA; and 3) evaluate changes in patient reported outcomes between these implant designs. Methods. Following IRB approval with informed consent, self-reported asymptomatic primary COP and HRA patients greater than one year post arthroplasty were evaluated with 4 annual (TP1–4) MRIs using a standardized protocol and serum ion level testing. Morphologic and susceptibility reduced images were acquired for each hip and evaluated for synovial thickness, volume, capsule dehiscence and the presence of ALTR. Patient reported outcomes were evaluated by Hip Disability and Osteoarthritis Outcome Scores (HOOS). Analyses were performed to detect differences of synovial thickness and volume, and HOOS subgroups between and within bearing surfaces at each time point and over time, and to compare the time to and the risk of developing MRI ALTR. Analyses were adjusted for age, gender, and length of implantation. Results. 86 hips were evaluated at the initial time point (TP1): HRA, n=41, age=58±8 y.o., 34/7 (M/F); COP, n=45, age=65±9 y.o., 22/23 (M/F). The mean synovial volume of the subjects was similar at TP1, and the synovial volume in HRA subjects increased significantly from TP1 to TP4 (mean volume difference=9 cm3, p=0.031) while COP subjects displayed a minimal increase from TP1 to TP4 (mean volume difference =0.3 cm3, p=0.9). The synovial volume in HRA subjects tended to be larger and with greater variability than COP subjects at TP4 (HRA=15±58 cm3; COP=6 ±10 cm3, p=0.3). By TP4, MRI ALTRs developed in 13/41 HRA subjects (mean time to ALTR=1.5 yr) compared to 2/25 COP subjects (mean time to ALTR=2.0 yr), p=0.001. While risk of MRI ALTRs in HRA subjects was 9.9 times the risk in COP subjects (p=0.07), 68% of HRA subjects did not have an MRI ALTR present. Significant differences of [Co] and [Cr] in HRA subjects with MRI ALTR present were not detected at 2/4 time points and 1/4 time points, respectively, and there were no significant differences in ion levels in the COP group. The HOOS sub-scores of Pain and Activity of Daily Living scores of HRA subjects were similar to COP subjects, and HRA subjects had better Sporting Ability than COP subjects at all time points. HRA subjects had higher Symptoms at TP1 (p=0.016) but both cohorts had high scores (HRA=92.3/100; COP=87.7/100). Initially dehiscent posterior capsules of HRA subjects (9%) tended not to resolve (10/11, 91%), while dehiscent COP subjects (15%) had greater resolution (6/22, 27%). The presence of osteolysis was limited (HRA: 6/41; COP: 3/45; p=0.101). Conclusion. A greater synovial volume and higher rate of MRI ALTRs was found in HRA subjects, while the patient symptomatology via HOOS remained slightly better in HRA subjects than COP subjects, suggesting a poor association between MRI ALTRs and symptoms. The presence of posterior decompression of the posterior capsule into the bursa alone was not necessarily indicative of an ALTR, and is likely a normal postoperative finding. The inconsistent findings of the serum ion level testing further supports MRI as a non-invasive imaging modality capable of assessing peri-prosthetic soft tissue complications, and should be considered as part of the routine patient follow up to allow early detection and monitoring of ALTRs

Recently, corrosion at the head-neck junction in metal-on-polyethylene bearing total hip arthroplasty (THA) has been recognized as a cause of adverse local tissue reactions (ALTR). Serum metal levels have been advocated as a tool for the diagnosis of ALTR, however no prior studies have specifically examined their utility. The purpose of this study was to determine the optimal cut-off values for serum cobalt and chromium in diagnosing ALTR after metal-on-polyethylene bearing THA. We reviewed 447 consecutive patients with serum metal levels tested at our institution and identified 62 with a metal-on-polyethylene bearing who had axial imaging or underwent reoperation to confirm the presence or absence of ALTR. Receiver operating characteristic curves were produced to identify cut-off thresholds to optimize sensitivity and diagnostic test performance was characterized. 42 Of the 62 patients (66%) were positive for an ALTR. The best test for the diagnosis of ALTR was the serum cobalt level (area under the curve [AUC]=99%). A threshold cut-off of ≥ 1.0 ng/ml had a sensitivity of 100%, specificity of 90%, positive predictive value (PPV) of 96%, and negative predictive value (NPV) of 100%. Serum chromium levels were also diagnostic (AUC=87%). A threshold cut-off of ≥ 0.15 ng/ml had a sensitivity of 100%, specificity of 50%, PPV of 81%, and NPV of 100%. Finally, serum cobalt to chromium ratio was also helpful for diagnosis (AUC=90%). A threshold cut-off of 1.4 for the cobalt to chromium ratio offered a sensitivity of 93%, specificity of 70%, PPV of 87%, and NPV of 82%. Measurement of serum cobalt with a threshold value of 1.0 ng/ml in our experience is the best test for identifying the presence of ALTR in patients with a metal-on-polyethylene THA. Measurement of chromium and the ratio of cobalt to chromium are also of value

Introduction:. To date, there have been few reports of the results of revisions for failed metal-on-metal hip arthroplasties (MoM HA's). These series have included relatively modest numbers, and classification of the severity of adverse local tissue reaction (ALTR) has been under-reported. In this study, early outcomes and complications are analyzed as a function of pre-operative MRI grade and intra-operative ALTR severity to determine their prognostic value. Methods:. This is a retrospective review of revisions of 121 failed MoM HA's performed between 2008 and 2012. Indications for revision include ALTR (n = 97), loose cup (n = 13), and combined loose cup and ALTR (n = 11). When pre-operative MRI's were available, these were graded according to Anderson's system by 2 radiologists who were blinded to the clinical results. Intra-operative findings were graded for severity according to an ALTR classification. Post-operative complications were recorded. Correlations between pre-operative MRI grade, intra-operative ALTR classification and post-operative complications were analyzed using Spearman's rank correlation. ALTR Classification:. Type 0: No abnormal fluid or pseudotumor. Peri-articular structures intact. Type 1: Abnormal fluid and/or pseudotumor. Peri-articular structures disrupted but repairable. Type 2: Abnormal fluid and/or pseudotumor. Peri-articular structures disrupted and no meaningful repair possible. Type 3: Abnormal fluid and/or pseudotumor. Peri-articular structrues disrupted, no meaningful repair possible, AND significant necrosis involving abductor muscles. Results:. The average time to revision was 47 months (range: 7–198 months). In cases where the cup required revision, the average increase in outer diameter was 4.1 mm (range: 2–10 mm). Average revision head size was 38 mm (range: 32–48 mm). 19 patients (16%) experienced at least one complication which included dislocation (n = 12/10%), infection (n = 6/5%), recurrent pseudotumor requiring surgery (n = 2/1.7%), and VTE (n = 1/0.9%). The pre-operative MRI grade correlated significantly with the intra-operative ALTR classification (p = 0.03), and both the MRI grade and ALTR classification correlated significantly with post-operative complications (p < 0.01). Among the 23 patients with the most severe ALTR's (Type 2 and 3), 11 patients (48%) experienced complications. Conclusion:. Revisions for failed MoM HA's can be heterogenous with varying degrees of soft tissue compromise. Despite the use of large femoral head sizes in the current series, the overall dislocation rate was 10%. The pre-operative MRI grade and intra-operative ALTR classification have good prognostic significance and may alert the surgeon and patient to an increased potential for complications after surgery

Increased failure rates due to metallic wear particle-associated adverse local tissue reactions (ALTR) is a significant clinical problem in resurfacing and total hip arthroplasty. Histological analysis and particle characterization are important elements for understanding the biological mechanisms of the reaction and different histological subtypes may have unique needs for longitudinal clinical follow-up and complication rates after revision arthroplasty. Consecutive patients (N=285 cases) presenting with ALTR from three major hip implant classes, metal-on-metal resurfacing and total hip arthroplasty (THA) and non-metal-on-metal THA with dual modular neck were identified from our prospective Osteolysis Tissue Database and Repository and 53 cases were selected for wear particle nano-analysis. Conventional histology: Tissue samples taken from multiple regions around the hip with extensive sampling performed at macroscopic examination were examined by light microscopy. Particle analysis: Tissue samples selected after frozen section evaluation for cellularity and particle content were examined by scanning electron microscopy (SEM), backscatter scanning electron microscopy (BSEM), BSEM-energy-dispersive X-ray spectroscopy (EDS) element mapping examination, transmission electron microscopy (TEM), TEM-EDS element mapping, and X-ray diffraction spectrometry (XRD) examination. ALTR encompasses three main histological patterns: 1) macrophage predominant, 2) mixed lymphocytic and macrophagic, and 3) predominant sarcoid-like granulomas. Duration of implantation and composition of periprosthetic cellular infiltrates was significantly different among the three implant types examined. Distinct differences in the size, shape, and element composition of the metallic particulate material were detected in each implant class, with correlation of the severity of the adverse reaction with element complexity of the particles. ALTR encompasses a diverse range of histological patterns, which are reflective of both the implant configuration independent of manufacturer and clinical features such as duration of implantation. Distinct differences in the metallic particulate material can contribute to explain the histological features of the ALTR and variability of performance of the implants. ALTR exhibits different histological patterns and is dependent on the characteristics of the wear particulate material of each implant class and host immunological reaction

INTRODUCTION. Corrosion of modular tapers is increasingly recognized as a source of adverse tissue reaction (ALTR) and revision surgery in total hip arthroplasty (THA). The incidence of corrosion and rate of revision for ALTR may differ among different types of implants. OBJECTIVE. The objective of this study was to determine if a difference exists in rate of THA revision for corrosion and ALTR with tapered broach only stems compared to ream-broach femoral stems. METHODS. We reviewed the results of 3741 primary THA performed over a 5 year period at our institution using 2 different implants by the same manufacturer, a tapered proximally coated cementless titanium stem inserted via a broach only technique (Group A) and dual tapered proximally coated cementless titanium stem inserted via a ream and broach technique (Group B). RESULTS. Of 1567 THA in group A, 964 were combined with a chrome cobalt metal head, while 603 were ceramic. Of 2174 THA in group B, 1302 were metal and 872 were ceramic. Head sizes used were similar between groups. The same polyethylene was used in all THA. At a minimum follow-up of 2 years and average follow-up of 5 years, the overall revision rate for all causes was 3.1% in group A and 1.4% in group B. There were 29 revisions for ALTR due to corrosion of the morse taper junction in group A (3.4%) and 0 in group B. Univariate and multivariate analysis indicated no relationship between revision for corrosion/ALTR and age, gender, stem size, stem offset and head size. A significant relationship was identified between revision and head length, with an increased rate of revision among longer head lengths. There were no revisions for corrosion, ALTR or unexplained pain among patients receiving ceramic heads in either group. CONCLUSION. There was a significant difference in the rate of revision for corrosion and adverse tissue reaction encountered with the use of stem A when compared to stem B. The stem geometry, taper geometry and exact metallurgy of these femoral components likely influences the incidence and severity of taper corrosion, however, more research is required to identify the exact contributions of these factors

Aims. Advances in surgical technique and implant design may influence the incidence and mechanism of failure resulting in revision total hip arthroplasty (rTHA). The purpose of the current study was to characterize aetiologies requiring rTHA, and to determine whether temporal changes existed in these aetiologies over a ten-year period. Methods. All rTHAs performed at a single institution from 2009 to 2019 were identified. Demographic information and mode of implant failure was obtained for all patients. Data for rTHA were stratified into two time periods to assess for temporal changes: 2009 to 2013, and 2014 to 2019. Operative reports, radiological imaging, and current procedural terminology (CPT) codes were cross-checked to ensure the accurate classification of revision aetiology for each patient. Results. In all, 2,924 patients with a mean age of 64.6 years (17 to 96) were identified. There were 1,563 (53.5%) female patients, and the majority of patients were Caucasian (n = 2,362, 80.8%). The three most frequent rTHA aetiologies were infection (27.2%), aseptic loosening (25.2%), and wear (15.2%). The frequency of rTHA for adverse local tissue reaction (ALTR) was significantly greater from 2014 to 2019 (4.7% vs 10.0%; p < 0.001), while the frequency of aseptic loosening was significantly greater from 2009 to 2013 (28.6% vs 21.9%; p < 0.001). Conclusion. Periprosthetic joint infection was the most common cause for rTHA in the current cohort of patients. Complications associated with ALTR necessitating rTHA was more frequent between 2014 to 2019, while aseptic loosening necessitating rTHA was significantly more frequent between 2009 to 2013. Optimizing protocols for prevention and management of infection and ALTR after THA may help to avoid additional financial burden to institutions and healthcare systems. Cite this article: Bone Joint Open 2020;2(1):16–21

Introduction. Modular neck (MN) components in total hip arthroplasty (THA) offer intraoperative flexibility, but adverse local tissue reactions (ALTR) due to tribocorrosion at modular junctions are a potential complication of such designs. Serum ion levels and metal artifact reduction sequence (MARS) MRI are used to assess ALTR following modular THA. This study investigates serum ion levels and MARS MRI findings in a series of hips with MN components and differing articulating surfaces. Methods. We retrospectively evaluated a cohort of 184 primary THAs in 159 patients implanted with a dual modular femoral stem by one surgeon from 2005–2013. 121 THAs had a cobalt-chromium neck component and non-metal-on-metal articulation, while 63 THAs had a titanium neck component and metal-on-metal (MoM) articulation. Serum ion levels were recorded for all patients. MARS MRI scans were read by musculoskeletal-trained radiologists. Pseudotumor grade and location were measured. Results. Serum cobalt levels as a function of time post-operatively demonstrated no correlation. In THAs with non-MoM articulation, pseudotumors were visualized in 13 of 54 (24.1%) initial MARS MRIs performed 1–40 months post-operatively compared to 5 of 67 (7.5%) performed 41–120 months post-operatively (p=0.02), and findings typically remained consistent across multiple MARS MRI scans. Pseudotumors were generally located lateral to the hip joint in hips with non-MoM articulation compared to anteromedial following MoM arthroplasty. In the cobalt-chrome MN group, cobalt levels were elevated in 11 of 20 (55%) of patients with pseudotumor compared to 15 of 19 (79%) in the MoM group. Conclusion. Generation of ALTR leading to pseudotumor formation is a concern with cobalt-chrome MN designs. Psuedotumor characteristics differ between patients with cobalt-chrome designs versus MoM articulation. Normal serum ion levels did not exclude the presence of a pseudotumor and routine MARS MRI should be included in follow-up of patients with cobalt-chromium MN prostheses

Adverse local tissue reactions (ALTR), such as so-called pseudotumours associated with metal-metal bearings, can also occur secondary to corrosion products from modular tapers where at least one side is composed of cobalt alloy. In 1988, Svensson et al. reported a fulminant soft-tissue pseudotumour following a cementless, metal-on-polyethylene total hip. This case had all of the features of ALTR that were subsequently observed in association with contemporary large diameter metal-metal bearings, having the same histological characteristics that Willert and colleagues termed ALVAL in 2005. There is a documented increased risk of femoral taper corrosion in association with larger diameter (>32 mm) metal-metal bearings. There may be a generic increase in the risk of taper corrosion with larger diameter bearings, regardless of acetabular bearing type. Other variables include the design and manufacturing tolerances of the taper and head, the stiffness of the neck, implantation time, and possibly in vivo assembly. Head and neck moment arm and neck length have not been demonstrated to be independent risk factors for taper corrosion or fretting. Retrieval analyses indicate that fretting and corrosion tend to be higher on the head than on the stem. ALTR has similarly been described in association with corrosion of the modular neck-stem junction. Taper corrosion is the probable explanation for elevated ion levels and ALTR in association with well-positioned metal-metal total hip bearings and low bearing wear. Whole blood or serum metal levels are elevated with a greater elevation of cobalt compared to chromium. Ion analyses are now relatively accessible and reliable and should be obtained in the evaluation of a painful total hip without an obvious cause. Cross-sectional imaging, such as a MARS MRI scan, can demonstrate associated changes in the periprosthetic tissues and secure the diagnosis. Treatment recommendations are similar to those established for hips with metal-metal bearings and ALTR. Removal of the modular cobalt alloy head and/or neck component is recommended. At this time, there are no established criteria for the degree of “acceptable” femoral taper damage. The dilemma faced by the revising surgeon is whether to expose the patient to the potential morbidity associated with revision of a well-fixed femoral stem, particularly a distally-fixed, extensively porous-coated stem, in the setting of mild-to-moderate fretting and corrosion of the femoral taper. Several manufacturers offer ceramic heads with a titanium alloy taper sleeve inside the head specifically for mating to previously used femoral tapers. It is not recommended to put a ceramic head taper directly onto a used femoral taper. Surface damage of the used femoral taper can create high localised stresses in the ceramic head and predispose to head fracture. The same principles can be applied to corrosion of a stem-neck taper. If the modular neck is made of cobalt alloy, it is preferable to exchange it for one made of titanium alloy (if available). Again, there are no established criteria for the degree of “acceptable” femoral taper damage. The paucity of reported experience with such revisions inhibits further comment at this time. It is prudent to be suspicious of “taperosis” considering that the majority of heads used over the past 5 years are cobalt alloy and >36 mm in diameter, many contemporary stems have narrower, and hence more flexible necks, some tapers are smaller (shorter), more variable in vivo assembly secondary to “minimally invasive” surgical techniques, and the risk of taper corrosion increases with time in situ. Additional studies are needed to determine the incidence of clinically significant taper corrosion. There are more than 30 different head-stem tapers worldwide and the incidence of clinically significant taper corrosion is likely variable for different head-stem combinations. Similar to ALTR that occur with metal-metal bearings, some cases of ALTR secondary to taper corrosion may be asymptomatic

Introduction. Neck-stem corrosion has been associated with Adverse Local Tissue Reaction (ALTR) in dual-taper femoral stems. Several diagnostic tests, of varying specificity and sensitivity, are used to identify ALTR. The purpose of this study was to document the clinical presentation, diagnostic workup and surgical findings in a large cohort of patients with dual modular stems, and use this information to propose an evaluation protocol that assists surgical decision-making. Methods. This is a single center, single surgeon's retrospective case series of 38 patients who underwent 42 primary total hip arthroplasty (THA) with a dual-taper femoral components between March 2010 and May 2011 The evaluation included clinical exam, hip radiographs, labs including serum metal ion levels, metal artifact reduction sequence magnetic resonance imaging (MARS MRI), and fluoroscopic hip aspiration with qualitative and quantitative assessment of synovial fluid. Each hip aspirate was classified into Class 1 (clear, <10cc), 2(brown, clear, >10cc), or 3 (cloudy, turbid, viscous). 20 patients to date have undergone revision THA. Results. 19/42 hips were symptomatic. Serum cobalt levels were elevated in 38/42 patients. 23/42 had abnormal MRI findings. MRI was able to identify abnormalities in 79% (15/19) of symptomatic patients and 35% (8/23) asymptomatic patients. Class 2 and 3 hip aspirates were associated with abnormal MRI (in 86% and 61%, respectively), elevated Cobalt, and a high rate of revision (71% and 72%, respectively). ESR and CRP were normal in most patients (76% and 66%, respectively). A small subset of patients (2/38) with symptoms, normal metal ion levels and normal MRI, had abnormal aspirates (Class 2 or 3) with extensive tissue necrosis at revision. Conclusion. The diagnosis of ALTR can be challenging and requires integrating data from several sources: clinical exam, radiographs, serum metal testing, MARS MRI and hip aspirations. Hip aspiration appears to be useful not only in excluding infection, as proposed in current literature, but also in identifying ALTR in patients with otherwise normal tests. Abnormal results on MARS MRI and/or hip aspiration appear to be most predictive of surgical pathology. Both should be included in the protocol to evaluate for underlying ALTR in patients with dual-taper femoral stems

Introduction. Taper corrosion at modular junctions can cause a spectrum of adverse local tissue reactions (ALTR) in the periprosthetic soft tissues in patients who have undergone total hip arthroplasty (THA). Because these reactions are usually painful, taper corrosion has become part of the differential diagnosis of hip pain following THA. However these destructive lesions may not always cause pain, and can occasionally result in other atypical presentations. The purpose of this study is to describe a cohort of patients presenting with late and recurrent instability following THA due to underlying ALTR and taper corrosion. Methods. This is a multicenter retrospective case series of fourteen patients presenting with late instability secondary to ALTR and corrosion at the modular head-neck taper. The cohort included nine women and five men with a mean age of 66.8 years (range, 49 to 74). All patients had a metal (CoCr)-on-polyethylene bearing surface, but had a range of CoCr and Ti-alloy stem designs from three different manufacturers. Seven patients had 28 mm heads, while the rest had 32–40 mm heads. Patients experienced a mean of 3.4 dislocations (range, 2 to 6) at an average of 5.2 years (range, 0.4 to 17.0) following their index surgery. Although most reported some degree of discomfort around the hip, instability was the primary presenting symptom in all fourteen patients, and four were otherwise completely asymptomatic. Serum metal levels demonstrated a greater elevation of cobalt (mean 3.13 ng/mL) than chromium (mean 2.33 ng/mL). Preoperative infection workup including serum inflammatory markers and a hip aspiration documented the absence of sepsis. Results. Radiographic analysis demonstrated cups were well positioned, with a mean abduction angle of 43.2° (range, 40° to 48°) and mean anteversion angle of 19.5° (range, 16° to 26°). Hips were revised at a mean of 7.4 years (range, 2.4 to 19.4) following their index surgery. At the time of revision, ALTR was encountered in every case, with extensive tissue necrosis and abductor damage or insufficiency in the majority. The modular head-neck junction demonstrated visible corrosion seen as fretting, surface damage, and deposition of a black, flaky material. Constrained liners were placed in all patients. Conclusions. Although ALTR resulting from modular taper corrosion typically presents with hip pain, some patients can present with recurrent instability in the absence of other significant symptoms. Recurrent instability in the setting of otherwise well-positioned components and without another obvious cause should raise concern for ALTR as a potential underlying etiology

Introduction. Complication and revision rates have shown to be high for all metal-on-metal (MoM) bearings, especially for the ASR Hip System (ASR hip resurfacing arthroplasty (HRA) and ASR XL total hip arthroplasty (THA)). This prompted the global recall of the ASR Hip System in 2010. Many studies have previously explored the association between female gender and revision surgery MoM HRA implants; yet less research has been dedicated to exploring this relationship in MoM THA. The first purpose of this study was to assess the associations between gender and implant survival, as well as adverse local tissue reaction (ALTR), in patients with MoM THA. Secondly, we sought to report the differences between genders in metal ion levels and patient reported outcome measures (PROMs) in patients with MoM THA. Methods. The study population consisted of 729 ASR XL THA patients (820 hips) enrolled from September 2012 to June 2015 in a multicenter follow-up study at a mean of 6.4 (3–11) years from index surgery. The mean age at the time of index surgery was 60 (22–95) years and 338 were women (46%). All patients enrolled had complete patient and surgical demographic information, blood metal ion levels and PROMs obtained within 6 months, and a valid AP pelvis radiograph dating a maximum of 2 years prior to consent. Blood metal ion levels and PROMs were then obtained annually after enrollment. A sub-set of patients from a single center had annual metal artifact reduction sequence (MARS) MRI performed and were analyzed for the presence of moderate-to-severe ALTR. Results. Eighty-nine hips (11%) were revised during the study period. Forty-five of the 338 men underwent revision (13%), and 44 of the 391 women underwent revision (11%). The mean time from index surgery to revision was 7 years for both males and females. After controlling for confounding variables, the only variables found to be associated with revision surgery in patients with unilateral THA were VAS pain (hazard ratio [HR], 1.28; p < 0.001) and elevated cobalt metal ion levels (HR, 1.02; p < 0.001). Patients with bilateral arthroplasties with low HHS (HR, 0.96; p < 0.001) and high cobalt levels (HR, 1.02; p < 0.001) were at increased risk for revision. Moderate-to-severe ALTRs were identified in 48 of the 133 hips with MARS MRI (36%), 17 of which were in females (30% of females) and 31 in males (40% of males). The only variables found to be associated with the presence of moderate-to-severe ALTR were abduction angle (HR, 0.92; p = 0.004) and Corail AMT stem type (HR, 2.31; p = 0.012). Female gender did not influence the risk of revision or ALTR. Chromium concentrations were greater in female patients than males, while cobalt levels were similar between genders. Males reported higher HHS, EQ-5D and UCLA scores than females. Discussion and Conclusion. Both males and females with MoM THA implants should be followed with equal vigilance as gender does not appear to be associated with poor outcomes, such as revision surgery and presence of ALTR

Background. Reasons for revision of metal-on-metal hip resurfacing arthroplasty (MoMHRA) have evolved with improving surgical experience and techniques. Early revisions were often due to fracture of the femoral neck while later revisions are associated with loosening and/or adverse local tissue reactions (ALTR) to wear debris. In some studies, revisions of MoMHRA with ALTR have been complicated by an increased risk of rerevision and poor outcome. The purpose of this study was to investigate the causes of failure and to identify factors that improve outcome following revision of a failed HRA. Methods. From 2001 to May 2015, 180 consecutive HRA revisions were performed in 172 patients. Ninety-nine primary surgeries were done at a HRA specialist centre (99/4211, revision rate: 2.4%), 81 elsewhere. Eight different HRA designs were revised mainly in females (60%). Components’ orientation was measured from radiographs using EBRA. Ion levels were used as a diagnostic tool since 2006 (n=153). Harris-Hip-Score (HHS) was obtained prerevision and at latest follow-up. The initial experience of the first 42 cases (Initial Group) was compared to cases 43–180 (Later Group). Patients of the Later group were noted to have less soft tissue damage, had significantly bigger THA heads implanted at surgery, were educated of the increased complication risk and some wore an abduction brace for 6 weeks. Results. All patients presented with some pain/discomfort. Mean time to revision was 38 months (0–160). Eight HRAs were revised for fracture and 8 for infection. The most common reason for revision was component malpositioning (acetabular 48%, excessive abduction and/or anteversion; femoral 10%) usually associated with high metal ions (62%). The most common intra-operative finding was ALTR (48%) followed by metallosis (36%) and impingement (29%). Metal sensitivity was suspected in 8 patients (6F/2M). There were gender-specific differences in component sizes and causes of failure, with a higher incidence of component malpositioning, osteolysis and elevated metal ions in women. Time to revision in patients with high metal ion levels was shorter with the ASR (21 months, SD:10) in comparison to the BHR (38 months, SD: 25) (p=0.05). For the whole cohort, HHS significantly improved post revision (93, 42–100) (p<0.001). Fourteen complications (9 dislocations; 5 infections) and 9 re-revisions occurred. Outcome {HHSpost-op (p=0.04), complication and re-revision rates (p=0.005)} was significantly better in the Later Group compared to the Initial group. The incidence of complications/re-revisions significantly reduced since the introduction of metal ions (p=0.004). The presence of ALTR did not significantly affect outcome (p=0.65). However, patients with ALTR in the Later group (n=51) had significant reduced complication(p=0.005) and re-revision(p=0.016) rates in comparison to those in the Initial Group. Conclusion. Component malpositioning is the most common cause of HRA failure. Metal ion measurements are an excellent tool to detect wear at an early stage. The revision analysis highlights the importance of surgical experience, indications and prosthesis design. Use of ion levels, big THA-heads and patient education/compliance were identified as factors improving outcome following HRA revision. Patients with soft tissue reactions can have good outcome if operated prior to extensive soft tissue destruction

Introduction. There have been increased concerns with trunnion fretting and corrosion and adverse local tissue reactions (ALTR) in total hip arthroplasty. We report on 11 catastrophic trunnion failures associated with severe ALTR requiring urgent revision arthroplasty. Methods. We retrospectively reviewed 10 patients with gross trunnion failure (n=11) and an additional 3 patients with impending trunnion failure. Results. All patients presented to the emergency department with severe pain, an inability to bear weight, and dramatic radiographs demonstrating implant failure. Patients were an average of 7.8 years from the initial index procedure. Implants were a cementless component with metal on polyethylene bearing from a single manufacturer with a 36mm femoral head size and a range of extended offset of 2.5 to 5.5 and neck length of +0 (n=1), +5 (n=5), and +10 (n=5). The implant was used during a limited time (2.5 years) by single surgeon in our practice using a posterior approach, with the last implant placed 7 years ago. Prior to revision, serum cobalt levels were elevated, typically more than chromium levels. Radiographs demonstrated failure of the implant with a dissociation of the head from the taper and large radiolucent fluid collections from the metal debris (Fig 1). Intraoperative findings and magnetic resonance imaging confirmed a diagnosis of ALTR with loss of abductors, and severe material loss from the taper (Fig 2). We estimate a conservative incidence of catastrophic trunnion failure in our series to be 2.2% (n = 636 total implanted). A femoral revision with a modular Wagner stem was performed, and when necessary the acetabulum was revised secondary to destruction of the locking mechanism from mechanical wear. Discussion and Conclusion. ALTR can occur in patients with catastrophic failure of their trunnion. Radiographs are dramatic. Serum metal ion levels and magnetic resonance imaging is comparable to adverse local tissue reaction in metal on metal bearing surfaces, corrosion at the head neck taper, and corrosion of dual modular taper stems. The initiating events leading to this mechanism of trunnion failure is unknown. We observed trunnion failure at large head sizes and at increased femoral head offsets. Other groups have reported an association of trunnion failure at increased neck length and head size with a variety of manufacturers. Based on our experience, we have been able to identify impending failure based on subtle radiographic criteria and elevated metal ion levels. A failure rate of 2% at 7.8 years is non-trivial. Impending trunnion failure should be considered as a possible diagnosis in a painful total hip arthroplasty with unknown etiology. Serum metal ion levels and magnetic resonance imaging should be obtained as part of the initial evaluation

Abstract. Objective. The aim of our systematic review was to report the latest evidence on the effects of CoCr particles on local soft tissue with a focus on its clinical relevance. Methods. PubMed, Embase, and Cochrane Library databases were screened to perform an extensive review. Inclusion criteria were studies of any level of evidence published in peer-reviewed journals reporting clinical and preclinical results written in English. Relative data were extracted and critically analyzed. PRISMA guidelines were applied, and the risk of bias was assessed, as was the methodological quality of the included studies. Results. 30 studies were included after applying the inclusion and exclusion criteria. Of these, 24 were preclinical studies (18 in vitro human studies, 6 animal modal studies, including 3 in vitro and 3 in vivo), 5 were clinical studies and 1 was previous review on similar topic. The presence of metal ions causes cell damage by reducing cell viability, inducing DNA damage, and triggering the secretion of cytokines. Mechanisms of apoptosis, autophagy and necrosis are responsible for the inflammatory reaction observed in ALTR. Conclusion. The available literature on the effects of CoCr particles released from MoM implants shows that metal debris can cause damage to skeletal muscle, the capsule, and provoke osteolysis and inflammation. Therefore, the cytotoxic and genotoxic damages, as well as the interaction with the immune system, affect the success of the arthroplasty and lead to a higher rate of revision surgeries. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Wear debris and metal ions originating from metal on metal hip replacements have been widely shown to recruit and activate macrophages. These cells secrete chemokines and pro-inflammatory cytokines that lead to an adverse local tissue reaction (ALTR), frequently requiring early revision. The mechanism for this response is still poorly understood. It is well documented that cobalt gives rise to apoptosis, necrosis and reactive oxygen species generation. Additionally, cobalt stimulates T cell migration, although the effect on macrophage motility remains unknown. This study tests the hypothesis that cobalt ions and nanoparticles affect macrophage migration stimulating an ALTR. Methods. This study used Co. 2+. ions (200µM) and cobalt nanoparticles (CoNPs, 100µM, 2–60nm diameter). PMA differentiation of the U937 cell line was used as macrophage-like cells. The effect of cobalt on macrophage migration was investigated by live cell imaging. After 12 hours of each treatment, timelapse images of 20 cells were collected over a 6 hour period with images captured every 5 min. Migration of individual cells was tracked in 2D using ImageJ software. The transwell migration assay was also applied to study the effect of cobalt on macrophage directional migration. U937 cells in serum free medium were added to the upper chamber of a 8µm pore size Transwell insert in the presence of cobalt, whilst the lower chamber was filled with medium plus 10% FBS. After 6 hours treatment, cells remaining on the membrane were fixed, stained with crystal violet and counted. Cellular F-actin and podosomes were visualized by labeling with TRITCconjugated phalloidin and anti-vinculin antibody after 12 hours of cobalt exposure (Co. 2+. and CoNPs). Results. Cells incubated with cobalt ions and nanoparticles showed a substantial reduction in cell migration compared with control cells. The total migration path length of cells treated with Co. 2+. (362.4±96.6µm) and CoNPs (217.3±128.1µm) were significantly shorter than those for untreated cells (801.1±198.3µm). The ability of macrophages to migrate through the transwell membrane was significantly impaired by pre-treatment with cobalt, with 16±4 and 18± migrated cells/field for Co. 2+. and CoNPs respectively with the control at 42±7 migrated cells/field. In addition, cobalt influenced macrophage morphology and actin cytoskeletal organization with a dramatic increase in the presence of intracellular podosome-type adhesions structure. Discussion. Co. 2+. ions and nanoparticles dramatically inhibited the migration of U937 macrophages in contrast to the enhanced migration reported for T cells. We propose that macrophages recruited into the area of CoCr implants would lose their responsiveness to migration signals and be retained in situ due to cobalt-induced cytoskeleton rearrangement. This enhanced macrophage accumulation and cobalt-induced formation of podosomes may therefore represent a mechanism through which cobalt wear debris and metal ions from joint prostheses exacerbate the ALTR leading to revision surgery

INTRODUCTION. Metal-on-metal hip resurfacing (MoMHRA) requires a new standardized radiographic evaluation protocol. Evaluation of the acetabular component is similar to total hip arthroplasty but the femoral component requires different criteria since there is no component in the femoral canal and the metallic femoral implant overlies the junctions between bone-cement and cement-prosthesis. Lucencies around the metaphyseal HRA femoral stem can be described with the femoral zonal system into 3 peg-zones (Amstutz' et al) but this doesn't account for bony changes of the femoral neck away from the stem. This study proposes a new femoral zonal system for radiographic HRA assessment. We tested the efficacy of radiographs in identifying a problem by reviewing 711 radiographs of resurfaced hips and correlating radiographic features to outcome. METHODS. 611 in-situ HRA (one surgeon) with minimum two radiographs at >12 months postoperatively and 100 revised HRA (55 referred) were assessed for component positioning, reactive lines±cortical thickening±cancellous condensation (borderline) and lucent lines±osteolysis±bone resorption (sinister). Findings around the acetabular implant were classified in six zones: Zones I-III equally distributed acetabular zones (DeLee-Charnley); Zone IV, V and VI situated in the iliac, pubic and ischial bone respectively. Findings around the proximal femur are defined with a new zonal system, dividing the implant-cement-bone interfaces and the femoral neck into 7 areas. Zones 1,7 at the superior and inferior part of the femoral neck-head, zones 2,3 at the proximal and distal halves of the superior aspect of the stem, zone 4 at the tip, zones 5,6 at the distal and proximal inferior aspects of the stem). Radiological findings and zones were correlated with gender, size, survival, Harris Hip Scores (HHS), metal ions, and adverse soft tissue reactions (ALTR). RESULTS. Radiological changes were found in 260 cases (36.7%), 151 sinister (21.2%) and 110 borderline (15.5%). 82% of revisions had sinister findings versus 11.3% of in-situ HRA (p<0.001). Of the 52 revised cases with ALTR, 2 had normal Xrays, 3 borderline and 47 sinister (90.4%). Females had a higher incidence of sinister findings (28.9%) compared to males (16.6%)(p<0.001). Sinister radiographs were significantly associated with lower HHS (mean 85 versus 98)(p<0.001), smaller sizes (median 48 versus 50)(p<0.001) and ASR design (58.8%). Metal ions were significantly higher with sinister (mean Cr:17.6μg/l-Co:17.8μg/l)(p<0.001) and borderline findings (mean Cr:3.34μg/l-Co:3.01μg/l)(p<0.01) compared to normal radiographs (mean Cr:2.61μg/l-Co:2.26μg/l). A higher number of pathological zones was correlated with risk of revision(p=0.006), ALTR(p<0.001), female gender(p<0.001), smaller size(p<0.001), and lower HHS(p<0.001). Pathological findings in . 3. 4 zones had a sensitivity of 50% and specificity of 94.2% (AUC=0.898) in detecting hips with ALTR (risk ratio=19.6). DISCUSSION. Radiographic assessment of HRA provides valuable information: 82% of problematic hips had sinister changes and 90.4% of cases with proven ALTR. In order to accurately evaluate progressive radiographic changes in HRA, specific zones have been established around the HRA femoral component. There was a high correlation between radiographic findings, clinical outcome and metal in levels. However, the absence of sinister radiologic findings does not eliminate a problematic HRA and further investigations (ion levels, imaging) would be indicated in symptomatic patients