Metal-on-metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study

Isolated acetabular cup revision in Metal-on-Metal total hip arthroplasty: a low-complication strategy feasible in only half of cases

PURPOSE

There is still a debate regarding the removal of the femoral stem due to the risk of trunnion. To answer this question, we conducted a study to compare long terms outcomes of isolated acetabular to total revision of MoM THA using an institutional arthroplasty registry.

METHODS

From 1996 to 2019, 150 patients (12.5%) of the 1202 revision THAs (rTHA) recorded in Geneva Arthroplasty Registry (GAR) underwent a revision of a MoM THA. After matching the two groups,126 patients were finally included: 63 in each group. The mean age was 64.4 (SD 11.6) years, 48.4% (61/126) were women with a mean BMI of 27.2 (SD 5.5) Kg/m2.

RESULTS

The overall survival rate was 88.1% [79.9-97.2%] at ten years. 10-year survival rate was 93.5% [86.2-100.0%] after isolated acetabular rTHA and 79.5% [61.7-100.0%] after total rTHA (p = 0.16). Regarding Hip Harris score and Merle d'Aubigne score, no difference at last follow-up was observed between the two groups (respectively: p = 0.39; p = 0.33). Regarding the chrome, cobalt, and nickel level reduction, no difference was observed between the two groups (respectively, p = 0.38, 0.81 and 0.97).

CONCLUSION

No difference was observed between isolated acetabular and total revision of MoM THAs regarding survival rate and ions levels at long term. It seems advisable to perform an isolated acetabular revision of a MoM THA when it is indicated.

LEVELS OF EVIDENCE

Level III, case control studies.

Nanoscale ZnO doping in prosthetic polymers mitigate wear particle-induced inflammation and osteolysis through inhibiting macrophage secretory autophagy

Wear particles produced by joint replacements induce inflammatory responses that lead to periprosthetic osteolysis and aseptic loosening. However, the precise mechanisms driving wear particle-induced osteolysis are not fully understood. Recent evidence suggests that autophagy, a cellular degradation process, plays a significant role in this pathology. This study aimed to clarify the role of autophagy in mediating inflammation and osteolysis triggered by wear particles and to evaluate the therapeutic potential of zinc oxide nanoparticles (ZnO NPs). We incorporated ZnO into the prosthetic material itself, ensuring that the wear particles inherently carried ZnO, providing a targeted and sustained intervention. Our findings reveal that polymer wear particles induce excessive autophagic activity, which is closely associated with increased inflammation and osteolysis. We identified secretory autophagy as a key mechanism for IL-1β secretion, exacerbating osteolysis. Both in vitro and in vivo experiments demonstrated that ZnO-doped particles significantly inhibit autophagic overactivation, thereby reducing inflammation and osteolysis. In summary, this study establishes secretory autophagy as a critical mechanism in wear particle-induced osteolysis and highlights the potential of ZnO-doped prosthetic polymers for targeted, sustained mitigation of periprosthetic osteolysis.

Friend or foe? Inflammation and the foreign body response to orthopedic biomaterials

The use of biomaterials and implants for joint replacement, fracture fixation, spinal stabilization and other orthopedic indications has revolutionized patient care by reliably decreasing pain and improving function. These surgical procedures always invoke an acute inflammatory reaction initially, that in most cases, readily subsides. Occasionally, chronic inflammation around the implant develops and persists; this results in unremitting pain and compromises function. The etiology of chronic inflammation may be specific, such as with infection, or be unknown. The histological hallmarks of chronic inflammation include activated macrophages, fibroblasts, T cell subsets, and other cells of the innate immune system. The presence of cells of the adaptive immune system usually indicates allergic reactions to metallic haptens. A foreign body reaction is composed of activated macrophages, giant cells, fibroblasts, and other cells often distributed in a characteristic histological arrangement; this reaction is usually due to particulate debris and other byproducts from the biomaterials used in the implant. Both chronic inflammation and the foreign body response have adverse biological effects on the integration of the implant with the surrounding tissues. Strategies to mitigate chronic inflammation and the foreign body response will enhance the initial incorporation and longevity of the implant, and thereby, improve long-term pain relief and overall function for the patient. The seminal research performed in the laboratory of Dr. James Anderson and co-workers has provided an inspirational and driving force for our laboratory's work on the interactions and crosstalk among cells of the mesenchymal, immune, and vascular lineages, and orthopedic biomaterials. Dr. Anderson's delineation of the fundamental biologic processes and mechanisms underlying acute and chronic inflammation, the foreign body response, resolution, and eventual functional integration of implants in different organ systems has provided researchers with a strategic approach to the use of biomaterials to improve health in numerous clinical scenarios.

The relationship between pseudotumours and infected complications in patients who have undergone metal-on-metal total hip arthroplasty

Aims

This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection.

Methods

A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years' clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery.

Results

The rate of PJI for all identified MoM THAs was 3.5% (41/1,171), with a mean follow-up of 10.9 years (2.0 to 20.4). Of the patients included in the final cohort, 8.2% (27/328) had PJI, with a mean follow-up of 12.2 years (2.3 to 20.4). Among this cohort, 31.1% (102/328) had a history of pseudotumour. The rate of PJI in these patients was 14.7% (15/102), which was greater than those without pseudotumour, 5.3% (12/226) (p = 0.008). Additionally, logistic regression analysis showed an association between history of pseudotumour and PJI (odds ratio 4.36 (95% confidence interval 1.77 to 11.3); p = 0.002). Optimal diagnostic cutoffs for PJI in patients with history of pseudotumour versus those without were 33.1 mm/hr and 24.5 mm/hr for ESR and 7.37 mg/dl and 1.88 mg/dl for CRP, respectively.

Conclusion

Patients with history of pseudotumour secondary to MoM THA had a higher likelihood of infection than those without. While suspicion of infection should be high for these patients, ESR and CRP cutoffs published by the European Bone and Joint Infection Society may not be appropriate for patients with a history of pseudotumour, as ESR and CRP levels suggestive of PJI are likely to be higher than for those without a pseudotumour. Additional investigation, such as aspiration, is highly recommended for these patients unless clinical suspicion and laboratory markers are low.

Mid-term clinical and radiographic outcome of metal-on-metal hip resurfacing through an anterolateral approach

PURPOSE

The aim of this retrospective study was to evaluate the medium-term clinical and radiographic results of current generation metal-on-metal resurfacing prostheses performed through anterolateral approach.

MATERIALS AND METHODS

Fifty-seven hips in 52 patients underwent resurfacing arthroplasty. Two patients died from unrelated causes, leaving 55 hips in 35 males (3 bilateral) and 15 females (2 bilateral), with a mean age at surgery of 56.2 years (range, 27-70 years). Clinical and radiographic assessment was carried out preoperatively and at follow-up in all the survived cases. The cumulative survival rate was determined according to the method of Kaplan-Meier.

RESULTS

At a mean follow-up of 5.2 years (range, 1.8-9.1 years), 2 HRs of the same female patient were revised because of early loosening of the acetabular component. Deep venous thrombosis and transient femoral nerve palsy occurred both in 1 case. No specific complications of HR were observed. Average Harris hip score improved significantly from 59.8 points (range, 30.4-90.6) preoperatively to 93.7 points (range, 53-100) at the latest examination. Neck narrowing showed an average of 3.27%, but it never exceeded 10%. Nonprogressive acetabular radiolucencies and osteolysis were detected both in 2 hips. A high rate of patients (32, 60.4%) developed heterotopic ossifications, although low-grade in most cases (27, 84.4%). The cumulative survival rate at 9.1 years with revision for any reason as the end point was 93.0%.

CONCLUSIONS

The early clinical and radiographic results of modern metal-on-metal hip resurfacing performed through an anterolateral approach are promising, but longer-term follow-up studies are necessary.

Comprehensive Review on Biomaterials and Their Inherent Behaviors for Hip Repair Applications

Developing biomaterials for hip prostheses is challenging and requires dedicated attention from researchers. Hip replacement is an inevitable and remarkable orthopedic therapy for enhancing the quality of patient life for those who have arthritis as well as trauma. Generally, five types of hip replacement procedures are successfully performed in the current medical market: total hip replacements, hip resurfacing, hemiarthroplasty, bipolar, and dual mobility systems. The average life span of artificial hip joints is about 15 years, and several studies have been conducted over the last 60 years to improve the performance and thereby increase the lifespan of artificial hip joints. Present-day prosthetic hip joints are linked to the wide availability of biomaterials. Metals, ceramics, and polymers are some of the most promising types of biomaterials; nevertheless, each biomaterial has advantages and disadvantages. Metals and ceramics fail in most applications owing to stress shielding and the emission of wear debris; ongoing research is being carried out to find a remedy to these unfavorable responses. Recent research found that polymers and composites based on polymers are significant alternative materials for artificial joints. With growing research and several biomaterials, recent reviews lag in effectively addressing hip implant materials' individual mechanical, tribological, and physiological behaviors. This Review comprehensively investigates the historical evolution of artificial hip replacement procedures and related biomaterials' mechanical, tribological, and biological characteristics. In addition, the most recent advances are also discussed to stimulate and guide future researchers as they seek more effective methods and synthesis of innovative biomaterials for hip arthroplasty application.

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).

Metallosis Following Titanium Implant Use in the Hand: A Case Report and Review of Current Literature

Adverse reaction to metal debris (ARMD) consists of a spectrum of changes ranging from pure metallosis to aseptic lymphocytic vasculitis-associated lesion and granulomatous inflammation. Currently described ARMD cases are mainly limited to arthroplasty, typically total hip and knee arthroplasties in the lower limb and total wrist arthroplasty in the upper limb. Hypersensitivity to a metallic implant in fracture fixation is rare, and a severe form of metallosis has not been reported so far. In this paper, we present a case of ARMD occurring 10 years after the use of titanium implants for fracture fixation in the hand. Intra-operative findings, histopathological results, and a literature review on ARMD are also described.

Case report and review: Angiosarcoma with thrombocytopenia after total hip arthroplasty

Total hip arthroplasty (THA) is a common treatment for osteoarthritis and is also performed for other conditions, such as secondary arthritis due to developmental dysplasia of the hip. Various THA types may be complicated by osteolysis and an inflammatory pseudotumor due to an adverse reaction to metal debris. Rarely, THA has been associated with malignant tumors, but their causality remains unclear. In this case report, we describe a female patient with developmental dysplasia of the hip. She had undergone left metal-on-polyethylene THA, acetabular revision of the THA, and left total knee arthroplasty. In addition, she had a history of dyslipidemia and telangiectasia of the eyes, anemia, hiatal hernia, and pleuritis. A THA-associated mass (suspected to be a pseudotumor) had been detected during a previous hospital admission due to pleuritis. She was hospitalized due to swelling in her left lower limb, fatigue, and bruises. A clinical examination revealed anemia, thrombocytopenia, and growth of the suspected pseudotumor. Within 6 weeks, she presented with bleeding of the oral mucosa, hemoptysis, melena, severe thrombocytopenia that did not respond to treatment, elevated D-dimer and C-reactive protein levels, severe pain, increased osteolysis, and fractures around the THA. Infection or malignancy was suspected, but two trocar biopsies suggested an inflammatory pseudotumor. Since her anemia and thrombocytopenia were considered to have been caused by an inflammatory process within the suspected pseudotumor, her suspected pseudotumor and all THA components were surgically removed. However, she developed severe alveolar hemorrhaging and hypoxia and died 2 weeks after her surgery. Histopathological analysis of her surgical and autopsy samples revealed highly malignant angiosarcoma. Although individual cases of malignancies associated with THA have been reported, the literature lacks a clear association between THA and increased cancer risk. Most pseudotumors are non-malignant. The patient's case presented in this report exemplifies the challenges to the differential diagnosis of a THA-associated pseudotumor and rare angiosarcoma. Atypically rapid tumor growth, severe osteolysis, and deterioration in the general wellbeing suggest a malignant disease.

Similar clinical and radiographic outcomes after two different hypoallergenic medial unicompartmental knee in patients with metal allergy

BACKGROUND

The purpose in the present study was to compare clinical and radiological outcomes of patients who had undergone a mobile-bearing unicompartmental knee arthroplasty (UKA) with either titanium niobium nitride (TiNbN) alloy implants or with fixed-bearing oxidized zirconium alloy implants.

METHODS

The records of two consecutive cohorts for a total of 86 hypoallergenic implants were prospectively analyzed. The first cohort consisted of 49 consecutive implantations of the hypoallergenic UKA Journey Uni Oxinium (Ox Group), while the second consisted of 37 consecutive series of UKA Oxford (TiNbN Group). All patients were evaluated by two independent surgeons who were not involved in the index surgery. The clinical evaluation consisted of evaluating each patient's Oxford Knee Score and Knee Society Score day before surgery (T0), and with two consecutive follow-ups at T1 (minimum follow-up 9 months) and T2 (minimum follow-up 24 months).

RESULTS

The two groups were homogeneous in all preoperative values, except Body Mass Index (BMI) and duration of final follow-up [both statistically higher (p < 0.05) in the TiNbN group]. Both groups showed a clinically significant improvement for all scores at final follow-up (p < 0.05). The only differences between the two groups involved a higher pre-operative Oxford Score in TiNbN group (p = 0.031), and different tibial and femoral angles at the final follow-up.

CONCLUSIONS

Both TiNbN and Oxinium UKA procedures enabled patients from good to excellent clinical and radiographic outcomes after the final follow-up, regardless of the age, gender, BMI bearing type, and implant size.

LEVEL OF EVIDENCE

LEVEL II: Comparative study.

Targeting of Periprosthetic Muscles for the Ultrasonographic Screening of Hip Abnormalities in Hip Resurfacing Arthroplasty Patients

BACKGROUND

Hip resurfacing arthroplasty (HRA) patients require subsequent annual screening for postoperative complications. Ultrasonography may be useful for this purpose but lacks a screening protocol for hips. The purpose of this study was to evaluate the accuracy of ultrasonography for detecting postoperative complications in HRA patients using a screening protocol that specifically targets periprosthetic muscles.

METHODS

We enrolled 45 hips from 40 HRA patients with a mean follow-up period of 8.2 years. MRI and ultrasonography scans were simultaneously conducted at follow-up. The ultrasonography assessments were conducted on the anterior part of the hip that targets iliopsoas, sartorius, rectus femoris, lateral with anterior superior and inferior iliac spine (ASIS and AIIS) as bony landmarks, and the lateral and posterior parts that target fascia tensor, short rotators, and gluteus minimus, medius, and maximus with greater trochanter and ischial tuberosity as bony landmarks. The accuracy of diagnosing postoperative abnormalities and the visibility of periprosthetic muscles were compared between these two modalities.

RESULTS

Both MRI and ultrasonography detected an abnormal region in eight cases comprising two infections, two pseudotumors, and four patients with greater trochanteric bursitis. Among these cases, four hips required implant removal. The increase in anterior space, measured as the distance between the iliopsoas and resurfacing head, was a good indicator for the abnormal mass in these four HRA cases. In the assessment of periprosthetic muscles, MRI showed a much lower visibility than ultrasonography in the iliopsoas (6.7% vs. 100%), gluteus minimus (6.7% vs. 88.9%), and short rotators (8.8% vs. 71.4%) due to implant halation.

CONCLUSIONS

By targeting periprosthetic muscles, ultrasonography can detect postoperative complications as effectively as MRI assessments in HRA patients. Ultrasonography has superior visibility in the periprosthetic muscles of HRA patients, indicating its utility for the screening of small legions in these cases which may not be visible by MRI.

Bone and Soft Tissue Reaction to Co(II)/Cr(III) Ions Stimulation in a Murine Calvaria Model: A Pioneering in vivo Study

Metal ions released during wear and corrosion of the artificial knee/hip joints are considered to contribute to aseptic implant failure. However, there are few convincing in vivo studies that demonstrate the effects of metal ions on bone and soft tissue. This study examined the in vivo effects of Co(II)/Cr(III) ions on mouse calvaria and the supra-calvaria soft tissue in an original mouse model. With the implantation of a helmet-like structure, we set up a subcutaneous cavity on the calvaria in which Co(II) Chloride or Cr(III) Chloride solutions were administered respectively. A layer of interface membrane formed on the calvaria along with the implantation of the helmet. The administered Cr(III) ions accumulated in the interface membranes while Co(II) disseminated into the circulation. Accumulated Cr(III) and related products induced local massive macrophage infiltration and skewed the bone metabolic balance. At last, we revealed that lymphocyte aggregates, which are the pathologic hallmark of human periprosthetic tissue, could be caused by either Co(II) or Cr(III) stimulation. These in vivo results may shed light on the effects and pathogenic mechanism of the Co(II)/Cr(III) ions released from the joint prosthesis. STATEMENT OF SIGNIFICANCE: Macrophage infiltration and lymphocyte aggregates are hallmarks of human joint periprosthetic tissue. We chronically administered Co(II)/Cr(III) ions on mouse calvaria and reproduced these two histopathologic hallmarks on mouse tissue based on an implanted helmet-like structure. Our results reveal that Cr(III) ions are locally accumulated and are effective in inducing macrophage infiltration and they can be phagocytosed and stored. However, the lymphocytes aggregates could be induced by both Co(II), Cr(III) and other unspecific inflammatory stimuli.

The plasticity of biocompatibility

Biocompatibility concerns the phenomena that occur within the interactions between biomaterials and human patients, which ultimately control the performance of many facets of medical technology. It involves aspects of materials science, many different forms of engineering and nanotechnology, chemistry, biophysics, molecular and cellular biology, immunology, pathology and a myriad of clinical applications. It is not surprising that an overarching framework of mechanisms of biocompatibility has been difficult to elucidate and validate. This essay discusses one fundamental reason for this; we have tended to consider biocompatibility pathways as essentially linear sequences of events which follow well-understood processes of materials science and biology. The reality, however, is that the pathways may involve a great deal of plasticity, in which many additional idiosyncratic factors, including those of genetic, epigenetic and viral origin, exert influence, as do complex mechanical, physical and pharmacological variables. Plasticity is an inherent core feature of the performance of synthetic materials; here we follow the more recent biological applications of plasticity concepts into the sphere of biocompatibility pathways. A straightforward linear pathway may result in successful outcomes for many patients; we may describe this in terms of classic biocompatibility pathways. In other situations, which usually command much more attention because of their unsuccessful outcomes, these plasticity-driven processes follow alternative biocompatibility pathways; often, the variability in outcomes with identical technologies is due to biological plasticity rather than material or device deficiency.

CoNiCrMo Particles, but Not TiAlV Particles, Activate the NLRP3 Inflammasome in Periprosthetic Cells

Aseptic loosening is the main reason for arthroplasty failure. The wear particles generated at the tribological bearings are thought to induce an inflammatory tissue response, leading to bone loss and the subsequent loosening of the implant. Different wear particles have been shown to activate the inflammasome, thereby contributing to an inflammatory milieu in the direct vicinity of the implant. The aim of this study was to investigate whether the NLRP3 inflammasome is activated by different metal particles in vitro and in vivo. Three different cell lines representing periprosthetic cell subsets (MM6, MG63 and Jurkat) were incubated with different amounts of TiAlV or CoNiCrMo particles. The activation of the NLRP3 inflammasome was determined through the detection of the caspase 1 cleavage product p20 in a Western blot. The formation of the inflammasome was also investigated in vivo using immunohistological staining for ASC in primary synovial tissues as well as tissues containing TiAlV and CoCrMo particles and in vitro after the stimulation of the cells. The results show that the CoCrMo particles induced ASC more markedly, as a readout for inflammasome formation in vivo, compared to TiAlV particular wear. The CoNiCrMo particles also induced ASC-speck formation in all the tested cell lines, which was not induced by the TiAlV particles. The Western blot shows that NRLP3 inflammasome activation, measured through caspase 1 cleavage, was increased only by the CoNiCrMo particles in the MG63 cells. We conclude from our data that the activation of the inflammasome is mainly driven by CoNiCrMo particles and less by TiAlV particles, indicating that different inflammatory pathways are activated by the different alloys.

Allergic reaction and metal hypersensitivity after shoulder joint replacement

PURPOSE

Metal ion release may cause local and systemic effects and induce hypersensitivity reactions. The aim of our study is first to determine if implant-related hypersensitivity correlates to patient symptoms or not; second, to assess the rate of hypersensitivity and allergies in shoulder arthroplasty.

METHODS

Forty patients with shoulder replacements performed between 2015 and 2017 were studied with minimum 2-year follow-up; no patient had prior metal implants. Each patient underwent radiographic and clinical evaluation using the Constant-Murley Score (CMS), 22 metal and cement haptens patch testing, serum and urine tests to evaluate 12 metals concentration, and a personal occupational medicine interview.

RESULTS

At follow-up (average 45 ± 10.7 months), the mean CMS was 76 ± 15.9; no clinical complications or radiographic signs of loosening were detected; two nickel sulfate (5%), 1 benzoyl peroxide (2.5%) and 1 potassium dichromate (2.5%) positive findings were found, but all these patients were asymptomatic. There was an increase in serum aluminum, urinary aluminum and urinary chromium levels of 1.74, 3.40 and 1.83 times the baseline, respectively. No significant difference in metal ion concentrations were found when patients were stratified according to gender, date of surgery, type of surgery, and type of implant.

CONCLUSIONS

Shoulder arthroplasty is a source of metal ion release and might act as a sensitizing exposure. However, patch test positivity does not seem to correlate to hypersensitivity cutaneous manifestations or poor clinical results. Laboratory data showed small constant ion release over time, regardless of gender, type of shoulder replacement and implant used.

LEVELS OF EVIDENCE

Level II.

Wear debris in metal-on-metal bearings and modular junctions : What have we learned from the last decades?

Metal-on-metal (MoM) bearing hip arthroplasty saw increasing utilization and peaked in the 1990s and early 2000s. Although the linear and volumetric wear rate for a MoM bearings was lower than its polyethylene counterpart, metal ion particles were found to be approximately 10 × smaller and 500 × higher in quantity compared to polyethylene wear debris. Research into these articulations have demonstrated their relationship to the formation of lymphocyte-mediated adverse local tissue reactions. The work-up for metal particle-associated conditions (metallosis) includes a thorough patient history and physical examination, blood laboratory studies for metal ion concentrations, and advanced imaging studies including magnetic resonance imaging (MRI). The treatment of metallosis and adverse local tissue reactions ranges from close serial observation to extensive debridement and full revision of arthroplasty components, when indicated.

Hypersensitivity reactions to metals in spine surgery

Hypersensitivity to orthopedic devices is a rare condition with an underestimated incidence due to the lack of diagnostic guideline and ambiguous clinical manifestations. Although hypersensitivity to metal is common, a few cases of hypersensitivity reactions have been reported after spinal instrumentation. Spinal fusion and stabilization require a wide range of devices such as screws, wires, bands, and artificial disk replacement devices. Spinal instrumented surgeries are different from total joint arthroplasty in several aspects such as degree and pattern of motion, loading environment, and adjacent tissues with distinct characteristics. The interval for hypersensitivity reactions to occur after spinal metallic implantation is usually weeks to months. The present review covers the topic of hypersensitivity reactions that have been reported after spinal surgeries with the focus on cutaneous presentations.

Hypersensitivity and lymphocyte activation after total hip arthroplasty

In the last decades total hip arthroplasty (THA) has become a standard procedure with many benefits but also a few still unsolved complications, which can lead to surgical revision in 19-23% of cases. Thus, aseptic loosening and metal hypersensitivity remain challenges. The phenomenon of wear debris causes chronic inflammation, which produces osteolysis and aseptic loosening. Wear debris promotes osteoclast production and inhibits osteoblasts by secretion of pro-inflammatory cytokines. Micro-abrasions can be induced by abrasive, adhesive and fatigue wear and cause a liberation of metal ions, which lead to another immune response elicited mostly by macrophages. Another reaction in the neocapsule can be a type IV hypersensitivity reaction to various alloys, containing metals such as nickel, cobalt and chromium. Patch testing and the lymphocyte transformation test (LTT) are not the best diagnostic possibilities to exclude a postoperative hypersensitivity reaction, because of the different alignment of the epicutaneous cells compared to the periprosthetic deep tissue. This hypersensitivity reaction is mostly induced by cytokines, which are secreted by macrophages rather than lymphocytes. In cell cultures and in animal studies, multipotent mesenchymal stem cells (MSC) have been shown to play a role in improving initial implant integration, to limit periprosthetic osteolysis and also to reconstitute peri-implant bone stock during implant revision. Thus, MSC might be used in the future to prolong the durability of THA. A better understanding of the interactions between primary chronic inflammation, corrosion, osteolysis and hypersensitivity is mandatory to develop new therapeutic strategies, aiming at the reduction of the incidence of implant failures. In this article the underlying immunological mechanisms to aseptic loosening are presented.

Periarticular metal hypersensitivity complications of hip bearings containing cobalt-chromium

Hip joints with bearings composed of cobalt-chromium alloy (metal-on-metal bearings) have been one of the most widely used implants in joint replacement arthroplasty. Unfortunately, these implants can contribute to a complication called aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL), a type IV metal hypersensitivity response around the joint. Consistent with such bearings, increased metal debris can be found in the surrounding fluids and in remote tissues and organs, due to wear and corrosion. It is hypothesized that metal ions released from the prosthesis (including Co2+) can potentially form haptens with proteins such as serum albumin in synovial fluid that in turn elicit ALVAL. Generally, elevated cobalt and chromium levels in synovial fluids may indicate implant failure. However, such measurements cannot be used as a reliable tool to predict the onset of ALVAL. To detect ALVAL, some diagnostic tests, questionnaires and imaging techniques have been used clinically with some success, but a standardized approach is lacking. At present, guidelines for implant usage and patient management are ambiguous and inconsistent across health care authorities. To reduce and better manage the development of ALVAL, further research into the precise molecular mechanism(s) by which ALVAL develops is urgently needed. Identification of diagnostic and prognostic biomarkers for ALVAL is required, as are more standardized guidelines for surgery and patient management.

Metal-on-metal total hip arthroplasty: does increasing modularity affect clinical outcome?

BACKGROUND

Modularity of metal-on-metal (MoM) implants has come under scrutiny due to concerns regarding additional sources of metal debris. This study is a retrieval analysis of implants from the same manufacturer with the same MoM bearing surface. The difference between the implants was presence or absence of modular junctions.

METHODS

This is a retrospective study of 31 retrieved implants from 31 patients who received a Conserve Wright Medical MoM hip prosthesis. The 31 implants consisted of 16 resurfacings and 15 implants with modular junctions; 4 conventional THAs and 11 modular-neck THAs.

RESULTS

43% of pre-revision MRI scans performed on resurfacing implants and 91% performed on the modular implants illustrated evidence of an adverse local tissue reaction. There was no difference in pre-revision blood metal ion levels or bearing surface wear between the resurfacings and modular implants. The neck-head tapers of the modular group showed low levels of material loss. However, the neck-stem tapers showed increased severity of corrosion and material loss.

CONCLUSIONS

The modular implants had an increased incidence of adverse local tissue reaction. This could be related to the presence of modular junctions, particular the neck-stem junction which showed increased susceptibly to corrosion.

Cervical Implant Allergy With Chronic Neck Pain: A Case Report

A 57-year-old woman underwent cervical implant surgery for a dislocated cervical spine fracture, and she complained of continuous intractable neck pain after surgery. Eight years later, she developed a plantar skin rash, subsequently diagnosed as a metal allergy, and metal dentures were replaced with ceramic ones. The skin rash, however, persisted for four more years after that and was eventually treated with cervical implant removal. Subsequently, her skin rash and her neck pain improved simultaneously. This synchronous improvement strongly suggested that the neck pain could have been caused by a cervical implant allergy. We discuss a case of posterior cervical implant allergy that presented with neck pain and plantar skin rash years after surgery.

Diagnostic tests for titanium hypersensitivity in implant dentistry: a systematic review of the literature

PURPOSE

There are rising concerns about titanium hypersensitivity reaction regarding dental endosseous implants. This review aims to summarize and compare the validity and reliability of the available dermatological and laboratory diagnostic tests regarding titanium hypersensitivity. The following PICO design was used: In Patients with titanium dental implants (P) does epicutaneous testing (ECT) (I), compared to lymphocyte transformation test (LTT) or Memory Lymphocyte Immunostimulation Assay (MELISA) (C) detect hypersensitivity reactions (O)? A literature search was performed including all studies dealing with this topic. Studies regarding orthopedic implants were excluded.

METHODS

Three databases (MEDLINE PubMed, Cochrane Library, SciELO) were screened for suitable studies and an additional manual search was also performed. Literature regarding hypersensitivity reactions in orthopedic implants, hypersensitivity reactions regarding implants not related to dental or maxillofacial surgery, animal studies and in vitro studies were excluded. A quality assessment of all selected full-text articles was performed. Randomized, controlled trials were evaluated with the Cochrane Risk of Bias Tool I. Cohort studies were assessed according to the New Castle-Ottawa Scale and case series according to Moga et al. (Development of a quality appraisal tool for case series studies using a modified Delphi technique. 2012).

RESULTS

10 studies were included in the quantitative synthesis and available for the endpoint diagnostics of intolerance reactions to titanium dental implants: 2 clinical studies, 7 cohort studies and 1 case series. The potential for bias (internal validity) for these studies was overall rated as high.

CONCLUSIONS

The study of the available literature regarding ECT and MELISA or LTT in patients with suspected titanium hypersensitivity showed inconsistent results in terms of reliability and validity and thus, those tests should be regarded cautiously. There is strong evidence that titanium hypersensitivity in dental implants is associated with innate immunity: unspecific pro-inflammatory responses due to particle induced hyperreactivity of macrophages or toxicological responses especially towards nanoparticles rather than activation of the adaptive immune system. Therefore, tests detecting allergies do not seem expedient and inflammatory clinical signs should be regarded as leading parameters.

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 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.

Nickel-free high-nitrogen austenitic steel outperforms CoCrMo alloy regarding tribocorrosion in simulated inflammatory synovial fluids

CoCrMo alloys are well-established biomaterials used for orthopedic joint replacement implants. However, such alloys have been associated with clinical problems related to wear and corrosion. A new generation of austenitic high-nitrogen steels (AHNSs) has been developed for biomedical applications. Here, we have addressed influences of hyaluronic acid, combined with inflammatory (oxidizing) conditions, on tribocorrosion of the high-nitrogen FeCrMnMoN_0.9 steel (DIN/EN X13CrMnMoN18-14-3, 1.4452), and of the low carbon CoCrMo_0.03 alloy (ISO 5832-12). We aimed to elucidate critical and clinically relevant conditions affecting the implant's performance in certain orthopedic applications. Tribocorrosion tests were conducted in triplicate, with discs under reciprocating sliding wear against a ceramic ball. Different lubricants were prepared from standardized bovine serum solution (ISO 14242-1), with variable additions of hyaluronic acid (HA) and hydrogen peroxide (H₂ O₂ ). Test conditions were: 37°C, 86,400 cycles, 37 N load (20-40 MPa after run-in phase). Volumetric wear was quantified; surfaces were evaluated by electrochemical parameters and microscopy/spectroscopy analyses (SEM/EDS). Factorial analysis of variance tests was conducted to examine the effects of HA, H₂ O₂ , and test material on wear- and corrosion-related dependent variables. Tribocorrosion performances of CoCrMo_0.03 and FeCrMnMoN_0.9 were comparable in fluids without H₂ O₂ . With higher H₂ O₂ concentrations, tribocorrosion increased for CoCrMo_0.03 , while this was not the case for FeCrMnMoN_0.9 . HA significantly enhanced wear of CoCrMo_0.03 in the absence of H₂ O₂ , while it mitigated the tribocorrosive action of 3 mM H₂ O₂ ; HA had no impact on FeCrMnMoN_0.9 . These results indicate a favorable performance of FeCrMnMoN_0.9 compared to CoCrMo_0.03 , and encourage further research on AHNS for certain orthopedic applications.

Ellagic Acid from Terminalia arjuna Fruits Protects Against Chromium and Cobalt Toxicity in Primary Human Lymphocytes

Increased accumulation of heavy metal ions such as Cr⁶⁺ and Co²⁺ due to release from prostheses and metallic implants has been reported. These metal ions have been shown to affect both resting and activated lymphocytes. Natural remedies towards mitigating the cytotoxic effects of metal ions are clearly warranted. Polyphenolic compounds which are part of hydrolysable tannins from natural plant sources are considered effective in cheating heavy metal ions in a biological system. We have isolated and characterized a polyphenolic compound (ellagic acid) from Terminalia arjuna fruits that has been tested for its ability to attenuate the metal ion toxicity in primary human lymphocytes in culture. Cr⁶⁺ and Co²⁺ (100 μM) decreased lymphocyte viability and proliferation and increased apoptosis of resting as well as CD3 and/or CD28-stimulated lymphocytes. Metal ions markedly diminished the cytokine (interleukin-2 and interferon-γ) secretion from activated lymphocytes. Pretreatment with ellagic acid at 25, 50, and 100 μM concentrations effectively improved viability and proliferative responses of both resting and activated lymphocytes, while attenuating the apoptotic index. Ellagic acid also tended to normalize the cytokine secretion from the activated lymphocytes even in the presence of metal ions, suggesting broad effects on the adaptive immune system.

Fracture of a triple-polished tapered cemented femoral stem at the Morse taper after metal-on-metal primary total hip arthroplasty

Total hip arthroplasty, one of the most successful orthopaedic procedures, is influenced by several variables. Corrosion at the modular junction is known as trunnionosis. Despite being reported infrequently, corrosion between the femoral head and the Morse taper can result in severe complications. Fracture of the femoral component in primary metal-on-metal (MoM) total hip arthroplasty at the Morse taper is an extremely rare event and can be associated with several risk factors. We report a case of corrosion at the Morse taper in a hybrid primary MoM total hip arthroplasty, resulting in Morse taper fracture with consequent femoral head entrapment inside the acetabular component. We hypothesise that some risk factors, such as age over 60years, active male patients, body mass index above 30kg/m², large femoral heads, high-offset stems, 9/10 Morse taper and MoM-bearing surfaces, are associated with this mode of failure.

Semi-quantitative histology confirms that the macrophage is the predominant cell type in metal-on-metal hip tissues

Numerous studies have examined the histology of metal-on-metal hip tissues for evidence of a dose response to metal wear but have often reported inconclusive or contradictory findings. The aim of the present study was to address these discrepancies using multiple histological scoring methods to characterize the tissue features of one large group of revised metal-on-metal total hips. Periprosthetic tissues from 165 metal-on-metal hip revisions were examined for features of aseptic lymphocytic vasculitis associated lesions (ALVAL) as rated using two scoring systems as well as rankings for macrophage and lymphocyte numbers, intracellular wear debris and necrosis. Correlations between histological features and clinical variables including gender and time to revision and implant variables including articular surface wear volume or visual taper corrosion scores were examined. Both ALVAL scores reflected the macrophage dominated histology with average scores of 5.9/10 and 1.5/3. There was a statistically significant correlation between the original ALVAL score and wear rate per year (correlation coefficient = 0.17, p = .05) and a moderate correlation between the number of macrophages and wear particles and wear volume. There was no statistically significant correlation between wear and any other feature including lymphocytic inflammation or necrosis. Strong correlations between combined cup and ball wear volume and histological characteristics were not observed, although the number of macrophages was more closely correlated with wear than lymphocytes or necrosis.

Tigecycline sclerotherapy for recurrent pseudotumor in aseptic lymphocyte-dominant vasculitis-associated lesion after metal-on-metal total hip arthroplasty: A case report

BACKGROUND

Metal-on-metal (MoM) total hip arthroplasty (THA) has been associated with adverse reactions to metal debris, presenting clinically as pseudotumors.

CASE SUMMARY

This case report presents a female aged 73 year-old with MoM THA-related pseudotumor. After arthrotomy and bursectomy surgeries, histologic examinations of surgical specimens revealed a specific lymphocyte-dominant immunologic response, now known as aseptic lymphocyte-dominant vasculitis-associated lesion (ALVAL). Due to soft tissue persisting effusion after arthrotomy and bursectomy, revision surgery was then performed with ceramic-on-polyethylene THA. However, revision did not resolve the patient’s symptoms. Here we describe our application of tigecycline sclerotherapy to treat recurrent pseudotumor after revision THA and no recurrence after 24-mo follow-up.

CONCLUSION

Tigecycline sclerotherapy is safe and effective in the management of recurrent pseudotumor after revision non-MoM THA in ALVAL cases.

Osteolysis in total hip arthroplasty in relation to metal ion release: Comparison between monolithic prostheses and different modularities

BACKGROUND

Among the various complications associated with total hip arthroplasty (THA) periprosthetic osteolysis and wear phenomena due to the release of metal particles, are two of the most common and have been reported to be correlated because of inflammatory responses directed towards released particles that generally activate macrophagic osteolytic effects. Therein, new masses known as pseudotumors can appear in soft tissues around a prosthetic implant. To date, there is paucity of reliable data from studies investigating for any association between the above mentioned adverse events.

AIM

To investigate for the existence of any association between serum and urine concentrations of metal-ions released in THA and periprosthetic osteolysis for modular neck and monolithic implants.

METHODS

Overall, 76 patients were divided into three groups according to the type of hip prosthesis implants: Monoblock, modular with metal head and modular with ceramic head. With an average f-up of 4 years, we conducted a radiological evaluation in order to detect any area of osteolysis around the prosthesis of both the femur and the acetabulum. Moreover, serum and urinary tests were performed to assess the values of Chromium and Cobalt released. Statistical analysis was performed to determine any association between the ion release and osteolysis.

RESULTS

For the 3 study groups, the monolithic, modular ceramic-headed and modular metal-headed implants had different incidences of osteolysis events, which were higher for the modular implants. Furthermore, the most serious of these (grade 3) were detected almost exclusively for the modular implants with metal heads. A mapping of the affected areas was performed revealing that the highest incidences of osteolysis were evidenced in the pertrochanteric region at the femur level, and in the supero-external region at the acetabular level. Regarding the evaluation of the release of metals-ions from wear processes, serum and urinary chromium and cobalt values were found to be higher in cases of modularity, and even more so for those with metal head. Statistical linear correlation test results suggested positive correlations between increasing metal concentrations and incidences areas of osteolysis. However, no cases of pseudo-tumor were detected.

CONCLUSION

Future studies are needed to identify risk factors that increase peri-prosthetic metal ion levels and whether these factors might be implicated in the triggering of local events, including osteolysis and aseptic loosening.

Influence of Psychological Distress in Patients with Hypoallergenic Total Knee Arthroplasty. Treatment Algorithm for Patients with Metal Allergy and Knee Osteoarthritis

The outcome in total knee arthroplasty (TKA) depends on multiples factors, among them is the psychological condition. In addition, up 15 to 30% of the patients that undergo TKA show little or no improvement after surgery, which implies the diagnosis of a painful TKA is a challenge for the orthopedic surgeon, who must rule out a possible metal allergy (MA). It is considered an exclusion diagnosis. Due to the complex relationship between psychological condition and MA, and according to the worse results in patients treated with a hypoallergenic TKA, we asked: (1). What degree of psychological distress (PD) is present in patients who have a hypoallergenic TKA, and how does it influence the results of quality of life (QoL) and functional capacity. (2). Can we develop a new algorithm for patients with a possible MA that improves the outcomes? A pragmatic clinical study was carried out that included patients who underwent hypoallergenic TKA during three consecutive years. Quality of life and functional capacity were measured with (Western Ontario McMaster Universities Osteoarthritis Index) WOMAC index, the Short Form 12 questionnaire (SF-12) questionnaire, and the The EQ-5D-5L questionnaire essentially consists of two pages: the EQ-5D descriptive system and the EQ visual analogue scale (EQ VAS) (Euro-QoL-5D L-VAS (EQ5D)), in all patients. To assess PD, a Psychological Distress Score was developed. SPSS software was performed to statistical analysis, and Student´s test for independent variables with a p < 0.005 as statistically significant. A total of 72 anallergic TKAs in 64 patients were treated during this period; 31.3% of these patients showed features of PD before the surgery. According with the severity of the PD, 60% were classified as severe, 10% as moderate and 30% as mild. Patients with PD had statistically significant worse results on the final WOMAC, SF-12, and EQ5D questionnaires. The final scores of the physical subscale of the SF-12 and EQ5D showed better results in patients diagnosed by psychiatrist. Up to one third of the patients with hypoallergenic TKAs have PD, and their results are clearly inferior to those patients with MA without PD. When PD was diagnosed according with Psychological Distress Score, patients should be carefully assessed in order to determine if a specialist referral is recommended. According with our results, PD should be assessed either by the PCP or by us. If the PD is confirmed, a psychiatry referral is then requested for better preoperative management and treatment. We believe that this approach would lead to better TKA outcomes.

Metal-induced delayed type hypersensitivity responses potentiate particle induced osteolysis in a sex and age dependent manner

It is widely recognized that innate macrophage immune reactions to implant debris are central to the inflammatory responses that drive biologic implant failure over the long term. Less common, adaptive lymphocyte immune reactions to implant debris, such as delayed type hypersensitivity (DTH), can also affect implant performance. It is unknown which key patient factors, if any, mediate these adaptive immune responses that potentiate particle/macrophage mediated osteolysis. The objective of this investigation was to determine to what degree known adaptive immune responses to metal implant debris can affect particle-induced osteolysis (PIO); and if this pathomechanism is dependent on: 1) innate immune danger signaling, i.e., NLRP3 inflammasome activity, 2) sex, and/or 3) age. We used an established murine calvaria model of PIO using male and female wild-type C57BL/6 vs. Caspase-1 deficient mice as well as young (12–16 weeks old) vs. aged (18–24 months old) female and male C57BL/6 mice. After induction of metal-DTH, and Cobalt-alloy particle (ASTM F-75, 0.4um median diameter) calvaria challenge, bone resorption was assessed using quantitative micro-computed tomography (micro-CT) analysis and immune responses were assessed by measuring paw inflammation, lymphocyte transformation test (LTT) reactivity and adaptive immune cytokines IFN-gamma and IL-17 (ELISA). Younger aged C57BL/6 female mice exhibited the highest rate and severity of metal sensitivity lymphocyte responses that also translated into higher PIO compared to any other experimental group. The absence of inflammasome/caspase-1 activity significantly suppressed DTH metal-reactivity and osteolysis in both male and female Caspase-1 deficient mice. These murine model results indicate that young female mice are more predisposed to metal-DTH augmented inflammatory responses to wear debris, which is highly influenced by active NLRP3 inflammasome/caspase-1 danger signaling. If these results are clinically meaningful for orthopedic patients, then younger female individuals should be appropriately assessed and followed for DTH derived peri-implant complications.

Can hip resurfacing be safely revised with short-stem total hip arthroplasty? A case series of six patients

BACKGROUND

The usage of short stems in primary total hip arthroplasty (THA) has constantly gained popularity over the last decade, however, to date, short stems are not eligible to be used as revision implants. The aim of this study was to retrospectively evaluate the outcome of revision surgery of failed hip resurfacing arthroplasty (HRA) using short-stem THA.

METHODS

In a single center, retrospective analysis, 6 consecutive patients who were treated with a calcar-guided short stem after failure of HRA were evaluated. The mean follow-up was 3.25 years (SD 0.45). Patient reported outcome measurements (PROMs) were recorded using the Harris hip score (HHS) and The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The health status was evaluated by the EQ-5D-5L score. Pain and satisfaction were obtained using the visual analogue scale (VAS). Radiographic analysis was performed by evaluating osteolysis, stress shielding, alignement and signs of aseptic loosening. Complications were documented.

RESULTS

At last follow-up, clinical outcome was excellent (HHS ≥ 90) in 5 patients and good (HHS = 87) in 1 patient. The mean WOMAC score was 5.73% (SD 3.66%). The mean EQ-5D-5L index was 0.914 (SD 0.07). Pain and satisfaction on VAS was 1.83 (SD 5.18) and 8.67 (SD 0.94), respectively. Radiologically, no signs of subsidence, aseptic loosening, stress shielding and fracture were obvious. No major complications occurred. To date, no further revision surgery was needed.

CONCLUSIONS

The outcomes of the present case series propose that HRA can be safely revised using short-stem THA in a selected patient group. Clinical and radiological results are encouraging. Based on the present data, short stems may be considered as a revision implant for failed HRA for experienced surgeons.

Does load-bearing materials influence hip capsule thickness in total hip replacement? An MRI case-matched study

BACKGROUND

Ceramic-on-ceramic (COC) total hip replacements (THR) have exhibited less instability and late dislocation. Hip capsule plays an important role in hip stability. Different surrounding soft tissue reactions have been observed according to the bearing material used but no study compared these data using MRI investigation. Therefore, we performed a retrospective case control study to compare hip capsule thicknesses according to the bearing materials in THR and in native hips.

HYPOTHESIS

Hip capsule is thicker after COC THR compared to ceramic- or metal-on-polyethylene (PE) bearings, or native hips.

MATERIALS AND METHOD

Magnetic resonance imaging (MRI) images, combined with a multi acquisition variable resonance image combination (MAVRIC) sequence, was used to measure the hip capsule thickness in 16 patients (29 hips) who had either COC (13 hips, median age at surgery: 64.8 years old, median follow-up at imaging: 2482 days), PE bearings (11 hips, median age at surgery: 48.4 years old (significantly different from COC THR), median follow-up at imaging: 1860 days (NS)), or a native hip with no implant (5 hips). Two independent radiologists measured capsular thicknesses in 4 different zones and were blinded regarding the bearing components. The imaged hips were classified into three groups: native, COC and PE.

RESULTS

The COC THR group had the thickest capsules (median 7.0mm, range 2.9-15.5mm). This result was statistically significant (p<0.0001) when compared to PE THR (median 4.9mm, range 2.2-10.5mm), and to native hips (median 4.1mm, range 2.7-6.9mm) measurements, respectively. Furthermore, painful hips had thinner capsules (4.6mm, range 2-10.5) compared to not painful hips (6.8mm, range 2.3-15.5) (p=0.0006).

DISCUSSION

This is the first in-vivo study measuring capsular thickness in THR with the objective of measuring variations according to the hip implant materials used. The results revealed a significantly thicker capsule for the COC bearing compared to either PE or native hips, and a thinner capsule in painful hips.

LEVEL OF EVIDENCE

III, retrospective non-consecutive cohort study.

Course of Metal Ions after a Revision of Malfunctioning Metal-on-Metal Total Hip Prostheses

The present research evaluated the course of cobalt and chromium in the blood and urine after the revision of metal-on-metal with a ceramic-on-polyethylene total hip arthroplasty. Seven patients were enrolled for hip prosthesis revision owing to ascertained damage of the implant. Metals in the blood and urine were evaluated before and after the hip revision. The double measurement before the total hip revision revealed high levels of metal ions (on average, 88.1 µg/L of cobalt in the blood, 399.0 µg/g of creatinine cobalt in the urine, 46.8 µg/L of chromium in the blood, and 129.6 µg/g of creatinine chromium in the urine at the first measurements), with an increasing trend between the first and second dosage. Within a week after the hip revision, the levels of metal ions significantly decreased by approximately half. Four to six months after the operation, the cobalt levels were found near to the reference values, whereas the chromium levels reached 25% of the values measured before the revision. The revision of malfunctioning metal-on-metal implants produced a dramatic decrease of metal ions in biological fluids, although it did not completely rescue the chromium level.

Allergic Dermatitis Following Bilateral Oxidized Zirconium Total Knee Replacements

Introduction:

Total knee replacement (TKR) utilization is expected to increase by 673% in 2030, with patients between the ages of 45 to and 64 years representing the fastest-growingfastest growing age group requiring joint replacement. This group not only demands a higher- performinghigher performing, durable prosthesis but are is also the most likely to be dissatisfied if their expectations are not met. Hypo-allergenic implants have been developed by some implant manufacturers to fill this need, so the occurrence of allergic skin reactions after surgery is unanticipated and can have unwanted consequences if not recognized and managed appropriately.

Case Report:

We present the case of a 55-year-old woman who underwent bilateral staged TKR using oxidized zirconium implants and subsequently developed eczematous skin reactions. In both instances, she presented with a peri-incisional erythematous blistering skin reaction that was successfully treated with topical corticosteroids. Investigations revealed no evidence of infection or allergic-typeallergic type reactions to the metals contained in the knee replacements.

Conclusion:

Allergic skin reactions following TKR are very rare, and are not necessarily due to a metal hypersensitivity. Infection must be excluded in all cases and a trial of topical corticosteroids is useful before prior to more aggressive treatment, with the removal of the implant reserved as a last resort. To the best of our knowledge, this is the first case in the literature that reports the occurrence of allergic skin reactions following oxidized zirconium TKRs, and highlights the fact that allergic skin reactions can occur when using hypo-allergenic implants. Surgeons should be aware of this possibility and counsel their patients appropriately during the informed consent process.

Allergy Considerations in Implanted Neuromodulation Devices

OBJECTIVES

Allergic reactions are rare and poorly understood complications of neuromodulation device implantation. There are currently no guidelines for management of allergic reactions to these devices and their components. Here we review the published cases of allergic reactions to implanted neuromodulatory devices and leverage the experiences of other specialties that deal with similar complications to formulate recommendations for prevention and management.

MATERIALS AND METHODS

A review and assessment of the literature.

RESULTS

Allergic reactions to a number of implantable devices have been observed and published. In dentistry and orthopedics, metals such as nickel are the most frequent cause of allergic reactions. In interventional cardiology, where devices closely resemble neuromodulatory devices, titanium, silicone, and polyurethanes are the most common causes of allergic reactions. In neurosurgery, allergic reactions to implantable neuromodulatory devices are rare, and we summarize 13 cases published to date. Such allergic reactions generally present as local dermatitis, erythema, and pruritus, which can be difficult to distinguish from surgical site infection. In one published case, symptoms resolved with corticosteroid treatment, but all other cases required explantation. The successful reimplantation with a modified device was reported in some cases.

CONCLUSIONS

Patients should be screened for a personal history of contact allergy before implantation procedures. A multidisciplinary approach to suspected cases of postoperative allergic reactions involving collaboration between neurosurgeons and other implanting physicians, dermatologists or allergists, and device manufacturers is recommended. In cases where an allergic reaction is suspected, an infectious etiology should be ruled out first. Clinical suspicion can then be supported with the use of patch testing, interpreted by an experienced dermatologist or allergist. If patch testing supports an allergic etiology, the implanting physician and the device manufacturer can work together to modify the device for safe reimplantation.

Metasul vs Cerasul bearings: a prospective, randomized study at a mean eighteen years

BACKGROUND

The aims of our study were to compare the clinical, radiographic outcomes and survivals between second-generation metal-on-metal (Metasul) and ceramic-on-ceramic (Cerasul) bearings at a very long-term follow-up.

METHODS

A prospective, randomized study was originally performed on a consecutive series of 250 cementless, 28-mm head and primary total hip arthroplasties between 1999 and 2002. For each bearing (Metasul or Cerasul), 125 THAs were initially included. All cases were evaluated both clinically and radiographically, and survival was assessed, considering revisions for aseptic loosening or for any reason as the end points for failure.

RESULTS

At a mean 18-year follow-up, clinical and radiographic outcomes were similar. Harris Hip Score increased 30% in the Metasul group and 32% in the Cerasul group (p = 0.6). Survival free of aseptic loosening was higher for Cerasul (100%), than for Metasul (94% [CI 88-99.9]) (p = 0.04). Survival free of any revision was 91% ([CI 84-98%]) for Cerasul and 91% ([CI 84-98%]) for Metasul. Fractures of Cerasul insert occurred in four cases (3%) at a mean 12.5 ± 3.3 years (range, 6 to 17 years).

CONCLUSION

At 18 years, Cerasul demonstrated higher survivorship than Metasul considering aseptic loosening as an end point. However, Cerasul liners had high rate of fracture because of its sandwich design (thin ceramic liner into polyethylene). These implants are no more available on the market.

Decrease of Quality of Life, Functional Assessment and Associated Psychological Distress in Patients with Hypoallergenic Total Knee Arthroplasty

Total knee arthroplasty (TKA) is the final treatment for knee osteoarthritis, and 15-30% of patients show little or no improvement. This high percentage is related to aspects of the surgical technique, the selected implant, and specific patient characteristics. The aim of this study was to analyze whether there are differences in quality of life (QoL) and functional capacity among patients undergoing TKA with conventional implants compared to those treated with hypoallergenic oxinium implants. A pragmatic clinical study was carried out that included patients who underwent TKA between January 2013 and December 2015. During this period, 245 knees in 228 patients were treated. Eleven patients were excluded, leaving a sample of 161 conventionally treated knees, 72 knees treated with hypoallergenic implants, and one patient who received both implant types. In all patients, QoL and functional capacity were measured with the WOMAC index, the SF-12 questionnaire, and the Euro-Qol-5D L-VAS. We also assessed the psychological distress of each patient and related the findings to the functional results. The differences in QoL were tested using ANCOVA and propensity score matching (PSM) models adjusted for sex, age, weight, psychiatric history and associated complications. Patients who underwent TKA using conventional prostheses had significantly better scores on the total WOMAC index and in the pain domain (p < 0.05) than those who received hypoallergenic prostheses, but no significant differences were observed for the other domains in the ANCOVA. In contrast, with the PSM, we also found statistically significant differences in the difficulty domain of the WOMAC. Significant differences were found for the SF-12 mental health questionnaire results (p = 0.038), but the same did not occur for the physical health domain in the ANCOVA and PSM. We also found statistically significant differences in the Euro-Qol-5D index results (p = 0.041), but not in the VAS scale scores for the same questionnaire in the ANCOVA, and we did not find significant differences in either with the PSM. Patients with metal allergies and those who present psychological distress had WOMAC, SF-12, and Euro-Qol-5D results that were statistically significantly worse than those of patients who received conventional implants. Patients who underwent hypoallergic TKA had lower scores on the QoL and functional capacity scales than patients who received conventional Cr-Co implants. Additionally, patients with psychological distress had worse results on the questionnaires, and those with a metal allergy had even lower scores; the differences were statistically significant.

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.

Peripheral Blood Lymphocyte Subpopulations in Patients Following Small Diameter Metal-On-Metal Total Hip Replacement at Long-Term Follow-Up

(1) Background: The objective of the present study was to investigate peripheral blood lymphocyte subpopulations in patients with small diameter metal-on-metal total hip arthroplasty (MoM THA) and elevated blood metal ion concentrations at long-term follow-up. The hypothesis was that increased blood metal ion levels or the presence of adverse local tissue reactions (ALTR) would be associated with changes in the peripheral expression of lymphocyte subpopulations, which could potentially serve as early diagnostic markers for metal wear related complications. (2) Methods: Peripheral blood samples were analyzed for leucocyte subgroups (CD3⁺, CD4⁺, CD8⁺, CD14⁺, CD16⁺/CD56⁺, CD25⁺/CD127⁻, CD19⁺, IFN-γ⁺, IL-4⁺ and IL-17A⁺ cells) in 34 patients with elevated blood metal ion levels (combined cobalt and chromium levels >2 µg/L) following small head MoM THA at a mean follow-up of 15.6 years. Fifteen patients with small head MoM THA and blood metal ion levels within the normal range and 15 patients with conventional ceramic-on-polyethylene THA served as control groups. In addition, blood metal ion levels and leucocyte subpopulations were compared between patients with and without adverse local tissue reactions (ALTR), which was investigated by MRI in 27 patients of the study cohort. (3) Results: There was a significant decrease in the levels of IFN-γ⁺ Type-1 T helper cells (Th1) in patients with MoM THA compared to the ceramic-on-polyethylene control group (p < 0.001). No statistically significant differences in the cell counts of other lymphocyte subpopulations were found between the three groups. Cobalt ion levels were significantly higher in patients with ALTR (p < 0.001) compared to the non-ALTR group, but no differences in the levels of lymphocyte subsets were found between the two groups. (4) Conclusions: No adverse systemic effects with respect to peripheral blood leucocyte subpopulations could be detected in the present study in patients following THA with a small diameter MoM articulation at long-term follow-up. We found a significant decrease of IFN-γ⁺ Th1 cells in patients with MoM THA compared to the control group, but no differences in the peripheral expression of leucocyte subpopulations were seen between patients with and without ALTR. Future studies with larger patient cohorts and additional histopathological investigations could help to better understand the role of Th1 cells and other cell lines of the adaptive immune system in the development of metal wear related complications after total joint replacement.

Activation of synovial fibroblasts from patients at revision of their metal-on-metal total hip arthroplasty

Background

The toxicity of released metallic particles generated in metal-on-metal (MoM) total hip arthroplasty (THA) using cobalt chromium (CoCr) has raised concerns regarding their safety amongst both surgeons and the public. Soft tissue changes such as pseudotumours and metallosis have been widely observed following the use of these implants, which release metallic by-products due to both wear and corrosion. Although activated fibroblasts, the dominant cell type in soft tissues, have been linked to many diseases, the role of synovial fibroblasts in the adverse reactions caused by CoCr implants remains unknown. To investigate the influence of implants manufactured from CoCr, the periprosthetic synovial tissues and synovial fibroblasts from patients with failed MoM THA, undergoing a revision operation, were analysed and compared with samples from patients undergoing a primary hip replacement, in order to elucidate histological and cellular changes.

Results

Periprosthetic tissue from patients with MoM implants was characterized by marked fibrotic changes, notably an increase in collagen content from less than 20% to 45–55%, an increase in α-smooth muscle actin positive cells from 4 to 9% as well as immune cells infiltration. Primary cell culture results demonstrated that MoM synovial fibroblasts have a decreased apoptosis rate from 14 to 6% compared to control synovial fibroblasts. In addition, synovial fibroblasts from MoM patients retained higher contractility and increased responsiveness to chemotaxis in matrix contraction. Their mechanical properties at a single cell level increased as observed by a 60% increase in contraction force and higher cell stiffness (3.3 kPa in MoM vs 2.18 kPa in control), as measured by traction force microscopy and atomic force microscopy. Further, fibroblasts from MoM patients promoted immune cell invasion by secreting monocyte chemoattractant protein 1 (MCP-1, CCL2) and induced monocyte differentiation, which could also be associated with excess accumulation of synovial macrophages.

Conclusion

Synovial fibroblasts exposed in vivo to MoM THA implants that release CoCr wear debris displayed dramatic phenotypic alteration and functional changes. These findings unravelled an unexpected effect of the CoCr alloy and demonstrated an important role of synovial fibroblasts in the undesired tissue reactions caused by MoM THAs.

Multivariate use of MRI biomarkers to classify histologically confirmed necrosis in symptomatic total hip arthroplasty

The failure of total hip arthroplasty (THA) is commonly associated with the necrosis of the periprosthetic tissue. To date, there is no established method to noninvasively quantify the progression of such necrosis. Magnetic resonance imaging (MRI) of soft tissues near implants has undergone a recent renaissance due to the development of multispectral metal-artifact reduction techniques. Advanced analysis of multispectral MRI has been shown capable of detecting small magnetism effects of metallic debris in periprosthetic tissue. The purpose of this study is to demonstrate the diagnostic utility of these MRI-based tissue-magnetism signatures. Together with morphological MRI metrics, such as synovial volume and thickness, these measurements are utilized as biomarkers to noninvasively detect soft-tissue necrosis in symptomatic THA patients ( N = 78 ). All subjects underwent an advanced MRI scan before revision surgery and tissue biopsies utilized for necrosis grading. Statistical analyses demonstrated a weak, but significant positive correlation (P = .04) between MRI magnetism signatures and necrosis scores, while indicating no meaningful association between the latter and serum cobalt and chromium ion levels. Receiver-operating characteristic (ROC) analyses were then performed based on uni- and multivariate logistic regression models utilizing the measured MRI biomarkers as predictors of severe necrosis. The area under the curve of the ROC plots for MRI biomarkers as combined predictors were found to be 0.70 and 0.84 for cross-validation and precision-recall tests, respectively.

No generally increased risk of cancer after total hip arthroplasty performed due to osteoarthritis

Previous studies on the risk of cancer after total hip arthroplasty (THA) contradict each other, and many are hampered by small cohort sizes, residual confounding, short observation times or a mix of indications underlying the THA procedure. We evaluated the risk of cancer after total hip arthroplasty due to osteoarthritis in a nationwide cohort by comparing cancer incidences in individuals exposed to total hip arthroplasty due to osteoarthritis and in unexposed, sex-, age- and residence matched individuals. To address some previous studies' shortcomings, information on comorbidity and socioeconomic background were obtained and adjusted for. We included 126,276 patients exposed to a cemented THA between 1992 and 2012, and 555,757 unexposed individuals. Follow-up started on the day of surgery for exposed individuals and respective date for matched, unexposed individuals, and ended on the day of death, emigration, censuring or December 31st, 2012, whichever came first. The Swedish Hip Arthroplasty Registry (SHAR), the Swedish Cancer Registry, the Swedish National Patient Registry and Statistics Sweden were accessed to obtain information on procedural details of the THA, cancer diagnoses, comorbidities, and socioeconomic background. The primary outcome measure was the occurrence of any cancer after the index date. Exposed individuals had a slightly lower adjusted risk of developing any cancer than unexposed individuals (hazard ratio [HR] 0.97; CI 0.95-0.99). The only cancer with a statistically significant risk increase in exposed individuals was skin melanoma (HR 1.15; CI 1.05-1.24). We attained similar risk estimates in analyses stratified by sex, in individuals with minimum 5 years of follow-up, in an analysis including individuals with a history of previous cancer, and in patients with cementless THA. In this study on a large and well-defined population with long follow-up, we found no increased overall risk of cancer after THA. These reassuring findings could be included in the guidelines on preoperative information given to THA patients.

Mechanically Assisted Crevice Corrosion in a Metal-on-Polyethylene Total Hip Presenting With Lower Extremity Vascular Compromise

Mechanically assisted crevice corrosion in modular total hip replacements may lead to an adverse local tissue reaction (ALTR) with a variety of sequelae. Although an ALTR is most commonly recognized with metal-on-metal modular hip constructs, tribocorrosion at the head-neck junction of metal-on-polyethylene (MoP) total hip arthroplasties may also lead to an ALTR. We present a case of a 79-year-old woman with a history of MoP total hip arthroplasty who presented with unilateral leg swelling, joint pain, and stiffness and subsequently underwent revision for an ALTR secondary to mechanically assisted crevice corrosion. This unique case of lower extremity vascular compromise resulting from an ALTR is important because clinicians should consider corrosion-related ALTRs when treating patients with an MoP hip prosthesis presenting with new-onset lower extremity swelling.

What Surgeons Need to Know About Adverse Local Tissue Reaction in Total Hip Arthroplasty

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.