Cutaneous metal sensitivity in patients with orthopaedic injuries

Understanding immune-mediated cobalt/chromium allergy to orthopaedic implants: a meta-synthetic review

BACKGROUND

The frequency of primary joint replacement surgery continues to increase worldwide. While largely considered biologically inert entities, an increasing body of evidence continues to validate a not insignificant incidence of allergic reactions to such implants. Little previous work has explored genuinely immune-mediated reactivity in this context. In the absence of a contemporary published summary on the topic, this paper explored the current state of understanding of cobalt/chromium allergy and proposes a patient management algorithm whereby such immune reactions are clinically suggested.

METHODS

A structured, systematic literature review was performed by following PRISMA search principles to provide an updated review of this area.

RESULTS

Thirty-six topic-related articles were identified, the majority reflecting lower tiers of scientific evidence with a lack of homogeneous quantitative data to facilitate valid cohort comparisons. Largely, the available literature represented small case series' or expert opinions.

CONCLUSIONS

Despite increasing clinical awareness and acknowledgement of true allergy to joint replacement components, this review highlighted that the evidence base underpinning the diagnosis and management of such patients is limited. Both patient-reported metal allergy or skin patch testing are grossly unreliable methods and show almost no correlation with true immune reactivity. Recent studies suggested a potential role for patient-specific in vitro cellular activation testing and/or targeted genetic testing when cobalt/chromium allergy is clinically suspected. However, while likely representing the contemporary "best available" approaches both can be costly undertakings, are not yet universally available, and still require broader validation in non-research settings before wider uptake can be championed.

Pediatric fractures following implant removal: A systematic review

OBJECTIVES

To evaluate the available literature for postoperative fracture rates following implant removal in the pediatric population.

METHODS

A systematic review of articles in the PubMed and Embase computerized literature databases from January 2000 to June 2022 was performed using PRISMA guidelines. Randomized controlled trials, case-control studies, cohort studies (retrospective and prospective), and case series involving pediatric patients that included data on fracture rate following removal of orthopedic implants were eligible for review. Two authors independently extracted data from selected studies for predefined data fields for implant type, anatomic location of the implant, indication for implantation, fracture or refracture rate following implant removal, mean time to implant removal, and mean follow-up time.

RESULTS

Fifteen studies were included for qualitative synthesis. Reported fracture rates following implant removal vary based on several factors, with an overall reported incidence of 0%-14.9%. The available literature did not offer sufficient data for conduction of a meta-analysis.

CONCLUSION

Our systematic review demonstrates that fracture following implant removal in pediatric patients is a relatively frequent complication. In children, the forearm and femur are the most commonly reported sites of fracture following removal of implants. Traumatic fractures treated definitively with external fixation have the highest reported aggregate rate of refracture. Knowledge of the incidence of this risk is important for orthopedic surgeons. There remains a need for well-designed studies and trials to further clarify the roles of the variables that contribute to this complication.

Current opinions on the mechanism, classification, imaging diagnosis and treatment of post-traumatic osteomyelitis

Post-traumatic osteomyelitis (PTO) is a worldwide problem in the field of orthopaedic trauma. So far, there is no ideal treatment or consensus-based gold standard for its management. This paper reviews the representative literature focusing on PTO, mainly from the following four aspects: (1) the pathophysiological mechanism of PTO and the interaction mechanism between bacteria and the body, including fracture stress, different components of internal fixation devices, immune response, occurrence and development mechanisms of inflammation in PTO, as well as the occurrence and development mechanisms of PTO in skeletal system; (2) clinical classification, mainly the etiological classification, histological classification, anatomical classification and the newly proposed new classifications (a brief analysis of their scope and limitations); (3) imaging diagnosis, including non-invasive examination and invasive examination (this paper discusses their advantages and disadvantages respectively, and briefly compares the sensitivity and effectiveness of the current examinations); and (4) strategies, including antibiotic administration, surgical choices and other treatment programs. Based on the above-mentioned four aspects, we try to put forward some noteworthy sections, in order to make the existing opinions more specific.

Self-reported metal hypersensitivity in patients undergoing unicondylar knee arthroplasty

OBJECTIVES

There is ongoing discussion about arthroplasty surgery of patients with metal hypersensitivity. The aim of this study was to compare the functional outcomes and eosinophil counts of unicondylar knee arthroplasty (UKA) patients with and without a history of metal hypersensitivity.

METHODS

A retrospective review was made of the medical records of 148 extremities of 140 consecutive patients who underwent primary UKA between January 2016 and December 2017. The patients who met the inclusion criteria were screened for history of metal hypersensitivity using a questionnaire. The functional outcomes of patients and eosinophil levels were evaluated immediately before and at 6 weeks after surgery.

RESULTS

The mean follow-up period was 37 months (range, 18-48 months). Of the total 128 patients, 13 (10.2%) reported a history of metal hypersensitivity before the operation. There was no statistically significant difference between patients with or without a history of metal hypersensitivity in respect of the functional outcomes or eosinophil counts (p > 0.05).

CONCLUSIONS

The results of this study showed that the functional outcomes of patients who underwent UKA using a standard alloy did not change between the groups who reported having or not having a history of metal hypersensitivity. Although the study also showed that the eosinophil counts decreased after surgery compared to the preoperative counts, there was no statistical relationship between the eosinophil count and functional outcomes or metal hypersensitivity history.

Increased risk of eczema after joint replacement: A population-based retrospective cohort study

There are very few reports of eczema and other prosthetic-related allergic skin complications following arthroplasty. We aimed to assess the risk of eczema after joint replacement.We performed a retrospective population-based cohort study in 2024 joint replacement patients using the Longitudinal Health Insurance Database. For comparison, 8096 controls were selected, with 4 control subjects for each joint replacement patient matched for age, sex, and index year, to assess eczema risk. We examined 14-year cumulative eczema incidence associated with age, sex, immunity, disease history, and joint replacement location.Eczema rates in the joint replacement patients were 38% higher than in the control group (57.90 vs 41.84 per 1000 person-years, respectively). Compared with the control group, joint replacement patients showed a 1.35-fold increased risk of eczema according to the multivariable Cox model (95% Confidence interval [CI] = 1.23-1.49). Knee replacement patients had higher eczema risk compared with the control group (Hazard ratio [HR] = 1.45, 95% CI = 1.33-1.70). Stratified by study period, the joint replacement cohort had a higher eczema risk after the 3-month follow-up.Our study revealed that joint arthroplasty increased risk of eczema in this 14-year follow-up study, and this was not related to personal atopic history or gender.

Pulmonary Staple-Stump Granuloma After Segmentectomy: Two Case Reports and Comparison with Cases of Stump Recurrence

BACKGROUND Correctly diagnosing a staple-line mass after pulmonary resection for lung malignant tumor can be difficult. Differential diagnoses of recurrence, infectious mass, granuloma, and so on must be considered, despite their rarity. We report two cases of pulmonary staple-stump granuloma after segmentectomy for lung cancer. CASE REPORT Case 1 involved a 70-year-old man with small nodule in the left upper lobe identified on computed tomography (CT). Video-assisted thoracoscopic (VATS) left upper division segmentectomy was performed. Histopathological examination revealed squamous carcinoma. Follow-up CT 1 year postoperatively showed a shadow at the staple-stump, with growth evident later. CT-guided biopsy found no malignancy. However, complete left upper lobectomy was performed because of the gradually enlarging lesion. Histopathological examination revealed epithelioid granuloma. Case 2 involved a 60-year-old with suspected lung cancer in the right upper lobe. VATS right upper division segmentectomy (S2) was performed. CT at 30 months postoperatively showed a shadow at the staple line, with subsequent growth. VATS right upper lobectomy was performed. Intraoperative rapid diagnosis revealed epithelioid granuloma. These two cases were compared with five cases of staple-stump recurrence in our institution. All cases of recurrence grew concentrically or radially from the staple line with the mass surrounding the staple line. On the other hand, cases of granuloma extended along the long axis of the staple line, and 3-dimensional CT (3DCT) may help to understand the morphology. CONCLUSIONS Although preoperative differentiation of staple-line granuloma is difficult and pathological diagnosis is important, characteristic radiologic features and 3DCT may facilitate diagnosis.

Benefits of hardware removal after plating

Routine implant removal is frequently performed although evidence-based guidelines are lacking. But routinely planned implant removal has significant economic implications and shows considerable complication rates. In general, clinical outcome seems to improve but pain relief after operation is often unpredictable. Even in patients reporting implant-related pain, implant removal does not guarantee relief and may be associated with further complications. The intra- and postoperative complication rate remains very high. Implant removal demonstrates a significant learning curve and unsupervised junior surgeons tend to cause more complications. The need for implant removal may be questioned. Even with the implant in place, contact activities can be resumed. However, a new adequate trauma can create a new fracture independently if there is an implant in-situ or not. It is important to understand the complications and outcomes to be expected with hardware removal to carefully evaluate its indication.

Allergic or Hypersensitivity Reactions to Orthopaedic Implants

Allergic or hypersensitivity reactions to orthopaedic implants can pose diagnostic and therapeutic challenges. Although 10% to 15% of the population exhibits cutaneous sensitivity to metals, deep-tissue reactions to metal implants are comparatively rare. Nevertheless, the link between cutaneous sensitivity and clinically relevant deep-tissue reactions is unclear. Most reactions to orthopaedic devices are type IV, or delayed-type hypersensitivity reactions. The most commonly implicated allergens are nickel, cobalt, and chromium; however, reactions to nonmetal compounds, such as polymethyl methacrylate, antibiotic spacers, and suture materials, have also been reported. Symptoms of hypersensitivity to implants are nonspecific and include pain, swelling, stiffness, and localized skin reactions. Following arthroplasty, internal fixation, or implantation of similarly allergenic devices, the persistence or early reappearance of inflammatory symptoms should raise suspicions for hypersensitivity. However, hypersensitivity is a diagnosis of exclusion. Infection, as well as aseptic loosening, particulate synovitis, instability, and other causes of failure must first be eliminated.

Making Sense of Metal Allergy and Hypersensitivity to Metallic Implants in Relation to Hand Surgery

All metals implanted into a biological system undergo some degree of corrosion depending upon its composition. The electrochemical process of corrosion produces free metal ions, which may activate the host's immune system through a variety of mechanisms. Whereas dermal metal hypersensitivity is common, affecting 10% to 15% of the population, the immune reaction from implanted metals is much less common (< 0.1%), but has been associated with metal allergy and hypersensitivity producing a multitude of patient symptoms. Superficial symptoms may be mild to severe forms of dermatitis, urticaria, pruritus, and vasculitis, whereas deep sequelae include metallosis-related pseudotumor, implant loosening, and joint stiffness. Currently, there are clinical tests to evaluate patients for metal hypersensitivity, but there is little agreement regarding the ideal timing and clinical situation prompting the work-up of a patient for a metal allergy or hypersensitivity. An understanding of the epidemiology, etiology, basic science, diagnostic testing, and treatment of patients with suspected metal allergy, as it pertains to the current literature, will aid orthopedic and plastic surgeons of all subspecialties in the management of patients requiring metallic implants.

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

BACKGROUND

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

Hypersensitivity to Orthopedic Implants: A Review of the Literature

Awareness of rare etiologies for implant failure is becoming increasingly important. In addition to the overall increase in joint arthroplasties, revision surgeries are projected to increase dramatically in the coming years, with volume increasing up to seven-fold between 2005 and 2030. The literature regarding the relationship between metal allergy and implant failure is controversial. It has proven difficult to determine whether sensitization is a cause or a consequence of implant failure. Testing patients with functional implants is not a clinically useful approach, as the rate of hypersensitivity is higher in implant recipients than in the general population, regardless of the status of the implant. As a result of the ineffectiveness of preoperative patch testing for predicting adverse outcomes, as well as the high cost of implementing such patch testing as standard procedure, most orthopedists and dermatologists agree that an alternative prosthesis should only be considered for patients with a history of allergy to a metal in the standard implant. In patients with a failed implant requiring revision surgery, hypersensitivity to an implant component should be considered in the differential diagnosis. Because a metal allergy to implant components is currently not commonly considered in the differential for joint failure in the orthopedic literature, there should be improved communication and collaboration between orthopedists and dermatologists when evaluating joint replacement patients with a presentation suggestive of allergy.

Biomaterial hypersensitivity: is it real? Supportive evidence and approach considerations for metal allergic patients following total knee arthroplasty

The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected.

Potential release of in vivo trace metals from metallic medical implants in the human body: from ions to nanoparticles--a systematic analytical review

Metal ion release from metallic materials, e.g. metallic alloys and pure metals, implanted into the human body in dental and orthopedic surgery is becoming a major cause for concern. This review briefly provides an overview of both metallic alloys and pure metals used in implant materials in dental and orthopedic surgery. Additionally, a short section is dedicated to important biomaterials and their corrosive behavior in both real solutions and various types of media that model human biological fluids and tissues. The present review gives an overview of analytical methods, techniques and different approaches applied to the measurement of in vivo trace metals released into body fluids and tissues from patients carrying metal-on-metal prostheses and metal dental implants. Reference levels of ion concentrations in body fluids and tissues that have been determined by a host of studies are compiled, reviewed and presented in this paper. Finally, a collection of published clinical data on in vivo released trace metals from metallic medical implants is included.

Currently available devices for female sterilization

Sterilization is now the method of family planning most commonly used in the world. Over the last 150 years, research has evolved in the search for the ideal method of female sterilization. The procedure should ideally have high efficacy, be readily accessible and be personally and culturally acceptable. The method should be simple, quick, easily learned and be able to be performed in an outpatient setting without general anesthesia. The most common and effective method for sterilization has, thus far, been via the laparoscopic route. Hysteroscopic sterilization, however, potentially fulfills many of these ideal criteria, but until recently has remained more of a concept than a reality.

Carbon Coated Implants as a New Solution for Metal Allergy in Early-Onset Scoliosis: A Case Report and Review of the Literature

STUDY DESIGN

Retrospective case report.

OBJECTIVE

To report the first known case of immunological camouflage of a metal spinal implant with carbon coating.

SUMMARY OF BACKGROUND DATA

Metal sensitivity is common and is a consideration when choosing orthopedic implants in susceptible individuals. The sensitivity often is to nickel, cobalt, or chromium, and titanium is used as a safe alternative. However, when the allergy is also to titanium, solutions may be much more difficult. This case describes an innovative solution to a complex metal allergy that includes titanium in a child requiring spinal instrumentation for early-onset scoliosis.

METHODS

At age 6 years 7 months, the patient underwent an uncomplicated placement of bilateral posterior Vertical Expandable Prosthetic Titanium Ribs (VEPTRs; Synthes, Inc., West Chester, PA). At that time, there were no known metal allergies. At 3 weeks, the right side had become erythematous and had serosanguineous drainage. It briefly improved after each of 2 surgical debridements and a course of intravenous antibiotics, but within 6 weeks of the index procedure, the pain was still worsening. A titanium allergy was suspected and blood was sent for allergy testing. A test confirmed hypersensitivity to titanium, niobium, molybdenum, iron, and aluminum, among others. The remaining rod was removed. An in vivo trial for tolerance to high-grade stainless-steel implants was done. The implant was removed after 2 weeks because of systemic symptoms that occurred.

RESULTS

A plasma-spray, carbon-coated VEPTR rod was designed. A rod sample was inserted into the patient's forearm for trial. After 3 months, there was no appreciable reaction. Carbon-coated VEPTRs were placed without complications. The patient has undergone multiple lengthening using the carbon-coated VEPTRs.

CONCLUSIONS

In the rare patient with multiple allergies, choosing orthopedic implants can be challenging. An innovative carbon coating was applied by plasma spray to the VEPTR system, with good results.

Bearing exchange in the management of pseudotumours

INTRODUCTION

Soft tissue reactions following metal-on-metal (MoM) arthroplasty of the hip have been under considerable discussion. These reactions are seen following both hip resurfacing and MoM total hip arthroplasty (THA). The phenomenon may arise owing to shedding of metal particles in high wear states, hypersensitivity with normal metal wear rates or a combination of the two.

METHODS

Three patients were identified who had developed a soft tissue reaction (pseudotumour) following MoM hip resurfacing procedures. The prostheses were revised to ceramic-on-ceramic (CoC) THA with only minimal debridement of the pseudotumour. Pre and postoperative magnetic resonance imaging was performed to assess the size of the lesions.

RESULTS

Progressive and satisfactory resolution of the associated pseudotumours was identified following revision of the prostheses to CoC THA.

CONCLUSIONS

In the early stages of pseudotumour formation following MoM hip resurfacing, this potentially devastating condition can be managed adequately with revision to a CoC bearing THA with minimal soft tissue excision.

Inhalation toxicity of 316L stainless steel powder in relation to bioaccessibility

The Globally Harmonized System for Classification and Labelling of Chemicals (GHS) considers metallic alloys, such as nickel (Ni)-containing stainless steel (SS), as mixtures of substances, without considering that alloys behave differently compared to their constituent metals. This study presents an approach using metal release, explained by surface compositional data, for the prediction of inhalation toxicity of SS AISI 316L. The release of Ni into synthetic biological fluids is >1000-fold lower from the SS powder than from Ni metal, due to the chromium(III)-rich surface oxide of SS. Thus, it was hypothesized that the inhalation toxicity of SS is significantly lower than what could be predicted based on Ni metal content. A 28-day inhalation study with rats exposed to SS 316L powder (<4 µm, mass median aerodynamic diameter 2.5–3.0 µm) at concentrations up to 1.0 mg/L showed accumulation of metal particles in the lung lobes, but no signs of inflammation, although Ni metal caused lung toxicity in a similar published study at significantly lower concentrations. It was concluded that the bioaccessible (released) fraction, rather than the elemental nominal composition, predicts the toxicity of SS powder. The study provides a basis for an approach for future validation, standardization and risk assessment of metal alloys.

The Gulf War depleted uranium cohort at 20 years: bioassay results and novel approaches to fragment surveillance

During the 1991 GulfWar, U.S. service members were exposed to depleted uranium (DU) through friendly-fire incidents involving DU munitions and vehicles protected by DU armor. Routes of exposure to DU involved inhalation of soluble and insoluble DU oxide particles, wound contamination, and retained embedded DU metal fragments that continue to oxidize in situ and release DU to the systemic circulation. A biennial health surveillance program established for this group of Veterans by the U.S. Department of Veterans Affairs has shown continuously elevated urine DU concentrations in the subset of veterans with embedded fragments for over 20 years. While the 2011 assessment was comprehensive, few clinically significant U-related health effects were observed. This report is focused on health outcomes associated with two primary target organs of concern for long term effects of this combat-related exposure to DU. Renal biomarkers showed minimal DU-related effects on proximal tubule function and cytotoxicity, but significant biomarker results were observed when urine concentrations of multiple metals also found in fragments were examined together. Pulmonary tests and questionnaire results indicate that pulmonary function after 20 y remains within the clinical normal range. Imaging of DU embedded fragment-associated tissue for signs of inflammatory or proliferative reactions possibly associated with foreign body transformation or with local alpha emissions from DU was also conducted using PET-CT and ultrasound. These imaging tools may be helpful in guiding decisions regarding removal of fragments.

Correlation between metal allergy and treatment outcomes after ankle fracture fixation

PURPOSE

To determine correlation between metal hypersensitivity and long-term foot and ankle function and pain after internal fixation using stainless steel implants.

METHODS

60 men and 46 women (mean age, 47 years) who underwent internal fixation for ankle fractures completed a questionnaire 13 to 38 (mean, 26) months after surgery to assess their existing medical condition, history of metal hypersensitivity, problems and outcome of the implant (revision or removal), and the American Academy of Orthopaedic Surgeons (AAOS) foot and ankle score. A subset of 12 men and 15 women then underwent patch testing for metal hypersensitivity to molybdenum, chromium, iron, manganese, and nickel. Patients with positive and negative reactions were compared.

RESULTS

21 of the 106 patients underwent removal of the metal implants. The AAOS score was not associated with any of the variables, except for a history of metal hypersensitivity from dental implants and irritation around the surgical scar. Multiple linear regression analysis showed that only irritation around the surgical scar remained associated with poorer AAOS scores. Five of the 27 tested patients had a positive reaction. The mean AAOS scores did not differ significantly between patients with positive and negative reactions (34 vs. 31, p=0.73). Gender was not associated with the test results (p=0.63). None of the 5 patients with a positive reaction underwent revision surgery or reported any history of asthma or metal hypersensitivity. Of the 27 patients, one of the 8 who reported itching, irritation, redness or rash around the surgical scar had a positive reaction, compared to 4 of 19 patients who reported no such symptoms (p=1). Two of the 27 patients reported development of eczema after fixation, one of whom had a positive reaction. Only one of the 27 patients reported a history of metal hypersensitivity to jewellery, but had a negative reaction..

CONCLUSION

Neither a history of metal hypersensitivity nor positive patch testing correlated with poor outcomes after internal fixation for ankle fractures using stainless steel implants.

Dermatitis associated with chromium following total knee arthroplasty

All metal implants release metal ions because of corrosion. Although 20% to 25% of patients develop metal sensitivity after total joint arthroplasty, which is 10% higher than that in the general population, only very few highly susceptible patients exhibit symptoms. Even patients with known metal allergy often do not react to their metal prosthesis. Systemic allergic contact dermatitis is particularly uncommon with total knee arthroplasty because there is no metal-on-metal contact between the femoral and tibial components. We present a case report of 62-year-old man with dermatitis most likely caused by chromium after total knee arthroplasty and review the relevant literature. Although this complication is very rare, it sometimes can be painful enough for the patient to undergo revision surgery.

Pragmatic approach to the clinical work-up of patients with putative allergic disease to metallic orthopaedic implants before and after surgery

Allergic complications following insertion of metallic orthopaedic implants include allergic dermatitis reactions but also extracutaneous complications. As metal-allergic patients and/or surgeons may ask dermatologists and allergologists for advice prior to planned orthopaedic implant surgery, and as surgeons may refer patients with complications following total joint arthroplasty for diagnostic work-up, there is a continuous need for updated guidelines. This review presents published evidence for patch testing prior to surgery and proposes tentative diagnostic criteria which clinicians can rely on in the work-up of patients with putative allergic complications following surgery. Few studies have investigated whether subjects with metal contact allergy have increased risk of developing complications following orthopaedic implant insertion. Metal allergy might in a minority increase the risk of complications caused by a delayed-type hypersensitivity reaction. At present, we do not know how to identify the subgroups of metal contact allergic patients with a potentially increased risk of complications following insertion of a metal implant. We recommend that clinicians should refrain from routine patch testing prior to surgery unless the patient has already had implant surgery with complications suspected to be allergic or has a history of clinical metal intolerance of sufficient magnitude to be of concern to the patient or a health provider. The clinical work-up of a patient suspected of having an allergic reaction to a metal implant should include patch testing and possibly in vitro testing. We propose diagnostic criteria for allergic dermatitis reactions as well as noneczematous complications caused by metal implants.

Increased metal allergy in patients with failed metal-on-metal hip arthroplasty and peri-implant T-lymphocytic inflammation

BACKGROUND

In 16 patients with revised metal-on-metal arthroplasty and peri-implant lymphocytic inflammation, we verified the role of metal hypersensitivity by patch testing (PT) and lymphocyte transformation test (LTT).

METHODS

In the 16 patients with lymphocyte dominated periprosthetic inflammation, allergy history was obtained by a questionnaire, specific serum IgE to aeroallergens was measured to assess atopy, PT to standard and metal series was performed and metal sensitivity was further assessed by LTT using blood mononuclear cells.

RESULTS

Revision surgery was performed because of pain (8/16), osteolysis (4/16), dislocation (3/16) and loosening of the stem (1/16). Histological examination showed perivascular infiltrates of T lymphocytes, high endothelial venules, fibrin exudation and accumulation of macrophages with drop-like inclusions. Five patients had a history of cutaneous metal allergy and atopy was found in 25% of the patients. In 13/16 patients (81%), systemic metal sensitivity was found based on PT and/or LTT. Patch test reactions were seen in 11/16 patients (69%; partly multiple reactions/patient): 7/16 to Cobalt (Co), 7/16 to Chromium (Cr), 4/16 to Nickel (Ni), and one each to Molybdenum (Mo) and Manganese (Mn). Ten of 16 patients (62%) showed enhanced LTT reactivity to metals: 7/16 to Ni, 7/16 to Co, 5/16 to Cr, 5/16 to Mo and 4/16 to Mn.

CONCLUSIONS

The lymphocyte dominated peri-implant inflammation may well reflect an allergic hyper-reactivity in these patients, given the high rate of concomitantly found metal allergy. Despite the overall incidence of metal implant allergy being low, allergic reactions should be included as differential diagnosis in failed metal-on-metal arthroplasty.

Bio-corrosion of stainless steel by osteoclasts--in vitro evidence

Most metals in contact with biological systems undergo corrosion by an electrochemical process. This study investigated whether human osteoclasts (OC) are able to grow on stainless steel (SS) and directly corrode the metal alloy leading to the formation of corresponding metal ions, which may cause inflammatory reactions and activate the immune system. Scanning electron microscopy analysis demonstrated long-term viable OC cultures and evident resorption features on the surface of SS discs on which OC were cultured for 21 days. The findings were confirmed by atomic emission spectrometry investigations showing significantly increased levels of chromium, nickel, and manganese in the supernatant of OC cultures. Furthermore, significant levels of pro-inflammatory cytokines IL-1beta, IL-6, and TNF-alpha, which are considered to be major mediators of osteolysis, were revealed in the same cultures by cytometric bead array analysis. Within the present study, it was shown that human osteoclast precursors are able to grow and differentiate towards mature OC on SS. The mature cells are able to directly corrode the metal surface and release corresponding metal ions, which induce the secretion of pro-inflammatory cytokines that are known to enhance osteoclast differentiation, activation, and survival. Enhanced corrosion and the subsequently released metal ions may therefore result in enhanced osteolytic lesions in the peri-prosthetic bone, contributing to the aseptic loosening of the implant.

Evidence-based analysis of removal of orthopaedic implants in the pediatric population

BACKGROUND

Requested project of the Pediatric Orthopaedic Society of North America Evidenced-Based Medicine Committee.

METHODS

The English literature was systematically reviewed for scientific evidence supporting or disputing the common practice of elective removal of implants in children.

RESULTS

Several case series reported implant removal, but none contained a control group with retained implants. No articles reported long-term outcomes of retained implants in large numbers. Several small series describe complications associated with retained implants without evidence of causation. The existing literature was not amenable to a meta-analysis. By compiling data from the literature, it is possible to calculate a complication rate of 10% for implant removal surgery. The complication rate for removal of implants placed for slipped capital femoral epiphysis is 34%. Articles regarding postmarket implant surveillance and basic science were also reviewed.

CONCLUSIONS

There is no evidence in the current literature to support or refute the practice of routine implant removal in children.

Myths and legends in orthopaedic practice: are we all guilty?

Over years of practice, many beliefs and practices become entrenched as tried and tested, and we subconsciously believe they are based on scientific evidence. We identified nine such beliefs by interviewing orthopaedic surgeons in which studies (or lack thereof) apparently do not support such practices. These are: changing the scalpel blade after the skin incision to limit contamination; bending the patient's knee when applying a thigh tourniquet; bed rest for treatment of deep vein thrombosis; antibiotics in irrigation solution; routine use of hip precautions; routine use of antibiotics for the duration of wound drains; routine removal of hardware in children; correlation between operative time and infection; and not changing dressings on the floor before scrubbing. A survey of 186 practicing orthopaedic surgeons in academic and community settings was performed to assess their routine practice patterns. We present the results of the survey along with an in-depth literature review of these topics. Most surgeon practices are based on a combination of knowledge gained during training, reading the literature, and personal experience. The results of this survey hopefully will raise the awareness of the selected literature for common practices.

[Orthopedic surgical implants and allergies. Joint statement by the Implant Allergy Working Group (AK 20) of the DGOOC (German Association of Orthopedics and Orthopedic Surgery), DKG (German Contact Dermatitis Research Group) and DGAKI (German Society for Allergology and Clinical Immunology)]

Materials used in osteosynthesis or artificial joint replacement are usually well tolerated. Complaints after such operations are mostly related to infection or mechanical problems but may also be caused by allergic reactions. The latter encompass skin changes, e.g., eczema, delayed wound/bone healing, recurrent effusion, pain, or implant loosening. In contrast to the high incidence of cutaneous metal contact allergy, allergies associated with implants are a rare condition. However, epidemiological data on the incidence of implant-related allergic reactions are still missing. Typical elicitors are nickel, chromium, cobalt, and constituents of bone cement (acrylates und additives such as gentamicin or benzoyl peroxide). After exclusion of the most common differential diagnoses, allergy diagnostic procedures are primarily based on patch tests including a metal and bone cement component series. Additional analysis of periimplant tissue is recommended. However, further studies are necessary to show the significance of the histologic findings and the role of the lymphocyte transformation test (LTT). Which combinations of factors will induce allergic sensitization to implants or trigger periimplant allergic reactions in the case of preexisting cutaneous metal allergy is still unknown. Titanium-based osteosynthesis materials are recommended for metal allergic patients. In elective hip replacements, a ceramic/polyethylene (PE) articulation should be used, and in knee replacements "alternative materials". If a regular, potentially applicable CoCr/PE articulation is preferred, the patient must be well informed and must give his/her written consent.

Special modes of corrosion under physiological and simulated physiological conditions

The aim of this article is to review those aspects of corrosion behaviour that are most relevant to the clinical application of implant alloys. The special modes of corrosion encountered by implant alloys are presented. The resistance of the different materials against the most typical corrosion modes (pitting corrosion, crevice corrosion and fretting corrosion) is compared, together with observations of metal ion release from different biomaterials. A short section is dedicated to possible galvanic effects in cases when different types of materials are combined in a biomedical device. The different topics covered are introduced from the viewpoint of materials science, and then placed into the context of medicine and clinical experience.

Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome: suspected association with titanium bioprosthesis

Drug rash with eosinophilia and systemic symptoms (DRESS), also known as hypersensitivity syndrome, is an idiosyncratic drug reaction presenting with fever, diffuse lymphadenopathy, exfoliative dermatitis, and visceral involvement, which may include hepatitis, pneumonitis, pericarditis, myocarditis, nephritis, and colitis. This report describes a 19-year-old, previously healthy man with manifestations of hypersensitivity (DRESS) syndrome after acquiring a titanium bioprosthesis for a spinal fracture. To our knowledge, there have been no prior reports of DRESS syndrome in association with titanium bioprosthetic implants.

Surface mechanical properties, corrosion resistance, and cytocompatibility of nitrogen plasma-implanted nickel-titanium alloys: a comparative study with commonly used medical grade materials

Stainless steel and titanium alloys are the most common metallic orthopedic materials. Recently, nickel-titanium (NiTi) shape memory alloys have attracted much attention due to their shape memory effect and super-elasticity. However, this alloy consists of equal amounts of nickel and titanium, and nickel is a well known sensitizer to cause allergy or other deleterious effects in living tissues. Nickel ion leaching is correspondingly worse if the surface corrosion resistance deteriorates. We have therefore modified the NiTi surface by nitrogen plasma immersion ion implantation (PIII). The surface chemistry and corrosion resistance of the implanted samples were studied and compared with those of the untreated NiTi alloys, stainless steel, and Ti-6Al-4V alloy serving as controls. Immersion tests were carried out to investigate the extent of nickel leaching under simulated human body conditions and cytocompatibility tests were conducted using enhanced green fluorescent protein mice osteoblasts. The X-ray photoelectron spectroscopy results reveal that a thin titanium nitride (TiN) layer with higher hardness is formed on the surface after nitrogen PIII. The corrosion resistance of the implanted sample is also superior to that of the untreated NiTi and stainless steel and comparable to that of titanium alloy. The release of nickel ions is significantly reduced compared with the untreated NiTi. The sample with surface TiN exhibits the highest amount of cell proliferation whereas stainless steel fares the worst. Compared with coatings, the plasma-implanted structure does not delaminate as easily and nitrogen PIII is a viable way to improve the properties of NiTi orthopedic implants.

Orthopaedic implants in children: survey results regarding routine removal by the pediatric and nonpediatric specialists

The role of orthopaedic implant removal in children is controversial. Some children later require adult reconstruction; implant removal may be difficult or may adversely affect the outcome. The purpose of this study is to compare the opinions of the pediatric and nonpediatric specialists regarding routine implant removal in children. Participants were asked to complete a Web-based questionnaire containing demographics, general opinions, and a series of specific case scenarios related to implant removal/retention. The study group consisted of 273 pediatric, and 99 nonpediatric specialists, with an average of 17-year experience. Regarding asymptomatic, stainless steel implants in children, 41% indicated removal most or all of the time, 36% reported sometimes, and the remaining 22% reported almost never or never. Implant location was the only important factor in the decision to remove or retain the implant. A greater percentage of pediatric specialists endorsed implant retention in the hip or pelvis in older children compared with nonpediatric specialists. More experienced surgeons, regardless of specialty area, recommended implant removal. Pediatric specialists may wish to reconsider their preference to retain large hip implants in older children because their nonpediatric colleagues, who presumably are faced with the removal from these children when they reach adulthood, recommend implant removal once they have served their purpose. The number of such cases and the role of early removal in improving the long-term outcome need further study.

Hardware removal: indications and expectations

Although hardware removal is commonly done, it should not be considered a routine procedure. The decision to remove hardware has significant economic implications, including the costs of the procedure as well as possible work time lost for postoperative recovery. The clinical indications for implant removal are not well established. There are few definitive data to guide whether implant removal is appropriate. Implant removal may be challenging and lead to complications, such as neurovascular injury, refracture, or recurrence of deformity. When implants are removed for pain relief alone, the results are unpredictable and depend on both the implant type and its anatomic location. Current literature does not support the routine removal of implants to protect against allergy, carcinogenesis, or metal detection. Surgeons and patients should be aware of appropriate indications and have realistic expectations of the risks and benefits of implant removal.

[Metallurgical differentiation of cobalt-chromium alloys for implants]

BACKGROUND

Cobalt Chromium alloys are used in cemented total hip or knee arthroplasty as well as in metal-on-metal bearings in total hip arthroplasty. An increasing number of publications report about (allergic) reactions to wear particles of Cobalt Chromium alloys. Reactions to nickel are more frequent in comparison to Cobalt or Chromium particles. It is well known that different kinds of Cobalt Chromium alloys contain different amounts of alloying elements; nevertheless. The aim of the current work was to compare the different Cobalt Chromium alloys according to ASTM F or ISO standards in respect to the different alloying elements.

MATERIAL AND METHODS

Co28Cr6Mo casting alloys according to ASTM F 75 or ISO 5832-4 as well as forging alloy types according to ASTM F 799 and ISO 5832 such as Co20Cr15W10Ni, Co35Ni20Cr, Fe40Co20Cr10Ni, Co20Cr20Ni, and Co28Cr6Mo were analyzed in respect to their element content of Co, Cr, Ni, Mo, Fe, W, and Mn.

RESULTS

In 1935 the Cobalt based alloy "Vitallium" Co30Cr5Mo basically used in the aircraft industry was introduced into medicine. The chemical composition of this alloy based on Cobalt showed 30 wt.% Chromium and 5 wt.% Molybdenum. The differentiation using alloy names showed no Nickel information in single alloy names.

CONCLUSION

The information given about different alloys can lead to an unprecise evaluation of histopathological findings in respect to alloys or alloying constituents. Therefore, implant manufacturers should give the exact information about the alloys used and adhere to European law, Euronorm 93/42/EWG.

Das Allergiepotenzial von Implantatwerkstoffen auf Titanbasis

AIM

The aim of this investigation is to evaluate the allergic potential of titanium and titanium alloys for surgical implant applications.

MATERIALS AND METHODS

Discs cut from rods supplied by five different titanium suppliers in several diameters were investigated. The samples were cp-Titanium as well as Ti6Al4 V and Ti6Al7Nb, 6 mm thick with a diameter of between 6 and 60 mm. The material was checked by optical spectral analysis.

RESULTS

In all samples except iodidtitanium, a Nickel content of 0.012-0,034 wt% could be detected.

CONCLUSION

The low nickel content in the implant material results from the production process. The nickel atoms are in solid solution in the titanium lattice. Nickel allergic patients may develop hypersensitivity reactions even due to this low nickel content. Hence, this reaction may be falsely attributed to the titanium material itself. Measurements of ion concentration in the body are helpful for quantifying the maximum content of nickel in titanium materials for surgical implant applications. In addition, technical questions related to the production of nickel free titanium materials for allergic patients have to be solved.

Hysteroscopic tubal sterilization

This article provides an overview of the history of hysteroscopic sterilization including the current state of the art and future ideals. Unlike laparoscopic techniques, sterilization by hysteroscopy can be performed in an outpatient setting without general anesthesia. Many attempts have been made to develop a safe and effective method, but until recently, without success. The Essure system is the first one that seems to be a realistic alternative to laparoscopic sterilization, but is irreversible. The search is still on for the optimum method of hysteroscopic sterilization.

A new austenitic stainless steel with negligible nickel content: an in vitro and in vivo comparative investigation

New nickel (Ni)-reduced stainless-steel metals have recently been developed to avoid sensitivity to Ni. In the present study, an austenitic Ni-reduced SSt named P558 (P558, Böhler, Milan, Italy) was studied in vitro on primary osteoblasts and in vivo after bone implantation in the sheep tibia, and was compared to ISO 5832-9 SSt (SSt) and Ti6Al4V. Cells were cultured directly on P558 and Ti6Al4V. Cells cultured on polystyrene were used as controls. Osteoblast proliferation, viability and synthetic activity were evaluated at 72 h by assaying WST1, alkaline phosphatase activity (ALP), nitric oxide, pro-collagen I (PICP), osteocalcin (OC), transforming growth factor-beta1 (TGFbeta-1) and interleukin-6 (IL-6) after 1.25(OH)2D3 stimulation. Under general anaesthesia, four sheep were submitted for bilateral tibial implantation of P558, SSt and Ti6Al4V rods. In vitro results demonstrated that the effect of P558 on osteoblast viability, PICP, TGF beta-1, tumor necrosis factor-alpha production did not significantly differ from that exerted by Ti6Al4V and controls. Furthermore, P558 enhanced osteoblast differentiation, as confirmed by ALP and OC levels, and reduced IL-6 production. At 26 weeks, the bone-to-implant contact was higher in P558 than in SSt (28%, p<0.005) and Ti6Al4V (4%, p<0.05), and was higher in Ti6Al4V than in SSt (22%, p<0.005). The tested materials did not affect bone microhardness in pre-existing host bone as evidenced by the measurements taken at 1000 microm from the bone-biomaterial interface (F=1.89, ns). At the bone-biomaterial interface the lowest HV value was found for SSt, whereas no differences in HV were observed between materials (F=1.55, ns). The current findings demonstrate P558 biocompatibility both in vitro and in vivo, and osteointegration processes are shown to be significantly improved by P558 as compared to the other materials tested.