Development of hematopoietic cancers after implantation of total joint replacement

Management of Vancouver B2 Periprosthetic Femoral Fractures, Revision Total Hip Arthroplasty Versus Open Reduction and Internal Fixation: A Systematic Review and Meta-Analysis

OBJECTIVE

To identify and analyze the current evidence for the use of open reduction and internal fixation (ORIF) constructs compared with conventional revision total hip arthroplasty (rTHA) for the management of Vancouver B2 periprosthetic femoral fractures (PFFs).

DATA SOURCES

A systematic literature search of the MEDLINE, CINAHL, and EMBASE databases was conducted. Prospective and retrospective studies were eligible. No limitation was placed on publication date, with only articles printed in English eligible.

STUDY SELECTION

Included studies were retrospective studies comparing ORIF and rTHA for the management of Vancouver B2 PFFs.

DATA EXTRACTION

The primary outcome was the overall complication rate. Other outcomes included as rate of dislocation, revision operation, refracture, infection, nonunion, and subsidence/loosening. Twenty-four studies were included totaling 1621 patients, of which 331 were treated with ORIF and 1280 with rTHA.

CONCLUSION

The 1621 patients included comprised a mixture of different fracture patterns, prostheses, and patient comorbidities. The overall complication rate for ORIF was 24% versus 18% for rTHA (P = 0.13). The results demonstrate that rTHA has a similar revision rate to ORIF in PFFs with a loose femoral component and adequate bone stock. ORIF was superior to rTHA in prevention of postoperative dislocation; however, there was no difference between other complications. This review suggests a potential role of both ORIF and rTHA in the management of Vancouver B2 PFFs.

LEVEL OF EVIDENCE

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

Site-specific cancer risk following cobalt exposure via orthopedic implants or in occupational settings: A systematic review and meta-analysis

In 2020, the European Commission up-classified metal cobalt as Class 1B Carcinogen (presumed to have carcinogenic potential) based primarily on data from rodent inhalation carcinogenicity studies. This up-classification requires an assessment under the Medical Device Regulations of cobalt cancer risk from medical devices. We performed a systematic review and meta-analysis to evaluate site-specific cancer risks with cobalt exposure from either total joint replacement (TJR) or occupational exposure (OC). Results were stratified by exposure type (OC or TJR), exposure level (metal-on-metal (MoM) or non-MoM), follow-up duration (latency period: <5, 5-10 or >10 years), and cancer incidence or mortality (detection bias assessment). From 30 studies (653,104 subjects, average 14.5 years follow-up), the association between TJR/OC and cancer risk was null for 22 of 27 cancer sites, negative for 3 sites, and positive for prostate cancer and myeloma. Significant heterogeneity and large estimate ranges were observed for many cancer sites. No significant increase in estimates was observed by exposure level or follow-up duration. The current evidence, including weak associations, heterogeneity across studies and no increased association with exposure level or follow-up duration, is insufficient to conclude that there exists an increased risk for people exposed to cobalt in TJR/OC of developing site-specific cancers.

Cementless total hip arthroplasty after failed internal fixation of acetabular fractures: A single center experience of 25 consecutive patients

PURPOSE

Total hip arthroplasty (THA) is an available surgical option for failed acetabular fracture, previously managed by open reduction and internal fixation. This study aimed to report the postoperative outcomes of cementless THA in patients with this condition.

MATERIALS AND METHODS

Between November 2000 and September 2016, 25 consecutive cementless THAs for failed internal fixation after acetabular fractures with a minimum follow-up of 2 years were analyzed. The mean age at the time of surgery was 58 years (36-85 years), and the time elapsed between fracture and THA was 70 months (7-213 months). Clinical and radiologic evaluations were performed on all patients.

RESULTS

Clinically, the mean Harris hip score at the last follow-up was 88 points. Walking ability recovered to pre-injury status in 92% patients, and activities of daily living recovered in 96% patients. Radiographically, none of the acetabular cups showed evidence of migration and loosening during the mean follow-up of 50 months. All cases showed stable femoral stem fixation at the last follow-up. Dislocation occurred in three cases (12%).

CONCLUSION

Outcomes of cementless THA after failed internal fixation for acetabular fractures were satisfactory. However, a relatively high incidence of postoperative dislocation is still a concern.

Genotoxic properties of materials used for endoprostheses: Experimental and human data

Approximately 2 million endoprostheses are implanted annually and metal ions as well as particles are released into the body from the materials which are used. This review describes the results of studies concerning genotoxic damage caused by artificial joints. DNA damage leads to various adverse long-term health effects in humans including cancer. Experiments with mammalian cells showed that metal ions and particles from orthopedic materials cause DNA damage. Induction of chromosomal aberrations (CA) was found in several in vitro experiments and in studies with rodents with metals from orthopedic materials. Human studies focused mainly on induction of CA (7 studies). Only few investigations (4) concerned sister chromatid exchanges, oxidative DNA damage (2) and micronucleus formation (1). CA are a reliable biomarker for increased cancer risks in humans) and were increased in all studies in patients with artificial joints. No firm conclusion can be drawn at present if the effects in humans are due to oxidative stress and if dissolved metal ions or release particles play a role. Our findings indicate that patients with artificial joints may have increased cancer risks due to damage of the genetic material. Future studies should be performed to identify safe materials and to study the molecular mechanisms in detail.

What is the Evidence of Lymphoma in Patients with Prostheses Other Than Breast Implants?

INTRODUCTION

Medical devices such as hip, knee, breast, vascular prostheses, among others, are very useful in different pathologies. We cannot doubt that their use is a great tool, besides being an advance in medicine; they provide a change in the quality of life of many patients; however, they are not exempt from adverse reactions and events.

METHODS

We conduct a systematic review about lymphoma in the presences of prostheses other than breast implants.

RESULTS

We selected 21 publications with a total of 24 patients. The largest number of prostheses was related to long bones in a total of 13 prostheses. The most frequent symptoms were: pain (52%), inflammation (24%), visible or palpable mass 20%. The most frequent type of lymphoma was non-Hodgkin B cell lymphoma in 14 cases.

DISCUSSION

The presence of microparticles make biological degradation and wear of the implants, with macrophage and lymphocyte activation and the consequent production of proinflammatory cytokines such as tumor necrosis factor α, interleukin-1β, interleukin-6, and prostaglandin 2 (PGE2).

CONCLUSION

Lymphoma is not a common disease in patients with prostheses, and more data are needed to identify risk factors and make proper diagnoses.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Surface Replacement: The Hip Replacement of the Future?

Surface replacement is a significant development in the evolution of hip arthroplasty. Unlike conventional total hip arthroplasty, surface replacement does not require resection of the femoral head; thus, it presents a potentially effective, bone-conserving alternative to conventional replacements. Moreover, conversion to total hip replacement can be made readily, if necessary, with fewer complicating factors than with total hip revision surgery. It offers the greatest potential benefit to patients who are young and physically active. Previous surface replacement used metal-on-polyethylene devices; however, the large ball size of the femoral component contributed to high volumes of polyethylene wear. For some patients, osteolysis occurred due to tissue reaction to polyethylene debris, resulting in aseptic component loosening. Recent advances in technology have allowed metal-on-metal implants to be manufactured with great precision. Hybrid and all cementless fixation, have both shown good early results without the prevalence of loosening seen with polyethylene bearings. Metal-on-metal surface replacement has proved to be quite successful. Results from patients with metal-on-metal devices, especially those with ConservePlus™ implants, show no complications; moreover, there has been an absence of pain and a return to high functional levels, including participation in sports. Due to the large ball size, metal-on-metal devices offer high stability and low dislocation rates. Hemisurface replacement of the femoral head has also proved to be successful in patients with osteonecrosis with or without collapse of the femoral head, when the acetabulum remains relatively normal. For this type of surgery, some acetabular articular cartilage must be preserved. With high survivorship over time, it has emerged as the treatment of choice for this patient group.

Diffuse B Cell Non-Hodgkin's Lymphoma Presenting Atypically as Periprosthetic Joint Infection in a Total Hip Replacement

The occurrence of extranodal primary B cell non-Hodgkin's lymphoma is rare. Total hip replacement is one of the most common orthopaedic procedures performed. There has been an increased incidence of primary lymphomas involving periprosthetic sites. Chronic inflammation due to metal debris arising from the prosthetic implants has been evidenced as one of the causes for the development of soft tissue lymphomas albeit rarely. We describe a case report of a 77-year-old patient who had underwent a cemented total hip replacement in the past who further developed large B cell primary non-Hodgkin's lymphoma. She presented initially with signs and symptoms highly suggestive of underlying periprosthetic infection. The radiological imaging was also indicative of periprosthetic infection. The diagnosis was eventually confirmed after an open biopsy. This case underlines the importance of considering and including soft tissue malignancy in the differential diagnosis of suspected chronic periprosthetic infection.

Development of malignant lymphoma after metal-on-metal hip replacement: a case report and review of the literature

A number of previous studies have reported a potential risk of malignancy, particularly hematological malignancy, developing in patients receiving a metal-on-metal (MoM) hip replacement. We report a case of malignant lymphoma that arose in a patient who had an MoM hip arthroplasty complicated by development of a pseudotumour. The tumour was a B cell follicular lymphoma that involved lymph nodes and bone. Metal ions are known to have a genotoxic effect on lymphoid cells. Although epidemiological studies have not established that there is an increased risk of lymphoma associated with MoM implants, only a relatively short time period has elapsed since re-introduction of this type of implant and long-term follow-up of patients with MoM implants is indicated.

Early Outcomes Following Metal-on-Metal Reverse Total Shoulder Arthroplasty in Patients Younger Than 50 Years

Reverse total shoulder arthroplasty (TSA) is a useful intervention for older patients with glenohumeral arthritis and a deficient rotator cuff. However, as a semiconstrained prosthesis, conventional reverse TSA implanted in a young patient could fail over time secondary to polyethylene wear and subsequent osteolysis. A metal-on-metal prosthesis may avoid this type of failure. The purpose of this study is to assess the outcomes in an initial cohort of young patients who underwent reverse TSA using a metal-on-metal prosthesis. Surgical indications included age younger than 50 years with a functioning deltoid and significant impairment of shoulder function with irreparable rotator cuff due to tumor resection, arthritis, or revision surgery. Nine patients with an average age of 37 years underwent implantation of a custom metal-on-metal reverse TSA prosthesis. All patients had a minimum 12-month follow-up or a failure of their procedure requiring revision surgery prior to 1 year. American Shoulder and Elbow Surgeons (ASES) scores, Constant scores, and range of motion were recorded and analyzed pre- and postoperatively to assess improvement, and all complications were noted. Average ASES score improved from 47 points preoperatively to 73.4 points postoperatively (P=.013). Average Constant and adjusted Constant scores improved from 20.8 points and 16% preoperatively to 61.8 points and 67.3% postoperatively, respectively (P=.019 and P=.068). Mean postoperative active forward flexion and active external rotation were 119.4° and 10°, respectively. Complications included the following: 3 patients sustained a postoperative dislocation, 1 patient had a glenoid fracture and complete loss of fixation of the baseplate, and 1 patient experienced dissociation of the glenosphere from the base-plate. Although metal-on-metal reverse TSA may appear to be an attractive choice in the treatment of young patients with limited reconstructive options, postoperative outcomes are disappointing, and the complication rate is high. [Orthopedics.2016; 39(5):e957-e961.].

Risk of cancer following primary total hip replacement or primary resurfacing arthroplasty of the hip: a retrospective cohort study in Scotland

Background:

Release and dispersion of particles arising from corrosion and wear of total hip arthroplasty (THA) components has raised concerns about a possible increased risk of cancer. Concerns have been heightened by a recent revival in the use of metal-on-metal (MoM) hip prostheses.

Methods:

From a linked database of hospital discharge, cancer registration, and mortality records, we selected a cohort of patients who underwent primary THA (1990–2009) or primary resurfacing arthroplasty (mainly 2000–2009) in Scotland, with follow-up to the end of 2010. Available operation codes did not enable us to distinguish MoM THAs. Indirectly standardised incidence ratios (SIRs) were calculated for selected cancers with standardisation for age, sex, deprivation, and calendar period.

Results:

The study cohort included 71 990 patients yielding 547 001 person-years at risk (PYAR) and 13 946 cancers diagnosed during follow-up. For the total period of observation combined, the risks of all cancers (SIR: 1.05; 95% CI: confidence interval 1.04–1.07), prostate cancer (SIR: 1.07; 95% CI: 1.01–1.14), and multiple myeloma (SIR: 1.22; 95% CI: 1.06–1.41) were increased. These modest increases in risk emerged in the context of effectively multiple tests of statistical significance, and may reflect inadequate adjustment for confounding factors. For 1317 patients undergoing primary resurfacing arthroplasty between 2000 and 2009 (PYAR=5698), the SIR for all cancers (n=39) was 1.23 (95% CI: 0.87–1.68).

Conclusion:

In the context of previous research, these results do not suggest a major cause for concern. However, the duration of follow-up of patients receiving recently introduced, new-generation MoM prostheses is too short to rule out a genuinely increased risk of cancer entirely.

Risk of cancer with metal-on-metal hip replacements: population based study

OBJECTIVE

To assess the risk of cancer associated with modern primary metal-on-metal hip replacements.

DESIGN

Population based study.

SETTING

Nationwide retrospective comparative register.

PARTICIPANTS

10,728 patients who underwent metal-on-metal total hip arthroplasty and 18,235 patients who underwent conventional metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic total hip arthroplasty (the non-metal-on-metal cohort) in the Finnish Arthroplasty Register 2001-10. Data on cancer cases up to 2010 for these cohorts were extracted from the Finnish Cancer Registry.

MAIN OUTCOME MEASURES

The relative risk of cancer was expressed as the ratio of observed to expected number of cases from the Finnish population--that is, the standardised incidence ratio. The relative risk of cancer in the metal-on-metal cohort compared with the non-metal-on-metal cohort was estimated with analyses of these ratios and Poisson regression.

RESULTS

The overall risk of cancer in patients with metal-on-metal hip implants was similar to that in the Finnish population (378 observed v 400 expected, standardised incidence ratio 0.95, 95% confidence interval 0.85 to 1.04). The overall risk of cancer in patients with metal-on-metal hip implants was also no higher than in patients who had received non-metal-on-metal hip implants (relative risk 0.92, 0.81 to 1.05).

CONCLUSIONS

Metal-on-metal hip replacements are not associated with an increased overall risk of cancer during a mean follow-up of four years.

Local and systemic toxicity of nanoscale debris particles in total hip arthroplasty

Over the past 30 years joint replacement prostheses have been developed and refined to enhance durability and reproducibility. Total hip joint arthroplasty is being performed in an increasing number of younger patients; therefore orthopaedic surgeons seek implants with a longer life span. With regards to the progress of mechanical behaviour of the biomaterials used in an arthroplasty, little is known about the long-term biological effects of wear debris. Owing to the composition of the prostheses currently in use, systemic exposure to chromium (Cr), cobalt (Co), nickel (Ni) and aluminium (Al) alloys occurs as a result of the formation of metal wear nano-particles that are released both from metal-on-metal and polyethylene-on-metal bearings, resulting in a postoperative increase in metal ion levels at different organ sites. These particles circulate both locally and systemically, penetrate cell plasma membranes, bind to cellular proteins and enzymes and modulate cytokine expression. Their physiologic effects are poorly understood and their potential toxicity, hypersensitivity and carcinogenicity remain a cause for concern. In this article we will address the issue of whether these nanoscale degradation products are associated with adverse, clinically significant local or systemic toxicologic sequelae.

Origins of injection-site sarcomas in cats: the possible role of chronic inflammation-a review

The etiology of feline injection-site sarcomas remains obscure. Sarcomas and other tumors are known to be associated with viral infections in humans and other animals, including cats. However, the available evidence suggests that this is not the case with feline injection-site sarcomas. These tumors have more in common with sarcomas noted in experimental studies with laboratory animals where foreign materials such as glass, plastics, and metal are the causal agent. Tumors arising with these agents are associated with chronic inflammation at the injection or implantation sites. Similar tumors have been observed, albeit infrequently, at microchip implantation sites, and these also are associated with chronic inflammation. It is suggested that injection-site sarcomas in cats may arise at the administration site as a result of chronic inflammation, possibly provoked by adjuvant materials, with subsequent DNA damage, cellular transformation, and clonal expansion. However, more fundamental research is required to elucidate the mechanisms involved.

Titanium allergy: could it affect dental implant integration?

PURPOSE

Degradation products of metallic biomaterials including titanium may result in metal hypersensitivity reaction. Hypersensitivity to biomaterials is often described in terms of vague pain, skin rashes, fatigue and malaise and in some cases implant loss. Recently, titanium hypersensitivity has been suggested as one of the factors responsible for implant failure. Although titanium hypersensitivity is a growing concern, epidemiological data on incidence of titanium-related allergic reactions are still lacking.

MATERIALS AND METHODS

A computer search of electronic databases primarily MEDLINE and PUBMED was performed with the following key words: 'titanium hypersensitivity', 'titanium allergy', 'titanium release' without any language restriction. Manual searches of the bibliographies of all the retrieved articles were also performed. In addition, a complementary hand search was also conducted to identify recent articles and case reports.

RESULTS

Most of the literature comprised case reports and prospective in vivo/in vitro trials. One hundred and twenty-seven publications were selected for full text reading. The bulk of the literature originated from the orthopaedic discipline, reporting wear debris following knee/hip arthroplasties. The rest comprised osteosynthesis (plates/screws), oral implant/dental materials, dermatology/cardiac-pacemaker, pathology/cancer, biomaterials and general reports.

CONCLUSION

This review of the literature indicates that titanium can induce hypersensitivity in susceptible patients and could play a critical role in implant failure. Furthermore, this review supports the need for long-term clinical and radiographic follow-up of all implant patients who are sensitive to metals. At present, we know little about titanium hypersensitivity, but it cannot be excluded as a reason for implant failure.

Cobalt ions induce chemokine secretion in a variety of systemic cell lines

BACKGROUND AND PURPOSE

Metal ion toxicity both locally and systemically following MoM hip replacements remains a concern. Cobalt ions have been shown to induce secretion of proinflammatory chemokines locally; however, little is known about their effect systemically. We investigated the in vitro effect of cobalt ions on a variety of cell lines by measuring production of the proinflammatory chemokines IL-8 and MCP-1.

METHOD

Renal, gastrointestinal, and respiratory epithelium and also neutrophils and monocytes were exposed to cobalt ions at 4, 12, 24, and 48 hours.

RESULTS

We found that cobalt ions enhanced the secretion of IL-8 and MCP-1 in renal epithelial cells, gastric and colon epithelium, monocytes and neutrophils, and small airway epithelial cells but not in alveolar cells. Secretion of IL-8 and MCP-1 was markedly elevated in renal epithelium, where a 16-fold and 7-fold increase occurred compared to controls. There was a 6-fold and 4-fold increase in IL-8 and MCP-1 secretion in colon epithelium and a 4-fold and 3-fold increase in gastric epithelium. Small airway epithelial cells showed a maximum increase in secretion of 8-fold (IL-8) and of 4-fold (MCP-1). The increase in chemokine secretion observed in alveolar cells was moderate and did not reach statistical significance. Monocytes and neutrophils showed a 2.5-fold and 2-fold increase in IL-8 secretion and a 6-fold and 4-fold increase in MCP-1 secretion at 48 and 24 hours, respectively.

INTERPRETATION

These data demonstrate the potent bioactivity of cobalt ions in a variety of cell types and the potential to induce a proinflammatory response.

Metal-on-metal hip resurfacing arthroplasty: a review of periprosthetic biological reactions

Metal-on-metal hip resurfacing arthroplasty has undergone a recent resurgence as an alternative treatment option for young and active patients with significant osteoarthritis. The claimed advantages of metal-on-metal hip resurfacing arthroplasty include lower wear rate, preservation of bone stock for subsequent revision procedures, restoration of anatomic hip mechanics, and enhanced stability due to the larger diameter of articulation. A disadvantage, however, is that the metal-on-metal resurfacing releases large amounts of very small wear particles and metal ions. The long-term biological consequences of the exposure to these Co-Cr particles and ions remain largely unknown. The purpose of this review is to provide an overview of the current literature on the adverse periprosthetic biological reactions associated with metal-on-metal hip resurfacing arthroplasty.

Serum ion levels after ceramic-on-ceramic and metal-on-metal total hip arthroplasty: 8-year minimum follow-up

Alternative bearing surfaces for total hip arthroplasty, such as metal-on-metal and ceramic-on-ceramic, offer the potential to reduce mechanical wear and osteolysis. In the short and medium term, the second generation of metal-on-metal bearings demonstrated high systemic metal ion levels, whereas ceramic-on-ceramic bearings showed the lowest ones. We aimed to verify whether the long-term ion release in metal-on-metal subjects was still relevant at a median 10-year follow-up, and whether a fretting process at the modular junctions occurred in ceramic-on-ceramic patients and induced an ion dissemination. Serum levels were measured in 32 patients with alumina-on-alumina implants (group A), in 16 subjects with metal-on-metal implants (group B), and in 47 healthy subjects (group C). Group B results were compared with medium-term findings. Cobalt and chromium levels were significantly higher in metal-on-metal implants than in ceramic-on-ceramic ones and controls. Nevertheless, ion levels showed a tendency to decrease in comparison with medium-term content. In ceramic-on-ceramic implants, ion values were not significantly different from controls. Both in groups A and B, aluminum and titanium release were not significantly different from controls. In conclusion, negligible serum metal ion content was revealed in ceramic-on-ceramic patients. On the contrary, due to the higher ion release, metal-on-metal coupling must be prudently considered, especially in young patients, in order to obtain definitive conclusions.

High-resolution ICP-MS determination of Ti, V, Cr, Co, Ni, and Mo in human blood and urine of patients implanted with a hip or knee prosthesis

The main components (Ti, V, Cr, Co, Ni, and Mo) of metallic alloys currently used in hip and knee articular prostheses have been simultaneously determined in human whole blood and urine of implanted people by a (HR)-ICP-MS method previously developed in our laboratory. The determination of those elements has been carried out in patients with knee and hip prosthesis and in a group of pre-operation patients without any metallic device in their bodies, used as controls, demonstrating the usefulness of this technique to perform multielement analysis at ppt levels in complex matrices. The concentrations of V, Cr, Co, Ni, and Mo in urine and blood of implanted people turned out to be very similar to those obtained in control patients. However, raised Ti levels could be found both in urine and blood of patients with articular prostheses made or coated with a titanium alloy (Ti(6)Al(4)V).

Metal ion levels in patients with stainless steel spinal instrumentation

STUDY DESIGN

Case-control study.

OBJECTIVES

To determine whether metal ion concentrations are elevated in patients with spinal instrumentation.

SUMMARY OF BACKGROUND DATA

Studies have shown that serum and urinary levels of component metal ions are abnormally elevated in patients with total joint arthroplasties. Little is known of metal ion release and concentrations in patients with spinal instrumentation.

METHODS

The study group consisted of patients who had undergone spinal instrumentation for various spinal disorders with a variety of stainless steel implants, 5 to 25 years previously. A group of volunteers without metal implants were controls. All subjects were tested for serum nickel, blood chromium, and random urine chromium/creatinine ratio estimation.

RESULTS

The study group consisted of 32 patients with retained implants and 12 patients whose implants had been removed. There were 26 unmatched controls. There was no difference in serum nickel and blood chromium levels between all 3 groups. The mean urinary chromium/creatinine ratio for patients with implants and those with implants removed was significantly greater than controls (P < 0.001). The difference between study subgroups was not significant (P = 0.16). Of several patient and instrumentation variables, only the number of couplings approached significance for correlation with the urine chromium excretion (P = 0.07).

CONCLUSION

Spinal implants do not raise the levels of serum nickel and blood chromium. There is evidence that metal ions are released from spinal implants and excreted in urine. The excretion of chromium in patients with spinal implants was significantly greater than normal controls although lower where the implants have been removed. The findings are consistent with low-grade release of ions from implants with rapid clearance, thus maintaining normal serum levels. Levels of metal ions in the body fluids probably do not reach a level that causes late side-effect; hence, routine removal of the implants cannot be recommended.

Midterm results of Metasul metal-on-metal total hip arthroplasty

We assessed 106 total hip arthroplasties performed with a new metal-on-metal hip system; the patients were monitored for at least 5 years. The average Harris Hip Score of the patients was 39.5 points before surgery and 87.8 points at final follow-up evaluation. Radiographically, the acetabular component was stable in 103 hips and possibly unstable in 3 hips. The femoral component was bone ingrown in 97 hips and stable and fibrous in 9. After surgery, 6 hips dislocated. The polyethylene liner dissociated in one patient. No patient exhibited clear signs of loosening, migration, or osteolysis. Distal femoral cortical hypertrophy was seen in 35.8% of the cases. Survival at the mean follow-up point (6.4 years) was 99.1%. There was no significant difference in serum chromium concentration between metal-on-metal bearings and polyethylene-on-metal bearings (control subjects). This study found that metal-on-metal total hip arthroplasty produces excellent midterm results.

Serum metal levels and bearing surfaces in total hip arthroplasty

This study evaluates steady-state serum metal levels in patients with 4 different combinations of fixation modalities, materials, and bearing couples. Forty patients with a minimum of 5 years of follow-up and with well-functioning primary total hip arthroplasty were recruited to have serum metal levels measured. Serum chromium and cobalt levels in the metal-on-metal cohort were significantly higher (P < .05) than the other 3 cohorts. The noncemented ceramic-polyethylene cohort had significantly lower (P < .05) serum chromium levels compared to cemented and noncemented metal-polyethylene cohorts and significantly higher serum titanium levels compared to the cemented metal-polyethylene cohort which had no titanium-containing implants. Debris generated at the metal head/neck modular junction likely accounts for the significantly lower serum chromium concentration in ceramic-polyethylene bearing couples.

Cancer after Total Joint Arthroplasty: A Meta-analysis

BACKGROUND

Some epidemiologic and laboratory studies have suggested that total joint arthroplasty could increase the risk of cancer. In this meta-analysis, we attempt to clarify the association of joint arthroplasty with subsequent cancer incidence.

METHODS

We identified population-based studies reporting standardized incidence ratios (SIR) for cancer following large joint arthroplasty. After summing the observed and expected numbers of cases across all qualifying studies, we calculated SIRs for all cancers, and for those at 28 anatomic sites. Latency analysis involving 175,166 patients characterized short-term and long-term cancer associations.

RESULTS

The analyses included 1,435,356 person-years of follow-up and 20,045 cases of cancer. Overall cancer risk among patients with arthroplasty was equal to that for the general population. The relative risk of lung cancer, reduced in the first 5 years after arthroplasty, increased significantly over time to approach that of the general population. Risks for all sites in the luminal gastrointestinal tract were significantly reduced by 10% to 20%; with relative risks that were generally stable over time. Increased risks were seen for cancer of the prostate (SIR, 1.12; 95% confidence interval, 1.08-1.16); similar relative risks were seen in each time period after the procedure. For melanoma, relative risks increased with follow-up to a SIR of 1.43 (95% confidence interval, 1.13-1.79) for 10 or more years after arthroplasty. There was a similar delayed emergence of increased risks for cancers of the urinary tract and oropharynx. The relative risk for bone cancer decreased with time after the procedure.

CONCLUSIONS

There does not seem to be an overall increased risk of cancer following total joint arthroplasty. Although the risks of prostate cancer and melanoma seem to be elevated, there is no obvious mechanism for these associations. Reductions in risk for some malignancies may not be causal.

Differences in ion release after ceramic-on-ceramic and metal-on-metal total hip replacement. Medium-term follow-up

Modern metal-on-metal bearings produce less wear debris and osteolysis, but have the potential adverse effect of release of ions. Improved ceramic-on-ceramic bearings have the lowest wear of all, but the corrosion process has not been analysed. Our aim was to measure the serum ion release (ng/ml) in 23 patients having stable hip prostheses with a ceramic-on-ceramic coupling (group A) and to compare it with the release in 42 patients with a metal-on-metal bearing (group B) in the medium term. Reference values were obtained from a population of 47 healthy subjects (group C). The concentrations of chromium, cobalt, aluminium and titanium were measured. There was a significant increase of cobalt, chromium and aluminium levels (p < 0.05) in group B compared with groups A and C. Group A did not differ significantly from the control group. Despite the apparent advantage of a metal-on-metal coupling, especially in younger patients with a long life expectancy, a major concern arises regarding the extent and duration of ion exposure. For this reason, the low corrosion level in a ceramic-on-ceramic coupling could be advantageous.

Complications associated with hip resurfacing arthroplasty

Hip resurfacing arthroplasty is an old orthopedic concept that has undergone a resurgence of interest in the past decade. Because of the rapid increase in the number of procedures being performed, previously recognized complications have begun to recur. This article focuses on complications that are related to the hip resurfacing procedure such as femoral neck fractures, avascular necrosis, raised metal ion levels, and sound initial and durable long-term fixation of an all-metal monoblock cobalt/chrome acetabular component. Dislocation rates after resurfacing and other complications are briefly discussed.

The long-term wear of retrieved McKee-Farrar metal-on-metal total hip prostheses

Twenty-four cobalt-chrome alloy McKee-Farrar matching acetabular and femoral components were retrieved at revision total hip arthroplasty. The average time in situ was 16 years. Wear and loss of sphericity was very low. Polishing wear (type 1), fine abrasive (type 2), multidirectional dull abrasive (type 3), and unidirectional dull abrasive wear (type 4) of the articulating surfaces were identified. The mean percent area of femoral heads occupied by types 2, 3, and 4 wear was 18%, 5%, and 2%, respectively. There was no association between the type and distribution of wear and the time in situ. Impingement damage was evident on 9 implant pairs. The extent and types of wear described in this paper will be useful when analyzing the patterns of surface damage of newer designs of metal-on-metal articulations.

Pathologische Ver�nderungen im umgebenden Gewebe von revidierten Metall-Metall-Gleitpaarungen

INTRODUCTION

The aim of the current study was to elucidate the incidence of allergic reactions to metal/metal articulations in revised total hip arthroplasties.

MATERIALS AND METHODS

Between 1 January 1997 and 31 January 2002 a consecutive series of tissue samples from 13 revised total hip arthroplasties with metal/metal articulations were histopathologically examined for signs of delayed type hypersensitivity (DTH). Mean age at the time of revision of the eight women and five men was 58.7 years. The prostheses were revised after a mean follow-up of 45 months. Indications for revision were progressive osteolysis of the proximal femur in 12 cases and instability in one case. All patients were clinically and radiologically evaluated after a mean follow-up of 52 months (min. 22, max. 74) after revision.

RESULTS

No signs of infection were found in either histopathological or microbiological examinations. In ten cases, perivascular lymphocytic infiltrates could be found as a sign of DTH. After revision and changing of the articulation all osteolyses healed.

CONCLUSION

In 10/13 cases (76.9%) signs of DTH could be detected. The fact that all osteolyses healed after changing the articulation may give a strong hint that there is an immunological contribution to this radiological changes. Metal/metal articulations cannot be recommended as the optimum implant for young patients, as the number of patients with allergic reactions to nickel, chrome or cobalt is increasing continuously.

Metal-on-metal total hip replacement

Metal-on-metal bearings have wear rates that are 20 to 100 times lower than metal-on-conventional polyethylene. The amount of wear generally is the same order of magnitude for the head and the cup. There is an initial run-in period of higher wear followed by lower, steady-state wear. Wear rate is a function of the interplay of material(s), macrogeometry, microgeometry, and the resultant type and amount of lubrication. The wear resistance and clinical performance of a metal-on-metal bearing are more sensitive to macrogeometry and lubrication than a metal-on-polyethylene bearing. Metal wear particles are nanometers in linear dimension. They are much smaller and more numerous than the submicron polyethylene wear particles, but the volume of periprosthetic inflammatory tissue is less. Osteolysis seems to be relatively rare. Little is known about the systemic distribution of metal particles and ions. The significance of systemic distribution also is not known. The levels of serum and urine Co and Cr ions are elevated in patients with metal-on-metal bearings, but the long-term, steady-state levels are not much higher than those from corrosion of modular femoral components. Because of the elevated levels of Co and Cr ions, there is a greater risk of delayed type hypersensitivity. There also is concern about the potential for malignant degeneration secondary to prolonged exposure to these elements. The available data are insufficient to address this concern. Rigorous long-term studies are needed. It will take decades of close clinical observation to determine if the benefits of metal-on-metal bearings outweigh the associated risks.

Metal-on-metal total hip arthroplasty: the concerns

The metal-on-metal bearing couple is having a resurgence in clinical applications seen in total hip and hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation of metal ions seen in the blood and urine of patients with metal-on-metal implants. These elevated metal ions have theoretical, although not proven, risks related to carcinogenic and biologic concerns. Additionally, concerns exist regarding hypersensitivity, increased incidence of instability and increased costs. Specific patient selection issues arise with metal-on-metal implants. The current generation of implants has only early and mid-term results available, with no long-term series yet published. Therefore, although a metal-on-metal bearing may be considered a viable alternative to either polyethylene or ceramic implants, outstanding and unresolved issues continue to exist with this bearing, as they do with the alternatives.

Can a safe level for metal ions in patients with metal-on-metal total hip arthroplasties be determined?

The single most significant obstacle preventing a broader application of metal-on-metal hip arthroplasties continues to be the concerns regarding elevated metal ion levels in the blood and urine of patients with this bearing. A safe level for metal ions has yet to be defined for patients with metal-on-metal hip arthroplasties. A review of occupational exposure data gives some insight; however, longitudinal studies of large numbers of patients with metal-on-metal implants will ultimately be required to answer specific clinical concerns.

Mid-term results of a polyethylene-free metal-on-metal articulation

Beginning in December 1995, 193 patients (195 hips) were enrolled into this prospective, randomized, controlled multicenter investigational device exemption study. Ninety-eight patients (99 hips) with 46 polyethylene liners and 53 metal liners had minimum 5-year follow-up (mean, 5.7 years). Average follow-up, Harris hip score improvement, and radiographic analysis were not statistically different between groups. No stress shielding or osteolysis was observed in either group. Three polyethylene liners and no metal liners had acetabular radiolucencies <1 mm in 1 or more zones. There have been no device-related complications, no acetabular revisions performed, and none pending in either group. Based on these mid-term results, the authors conclude that a metal-on-metal articulation represents a viable alternative in young, high-demand, active patients.

Biocompatibility of micro- and nano-particles in the colon. Part II

Pathological colonic tissues were investigated with an Environmental Scanning Electron Microscope technique to verify the presence of inorganic, non-biodegradable pollutants, i.e. micro- and nano-debris of exogenous origin, after debris in liver and kidney had been discovered. In all, 18 samples of colon tissues affected by cancer and Crohn's disease were evaluated and found in all the cases to contain micro- and nano-particles. Their chemistry, detected with an X-ray microprobe, indicated a heterogeneous nature, whereas the size of the particles was homogeneous. Three control samples of healthy, young, cadavers were analysed and showed the absence of debris within the normal, healthy colon mucosa. The study reveals the presence of particulate debris, generally considered as biocompatible, in pathological specimens of human colon. The findings suggest a possible link between the presence of such particles and the underlying pathology in the cases analysed.

Ion release and chromosomal damage from total hip prostheses with metal-on-metal articulation

A prospective multicentric study was carried out in patients having metal-on-metal METASUL components (Sulzer Medica, Winterthur, Switzerland) in order to check the following null hypotheses: H1: The concentration of Co, Cr, Ni, and Mb in blood and urine is not modified by the implant of a hip prosthesis with METASUL components at 6 months. H2: The incidence of markers of chromosomal damage [sister chromatid exchanges (SCEs) and micronuclei (Mni)] in lymphocytes is not modified by the implant of METASUL components at 6 months. H3: The concentrations of Co, Cr, Ni, and Mb in blood and urine did not correlate with the incidence of the markers of chromosomal damage. The measurements showed a 2-fold increase of Co in blood, a 10-fold increase of Co in urine, a 1.5-fold increase of Cr in the blood, and a 3-fold increase of Cr in the urine at a follow-up of 6 months from the operation; there was also a significant increase in the Ni blood concentration at the 7 day checkup. The study cohort did not show any modification in the frequency of markers of chromosomal damage in the peripheral lymphocytes at any of the observation times. The amount of the SCEs and Mni recorded at all the observation times did not correlate with each other or with any of the ion levels measured in the blood and in the urine.

Ion release in stable hip arthroplasties using metal-on-metal articulating surfaces: a comparison between short- and medium-term results

The use of metallic heads articulating with metallic cups could solve the problem of polyethylene (PE) wear in total hip replacement (THR) with metal-on-PE bearings. A conspicuous release of metal ions from new models of metal-on-metal bearings has been found in the short-term, but it is yet unclear whether the medium-term corrosion rate is high or, on the contrary, it becomes negligible, because of the continuous surface finishing. Our purpose was to compare the serum ion values (nanograms per milliliter) in 15 patients with metal-on-metal stable prosthesis (Group A), in the short-term (subgroup A(1); mean follow-up: 24 mo) and medium-term (subgroup A(2); mean follow-up: 52 mo), in order to determine whether the ion release decreased with time of implant. Chromium (Cr), cobalt (Co), molybdenum (Mo) and aluminum (Al) were analyzed. Twenty-two presurgical patients were used for comparison (Group B). The reference range was obtained from a population of 27 healthy subjects (Group C). Co and Cr levels in the medium-term (subgroup A(2)) were not decreased in comparison with the short-term values (subgroup A(1)) and were significantly higher (p < 0.001) than presurgical and reference values. Otherwise, Mo and Al concentrations were not significantly increased in comparison with reference values. In conclusion, despite the apparent advantage of metal-on-metal coupling, especially in younger patient populations, there is a major concern about the extent and duration of the relevant "internal" exposure to Cr and Co ions. This exposure should be carefully monitored, in order to clarify the biologic effects of ion dissemination and, consequently, to identify risks concerning long-term toxicity of metals.

Ion release in patients with metal-on-metal hip bearings in total joint replacement: a comparison with metal-on-polyethylene bearings

Polyethylene (PE) wear has been shown to be a problem in long-term joint replacement using metal-on-PE bearing. The use of metallic heads articulating with metallic cups could solve this problem: success will be enhanced if wear and corrosion of the articulating surfaces are maintained at a low level. New models with metal-on-metal bearing have been proposed, to be used mainly for young subjects: such coupling seems to have a reduced release, but it is unclear yet if the medium-term corrosion rate is really negligible or, on the contrary, it is significantly higher than in the metal-on-PE bearing. Aim of our study was the comparison of ion release in the serum of two groups of patients who had the same type of stable cementless prosthesis, but different bearing: twenty-six patients with metal-on-metal (Group A) and fifteen patients with metal-on-PE bearing (Group B) were examined. The follow-up was 14-38 months for group A and 18-34 months for group B. The serum concentration of chromium (Cr), cobalt (Co) and molybdenum (Mo) was measured. Twenty-two patients before surgery were used for comparison (Group C). The reference values were obtained from a population of twenty-two healthy subjects (Group D). Our findings indicate that metal-on-metal bearings produce a significantly higher systemic release of cobalt and chromium (ng/ml) when compared with levels found in metal-on-PE, pre-surgery and reference groups. Such a high release should induce to improve the bearing materials or, at least, to study the biologic fate of metal ions and consequently their long-term effects. In such a way a risk-to-benefit ratio for the patient could be established.

Four-year study of cobalt and chromium blood levels in patients managed with two different metal-on-metal total hip replacements

BACKGROUND

Metal-on-metal total hip prostheses will produce a certain amount of wear debris. This results in increased whole-blood metal levels, which may cause adverse effects. It is not known to what extent the problem has been overcome by advances in alloy technology.

METHODS

In 259 patients who with total hip replacement, blood cobalt and chromium concentrations were measured with atomic absorption spectrophotometry over a period of four years after arthroplasty. Of the patients enrolled in the study, 131 had been managed with a METASUL cobalt-chromium alloy metal-on-metal bearing combination, while 128 had been given a SIKOMET-SM21 cobalt-chromium alloy metal-on-metal combination. The control group consisted of 31 age- and gender-matched subjects.

RESULTS

Compared with the controls, all the patients had higher cobalt and chromium levels. Cobalt concentrations were up to 50 times higher, while chromium concentrations were up to 100 times higher.

CONCLUSIONS

Both systems showed evidence, in the whole-blood samples, of wear debris production by the implants. Therefore, patients managed with metal-on-metal bearing combinations should be carefully monitored in order to ensure that any local or systemic complications are detected early on.

Incidence of cancer among patients with knee implants in Sweden, 1980-1994

BACKGROUND

As knee implants become more common, it is important to study their potential health risks. We investigated cancer occurrence in a nationwide population-based cohort of 30,011 patients who underwent knee replacement surgery in Sweden from 1980 to 1994.

METHODS

Patients were followed from 1 year after the date of their surgery through December 31, 1995, accruing 122,616 person-years of observation. The average follow-up time was 4.3 years, with 2365 patients followed for 10 years or more.

RESULTS

Overall cancer incidence was not elevated compared with the general population of Sweden (standardized incidence ratio [SIR] = 1.03; 95% confidence interval [CI] = 0.98-1.08). A reduced rate for all respiratory cancers (SIR = 0.73; 95% CI = 0.59-0.91) and for lung cancer (SIR = 0.73; 95% CI = 0.58-0.91) was found among both men and women. Elevated rates were found for prostate (SIR = 1.20; 95% CI = 1.06-1.34) and bone cancer (SIR = 6.00; 95% CI = 1.24-17.52) in men. The bone cancer excess was based on three observed cases, two of which occurred at a site unrelated to the implant and the site of the third tumor is unknown. Rates of connective tissue cancer and leukemia-lymphoma were not elevated significantly among knee implant recipients. Long-term follow-up (>or= 10 years) did not show a significant excess risk for all cancer (SIR = 1.10; 95% CI = 0.86-1.38) or for any site-specific cancer, including bone cancer, lymphoma, or leukemia. Subgroup analyses for patients with rheumatoid arthritis produced results similar to the overall results.

CONCLUSIONS

This epidemiologic study of cancer risk among patients with knee implants is the largest to date. It provides evidence that the incidence of cancer among patients with knee implants is similar to that of the general population. Continued follow-up of this cohort is warranted to evaluate further potential long-term effects of these implants.