Prevalence of Failure due to Adverse Reaction to Metal Debris in Modern, Medium and Large Diameter Metal-on-Metal Hip Replacements--The Effect of Novel Screening Methods: Systematic Review and Metaregression Analysis

Statistical models and implant customization in hip arthroplasty: Seeking patient satisfaction through design

Objectives

This study conducts a systematic literature review to explore the role of statistical models and methods in the design of orthopedic implants, with a specific focus on hip arthroplasty. Through a comprehensive analysis of the scientific literature, it aims to understand the relevance and applicability of these models in implant development and research trends in the field of design.

Methods

Data analysis and co-occurrence mapping techniques were employed to investigate the statistical models used as predictors of satisfaction in hip arthroplasty and in implant design. This approach facilitated a detailed and objective assessment of existing literature, revealing key trends and identifying gaps in current knowledge.

Key findings

The review's findings underscore a burgeoning interest in implant customization, with a significant emphasis on leveraging statistical techniques for optimal design. The logistic model methodology was applied to analyze a survey of hip surgery specialists, revealing that the physician's age does not influence the decision to use a customized implant. Furthermore, the review highlighted a knowledge gap at the intersection of statistics and design discipline concerning implant customization.

Significance

Despite the recognized importance of customization in implant design, there remains a dearth of contributions from the design discipline perspective in the existing literature, indicating substantial room for improvement and the need for interdisciplinary integration.

Conclusion

The integration of statistical methods in implant design is crucial, emphasizing the need for multidisciplinary approaches and customization to enhance patient satisfaction. This study provides a foundation for future research that could transform the field of hip arthroplasty through more personalized and effective solutions.

Adverse Metal Reaction in a Case of Metal-on-Polyethylene Hip Arthroplasty

Soft tissue inflammatory responses to metal debris from prostheses, categorised as adverse reactions to metal debris (ARMD), are frequent complications of total hip arthroplasty (THA) and often result in implant failure. Introducing modular implant designs in modern orthopaedics has brought benefits to total hip replacements but has also increased patients' susceptibility to corrosion-related risks. ARMD can develop from various metal articulating surfaces, including ceramic-on-polyethylene (CoP), ceramic-on-ceramic (CoC), metal-on-metal (MoM), and metal-on-polyethylene (MoP) configurations. In this case study, a 68-year-old male who underwent a MoP implant for osteoarthritis of the right hip 16 years ago presented with pain and difficulty walking, exacerbated over the past three months. Clinical examination revealed tenderness around the implant and a limited range of motion. Imaging studies, including X-rays and ultrasound-guided aspiration, coupled with normal serum and urinary cobalt (Co) and chromium (Cr) levels, confirmed the diagnosis of ARMD. Given the severity of symptoms and radiographic findings, surgical intervention was warranted, leading to a two-stage revision with implant augmentation using a Burch-Schneider cage. Three months post operation, the patient experienced significant improvements in pain levels, range of motion (ROM), and hip function. This case underscores the importance of vigilant surveillance for ARMD in patients undergoing non-MoM THA, even years post surgery. Prompt recognition and management of ARMD are crucial to mitigate the risk of long-term complications and optimise patient outcomes. Further research is needed to understand the risk factors and mechanisms underlying ARMD in MoP THA, aiding in developing preventive strategies and refined treatment protocols.

Under-reporting by surgical pathologists in tissue removed during revision surgery for metal-on-metal arthroplasties

Although adverse local tissue reactions (ALTR) have been reported for metal-on-metal implants (MoM) requiring early revision surgery, no study has looked at the accuracy of surgical pathologists in diagnosing ALTR. This study aims to investigate the accuracy of reporting adverse local tissue reactions in tissue samples following revision surgery from metal-on-metal implants. The authors reviewed histology glass slides as well as the original pathology reports of tissue processed in revision arthroplasties in 23 cases. These samples were microscopically analyzed for tissue necrosis and cystic degeneration, the presence of metal particles, corrosion byproducts, membrane formation, histiocytic cells, lymphocytic cells, and vascular pathology. The authors' findings were then compared to their corresponding original pathology reports. The authors found consistent under-reporting of the tissue findings. Most importantly, 18 samples showed evidence of metal present compared to 2 samples on original pathology reporting. The authors found that 15 samples showed evidence of pathological membranous tissue compared to just 6 on original pathology reporting. While just 3 of the original pathology reports indicated the presence of areas of predominantly lymphocytic inflammatory cells, the authors found 13 examples of such areas. Although ALTR reactions have been described as a sequala of failed MoM, the authors' data suggest that ALTR may occur more frequently than previously described. Under-reported findings of ALTR deprive both the patient and orthopaedic surgeon of important information that can help guide further follow-up.

Metal-on-Metal Hip Arthroplasty: A Comprehensive Review of the Current Literature

Metal-on-metal (MoM) total hip arthroplasty has been widely used since the end of the 20th century, although rates have now decreased due to concerns regarding adverse reactions and failure rates. The MoM implant has been replaced with other materials, such as ceramic-on-ceramic (CoC) and metal-on-polyethylene (MoP). This literature review looks at the past and present use of MoM prostheses to assess whether the turn away from MoM use is justified. Online literature searches were performed on PubMed, Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), and Web of Science online databases using the search terms "MoM and (ARMD and ALVAL)" (ARMD: adverse reaction to metal debris; ALVAL: aseptic lymphocyte-dominant vasculitis-associated lesion). A total of 64 relevant titles were included in the review. Although risk factors for adverse reactions and the causes of ARMD are generally agreed upon, more work is required to further understand the specific thresholds of blood metal ion levels that can be used to consistently identify ARMD and excessive metal wear-debris in patients who have not had their MoM implants revised. Metal-on-metal devices are not an acceptable option for total hip arthroplasties (THAs) in their current formulation due to the high rate and risk of ARMD. Some MoM hip resurfacing operations are appropriate for very carefully selected patients who are fully aware of the risks posed by the implant. It is recommended that device-specific thresholds for metal ion levels be developed to identify patients at risk of ARMD locally and systemically while using auxiliary tools to assist diagnosis, such as metal artefact reduction sequences (MARS)-MRI and hip scoring tools. Further work should investigate device-specific blood metal ion levels, the systemic effects of raised metal ion concentrations secondary to MoM arthroprosthetic wear, and the potential risks of ARMD caused by wear from tapered stems (including the implications this has for patients with CoC and MoP prostheses).

Long-term changes in blood metal ion levels in patients with hip resurfacing implants: implications for patient surveillance after 10 years follow-up

BACKGROUND

Studies investigating changes in blood metal ion levels during the second decade of the implant lifetime in MoM hip resurfacing patients are scarce.

METHODS

Patients implanted with either Birmingham Hip Resurfacing (BHR) or Articular Surface Replacement (ASR) hip resurfacings with >10 years follow-up and repeated blood metal ion measurements were identified at 2 large specialist European arthroplasty centres. After excluding patients with initial metal ion levels >7 ppb, the proportion of patients with an increase in blood metal ion levels above previously validated implant-specific thresholds (cobalt 2.15 ppb for unilateral implants, cobalt or chromium 5.5 ppb for bilateral) was assessed.

RESULTS

We included 2743 blood metal ion measurements from 457 BHR patients (555 hips) and 216 ASR patients (263 hips). Of patients with initial metal ion levels below implant specific thresholds, increases in cobalt or chromium level, respectively, to above these thresholds during the second decade were seen as follows: unilateral BHR (cobalt = 15.6%), unilateral ASR (cobalt = 13.8%), bilateral BHR (cobalt = 8.2%, chromium = 11.8%), bilateral ASR (cobalt = 8.5%, chromium = 4.3%). Measurement-to-measurement changes exceeding +2.15 ppb or +5.5 ppb were, however, uncommon during the second decade. Subgroup results with small diameter (<50 mm) implants were similar.

CONCLUSIONS

We recommend less frequent blood metal ion measurements are needed (every 3 to 5 years) for hip resurfacing patients if initial values were below 7ppb.

A Rare Case of Adverse Reaction to Metal Debris in a Ceramic-on-Ceramic Total Hip Replacement

Adverse Reaction to Metal Debris (ARMD) is one of the most frequent complications after Total Hip Replacement (THR) and often a cause of surgical revision. This is true especially for implants with Metal-on-Metal (MoM) and Large Diameter Heads (LDHs), which are frequently used to improve stability and reduce the risk of dislocation. However, ARMD is not exclusive to MoM replacement, as it can also occur in other implants such Ceramic-on-Ceramic (CoC), Metal-on-Polyethylene (MoP), and Ceramic-on-Polyethylene (CoP). In these non-MoM implants, ARMD is not caused by the tribo-corrosion between bearing surfaces but, rather, by the fretting at the interface between neck and stem of dissimilar metals. A case of a severe ARMD that happened to a 73-year-old female patient with CoC bearing THR at the right hip is presented in this case report. In this case, the ARMD was misdiagnosed for over a year, resulting in the development of a massive pseudotumor. The treatment of choice was a two-stage revision with the implant of a hip megaprosthesis. After more than 2 years of follow-up, complete recovery of hip Range of Motion (ROM) and normalization of chromium and cobalt levels in blood and urine were achieved. Despite the relatively short follow-up period, this can be considered a successful treatment of a major and misdiagnosed ARMD in a non-MoM hip replacement.

Involvement of NF-κB/NLRP3 axis in the progression of aseptic loosening of total joint arthroplasties: a review of molecular mechanisms

Particulate wear debris can trigger pro-inflammatory bone resorption and result in aseptic loosening. This complication remains major postoperative discomforts and complications for patients who underwent total joint arthroplasty. Recent studies have indicated that wear debris-induced aseptic loosening is associated with the overproduction of pro-inflammatory cytokines. The activation of osteoclasts as a result of inflammatory responses is associated with osteolysis. Moreover, stimulation of inflammatory signaling pathways such as the NF-κB/NLRP3 axis results in the production of pro-inflammatory cytokines. In this review, we first summarized the potential inflammatory mechanisms of wear particle-induced peri-implant osteolysis. Then, the therapeutic approaches, e.g., biological inhibitors, herbal products, and stem cells or their derivatives, with the ability to suppress the inflammatory responses, mainly NF-κB/NLRP3 signaling pathways, were discussed. Based on the results, activation of macrophages following inflammatory stimuli, overproduction of pro-inflammatory cytokines, and subsequent differentiation of osteoclasts in the presence of wear particles lead to bone resorption. The activation of NF-κB/NLRP3 signaling pathways within the macrophages stimulates the production of pro-inflammatory cytokines, e.g., IL-1β, IL-6, and TNF-α. According to in vitro and in vivo studies, novel therapeutics significantly promoted osteogenesis, suppressed osteoclastogenesis, and diminished particle-mediated bone resorption. Conclusively, these findings offer that suppressing pro-inflammatory cytokines by regulating both NF-κB and NLRP3 inflammasome represents a novel approach to attenuate wear-particle-related osteolytic diseases.

The incidence of adverse local tissue reaction due to head taper corrosion after total hip arthroplasty using V40 taper and 36 mm CoCr head

AIMS

Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors.

METHODS

Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti₁₂Mo₆Zr₂Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients.

RESULTS

A total of 20 ALTRs were identified on MRI, with an incidence of 26%. Patients with ALTR had significantly higher median Co levels compared with those without ALTR (2.96 μg/l (interquartile range (IQR) 1.35 to 4.98) vs 1.44 μg/l (IQR 0.79 to 2.5); p = 0.019). Radiological evidence of osteolysis was also significantly associated with ALTR (p = 0.014). Median Cr levels were not significantly higher in those with ALTR compared with those without one (0.97 μg/l (IQR 0.72 to 1.9) v 0.67 μg/l (IQR 0.5 to 1.19; p = 0.080). BMI, sex, age, type of femoral component, head length, the inclination of the acetabular component, and heterotopic ossification formation showed no significant relationship with ALTR.

CONCLUSION

Due to the high incidence of local ALTR in our cohort after more than ten years postoperatively, we recommend regular follow-up investigation even in asymptomatic patients with V40 taper and metal heads. As cobalt levels correlate with ALTR occurrence, routine metal ion screening and consecutive MRI investigation upon elevation could be discussed. Cite this article: Bone Joint J 2022;104-B(7):852-858.

Automatic Identification of Failure in Hip Replacement: An Artificial Intelligence Approach

Background: Total hip arthroplasty (THA) follow-up is conventionally conducted with serial X-ray imaging in order to ensure the early identification of implant failure. The purpose of this study is to develop an automated radiographic failure detection system. Methods: 630 patients with THA were included in the study, two thirds of which needed total or partial revision for prosthetic loosening. The analysis is based on one antero-posterior and one lateral radiographic view obtained from each patient during routine post-surgery follow-up. After pre-processing for proper standardization, images were analyzed through a convolutional neural network (the DenseNet169 network), aiming to predict prosthesis failure. The entire dataset was divided in three subsets: training, validation, and test. These contained transfer learning and fine-tuning algorithms, based on the training dataset, and were implemented to adapt the DenseNet169 network to the specific data and clinical problem. Results: After the training procedures, in the test set, the classification accuracy was 0.97, the sensitivity 0.97, the specificity 0.97, and the ROC AUC was 0.99. Only five images were incorrectly classified. Seventy-four images were classified as failed, and eighty as non-failed with a probability >0.999. Conclusion: The proposed deep learning procedure can detect the loosening of the hip prosthesis with a very high degree of precision.

The influence of HLA genotype on the development of metal hypersensitivity following joint replacement

Background

Over five million joint replacements are performed across the world each year. Cobalt chrome (CoCr) components are used in most of these procedures. Some patients develop delayed-type hypersensitivity (DTH) responses to CoCr implants, resulting in tissue damage and revision surgery. DTH is unpredictable and genetic links have yet to be definitively established.

Methods

At a single site, we carried out an initial investigation to identify HLA alleles associated with development of DTH following metal-on-metal hip arthroplasty. We then recruited patients from other centres to train and validate an algorithm incorporating patient age, gender, HLA genotype, and blood metal concentrations to predict the development of DTH. Accuracy of the modelling was assessed using performance metrics including time-dependent receiver operator curves.

Results

Using next-generation sequencing, here we determine the HLA genotypes of 606 patients. 176 of these patients had experienced failure of their prostheses; the remaining 430 remain asymptomatic at a mean follow up of twelve years. We demonstrate that the development of DTH is associated with patient age, gender, the magnitude of metal exposure, and the presence of certain HLA class II alleles. We show that the predictive algorithm developed from this investigation performs to an accuracy suitable for clinical use, with weighted mean survival probability errors of 1.8% and 3.1% for pre-operative and post-operative models respectively.

Conclusions

The development of DTH following joint replacement appears to be determined by the interaction between implant wear and a patient's genotype. The algorithm described in this paper may improve implant selection and help direct patient surveillance following surgery. Further consideration should be given towards understanding patient-specific responses to different biomaterials.

Limited need for screening of metal-on-metal hip resurfacing patients beyond 10 years of follow-up

BACKGROUND

National and international guidelines lack consistency on how to screen metal-on-metal (MoM) hip arthroplasty patients for adverse reactions to metal debris (ARMD). Long-term outcomes of MoM hip arthroplasty are scarce, hindering further development of such guidelines. We present the clinical, radiological and ARMD status of 158 cases of hip resurfacing with >10 years follow-up.

METHODS

A prospective analysis of a cohort of 298 consecutive hip resurfacing procedures was performed at a single institution. All patients underwent MARS-MRI scanning for pseudotumour screening at least once, regardless of symptoms. Implant survival and reasons for revision were analysed for all patients. Clinical, radiological and MARS-MRI results were analysed for 158 unrevised procedures with >10 years follow-up.

RESULTS

The implant survival was 85.9% at 14.5 years (95% CI, 81.9-90.6) with revision for all causes as endpoint and 92.3% with MoM disease-related revisions excluded (95% CI, 88.2-95.0). Of the 158 cases with >10 years follow-up, 1 had elevated metal ion levels, 29 had a stable C1 pseudotumour and 6 a stable C2 pseudotumour. All pseudotumours were observed within 3 years after initiating our intensified ARMD screening (2011), with no new pseudotumours observed after that period.

CONCLUSIONS

We suggest that follow-up of MoM hip resurfacing patients beyond 10 years after surgery can be done with large intervals (i.e. every 5 years), and only earlier if a patient becomes symptomatic.

Outcomes of patients with unexpected diagnosis of infection at total hip or total knee arthroplasty revisions

PURPOSE

The pre-operative differential diagnosis between periprosthetic joint infections (PJIs) and aseptic failure is challenging particularly in low virulence and biofilm-related infections. This study aimed to assess the incidence and survival of patients with unexpected PJIs in a presumed aseptic revision of total hip (THA) and knee (TKA) arthroplasties.

METHODS

A retrospective analysis of a prospective cohort of patients was performed with 295 patients undergoing THA (n = 241) or TKA (n = 54) revision for presumed aseptic causes. Patients were diagnosed with unexpected PJI taking into account leukocyte count in the synovial fluid, sonicate, synovial culture, and tissue cultures of samples collected during surgery. The primary endpoint was the infection-free implant survival rate at theone year follow-up.

RESULTS

The unexpected PJIs were 60 out of 295 (20.3%), whereas 235 (79.7%) were aseptic revisions. In the unexpected PJI group, 6 (11.1%) patients underwent knee revision and 54 (22.4%) hip revision. At the one year follow-up, one patient (1.6%) in the unexpected PJI group and 3 (1.3%) in the aseptic group (p = 1.0) failed for infection. The infection-free implant survival rate at the one year follow-up was 98.3% (C.I. 95%, 94.9-99.9%) for the unexpected PJI group and 98.7% (C.I. 95%, 97.3-99.9%) (p = 0.82) for the aseptic group.

CONCLUSION

The incidence of unexpected PJIs in a presumed aseptic revision of THAs and TKAs has been previously underestimated. The infection-free implant survival rate at the one year follow-up in patients with unexpected PJIs was not significantly lower compared with patients undergoing aseptic revision.

Small-head metal on metal total hip arthroplasty is associated with a high rate of complication and reoperation at mid-term follow-up

Background:

Adverse reactions to metal debris are significant complications after metal-on-metal total hip arthroplasty. Recently, late appearances of adverse reactions to metal debris and subsequent need for reoperations have been reported with small-diameter head metal-on-metal devices. We retrospectively investigated mid-term clinical outcomes of small-head metal-on-metal total hip arthroplasty.

Methods:

We reviewed 159 hips in 139 patients who had a small-head metal-on-metal total hip arthroplasty (M2a Taper; Biomet, Warsaw, IN) with a minimum 5-year follow-up and documented postoperative complications.

Results:

Focal osteolysis in either the femur or acetabulum was observed in 12 hips (7.5%, 44 months after surgery on average), with pseudotumor observed in 8 hips (5%, 120 months after surgery on average). Four hips (2.5%) had dislocations (84 months after surgery on average) and six hips (3.8%, 122 months after surgery on average) underwent reoperation.

Conclusion:

Small-head metal-on-metal total hip arthroplasty is associated with a high degree of complications at mid-term follow-up period. Considering this, we discourage the use of metal-on-metal total hip arthroplasty regardless of head size.

Incidence of Pseudotumors in a Dual Modular Stem Construct With and Without Metal-on-Metal Bearing Surface

BACKGROUND

The purpose of this study was to compare the incidence of pseudotumors in metal-on-metal (MoM) titanium modular neck hip arthroplasties to non-MoM modular neck hip arthroplasties. A secondary goal was to determine whether a correlation exists between elevated metal concentrations and pseudotumor incidence.

METHODS

The data were collected and evaluated from 49 MoM joints and 26 non-MoM joints between the years 2012 and 2017. Hip ultrasonography was done after a minimum of 5 years postimplantation. Whole serum metal (titanium, cobalt, and chromium) concentrations were measured at the hip ultrasonography study.

RESULTS

The average time elapsed between surgery and ultrasonography visit was 7.6 years. In the 49 patients with MoM joints, 22.4% (n = 11) had a pseudotumor. In the 26 patients with non-MoM joints, 9.1% of metal-on-polyethylene hips (n = 1) and 0% of ceramic-on-ceramic/polyethylene hips developed a pseudotumor. No significant statistical correlation was observed between serum metal concentrations and pseudotumor formation (P > 0.05). A significant correlation was observed of serum titanium concentration to pseudotumor size (P = 0.024).

CONCLUSION

The incidence of pseudotumor formation in MoM total hip arthroplasties was more than five times the incidence associated with non-MoM bearings. The correlation between serum titanium concentration and pseudotumor size suggests that titanium levels may be a useful indicator for pseudotumor formation in patients with this particular titanium modular neck femoral implant. No notable correlation was observed between serum cobalt and chromium concentration and pseudotumor formation or size.

Reasons for Revision: Primary Total Hip Arthroplasty Mechanisms of Failure

BACKGROUND

This study aimed to examine the major reasons for total hip arthroplasty (THA) failure and temporal patterns in THA revisions.

METHODS

A retrospective chart review was conducted on 535 revisions performed on 444 THAs from January 2010 to May 2019 at our institution.

RESULTS

The average time to revision THA was 8.51 ± 8.38 years, with 136 cases (30.9%) occurring within 2 years after primary THA. The major mechanisms of failure that resulted in revision surgery were mechanical failure (162, 36.5%), metallosis (95, 21.4%), dislocation or instability (65, 14.6%), periprosthetic fracture (46, 10.4%), infection (44, 9.9%), hematoma or poor wound healing (15, 3.4%), and pain or other (17, 3.8%).

CONCLUSION

Based on our institutional experience over the past decade, mechanical failure without dislocation, metallosis, dislocation, periprosthetic fracture, and infection are typical reasons patients present for primary THA revision. Revisions within 2 years after primary THA are more likely to be the result of infection and periprosthetic fracture. Mechanical failure is the most common reason for revision THA overall, and mechanical failure and metallosis are more likely to be the reason revision is necessary 2 or more years after primary THA.

Metal Ion Release, Clinical and Radiological Outcomes in Large Diameter Metal-on-Metal Total Hip Arthroplasty at Long-Term Follow-Up

Total hip arthroplasty (THA) with metal-on-metal (MoM) bearings have shown problems of biocompatibility linked to metal ion release at the local level causing an adverse reaction to metal debris (ARMD) and at a systemic level. The aim of this study was to evaluate clinical and radiological outcomes, and metal ion concentrations in the blood and urine of patients who underwent THA with the LIMA Met-Met hip system. Patients with ceramic-on-ceramic (CoC) bearings were included as a control group. In this study, 68 patients were enrolled: 34 with MoM THAs and 34 with CoC THAs. Patients were evaluated clinically (Harris Hip Score, SF-36) and radiologically at a median of 7.4 years after surgery. Whole blood and urinary cobalt and chromium levels were also assessed. Both types of implants were comparable in terms of clinical and functional results. Ion levels were significantly higher in the MoM group compared with CoC group 7 years after surgery. No correlations were found between metal ion levels and patient demographics, functional and radiological outcomes, and prosthesis features. Patient monitoring is thus advised to establish if prosthesis revision is necessary, especially in the case of MoM THA.

Retention of metals in periprosthetic tissues of patients with metal-on-metal total hip arthroplasty is reflected in the synovial fluid to blood cobalt transfer ratio in the presence of a pseudotumour

Background

Modern metal-on-metal (MOM) arthroplasties were performed for over a decade before alarming reports of adverse metal reactions dramatically reduced their use. Failures are seen more often with high-wearing implants, but also well-positioned components with more favourable wear patterns can cause problems. There are no specific clinical indicators that could help us to predict the prognosis of these implants. For this reason, we still need more information on the effect of underlying factors that contribute to this process.

Methods

In this prospective cohort study, we investigated how cup orientation and type of pseudotumour determined by the Hart classification effect the distribution of metals in blood, synovial fluid and tissues surrounding the metal-on-metal hip prosthesis in revision surgery patients. One thousand two hundred twenty-nine metal-on-metal hip patients were screened and of those, 60 patients that had a revision surgery due to adverse metal reaction were included. Whole blood, synovial fluid and synovial/pseudotumour tissue samples were analysed for metal ion concentrations (Co, Cr, Mo and Ti).

Results

The lowest metal concentrations were found when both cup anteversion and inclination were optimal, and the highest when both were suboptimal. Suboptimal anteversion alone raised Cr-ion concentrations more than suboptimal inclination. The concentrations of metals in blood, synovial fluid or synovial soft tissue were the same in patients with and without a pseudotumour, but the relative transfer percentage of cobalt from synovial fluid to blood was higher in patients with a pseudotumour.

Conclusions

The implant orientation alone does not explain the metal concentrations found in tissues or distribution of metals between different tissues. The accumulation of metals in periprosthetic soft tissues increase the total metal load, and in the presence of a pseudotumour this is reflected in the transfer ratio of Co from synovial fluid to the blood. The total metal load of the pseudotumour tissue should be defined in future studies to determine if this will provide new insights for clinical practice.

The number of lymphocytes increases in the periprosthetic tissues with increasing time of implant service in non-metal-on-metal total joint arthroplasties: A role of metallic byproducts?

BACKGROUND

The objective of the study was to determine the association between periprosthetic concentrations of selected metals and changes induced in periprosthetic tissues (PT).

METHODS

PT from 24 patients with metal-on-polyethylene or ceramic-on-polyethylene total joint replacements (TJRs) were examined. Samples underwent histological examination including quantification of cellular populations. Determination of metals was performed according to the published methodology. Results were processed using correlation analysis and Principal Component Analysis (PCA), respectively.

RESULTS

Growing concentration of metals in the PT was found as a function of length of exposure (LoE). Differences in Ti, Co, Cr and V concentrations (per α = 0.05) depended on the type of alloy the implants were made from. On the contrary, the implant composition did not reflect in the different numbers of immune cells per 1 high power field, not even in distribution of the membrane type according to the Krenn classification. PCA revealed several clusters in dependence on the LoE, type of the membrane and presence of immune cells. High representation of lymphocytes in the PT was typical for clusters with the longest LoE while a higher representation of neutrophils was typical for a shorter time to reoperation.

CONCLUSIONS

Correlation between the LoE and concentrations of metals in its surroundings was demonstrated. However, the tissue image analysis cannot differentiate finer, potentially metal-induced tissue changes. Importantly, the tissues become more similar with an increasing LoE. We draw a conclusion about predominantly non-specific stimulation of the PT jointly by metal and polyethylene particles in non-metal-on-metal TJRs.

Metal Ion Release after Hip and Knee Arthroplasty - Causes, Biological Effects and Diagnostics

All metal implants in human bodies corrode which results in metal ions release. This is not necessarily a problem and represents for most patients no hazard. However, if a critical metal ion concentration is exceeded, local or rarely systemic problems can occur. This article summarizes the mechanisms of metal ion release and its clinical consequences. Several situations can result in increased metal ion release: metal-on-metal hip arthroplasties with increased wear, increased micromotion at taper interfaces, direct metal-metal contact (polyethylene wear, impingement), erroneously used metal heads after ceramic head fracture. Possible problems are in most cases located close to the concerned joint. Furthermore, there are reports about toxic damage to several organs. Most of these reports refer to erroneously used metal heads in revisions after a broken ceramic head. There is currently no evidence of carcinogenic or teratogenic effects of implants but data is not sufficient to exclude possible effects. Cobalt and chromium blood levels (favorably in whole blood) should be measured in patients with suspected elevated metal ions. According to current knowledge levels below 2 µg/l seem to be uncritical, levels between 2 and 7 µg/l are considered borderline with unknown biological consequences and levels above 7 µg/l indicate a local problem which should be further diagnosed. Metal ion levels always need to be interpreted together with clinical symptoms and imaging results.

Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing

Objectives

Modern metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), while achieving good results with well-orientated, well-designed components in ideal patients, is contraindicated in women, men with head size under 50 mm, or metal hypersensitivity. These patients currently have no access to the benefits of HRA. Highly crosslinked polyethylene (XLPE) has demonstrated clinical success in total hip arthroplasty (THA) and, when used in HRA, potentially reduces metal ion-related sequelae. We report the early performance of HRA using a direct-to-bone cementless mono-bloc XLPE component coupled with a cobalt-chrome femoral head, in the patient group for whom HRA is currently contraindicated.

Methods

This is a cross-sectional, observational assessment of 88 consecutive metal-on-XLPE HRAs performed in 84 patients between 2015 and 2018 in three centres (three surgeons, including the designer surgeon). Mean follow-up is 1.6 years (0.7 to 3.9). Mean age at operation was 56 years (sd 11; 21 to 82), and 73% of implantations were in female patients. All patients were individually counselled, and a detailed informed consent was obtained prior to operation. Primary resurfacing was carried out in 85 hips, and three cases involved revision of previous MoM HRA. Clinical, radiological, and Oxford Hip Score (OHS) assessments were studied, along with implant survival.

Results

There was no loss to follow-up and no actual or impending revision or reoperation. Median OHS increased from 24 (interquartile range (IQR) 20 to 28) preoperatively to 48 (IQR 46 to 48) at the latest follow-up (48 being the best possible score). Radiographs showed one patient had a head-neck junction lucency. No other radiolucency, osteolysis, component migration, or femoral neck thinning was noted.

Conclusion

The results in this small consecutive cohort suggest that metal-on-monobloc-XLPE HRA is successful in the short term and merits further investigation as a conservative alternative to the current accepted standard of stemmed THA. However, we would stress that survival data with longer-term follow-up are needed prior to widespread adoption.

Cite this article: R. B. C. Treacy, J. P. Holland, J. Daniel, H. Ziaee, D. J. W. McMinn. Preliminary report of clinical experience with metal-on-highly-crosslinked-polyethylene hip resurfacing. Bone Joint Res 2019;8:443–450. DOI: 10.1302/2046-3758.810.BJR-2019-0060.R1

Repeated cobalt and chromium ion measurements in patients with large-diameter head metal-on-metal ReCap-M2A-Magnum total hip replacement

Background and purpose - Whole blood (WB) cobalt (Co) and chromium (Cr) ion levels have a major role in the follow-up of metal-on-metal total hip replacement (MoM THR). We investigated, first, if there was a change in WB Co or Cr levels over repeated measurements in patients with ReCap-M2A-Magnum THR, and, second, determined how many patients had WB Co or Cr levels that exceeded the safe upper limits (SUL) in the repeated whole blood metal ion assessment. Patients and methods - A Recap-M2A-Magnum THR was used in 1,329 operations (1,188 patients) at our institution between 2005 and 2012. We identified all patients (n = 319) with unilateral ReCap-M2A-Magnum implants who had undergone at least 2 repeated metal ion measurements with the first blood sample taken mean 5.5 years (1.8-9.3) after surgery and the second taken mean 2 years (0.5-3) after the first. Results - The median WB Co and Cr ion levels decreased in repeated measurements from 1.40 (0.40-63) ppb to 1.10 (0.20-68) ppb and from 1.60 (0.60-13.0) ppb to 1.10 (0.30-19.0) ppb, respectively. 7% of the Co ion values exceeded SUL at the initial measurement, and 7% at the control measurement. The proportion of Cr ion values exceeding the safe upper limit (SUL) decreased during the measurement interval from 5% to 4%. Interpretation - Repeated metal ion measurements in unilateral ReCap-M2A-Magnum patients in a mean 2-year time interval did not show any increase. Long-term ion levels are, however, not yet known.

Host-specific factors affect the pathogenesis of adverse reaction to metal debris

Background

Adverse Reaction to Metal Debris (ARMD) is a major reason for revision surgeries in patients with metal-on-metal (MoM) hip replacements. Most failures are related to excessively wearing implant producing harmful metal debris (extrinsic factor). As ARMD may also occur in patients with low-wearing implants, it has been suggested that there are differences in host-specific intrinsic factors contributing to the development of ARMD. However, there are no studies that have directly assessed whether the development of ARMD is actually affected by these intrinsic factors.

Methods

We included all 29 patients (out of 33 patients) with sufficient data who had undergone bilateral revision of ASR MoM hips (58 hips) at our institution. Samples of the inflamed synovia and/or pseudotumour were obtained perioperatively and sent to histopathological analysis. Total wear volumes of the implants were assessed. Patients underwent MARS-MRI imaging of the hips preoperatively. Histological findings, imaging findings and total wear volumes between the hips of each patient were compared.

Results

The difference in wear volume between the hips was clinically and statistically significant (median difference 15.35 mm³, range 1 to 39 mm³, IQR 6 to 23 mm³) (p < 0.001). The median ratio of total wear volume between the hips was 2.0 (range 1.09 to 10.0, IQR 1.67 to 3.72). In majority of the histological features and in presence of pseudotumour, there were no differences between the left and right hip of each patient (p > 0.05 for all comparisons). These features included macrophage sheet thickness, perivascular lymphocyte cuff thickness, presence of plasma cells, presence of diffuse lymphocytic infiltration and presence of germinal centers.

Conclusions

Despite the significantly differing amounts of wear (extrinsic factor) seen between the sides, majority of the histological findings were similar in both hips and the presence of pseudotumour was symmetrical in most hips. As a direct consequence, it follows that there must be intrinsic factors which contribute to the symmetry of the findings, ie. the pathogenesis of ARMD, on individual level. This has been hypothesized in the literature but no studies have been conducted to confirm the hypothesis. Further, as the threshold of metal debris needed to develop ARMD appears to be largely variable based on the previous literature, it is likely that there are between-patient differences in these intrinsic factors, ie. the host response to metal debris is individual.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2578-0) contains supplementary material, which is available to authorized users.

Transition from metal-DTH resistance to susceptibility is facilitated by NLRP3 inflammasome signaling induced Th17 reactivity: Implications for orthopedic implants

Metal hypersensitivity has been recognized as an adverse biologic reaction that can compromise total joint arthroplasty (TJA) performance. However, the etiology of metal hypersensitivity responses in TJAs remains unclear. Metal implant debris is known to act as a danger signal that drives NLRP3 inflammasome activation. It remains unknown if implant debris induced inflammasome activation regulates T cell lineage in TJA metal hypersensitivity responses. In this study, we show both in vivo and in vitro that the pathogenesis of metal hypersensitivity responses to implant debris are largely dependent on activation of the inflammasome/caspase-1 pathway and subsequent production of IL-17A/F by CD4+ T cells. Inhibiting either the inflammasome pathway or IL-17A bioactivity in vivo and in vitro (in vivo using NLRP3 and Caspase-1 deficient mice or in vitro using blocking agents such as Capase-1 inhibitor, IL-1Ra and anti-IL-17A), significantly (p<0.05) mitigated metal-DTH paw inflammation as well as lymphocyte cytokine (IFN-γ and IL-17) and proliferation responses in metal-sensitized mice and primary human PBMCs. This study provides mechanistic insight into how in vivo exposure to orthopedic implant debris, and metals in general, elicits NLRP3 inflammasome activation that mediates the generation of IL-17A/F producing CD4+ T cells, leading to metal-delayed type hypersensitivity reactions.

Blood cytokine pattern and clinical outcome in knee arthroplasty patients: comparative analysis 5 years after standard versus "hypoallergenic" surface coated prosthesis implantation

Background and purpose - Metal sensitivity might provoke complications after arthroplasty. Correspondingly, coated "hypoallergenic" implants are of interest but long-term follow-up data are missing. Thus, we assessed immunological and clinical parameters in such patients. Patients and methods - 5 years' follow-up data were obtained from 3 centers, which used either a standard total knee replacement (TKR) or the identical implant with multilayer surface zirconium nitride based coating. Of the 196 patients (mean age 68 years (44-84), 110 females) 97 had arthroplasty with a coated surface, and 99 were treated by a standard TKR of the same type. Investigations were Knee Society Score (KSS), Knee injury and Osteoarthritis Outcome Score (KOOS), radiographic analysis, and cytokine measurement in peripheral blood. Pro- and anti-inflammatory cytokines were evaluated by cytometric beads assay and RT-PCR. Results - Survival rate (Kaplan-Meier) was 98% for coated and 97% for uncoated implants after 5 years. Mechanical axis and KSS pain score (42 vs. 41 (0-50)) were comparable. Most serum cytokine levels were comparable, but mean interleukin-8 and interleukin-10 levels were higher in the group with an uncoated implant. IL-8: 37 (SD 7.5) pg/mL vs. 1.1 (SD 4.3) (p < 0.001); IL-10: 3.6 (SD 2.5) vs. 0.3 (SD 1.8) pg/mL (p < 0.001). Interpretation - There was similar clinical outcome 5 years after standard and surface-coated TKR. In peripheral blood there was an increased pro-inflammatory status, i.e., significant elevation of IL-8 and the anti-inflammatory IL-10, after standard uncoated prosthesis. Any long-term effects of these cytokine changes are unknown.

Implant Failure After Motec Wrist Joint Prosthesis Due to Failure of Ball and Socket-Type Articulation-Two Patients With Adverse Reaction to Metal Debris and Polyether Ether Ketone

We describe 2 cases of articulation-related failures resulting in revision surgery after a Motec total wrist arthroplasty: one with an adverse reaction to metal debris and the other with an adverse reaction to polyether ether ketone. In the first patient, blood cobalt and chrome levels were elevated and magnetic resonance imaging showed clear signs of a pseudotumor. The other patient had an extensive release of polyether ether ketone particles into the surrounding synovia due to adverse wear conditions in the cup, leading to the formation of a fluid-filled cyst sac with a black lining and diffuse lymphocyte-dominated inflammation in the synovia. We recommend regular follow-up including x-rays, monitoring of cobalt and chrome ion levels, and a low threshold for cross-sectional imaging in patients who have undergone total wrist arthroplasty with a Motec joint prosthesis. Wear-related problems can also develop in implants in which polyether ether ketone is the bulk material.

Total hip arthroplasty: Survival and modes of failure

Total hip arthroplasty (THA) is a very satisfactory surgical procedure for end-stage hip disorders.

Implant modifications, such as large femoral heads to improve stability, porous metals to enhance fixation and alternative bearings to improve wear, have been introduced over the last decade in order to decrease the rate of early and late failures.

There is a changing pattern of THA failure modes.

The relationship between failure modes and patient-related factors, and the time and type of revision are important for understanding and preventing short and late failure of implants.

The early adoption of innovations in either technique or implant design may lead to an increased risk of early failure.

Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.170068

Association between periprosthetic tissue metal content, whole blood and synovial fluid metal ion levels and histopathological findings in patients with failed metal-on-metal hip replacement

Adverse Reaction to Metal Debris (ARMD) is a major cause of implant failure leading to revision surgery in patients with metal-on-metal (MoM) hip arthroplasties. However, the pathogenesis and its association to implant wear are poorly understood and previous studies have yielded discrepant results. We sought to investigate the associations between histological findings, whole blood and synovial fluid metal ion concentrations and periprosthetic tissue metal concentrations in patients with MoM total hip replacements and hip resurfacings revised for ARMD. 107 hips in total were included in our study. Of these, 87 were total hip replacements and 20 were hip resurfacings, respectively. We found that whole blood, synovial fluid and periprosthetic tissue metal concentrations correlated poorly with histological findings. We suggest that the lack of a clear association between histological findings and wear measures in the present study as well as in previous studies is mostly influenced by variability in patient susceptibility. However, patients presenting with perivascular lymphocytic infiltration had lower chromium concentration in their periprosthetic tissues than patients with no perivascular lymphocytic infiltration. This may reflect the role of metal hypersensitivity in implant failure in these patients. Patients with total hip replacements evinced more necrosis and lymphocytic infiltration in their tissues than patients with hip resurfacings. This suggests that trunnion wear debris is more cytotoxic and/or immunogenic than bearing wear debris leading to higher failure rates seen in patients with total hip replacements.

Is the rate of revision of 36 mm metal-on-metal total hip arthroplasties with Pinnacle acetabular components related to the year of the initial operation? an interrupted time-series analysis using data from the National Joint Registry for England and Wales

AIMS

The aim of this study was to determine whether the rates of revision for metal-on-metal (MoM) total hip arthroplasties (THAs) with Pinnacle components varied according to the year of the initial operation, and compare these with the rates of revision for other designs of MoM THA.

PATIENTS AND METHODS

Data from the National Joint Registry for England and Wales included 36 mm MoM THAs with Pinnacle acetabular components which were undertaken between 2003 and 2012 with follow-up for at least five years (n = 10 776) and a control group of other MoM THAs (n = 13 817). The effect of the year of the primary operation on all-cause rates of revision was assessed using Cox regression and interrupted time-series analysis.

RESULTS

For MoM THAs involving Pinnacle components, those undertaken between 2007 and 2012 had higher rates of revision compared with those undertaken between 2004 and 2006 (hazard ratio (HR) 2.01; 95% confidence interval (CI) 1.57 to 2.57; p < 0.001). For THAs undertaken during and after 2007, the number of revisions per 1000 implant-years at risk significantly increased by 5.20 (95% CI 0.52 to 9.89; p = 0.033) compared with those undertaken before this time. In the control group, THAs undertaken between 2007 and 2012 also had higher rates of revision (HR 1.77; 95% CI 1.49 to 2.10; p < 0.001), with revisions per 1000 implant-years for those undertaken during and after 2007 significantly increasing by 6.13 (95% CI 1.42 to 10.83; p = 0.016).

CONCLUSION

The five-year revision rates were significantly increased for all primary MoM THAs undertaken from 2007 onwards. Contrary to recent reports, this finding was not specific to those involving Pinnacle acetabular components and may be explained by increased surveillance and recent lowering of the threshold for revision. Cite this article: Bone Joint J 2018;100-B:33-41.

Metal-on-Metal Hip Joint Prostheses: a Retrospective Case Series Investigating the Association of Systemic Toxicity with Serum Cobalt and Chromium Concentrations

INTRODUCTION

There have been concerns about prosthesis failure and the potential for systemic toxicity due to release of cobalt and chromium from metal-on-metal hip joint prostheses (MoM-HP). There is conflicting evidence on whether there is a correlation between higher cobalt and chromium concentrations and systemic toxicity.

METHODS

We undertook a retrospective review of consecutive patients with MoM-HP referred for outpatient review in toxicology clinics in London, UK, and in the USA recorded in the Toxicology Investigators Consortium (ToxIC) Registry from June 2011 to June 2015.

RESULTS

Thirty-one cases were identified; the median (IQR) serum cobalt concentration was 10.0 (3.8-32.8) mcg/L, and the median (IQR) serum chromium concentration was 6.9 (3.7-18.7) mcg/L. Twenty-three (74.2%) had symptoms, most commonly lethargy, hearing loss, and tinnitus. The odds ratios of symptomatic/asymptomatic patients for metal ion concentrations above/below 7 mcg/L were 1.87 (95% CI 0.37-9.57, p = 0.45) and 0.60 (95% CI 0.10-3.50, p = 0.57) for cobalt and chromium, respectively. Two (6.5%) patients with systemic cobalt toxicity had median (IQR) serum cobalt concentrations significantly higher than those without systemic features (630.4 [397.6-863.2] mcg/L versus 9.8 [2.9-16.4] mcg/L; p = 0.017). However, overall, there were no differences between cobalt (p = 0.38) or chromium (p = 0.92) concentrations between symptomatic and asymptomatic patients and no clinical features or investigation results correlated with cobalt or chromium concentration.

CONCLUSION

Two (6.5%) of 31 individuals referred for assessment of MoM-HP were diagnosed with systemic cobalt toxicity. However, despite a high prevalence of reported symptoms, neither symptoms nor investigation results correlated with serum cobalt or chromium concentrations.

Blood Metal Ion Thresholds to Identify Patients with Metal-on-Metal Hip Implants at Risk of Adverse Reactions to Metal Debris: An External Multicenter Validation Study of Birmingham Hip Resurfacing and Corail-Pinnacle Implants

BACKGROUND

The authors of recent studies have reported newly devised implant-specific blood metal ion thresholds to predict adverse reactions to metal debris (ARMD) in patients who have undergone unilateral or bilateral metal-on-metal (MoM) hip arthroplasty. These thresholds were most effective for identifying patients at low risk of ARMD. We investigated whether these newly devised blood metal ion thresholds could effectively identify patients at risk of ARMD after MoM hip arthroplasty in an external cohort of patients.

METHODS

We performed a validation study involving 803 MoM hip arthroplasties (323 unilateral Birmingham Hip Resurfacing [BHR], 93 bilateral BHR, and 294 unilateral Corail-Pinnacle implants) performed in 710 patients at 3 European centers. All patients underwent whole-blood metal ion sampling, and were divided into 2 groups: those with ARMD (leading to revision or identified on imaging; n = 75) and those without ARMD (n = 635). Previously devised implant-specific blood metal ion thresholds (2.15 μg/L of cobalt for unilateral BHR; 5.5 μg/L for the maximum of either cobalt or chromium for bilateral BHR; and 3.57 μg/L of cobalt for unilateral Corail-Pinnacle implants) were applied to the validation cohort, and receiver operating characteristic curve analysis was used to establish the discriminatory characteristics of each threshold.

RESULTS

The area under the curve, sensitivity, specificity, and positive and negative predictive values for the ability of each implant-specific threshold to distinguish between patients with and without ARMD were, respectively, 89.4% (95% confidence interval [CI] = 82.8% to 96.0%), 78.9%, 86.7%, 44.1%, and 96.9% for unilateral BHR; 89.2% (CI = 81.3% to 97.1%), 70.6%, 86.8%, 54.5%, and 93.0% for bilateral BHR; and 76.9% (CI = 63.9% to 90.0%), 65.0%, 85.4%, 24.5%, and 97.1% for unilateral Corail-Pinnacle implants. Using the implant-specific thresholds, we missed 20 patients with ARMD (2.8% of the patients in this series). We missed more patients with ARMD when we used the fixed thresholds proposed by regulatory authorities: 35 (4.9%) when we used the U.K. threshold of 7 μg/L for both cobalt and chromium (p = 0.0003), 21 (3.0%) when we used the U.S. threshold of 3 μg/L for both cobalt and chromium (p = 1.0), and 46 (6.5%) when we used the U.S. threshold of 10 μg/L for both cobalt and chromium (p < 0.0001).

CONCLUSIONS

This external multicenter validation study confirmed that patients with blood metal ion levels below new implant-specific thresholds have a low risk of ARMD after MoM hip arthroplasty. Using these implant-specific thresholds, we missed fewer patients with ARMD compared with when the thresholds currently proposed by regulatory authorities were used. We therefore recommend using implant-specific blood metal ion thresholds when managing patients who have undergone MoM hip arthroplasty.

LEVEL OF EVIDENCE

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

[Mid- and long-term effectiveness and failure causes analysis of large-head metal-on-metal total hip arthroplasty]

Objective

To explore the effectiveness and failure causes of large-head metal-on-metal total hip arthroplasty (large-head MoM THA).

Methods

Between March 2007 and May 2010, 159 patients (183 hips) underwent large-head MoM THA, and the clinical data were analyzed. There were 50 females (54 hips) and 109 males (129 hips) with an average age of 50 years (range, 20-78 years). Single hip was involved in 135 cases (left hip in 69 cases and right hip in 66 cases) and double hips in 24 cases. The causes included femoral head necrosis in 74 cases (93 hips), Legg-Calve-Perthes in 1 case (1 hip), osteoarthritis in 18 cases (19 hips), developmental dysplasia of the hip in 17 cases (18 hips), osteoarthritis after hip septic infection in 8 cases (8 hips), traumatic arthritis of the hip in 6 cases (6 hips), femoral neck fracture in 17 cases (17 hips), ankylosing spondylitis in 8 cases (11 hips), rheumatoid arthritis of hip in 9 cases (9 hips), and adult onset Still's disease in 1 case (1 hip). Before operation, visual analogue scale (VAS) was 6.59±0.87; Harris score was 45.99±8.07.

Results

Healing of incisions by first intention was achieved, and no operative complication occurred. The patients were followed up 1.2-8.2 years (mean, 6.1 years). Implant failure was observed in 15 cases (17 hips), and the 5-year survival rate of large-head MoM THA was 91.80% (168/183). The causes of implant failure after THA were inflammatory pseudotumor in 4 cases (4 hips), acetabular aseptic loosening in 3 cases (3 hips), osteolysis in 4 cases (5 hips), acetabular aseptic loosening combined with inflammatory pseudotumor in 3 cases (3 hips), and functional disused in 1 case (2 hips). Of them, 9 cases (11 hips) did not receive revision surgery for various reasons, while 6 cases (6 hips) underwent revision surgery at 1.2-5.4 years (mean 3.7 years) after large-head MoM THA. At last follow-up, VAS and Harris score were 1.72±1.48 and 81.37±10.75 respectively, showing significant differences when compared with preoperative scores ( t=-35.547， P=0.000； t=33.823， P=0.000). The function was excellent in 44 hips, good in 89 hips, fair in 33 hips, and poor in 17 hips.

Conclusion

Large-head MoM THA has a high revision rate during mid- and long-term follow-up because of inflammatory pseudotumor, acetabular aseptic loosening, and osteolysis. Early revision can effectively improve the function of the hip and improve patients'quality of life.

Halo and spillover effect illustrations for selected beneficial medical devices and drugs

BACKGROUND

Negative news media reports regarding potential health hazards of implanted medical devices and pharmaceuticals can lead to a 'negative halo effect,' a phenomenon whereby judgments about a product or product type can be unconsciously altered even though the scientific support is tenuous. To determine how a 'negative halo effect' may impact the rates of use and/or explantation of medical products, we analyzed the occurrence of such an effect on three implanted medical devices and one drug: 1) intrauterine contraceptive devices (IUDs); 2) silicone gel-filled breast implants (SGBI); 3) metal-on-metal hip implants (MoM); and 4) the drug Tysabri.

METHODS

Data on IUD use from 1965 to 2008 were gathered from the Department of Health and Human Services Vital and Health Statistics and peer-reviewed publications. Data regarding SGBI implant and explantation rates from 1989 to 2012 were obtained from the Institute of Medicine and the American Society of Plastic Surgeons. MoM implant and explantation data were extracted from the England and Wales National Joint Registry and peer-reviewed publications. Tysabri patient data were reported by Elan Corporation or Biogen Idec Inc. Data trends for all products were compared with historical recall or withdrawal events and discussed in the context of public perceptions following such events.

RESULTS

We found that common factors altered public risk perceptions and patterns of continued use. First, a negative halo effect may be driven by continuing patient anxiety despite positive clinical outcomes. Second, negative reports about one product can spill over to affect the use of dissimilar products in the same category. Third, a negative halo effect on an entire category of medical devices can be sustained regardless of the scientific findings pertaining to safety. Fourth, recovery of a product's safety reputation and prevalent use may take decades in the U.S., even while these products may exhibit widespread use and good safety records in other countries.

CONCLUSIONS

We conclude that the 'negative halo effect' associated with a stigma, rather than an objective risk-benefit assessment of medical products can increase negative health outcomes for patients due to reduced or inappropriate product usage.

Developments in imaging methods used in hip arthroplasty: A diagnostic algorithm

BACKGROUND

Several imaging modalities can be used to diagnose complications of hip prosthesis placement. Despite progress in these imaging techniques, there are, as yet, no guidelines as to their respective indications.

METHODS

We formed a panel of experts in fields related to prosthesis imaging (radiology, nuclear medicine, orthopedic surgery) and conducted a review of the literature to determine the value of each modality for diagnosing complications following hip replacement.

RESULTS

Few recent studies have investigated the benefits related to the use of the latest technical developments, and studies comparing different methods are extremely rare.

CONCLUSIONS

We have developed a diagnostic tree based on the characteristics of each imaging technique and recommend its use. Computed topography was found to be the most versatile and cost-effective imaging solution and therefore a key tool for diagnosing the complications of hip replacement surgery.