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The COVID-19 pandemic has disrupted every aspect of society in a way never previously experienced by our nation's orthopaedic surgeons. In response to the challenges the American Board of Orthopaedic Surgery has taken steps to adapt our Board Certification and Continuous Certification processes. These changes were made to provide flexibility for as many Candidates and Diplomates as possible to participate while maintaining our high standards. The American Board of Orthopaedic Surgery is first and foremost committed to the safety and well-being of our patients, physicians, and families while striving to remain responsive to the changing circumstances affecting our Candidates and Diplomates.

Adverse local tissue reactions (ALTRs) were first associated with patients with failed metal-on-metal surface replacements and total hip arthroplasty (THA). However, an increasing number of cases of ALTR in metal-on-polyethylene (MOP) THA patients is being reported. Clinically, ALTR appears as benign, aseptic masses or bursae in the periprosthetic tissues. Histopathologically, ALTRs are distinguished by an intense lymphocyte infiltrate, destruction of the synovial surfaces, widespread necrosis, and fibrin exudate. Tribocorrosion of modular junctions appears to be the cause of ALTR in MOP patients. The various tribocorrosion damage modes occurring at modular junctions produce metal ions and a diversity of particulates in relation to size, chemical composition, and structure. The mechanisms by which these various products of tribocorrosion lead to ALTR are still a matter of considerable research. This review clarifies what constitutes ALTR, its relationship to implant factors, and highlights current methods for diagnosis and management of patients with ALTR in the setting of MOP THA.

The purpose of this retrieval study was to determine the effect of implant positioning on wear, taking patient-related factors into account. Therefore, the volumetric material loss of 59 retrieved tibial liners was quantitatively determined using a coordinate measuring-machine. All retrievals were made of the same polyethylene and design by a single manufacturer. Using time in-situ and linear regression, a wear rate for each liner was determined and corrected for bedding-in. Backside damage was qualitatively scored. The following implant positioning parameters were obtained from radiographs: anatomical lateral-distal femoral angle, anatomical medial-proximal tibial angle, femoral tilt angle and posterior tibial slope. The patella position was assessed by the Blackburne-Peel Index and the Insall-Salvati Ratio. Unlike the Insall-Salvati Ratio, the Blackburne-Peel Index is known to detect surgical joint line elevation. Using general linear modeling the most impactful factors on wear rate and backside damage was determined, thereby taking patient demographic factors into account. The mean volumetric wear rate was 11.6 mm(3)/yr. Wear decreased with older age (p=0.021) and female sex (p=0.001). The wear rate increased with joint line elevation as indicated from a decreased Blackburne-Peel Index (p=0.019), and increased with increased posterior tibial slope (p = 0.026). The backside damage score also increased with joint line elevation (p=0.036). A Blackburne-Peel Index decrease of 0.1, signifying joint line elevation, was found to increase the wear rate by 1.8 mm(3)/yr and increase back-sided wear. A high tibial slope (>7°) led to a 9.3 mm(3)/yr increase in wear rate compared with a low tibial slope (

The aim of this study was to determine the effect of two in-vivo-determined gait patterns, one with low and one with high anteroposterior (AP) motion, on total and backside polyethylene insert wear in comparison with the ISO (International Organization for Standardization) standard 14243-3. In order to differentiate and accurately quantify topside and backside wear, a novel technique was employed where different lanthanide tracers were incorporated into the polyethylene during manufacture. Wear particle analysis was conducted following established protocols. For all tested liners and motion protocols, the chemically calculated wear rates correlated closely with gravimetrically determined wear. Both in vivo motion groups displayed higher wear rates than the ISO group following the order of the AP motion amplitudes. Backside wear for ISO constituted 2.76% ± 0.90% (mean ± SE) of the total wear, increasing significantly to 15.8% ± 3.2% for the low AP and further increasing to 19.3% ± 0.95% for the high AP motion protocol. The mean wear particle sizes were under 200 nm for all three motion patterns, being largest for the protocol with high AP motion. Particle release from the low and high AP gait patterns was 1.9 to 2.8 times that from the ISO protocol. Testing for the proportion of backside wear across various activities of daily living should be an important consideration in evaluating knee prostheses wear.

Recognizing and adopting standardized terms for adverse local tissue reaction associated with tribocorrosion in total hip arthroplasty are essential for clear scientific discourse and clinical communication. Our goal was to develop terms that can be broadly applied to characterize the local tissue response to tribocorrosion debris, based on current evidence regarding the etiology of this failure mode and its consequences. The proposed standardized terms will improve the understanding and interpretation of analytical tests, advance diagnostic and treatment algorithms, and reduce confusion in research by maintaining consistent nomenclature.

Background Recent studies indicate that, in addition to antibody production, lymphocyte responses to SARS-CoV-2 may play an important role in protective immunity to COVID-19 and a percentage of the general population may exhibit lymphocyte memory due to unknown/asymptomatic exposure to SARS-CoV-2 or cross-reactivity to other more common coronaviruses pre-vaccination. Total joint replacement (TJR) candidates returning to elective surgeries (median age 68 years) may exhibit similar lymphocyte and/or antibody protection to COVID-19 prior to vaccination Methods In this retrospective study, we analyzed antibody titters, lymphocyte memory, and inflammatory biomarkers specific for the Spike and Nucleocapsid proteins of the SARS-CoV-2 virus in a cohort of n=73 returning TJR candidates (knees and/or hips) pre-operatively. Results Peripheral blood serum of TJR candidate patients exhibited a positivity rate of 18.4% and 4% for IgG antibodies specific for SARS-CoV-2 nucleocapsid and spike proteins, respectively. 13.5% of TJR candidates exhibited positive lymphocyte reactivity (SI > 2) to the SARS-CoV-2 nucleocapsid protein and 38% to the spike protein. SARS-CoV-2 reactive lymphocytes exhibited a higher production of inflammatory biomarkers (i.e., IL-1β, IL-6, TNFα, and IL-1RA) compared to non-reactive lymphocytes. Conclusions A percentage of TJR candidates returning for elective surgeries exhibit pre-vaccination positive SARS-CoV-2 antibodies and T cell memory responses with associated pro-inflammatory biomarkers. This is an important parameter for understanding immunity, risk profiles, and may aid pre-operative planning. Trial registration Retrospectively registered.

Background A battlefield-related injury results in increased local and systemic innate immune inflammatory responses, resulting in wound-specific complications and an increased incidence of osteoarthritis. However, little is known about whether severe injuries affect long-term systemic homeostasis, for example, immune function. Moreover, it also remains unknown whether battlefield-acquired metal fragments retained over the long term result in residual systemic effects such as altered immune reactivity to metals. Questions/purposes Does a retained metal fragment from a battlefield injury contribute to increased (1) adaptive metal-specific immune responses, (2) systemically elevated metal ion serum levels, and (3) serum immunoglobulin levels compared with combat injuries that did not result in a retained metal fragment? Methods In this pilot study, we analyzed metal-immunogenicity in injured military personnel and noninjured control participants using lymphocyte transformation testing (LTT, lymphocyte proliferation responses to cobalt, chromium and nickel challenge at 0.001, 0.01 and 0.1-mM concentrations in triplicate for each participant), serum metal ion analysis (ICP-mass spectroscopy), and serum immunoglobulin analysis (IgE, IgG, IgA, and IgM ). Military personnel with a battlefield-sustained injury self-recruited without any exclusion for sex, age, degree of injury. Those with battlefield injury resulting in retained metal fragments (INJ-FRAG, n = 20 male, mean time since injury ± SD was 12 ± 10 years) were compared with those with a battlefield injury but without retained metal fragments (INJ-NO-FRAG, n = 12 male, mean time since injury ± SD was 13 ± 12 years). A control group comprised of male noninjured participants was used to compare measured immunogenicity metrics (n = 11, males were selected to match battlefield injury group demographics). Results Military participants with sustained metal fragments had increased levels of metal-induced lymphocyte responses. The lymphocyte stimulation index among military participants with metal fragments was higher than in those with nonretained metal fragments (stimulation index = 4.2 ± 6.0 versus stimulation index = 2.1 ± 1.2 (mean difference 2.1 ± 1.4 [95% confidence interval 5.1 to 0.8]; p = 0.07) and an average stimulation index = 2 ± 1 in noninjured controls. Four of 20 participants injured with retained fragments had a lymphocyte proliferation index greater than 2 to cobalt compared with 0 in the group without a retained metal fragment or 0 in the control participants. However, with the numbers available, military personnel with retained metal fragments did not have higher serum metal ion levels than military participants without retained metal fragment-related injuries or control participants. Military personnel with retained metal fragments had lower serum immunoglobulin levels (IgG, IgA, and IgM) than military personnel without retained metal fragments and noninjured controls, except for IgE. Individuals who were metal-reactive positive (that is, a stimulation index > 2) with retained metal fragments had higher median IgE serum levels than participants who metal-reactive with nonmetal injuries (1198 ± 383 IU/mL versus 171 ± 67 IU/mL, mean difference 1027 ± 477 IU/mL [95% CI 2029 to 25]; p = 0.02). Conclusions We found that males with retained metal fragments after a battlefield-related injury had altered adaptive immune responses compared with battlefield-injured military personnel without indwelling metal fragments. Military participants with a retained metal fragment had an increased proportion of group members and increased average lymphocyte reactivity to common implant metals such as nickel and cobalt. Further studies are needed to determine a causal association between exposure to amounts of retained metal fragments, type of injury, personnel demographics and general immune function/reactivity that may affect personal health or future metal implant performance. Level of evidence Level IV, therapeutic study.

Background Modular femoral trunnions enable the surgeon to independently adjust offset, leg length, and anteversion in total hip arthroplasty (THA). However, modularity may result in an increased risk of fretting and corrosion along with a higher risk of implant dissociation or fracture. The purpose of this study is to evaluate mid-term survivorship of THAs using a cementless modular system. Methods A consecutive series of 221 patients who underwent a primary THA using the ALFA II modular stem by a single surgeon between 2002 and 2004 were reviewed. Survivorship of the ALFA II modular hip system was evaluated at a minimum of 5 years postoperatively. Results Of the 221 patients, 28 (12.7%) died from causes unrelated to the surgery before adequate follow-up, and 64 (29.0%) patients were lost to follow-up. The remaining 129 patients had a mean 6.5-year (range: 5-8 years) follow-up. All-cause survivorship of the modular stem system was 81% (95% confidence interval = 69-90) at a mean 6.5-year follow-up. Of the 25 (19.4%) cases requiring revision surgery, 52.0% was for dissociation of the modular components, 32.0% was for fracture of the prosthesis, 12.0% was for instability/multiple dislocations, and 4.0% was for chronic septic THA. Body mass index (odds ratio = 1.080) and offset (odds ratio = 1.254) were independent risk factors for mechanical failures of the modular stem system. Conclusion The modular stem hip system of interest in this study demonstrates a high failure rate at mid-term follow-up, and we caution against the use of similar designs in primary THAs.

Augmented reality (AR) technology enhances a user's perception through the superimposition of digital information on physical images while still allowing for interaction with the physical world. The tracking, data processing, and display technology of traditional computer-assisted surgery (CAS) navigation have the potential to be consolidated to an AR headset equipped with high-fidelity cameras, microcomputers, and optical see-through lenses that create digital holographic images. This article evaluates AR applications specific to total knee arthroplasty, total hip arthroplasty, and the opportunities for AR to enhance arthroplasty education and professional development.

BACKGROUND: Fretting and corrosion in metal-on-polyethylene total hip arthoplasty (THA) modular junctions can cause adverse tissue reactions that are responsible for 2% to 5% of revision surgeries. Damage within cobalt-chromium-molybdenum (CoCrMo) alloy femoral heads can progress chemically and mechanically, leading to damage modes such as column damage, imprinting, and uniform fretting damage. At present, it is unclear which of these damage modes are most detrimental and how they may be linked to implant alloy metallurgy. The alloy microstructure exhibits microstructural features such as grain boundaries, hard phases, and segregation bands, which may enable different damage modes, higher material loss, and the potential risk of adverse local tissue reactions. QUESTIONS/PURPOSES: In this study, we asked: (1) How prevalent is chemically dominated column damage compared with mechanically dominated damage modes in severely damaged metal-on-polyethylene THA femoral heads made from wrought CoCrMo alloy? (2) Is material loss greater in femoral heads that underwent column damage? (3) Do material loss and the presence of column damage depend on alloy microstructure as characterized by grain size, hard phase content, and/or banding? METHODS: Surgically retrieved wrought CoCrMo modular femoral heads removed between June 2004 and June 2019 were scored using a modified version of the Goldberg visually based scoring system. Of the total 1002 heads retrieved over this period, 19% (190 of 1002) were identified as severely damaged, exhibiting large areas of fretting scars, black debris, pits, and/or etch marks. Of these, 43% (81 of 190) were excluded for metal-on-metal articulations, alternate designs (such as bipolar, dual-mobility, hemiarthroplasty, metal adaptor sleeves), or previous sectioning of the implant for past studies. One sample was excluded retroactively as metallurgical analysis revealed that it was made of cast alloy, yielding a total of 108 for further analysis. Information on patient age (57 ± 11 years) and sex (56% [61 of 108] were males), reason for removal, implant time in situ (99 ± 78 months), implant manufacturer, head size, and the CoCrMo or titanium-based stem alloy pairing were collected. Damage modes and volumetric material loss within the head tapers were identified using an optical coordinate measuring machine. Samples were categorized by damage mode groups by column damage, imprinting, a combination of column damage and imprinting, or uniform fretting. Metallurgical samples were processed to identify microstructural characteristics of grain size, hard phase content, and banding. Nonparametric Mann-Whitney U and Kruskal-Wallis statistical tests were used to examine volumetric material loss compared with damage mode and microstructural features, and linear regression was performed to correlate patient- and manufacturer-specific factors with volumetric material loss. RESULTS: Chemically driven column damage was seen in 48% (52 of 108) of femoral heads, with 34% (37 of 108) exhibiting a combination of column damage and imprinting, 12% (13 of 108) of heads displaying column damage and uniform fretting, and 2% (2 of 108) exhibiting such widespread column damage that potentially underlying mechanical damage modes could not be verified. Implants with column damage showed greater material loss than those with mechanically driven damage alone, with median (range) values of 1.2 mm(3) (0.2 to 11.7) versus 0.6 mm(3) (0 to 20.7; p = 0.03). Median (range) volume loss across all femoral heads was 0.9 mm(3) (0 to 20.7). Time in situ, contact area, patient age, sex, head size, manufacturer, and stem alloy type were not associated with volumetric material loss. Banding of the alloy microstructure, with a median (range) material loss of 1.1 mm(3) (0 to 20.7), was associated with five times higher material loss compared with those with a homogeneous microstructure, which had a volume loss of 0.2 mm(3) (0 to 4.1; p = 0.02). Hard phase content and grain size showed no correlation with material loss. CONCLUSION: Chemically dominated column damage was a clear indicator of greater volume loss in this study sample of 108 severely damaged heads. Volumetric material loss strongly depended on banding (microstructural segregations) within the alloy. Banding of the wrought CoCrMo microstructure should be avoided during the manufacturing process to reduce volumetric material loss and the release of corrosion products to the periprosthetic tissue. CLINICAL RELEVANCE: Approximately 30% of THAs rely on wrought CoCrMo femoral heads. Most femoral heads in this study exhibited a banded microstructure that was associated with larger material loss and the occurrence of chemically dominated column damage. This study suggests that elimination of banding from the alloy could substantially reduce the release of implant debris in vivo, which could potentially also reduce the risk of adverse local tissue reactions to implant debris.

Aims The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions. Methods Finite element models of generic cobalt-chromium (CoCr) heads on a titanium stem taper were developed and driven using dynamic assembly loads collected from clinicians. To verify contact mechanics at the taper interface, comparisons of deformed microgroove characteristics (height and width of microgrooves) were made between model estimates with those measured from five retrieved implants. Additionally, these models were used to assess the role of assembly technique—one-hit versus three-hits—on the taper interlock mechanical behaviour. Results The model compared well to deformed microgrooves from the retrieved implants, predicting changes in microgroove height (mean 1.1 μm (0.2 to 1.3)) and width (mean 7.5 μm (1.0 to 18.5)) within the range of measured changes in height (mean 1.4 μm (0.4 to 2.3); p = 0.109) and width (mean 12.0 μm (1.5 to 25.4); p = 0.470). Consistent with benchtop studies, our model found that increasing assembly load magnitude led to increased taper engagement, contact pressure, and permanent deformation of the stem taper microgrooves. Interestingly, our model found assemblies using three hits at low loads (4 kN) led to decreased taper engagement, contact pressures and microgroove deformations throughout the stem taper compared with tapers assembled with one hit at the same magnitude. Conclusion These findings suggest additional assembly hits at low loads lead to inferior taper interlock strength compared with one firm hit, which may be influenced by loading rate or material strain hardening. These unique models can estimate microgroove deformations representative of real contact mechanics seen on retrievals, which will enable us to better understand how both surgeon assembly techniques and implant design affect taper interlock strength. Cite this article: Bone Joint J 2020;102-B(7 Supple B):33–40.

Aims A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients. Methods In total, 11 retrieved polyethylene tibial inserts were matched with gait analysis testing performed on those patients. Volumetric wear on the articular surfaces was measured using a laser coordinate measure machine and autonomous reconstruction. Knee kinematics and kinetics from individual gait trials drove computational models to calculate medial and lateral tibiofemoral contact paths and forces. Sliding distance along the contact path, normal forces and implantation time were used as inputs to Archard’s equation of wear to predict volumetric wear from gait mechanics. Measured and modelled wear were compared for each component. Results Volumetric wear rates on eight non-delaminated components measured 15.9 mm3/year (standard error (SE) ± 7.7) on the total part, 11.4 mm3/year (SE ± 6.4) on the medial side and 4.4 (SE ± 2.6) mm3/year on the lateral side. Volumetric wear rates modelled from patient gait mechanics predicted 16.4 mm3/year (SE 2.4) on the total part, 11.7 mm3/year (SE 2.1) on the medial side and 4.7 mm3/year (SE 0.4) on the lateral side. Measured and modelled wear volumes correlated significantly on the total part (p = 0.017) and the medial side (p = 0.012) but not on the lateral side (p = 0.154). Conclusion In the absence of delamination, patient-specific knee mechanics during gait directly affect wear of the tibial component in TKA. Cite this article: Bone Joint J 2020;102-B(6 Supple A):129–137.

Background The purpose of this study is to determine if there is a difference in echocardiographic results between patients with metal-on-metal (MoM) vs non-MoM total hip arthroplasty (THA) and to determine if a correlation exists between serum metal levels and echocardiographic outcomes. Methods Seventy-five patients with the same modular THA enrolled in this prospective cohort study, and 49 had MoM bearings. All patients had serum cobalt, chromium, and titanium levels drawn at 2 study visits with a transthoracic echocardiogram at the second visit. Serum metal concentrations and echocardiographic parameters were compared with 2-way t-tests. Multiple linear regression analyses identified any significant predictors of echocardiographic outcomes. Results Mean serum cobalt and chromium levels were significantly greater in the MoM group at both time-points (P .05). MoM patients had significantly lower global longitudinal strain compared with the non-MoM group (18.4% vs 20.2%; P = .026). Serum cobalt concentration was found to be an independent predictor of tricuspid annular plane systolic excursion (P = .02). Conclusion MoM THA bearings are associated with increased serum cobalt and chromium levels. Patients with MoM THAs had decreased global longitudinal strain, a measure of left ventricular function, but both groups remained within normal range. The clinical impact of the positive association between serum cobalt concentration and tricuspid annular plane systolic excursion, a marker of right ventricular function, deserves further study. These findings can reassure physicians and patients that metal-induced cardiomyopathy is not typical in the setting of MoM THA. Level of Evidence Level II, Prospective Cohort Study.

Background Mechanically assisted crevice corrosion (MACC) at modular junctions can cause a spectrum of adverse local tissue reactions (ALTRs) in patients who have undergone total hip arthroplasty (THA). The purpose of this study is to describe the presentation, treatments, and related complications of a cohort of patients presenting with late instability following metal-on-polyethylene THA due to underlying MACC and ALTR. Methods This multicenter retrospective case series presents 17 patients (12 women, mean age 62.6, range 42-73) presenting with late instability secondary to ALTR and MACC. All patients had a metal (Cobalt Chrome)-on-polyethylene bearing surface. Patients experienced a mean 2.7 dislocations (range 1-6) at mean 4.3 years (range 0.4-17.0) following their index surgery. Serum metal levels (n = 12) demonstrated a greater elevation of cobalt (mean 6.9, range 0.13-20.88 ng/mL) than chromium (mean 1.9, range 0.13-3.23 ng/mL). Results Patients were revised for instability at a mean of 6.8 years (range 2.1-19.4) following their index surgery. ALTR was encountered in every case and the modular head-neck junction demonstrated visible corrosion. An exchange of the CoCr head to a ceramic head with a titanium sleeve and placement of a constrained liner was performed for a majority of patients (n = 15, 88.2%). Five patients (29.4%) had complications postoperatively including peroneal palsy (n = 2), periprosthetic joint infection (n = 2), and ALTR recurrence (n = 1). Conclusion Recurrent instability in the setting of otherwise well-positioned THA components and without another obvious cause should raise concern for ALTR as a potential underlying etiology.

Recurrent hemarthrosis is a burdensome complication following TKA, characterized by repeated episodes of intra-articular bleeding that cause effusions and reduced range of motion, and is readily confirmed on aspiration. Coagulopathies should be ruled out first. Excluding patients with coagulopathy, impingement of hypertrophied synovium is typically the most common cause of bleeding. Pseudoaneurysms represent another important cause. Diagnosis relies on angiography to identify offending vessels or arthroscopic/open visualization. Treatment is straightforward and begins with conservative modalities with concurrent evaluation to detect an underlying coagulopathy. If these measures fail, more aggressive treatments may be required.

Adverse local tissue reactions to corrosion products can lead to total hip arthroplasty failure. Although this problem has been well known for more than 25 years, it has seemingly increased in frequency over the recent years. The occurrence of corrosion is multifactorial—depending on implant, patient, and surgeon factors. As of now, there is no “one-size-fits-all” solution to prevent corrosion in total hip arthroplasty devices. Thus, it is imperative to fully understand the exact mechanisms of modular junction corrosion to prevent premature implant failure. This review highlights a few key concepts that need to be explored to minimize the impact of corrosion. The key concepts include (1) the prevention of micromotion, (2) the role of implant alloy metallurgy in the corrosion process, (3) the in vivo generation of a corrosive environment, and (4) potential unanticipated problems.

Peri-implant osteolysis is commonly diagnosed after substantial bone loss has occurred, making revision surgery more challenging. The goal of the current study was to identify urinary biomarkers that differentiate total hip replacement patients who eventually develop osteolysis from patients who do not. We used a repository of 24-h urine samples collected prior to surgery and annually thereafter in 26 patients, 16 who developed osteolysis, and 10 who did not. We examined the markers at radiographic diagnosis, annually for 6 years preceding diagnosis, at the first post-operative sampling point, and pre-operatively. Patients in the osteolysis and non-osteolysis groups were matched according to time post-surgery and did not differ in the male:female ratio or age at surgery. Seven candidate biomarkers were measured, including free deoxypyridinoline (DPD), cross-linked N-telopeptides (NTX), interleukin-6 (IL-6), interleukin-8 (IL-8), osteoprotegerin (OPG), α-crosslaps (α-CTX), and β-crosslaps (β-CTX). As an individual biomarker, DPD demonstrated the highest ability to predict osteolysis, with an area under the curve (AUC) in Receiver Operating Characteristic (ROC) analyses of 0.844 at 6 years prior to diagnosis. A panel of α-CTX and IL-6 was able to identify at-risk patients with an AUC of 0.941 or greater at all post-operative time points and an AUC of 1.000 pre-operatively. The results demonstrate the potential of using non-invasive biomarkers to identify patients at risk for peri-implant osteolysis long before the emergence of radiographic signs. Further, the high accuracy of the pre-operative biomarker levels demonstrates the potential importance of pre-existing, patient-specific factors driving subsequent osteolysis. Study Design © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2754-2761, 2018.

The mission of the Orthopaedic Research Society is to promote and advance musculoskeletal research worldwide. With this in mind, the Annual Meeting Program Committee sought to establish a debate as a key component of the meeting. Our purpose was to provoke discussion on topics that are core to our mission and to engage all constituencies within the society by examining questions of broad relevance. To this end, the topic "Regenerative medicine will make orthopaedic implants obsolete in our time" was selected as the title of the inaugural debate. The arguments for and against the motion are presented in this perspectives article. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2579-2585, 2018.

Adverse local tissue reactions (ALTRs) triggered by corrosion products from modular taper junctions are a known cause of premature THA failure. CoCrMo devices are of particular concern because cobalt ions and chromium-orthophosphates were shown to be linked to ALTRs, even in metal-on-polyethylene THAs. The most common categories of CoCrMo alloy are cast and wrought alloy, which exhibit fundamental microstructural differences in terms of grain size and hard phases. The impact of implant alloy microstructure on the occurring modes of corrosion and subsequent metal ion release is not well understood. The purpose of this study was to determine whether (1) the microstructure of cast CoCrMo alloy varies broadly between manufacturers and can dictate specific corrosion modes; and whether (2) the microstructure of wrought CoCrMo alloy is more consistent between manufacturers and has low implications on the alloy’s corrosion behavior. The alloy microstructure of four femoral-stem and three femoral-head designs from four manufacturers was metallographically and electrochemically characterized. Three stem designs were made from cast alloy; all three head designs and one stem design were made from wrought alloy. Alloy samples were sectioned from retrieved components and then polished and etched to visualize grain structure and hard phases such as carbides (eg, M23C6) or intermetallic phases (eg, σ phase). Potentiodynamic polarization (PDP) tests were conducted to determine the corrosion potential (Ecorr), corrosion current density (Icorr), and pitting potential (Epit) for each alloy. Four devices were tested within each group, and each measurement was repeated three times to ensure repeatable results. Differences in PDP metrics between manufacturers and between alloys with different hard phase contents were compared using one-way analysis of variance and independent-sample t-tests. Microstructural features such as twin boundaries and slip bands as well as corrosion damage features were viewed and qualitatively assessed in a scanning electron microscope. We found broad variability in implant alloy microstructure for both cast and wrought alloy between manufacturers, but also within the same implant design. In cast alloys, there was no difference in PDP metrics between manufacturers. However, coarse hard phases and clusters of hard phases (mainly intermetallic phases) were associated with severe phase boundary corrosion and pitting corrosion. Furthermore, cast alloys with hard phases had a lower Epit than those without (0.46 V, SD 0.042; 0.53 V, SD 0.03, respectively; p = 0.015). Wrought alloys exhibited either no hard phases or numerous carbides (M23C6). However, the corrosion behavior was mainly affected by lattice defects and banded structures indicative of segregations that appear to be introduced during bar stock manufacturing. Alloys with banding had a lower Ecorr (p = 0.008) and higher Icorr (p = 0.028) than alloys without banding (−0.76 V, SD 0.003; −0.73 V, SD 0.009; and 1.14 × 10−4 mA/cm2, SD 1.47 × 10−5; 5.2 × 10−5 mA/cm2, SD 2.57 × 10−5, respectively). Alloys with carbides had a slightly higher Ecorr (p = 0.046) than those without (−0.755 V, SD 0.005; −0.761 V, SD 0.004); however, alloys with carbides exhibited more severe corrosion damage as a result of phase boundary corrosion, hard phase detachment, and subsequent local crevice corrosion. The observed variability in CoCrMo alloy microstructure of both cast and wrought components in this study appears to be an important issue to address, perhaps through better standards, to minimize in vivo corrosion. The finding of the banded structures within wrought alloys is especially concerning because it unfavorably influences the corrosion behavior independent of the manufacturer. The findings suggest that a homogeneous alloy microstructure with a minimal hard phase fraction exhibits more favorable corrosion behavior within the in vivo environment of modular taper junctions, thus lowering metal ion release and subsequently the risk of ALTRs to corrosion products. Also, the question arises if hard phases fulfill a useful purpose in metal-on-polyethylene bearings, because they may come with a higher risk of phase boundary corrosion and pitting corrosion and the benefit they provide by adding strength is not needed (unlike in metal-on-metal bearings). Implant failure resulting from corrosion processes within modular junctions is a major concern in THA. Our results suggest that implant alloy microstructure is not sufficiently standardized and may also dictate specific corrosion modes and subsequent metal ion release.

Background Recently, corrosion at the head-neck junction in metal-on-polyethylene bearing surface total hip arthroplasty (THA) has been recognized as a cause of adverse local tissue reactions (ALTRs). 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 cutoff values for serum cobalt and chromium levels in diagnosing ALTR after metal-on-polyethylene bearing surface THA. Methods We reviewed 447 consecutive patients with serum metal levels tested at our institution and identified 64 patients 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 cutoff thresholds to optimize sensitivity, and diagnostic test performance was characterized. Results Forty-four of the 64 patients (69%) 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 cutoff 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 cutoff 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 cutoff value of 1.4 for the cobalt-to-chromium ratio offered a sensitivity of 93%, specificity of 70%, PPV of 87%, and NPV of 82%. Conclusion Measurement of serum cobalt level 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 level and the ratio of cobalt-to-chromium levels are also of value.

There is controversy regarding the clinical significance of metal hypersensitivity in total knee arthroplasty (TKA). Given the current state of the art, metal hypersensitivity, if it exists at all, is a diagnosis of exclusion. Clinical presentation may involve a cutaneous response, but current diagnostic methods do not have robust clinical validation and should be used with caution. The two most commonly used tests include cutaneous patch testing and in vitro lymphocyte transformation testing. Initially, conservative management is indicated and other more common causes of a symptomatic total knee replacement should be fully explored. In rare cases, device removal may be undertaken but this should be considered a last resort. Pre-operative testing prior to a primary total joint replacement may be helpful when there′s a patient-reported history of intolerance to jewelry or of an allergic reaction to a prior metal implant, but routine lab screening is not supported by the literature.

BACKGROUND Recent studies indicate that females demonstrate an increased risk of experiencing adverse local tissue reactions, aseptic loosening, and revision after primary metal-on-metal hip resurfacing arthroplasty compared with males; the underlying biological mechanisms responsible for sex discrepancies in implant failure remain unclear. In addition to anatomical and biomechanical sex differences, there may be inherent immunological disparities that predispose females to more aggressive adaptive immune reactivity to implant debris, i.e., metal sensitivity. METHODS In this retrospective study, we analyzed sex-associated rates and levels of metal sensitization in 1,038 male and 1,575 female subjects with idiopathic joint pain following total joint arthroplasty (TJA) who were referred for in vitro metal-sensitivity testing. RESULTS Females demonstrated a significantly higher rate and severity of metal sensitization compared with males. The median lymphocyte stimulation index (SI) among males was 2.8 (mean, 5.4; 95% confidence interval [CI], 4.9 to 6.0) compared with 3.5 (mean, 8.2; 95% CI, 7.4 to 9.0) among females (p < 0.05). Forty-nine percent of females had an SI of ≥4 (reactive) compared with 38% of males, and the implant-related level of pain was also significantly (p < 0.0001) higher among females (mean, 6.8; 95% CI, 6.6 to 6.9) compared with males (mean, 6.1; 95% CI, 6.0 to 6.3). CONCLUSIONS In a select group of patients who had joint pain following TJA and no evidence of infection and who were referred for metal-sensitivity testing, females exhibited a higher level of pain and demonstrated a higher rate and severity (as measured by lymphocyte SI) of metal sensitization compared with males. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background Failed metal-on-metal (MoM) bearings are being increasingly encountered with little information to guide evaluation for aseptic lymphocytic-dominated vasculitis-associated lesions (ALVAL). It is often assumed that elevated metal ion levels correlate with the occurrence of ALVAL. Our purpose was to determine the utility of the erythrocyte sedimentation rate, C-reactive protein, synovial white blood cell count, differential (%PMN), and serum metal ion levels in diagnosing ALVAL. Methods We identified 80-failed MoM total hip arthroplasties. Tissue was examined under light microscopy and graded on a scale of ALVAL severity. Mean laboratory values were compared between groups and receiver operating curves generated with an area under the curve to determine test performance and optimal cutoffs. Results ALVAL scores were graded as low in 30 (37.5%), moderate in 39 (49%), and severe in 8 (10%), with 3 being unreadable. No clear cutoff values for erythrocyte sedimentation rate, C-reactive protein, or synovial white blood cell count could be determined to reliably diagnose moderate or severe ALVAL. Furthermore, serum metal levels had no correlation with ALVAL score. The best test to diagnose ALVAL was the synovial fluid monocyte percentage with an optimal cutoff value of 39% and area under the curve of 69% (moderate testing performance). Conclusion The diagnosis of ALVAL remains challenging, with most of the screening tests being unreliable. Although serum metal ion levels are typically elevated in failed MoM bearings, higher levels do not appear to correlate with ALVAL grade. Elevated synovial fluid monocytes may provide diagnostic utility for ALVAL, suggesting a possible delayed-type hypersensitivity reaction.

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 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.

Prior studies have documented racial and ethnic disparities in total hip arthroplasty (THA) outcomes in the U.S. The purpose of this study was to assess whether racial/ethnic disparities in THA outcomes persist in a universally insured population of patients enrolled in an integrated health-care system.A U.S. health-care system total joint replacement registry was used to identify patients who underwent elective primary THA between 2001 and 2016. Data on patient demographics, surgical procedures, implant characteristics, and outcomes were obtained from the registry. The outcomes analyzed were lifetime revision (all-cause, aseptic, and septic) and 90-day postoperative events (infection, venous thromboembolism, emergency department [ED] visits, readmission, and mortality). Racial/ethnic differences in outcomes were analyzed with use of multiple regression with adjustment for socioeconomic status and other potential confounders.Of 72,755 patients in the study, 79.1% were white, 8.2% were black, 8.5% were Hispanic, and 4.2% were Asian. Compared with white patients, lifetime all-cause revision was lower for black (adjusted hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.66 to 0.94; p = 0.007), Hispanic (adjusted HR, 0.73; 95% CI, 0.61 to 0.87; p = 0.002), and Asian (adjusted HR, 0.49; 95% CI, 0.37 to 0.66; p0.001) patients. Ninety-day ED visits were more common among black (adjusted odds ratio [OR], 1.15; 95% CI, 1.05 to 1.25; p = 0.002) and Hispanic patients (adjusted OR, 1.18; 95% CI, 1.08 to 1.28; p0.001). For all other postoperative events, minority patients had similar or lower rates compared with white patients.In contrast to prior research, we found that minority patients enrolled in a managed health-care system had rates of lifetime reoperation and 90-day postoperative events that were generally similar to or lower than those of white patients, findings that may be related to the equal access and/or standardized protocols associated with treatment in the managed care system. However, black and Hispanic patients still had higher rates of 90-day ED visits. Further research is required to determine the reasons for this finding and to identify interventions that could reduce unnecessary ED visits.Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Adverse local tissue reactions (ALTRs) were initially reported as complications associated with metal-on-metal (MoM) bearings; however, there is increasing concern regarding the occurrence of adverse local tissue reactions from mechanically assisted crevice corrosion (MACC) at the femoral head-neck junction or between other modular junctions of the implant containing cobalt chromium parts in patients with metal-on-polyethylene (MoP) bearings. ALTR due to MACC at the head-neck junction has primarily been reported in association with cobalt chromium alloy femoral heads. As pain following total hip arthroplasty may have various intrinsic and extrinsic causes, a systematic approach to evaluation (risk stratification algorithm) based on the currently available data is recommended to optimize patient management. Evaluation should begin by ruling out common causes of pain, including component loosening and periprosthetic joint infection. While specialized tests such as blood metal analysis and metal artifact reduction sequence magnetic resonance imaging (MARS MRI) are useful modalities in evaluating for ALTRs, over-reliance on any single investigative tool in the clinical decision-making process should be avoided. There should be a low threshold to perform a systematic evaluation for ALTR due to MACC in patients with metal-on-polyethylene total hip arthroplasty as early recognition and diagnosis is critical, as delays in appropriate treatment initiation may result in soft-tissue damage, which complicates surgical treatment and is associated with a higher risk of complications and poorer patient outcomes.

Background There are increasing reports of total hip arthroplasty failure subsequent to modular taper junction corrosion. The surfaces of tapers are machined to have circumferential machining marks, resulting in a surface topography of alternating peaks and valleys on the scale of micrometers. It is unclear if the geometry of this machined surface topography influences the degree of fretting and corrosion damage present on modular taper junctions or if there are differences between modular taper junction material couples.

Innate immune reactions to orthopedic implant debris are the primary cause of total joint replacement (TJR) failure over the long term (15-20 years). The role of pathogen associated pattern recognition receptors (i.e., TLRs) in regulating immune reactivity to metal implant particles remains controversial. Do different TLRs (i.e., TLR2 vs. TLR4) activated by their respective ligands in concert with metal implant debris elicit equivalent innate immune responses? In this investigation, our in vitro and in vivo data indicate that Gram-negative PAMPs are more pro-inflammatory than Gram-positive PAMPs. In vitro results indicated TLR4 activation in concert with CoCrMo orthopedic implant debris (CoCrMo/LPS+) challenged primary macrophages resulted in significantly greater inflammatory responses than CoCrMo/PAM3CSK+ (TLR2). Similarly, in vivo results indicated CoCrMo/LPS+ TLR4 challenge induced a twofold increase in inflammation-induced bone resorption (osteolysis) than CoCrMo/PAM3CSK+ (p

Metal hypersensitivity in patients with a total knee arthroplasty (TKA) is a controversial topic. The diagnosis is difficult, given the lack of robust clinical validation of the utility of cutaneous and in vitro testing. Metal hypersensitivity after TKA is quite rare and should be considered after eliminating other causes of pain and swelling, such as low-grade infection, instability, component loosening or malrotation, referred pain, and chronic regional pain syndrome. Anecdotal observations suggest that two clinical presentations of metal hypersensitivity may occur after TKA: dermatitis or a persistent painful synovitis of the knee. Patients may or may not have a history of intolerance to metal jewelry. Laboratory studies, including erythrocyte sedimentation rate, C-reactive protein level, and knee joint aspiration, are usually negative. Cutaneous and in vitro testing have been reported to be positive, but the sensitivity and specificity of such testing has not been defined. Anecdotal reports suggest that, if metal hypersensitivity is suspected and nonsurgical measures have failed, then revision to components fabricated of titanium alloy or zirconium coating can be successful in relieving symptoms. Revision should be considered as a last resort, however, and patients should be informed that no evidence-based medicine is available to guide the management of these conditions, particularly for decisions regarding revision. Given the limitations of current testing methods, the widespread screening of patients for metal allergies before TKA is not warranted.

We reviewed 27 patients who underwent revision for an adverse local tissue reaction (ALTR) secondary to corrosion at the head-neck junction with MoP bearings. Serum cobalt and chromium levels were elevated in all cases, with a mean cobalt of 11.2 ppb and chromium of 2.2 ppb. Patients underwent modular bearing exchange, including a ceramic head with a titanium sleeve in 23 of 27 cases with only one recurrence of ALTR in one of the four patients not treated with a ceramic head. The diagnosis of ALTR secondary to corrosion is associated with cobalt levels of >1 ppb with cobalt levels elevated above chromium. Retention of a well-fixed stem and modular exchange to a ceramic head leads to resolution of symptoms and decreases in metal levels.

In the 1990s, metal-on-metal (MoM) bearings were reintroduced in total hip arthroplasty (THA), having the proposed advantages of decreased wear and improved stability. However, catastrophic adverse local tissue reaction (ALTR) secondary to metal debris from both the bearing surface and the head–neck junction is a well-recognized complication. The measurement of metal ion levels in the serum is often a first-line test to identify failure of a MoM bearing. The authors describe a 70-year-old man who presented with a multiply revised MoM THA and a large periprosthetic fluid collection incidentally seen during computed tomography for renal nephrolithiasis. The patient reported painless, progressive swelling over the lateral aspect of the hip. An infectious workup including serum erythrocyte sedimentation rate, C-reactive protein, and intraarticular hip aspiration yielded negative results. Metal ion levels in the serum, including a minimally elevated cobalt level, were unremarkable, and metal-lymphocyte transformation testing yielded negative results. Radiographic imaging revealed progressive osteolysis around the proximal femur, and magnetic resonance imaging showed large fluid collections with irregular wall thickening surrounding the gluteal and iliopsoas musculature. At revision surgery, a large fluid collection and corrosion at the head–neck junction were present. Pathology specimens confirmed the presence of an ALTR. This report presents a previously undescribed case of an ALTR secondary to MoM THA in the absence of elevated serum metal ion levels. This indicates the necessity of considering all aspects of a patient's clinical presentation, imaging modalities, and laboratory testing in the evaluation and diagnosis of a symptomatic MoM THA. [ Orthopedics. 2018; 41(3):e438–e441.]

There has been an increasing use of modularity at the head-neck junction in total hip arthroplasty to more closely mimic the native anatomy, allowing for optimal leg length and stability. Corrosion at this junction in metal-on-polyethylene bearings can lead to an adverse local tissue reaction (ALTR). This increasingly prevalent condition should be considered in the differential diagnosis of hip pain and difficulty ambulating. A recent symposium by the American Academy of Hip and Knee Surgeons described the diagnosis, etiology, management, and prevention of taper corrosion. This article describes the history, physical, plain and advanced imaging findings, laboratory tests, and other diagnoses that should be taken into consideration when diagnosing taper corrosion. The presence of ALTR due to taper corrosion can mimic other diagnoses such as periprosthetic joint infection, instability, or aseptic loosening. Serum metal levels have been found to be the most effective screening tool for identifying corrosion, but other common causes of hip pain and difficulty ambulating should always be ruled out with the use of radiographs and common laboratory techniques before diagnosing ALTR due to corrosion.

Concerns exist that high-risk patients in alternative payment models may face difficulties with access to care without proper risk adjustment. The purpose of this study is to identify the effect of medical and orthopedic specific risk factors on the cost of a 90-day episode of care following total hip (THA) and knee arthroplasty (TKA).We queried the Medicare 5% Limited Data Set for all patients undergoing primary THA and TKA from 2010 to 2014. To evaluate the cost of an episode of care, we calculated all claims for 90 days following surgery. Multivariate analysis was performed to quantify the added episode-of-care costs for demographic variables, geography, medical comorbidities, and orthopedic specific risk factors.Of the 58,809 TKA patients, the median 90-day Medicare costs was $23,800 (interquartile range, $18,900-$32,300), while the median of the 27,293 THA patients was $24,000 (interquartile range, $18,500-$33,900). Independent risk factors (all P.05) resulting in at least a 10% increase in episode-of-care costs following TKA included malnutrition, age over 85, male gender, pulmonary disorder, failed internal fixation, Northeast region, lower socioeconomic status, neurologic disorder, and rheumatoid arthritis. Independent risk factors (all P.05) resulting in at least a 10% increase in episode-of-care costs following THA included malnutrition, male gender, age over 85, failed internal fixation, hip dysplasia, Northeast region, neurologic disorder, lower socioeconomic status, conversion THA, avascular necrosis, and depression.Certain comorbidities and orthopedic risk factors increase 90-day episode-of-care costs in the Medicare population. The current lack of proper risk stratification could be a powerful driver of decreased access to care for our most medically challenged members of society.

Trace metal analysis, more commonly referred to as metal ion testing, was introduced as a clinical tool to evaluate metal-on-metal (MoM) implants that were used in hip replacements in the 1990s1-3. This test measures concentrations of various metals, such as cobalt and chromium, in either the serum or whole blood. It has been used with increasing frequency in the past decade as potential failures of MoM devices related to release of metal ions and debris have become better understood4-7. Elevated serum metal levels have been correlated with poor implant performance in numerous studies4-9. As a result, the Medicines and Healthcare products Regulatory Agency (MHRA) of the United Kingdom recently recommended obtaining metal ion levels in several groups of patients with MoM bearing surfaces as a method of ongoing surveillance10, and many surgeons in other parts of the world are using metal ion testing for similar purposes. In addition to metal release from MoM bearing surfaces, metal levels can also be notably elevated as a result of corrosion at modular taper junctions in patients with large-head MoM total hip arthroplasties11,12 and in patients with metal-on-polyethylene bearing surfaces13. Because metal ion levels are elevated in patients with problematic prostheses and these levels decrease after the source of metal debris is removed with revision arthroplasty surgery13,14, metal ion levels are currently being obtained on a routine basis in both clinical and research settings. Accordingly, accurate interpretation of these values is critical to the clinician, and other etiologies that could potentially affect these values should be clearly understood. We present a patient with a well-functioning total hip arthroplasty whose serum metal levels were substantially elevated secondary to dietary supplementation with vitamins; …

Case: A 25-year-old man with synovial chondromatosis of the hip was treated with a synovectomy through a transtrochanteric approach; the repair was made with use of a Dall-Miles cable. Approximately 13 years later, the patient returned with a massive bursal reaction and a cyst containing “rice bodies.” Although the physical examination and imaging were suggestive of recurrent synovial chondromatosis, the bursal reaction actually represented a novel complication of the Dall-Miles system. Conclusion: When a patient who has had prior orthopaedic instrumentation presents with pain and imaging that demonstrates formation of a bursal cyst, a cyst containing rice bodies secondary to bursal irritation by the implant should be considered.

Instability or dislocation after total hip arthroplasty continues to be one of the most prevalent complications and modes of failure of this largely successful operation. The purpose of this article is to describe a systematic algorithm for evaluation and treatment of the unstable total hip arthroplasty as well as review current literature and controversies surrounding the dislocating total hip arthroplasty.

Although metal-on-metal (MoM) bearing surfaces provide low rates of volumetric wear and increased stability, evidence suggests that certain MoM hip arthroplasties have high rates of complication and failure. Some evidence indicates that women have higher rates of failure compared with men; however, the orthopaedic literature as a whole has poorly reported such complications stratified by gender.This systematic review aimed to: (1) compare the rate of adverse local tissue reaction (ALTR); (2) dislocation; (3) aseptic loosening; and (4) revision between men and women undergoing primary MoM hip resurfacing arthroplasty (HRA).Systematic MEDLINE and EMBASE searches identified all level I to III articles published in peer-reviewed journals, reporting on the outcomes of interest, for MoM HRA. Articles were limited to those with 2-year followup that reported outcomes by gender. Ten articles met inclusion criteria. Study quality was evaluated using the Modified Coleman Methodology Score; the overall quality was poor. Heterogeneity and bias were analyzed using a Mantel-Haenszel statistical method.Women demonstrated an increased odds of developing ALTR (odds ratio [OR], 5.70 [2.71-11.98]; p0.001), dislocation (OR, 3.04 [1.2-7.5], p=0.02), aseptic loosening (OR, 3.18 [2.21-4.58], p0.001), and revision (OR, 2.50 [2.25-2.78], p0.001) after primary MoM HRA.A systematic review of the currently available literature reveals a higher rate of complications (ALTR, dislocation, aseptic loosening, and revision) after MoM HRA in women compared with men. Although femoral head size has been frequently implicated as a prime factor in the higher rate of complication in women, further research is necessary to specifically probe this relationship. Retrospective studies of data available (eg, registry data) should be undertaken, and moving forward studies should report outcomes by gender (particularly complications).Level III, therapeutic study.

Metal-on-metal (MoM) total hip arthroplasties (THAs) and the head-neck and neck-body junctions in modular THA are associated with a variety of local and systemic reactions to their related wear and corrosion products. Although laboratory testing is available, the relationship between laboratory values--including serum metal ion levels--and adverse local tissue reactions (ALTRs) remains controversial and incompletely characterized.(1) What is the range of serum metal levels associated with ALTR in patients who have MoM THAs or corrosion at the head-neck and neck-body junctions in metal-on-polyethylene (or ceramic-on-polyethylene) THAs? (2) How much wear occurs in patients with MoM total hips? (3) Is there evidence of a dose-response relationship between wear and ALTR?PubMed and Embase databases were reviewed for English-language studies assessing serum metal levels in the presence of ALTR and papers describing the results of wear measurements from revised MoM implants and ALTR histopathology were systematically reviewed. Reported linear wear data were separated into groups with ALTR and without ALTR as listed in individual papers and graphed to determine whether a dose-response relationship was present between wear and ALTR. Overall, 15 studies including 338 hips with ALTR with corresponding serum metal levels were identified and analyzed. Twelve studies reported the wear depth or volume of MoM components from patients with a variety of local reactions. Two studies investigated corrosion at the head-neck and neck-body junctions in metal-on-polyethylene THA. There was a high level of variability and study heterogeneity, and so data pooling (meta-analysis) could not be performed.Average reported metal concentrations were elevated above established normal values in patients with ALTR (cobalt concentrations ranged from 5 to 40 ppb, and chromium levels ranged from 5 to 54 ppb). Whereas several studies demonstrated that patients with ALTR had higher average linear wear of the bearing surfaces, this finding was not made in all studies that we identified in this systematic review. Because of this high degree of variability, no clear dose-response relationship between wear and ALTR could be established.Serum metal level analysis and implant retrieval analysis both contribute to the understanding of ALTR. Serum metal levels generally are elevated in the presence of ALTR but should not be used in isolation for clinical decision-making. Many but not all patients with ALTR, including those with pseudotumors, demonstrate high wear, but more data and more systematic descriptions of the histopathology are needed to define the amount of wear that induces adverse reactions.

Personality assessment tools are used effectively in many arenas of business, but they have not been embraced by the medical profession. There is increasing evidence that these tools have promise for helping to match resident candidates to specific fields of medicine, for mentoring residents, and for developing improved leadership in our field. This paper reviews many aspects of personality assessment tools and their use in orthopaedic surgery.

Recent investigations indicate that innate immune “danger-signaling” pathways mediate metal implant debris induced-inflammatory responses, e.g. NALP3 inflammasome. How the physical characteristics of particles, (size, shape and chemical composition) affect this inflammatory reactivity remains controversial. We examined the role of Cobalt-Chromium-Molybdenum (CoCrMo) alloy particle shape and size on human macrophage phagocytosis, lysosomal destabilization, and inflammasome activation. Round/smooth vs. irregularly shaped/rough CoCrMo-alloy particles of ~1µm and 6 to 7µm diameter were investigated for differential lysosomal damage and inflammasome activation in human monocytes/macrophages. While spherical/smooth 1µm CoCrMo-alloy particles did not measurably affect macrophage IL-1β production, irregular 1µm CoCrMo-alloy particles induced significant IL-1β increases over controls. Both round/smooth particles and irregular CoCrMo-alloy particles that were 6 to 7µ min size induced >10-fold increases in IL-1β production compared to similarly shaped smaller particles (p 3-fold increase in IL-1β vs. similarly sized round/smooth particles (at an equal dose, particles/cell). CoCrMo-alloy particle-size-induced IL-1β production was dependent on the lysosomal protease Cathepsin B, further supporting lysosomal destabilization as causative in inflammation. Phagocytosable larger/irregular shaped particles (6µm) demonstrated the greatest lysosomal destabilization (observed immunofluorescently) and inflammatory reactivity when compared on an equal dose basis (particles/cell) to smaller/spherical 1µm particles in vitro.

Background: Femoral stems with dual-taper modularity were introduced to allow additional options for hip-center restoration independent of femoral fixation in total hip arthroplasty. Despite the increasing availability and use of these femoral stems, concerns exist about potential complications arising from the modular neck-body junction. Methods: This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy. Results: Serum metal levels demonstrated greater elevation of cobalt (mean, 6.0 ng/mL) than chromium (mean, 0.6 ng/mL) or titanium (mean, 3.4 ng/mL). MRI with use of MARS demonstrated adverse tissue reactions in eight of nine patients in which it was performed. All hips showed large soft-tissue masses and surrounding tissue damage with visible corrosion at the modular femoral neck-body junction. Available histology demonstrated large areas of tissue necrosis in seven of ten cases, while remaining viable capsular tissue showed a dense lymphocytic infiltrate. Microscopic analysis was consistent with fretting and crevice corrosion at the modular neck-body interface. Conclusions: Corrosion at the modular neck-body junction in dual-tapered stems with a modular cobalt-chromium-alloy femoral neck can lead to release of metal ions and debris resulting in local soft-tissue destruction. Adverse local tissue reaction should be considered as a potential cause for new-onset pain in patients with these components, and early revision should be considered given the potentially destructive nature of these reactions. A workup including serologic studies (erythrocyte sedimentation rate and C-reactive protein), serum metal levels, and MARS MRI can be helpful in establishing this diagnosis. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The potential for corrosion at the modular head-neck junction in total hip arthroplasty has been well described, however the associated biological implications have recently received increasing clinical attention. Taper corrosion has been reported in patients with metal-on-polyethylene bearing surfaces, but it has also been recognized as an increasing cause of failure in patients with large head metal-on-metal hip replacements. Mechanical factors such as taper geometry, stem design, head size, or neck length may play a role in the etiology of taper corrosion. It can produce a range of clinical symptoms including pain, weakness, and instability that result from adverse local tissue reactions. While systemic effects have been reported, these remain poorly understood at present. A diagnostic algorithm to taper corrosion is provided, and treatment options are reviewed.

Since 1996 more than one million metal-on-metal articulations have been implanted worldwide. Adverse reactions to metal debris are escalating. Here we present an algorithmic approach to patient management. The general approach to all arthroplasty patients returning for follow-up begins with a detailed history, querying for pain, discomfort or compromise of function. Symptomatic patients should be evaluated for intra-articular and extra-articular causes of pain. In large head MoM arthroplasty, aseptic loosening may be the source of pain and is frequently difficult to diagnose. Sepsis should be ruled out as a source of pain. Plain radiographs are evaluated to rule out loosening and osteolysis, and assess component position. Laboratory evaluation commences with erythrocyte sedimentation rate and C-reactive protein, which may be elevated. Serum metal ions should be assessed by an approved facility. Aspiration, with manual cell count and culture/sensitivity should be performed, with cloudy to creamy fluid with predominance of monocytes often indicative of failure. Imaging should include ultrasound or metal artifact reduction sequence MRI, specifically evaluating for fluid collections and/or masses about the hip. If adverse reaction to metal debris is suspected then revision to metal or ceramic-on-polyethylene is indicated and can be successful. Delay may be associated with extensive soft-tissue damage and hence poor clinical outcome.

Although numerous in vitro studies report on the tribological performance of and, separately, on the corrosion properties of cobalt-based alloys in metal-on-metal (MoM) bearings, the few studies that take into account the synergistic interaction of wear and corrosion (tribocorrosion) have used canonical tribo-test methods. We therefore developed synergistic study using a test method that more closely simulates hip bearing conditions.(1) Is the total material loss during tribocorrosion larger than the sum of its components generated during isolated mechanical wear and isolated corrosion? (2) How is the tribocorrosive process affected by the presence of protein?High carbon CoCrMo alloy discs (18) were subjected to corrosion and tribocorrosion tests under potentiostatic conditions in an apparatus simulating hip contact conditions. The input variables were the applied potential and the protein content of the electrolyte (NaCl solution versus bovine serum, 30 g/L protein). The output variables were mass loss resulting from wear in the absence of corrosion, mass loss resulting from corrosion in the absence of wear, and the total mass loss under tribocorrosion, from which the additional mass loss resulting from the combined action of wear and corrosion, or synergism, was determined in the presence and absence of protein.The degradation mechanisms were sensitive to the interaction of wear and corrosion. The synergistic component (64 μg) in the presence of protein amounted to 34% of total material loss (187 μg). The presence of protein led to a 23% decrease in the total mass loss and to a considerable reduction in the mean current (4 μA to 0.05 μA) under tribocorrosion.Synergistic effects during tribocorrosion may account for a considerable portion of MoM degradation and are affected by proteins.The in vivo performance of some large-diameter MoM joints is unsatisfactory. The synergistic component resulting from tribocorrosion may have been missed in conventional preclinical wear tests.

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