Cancer risk after metal on metal and polyethylene on metal total hip arthroplasty

Possible Transformation of Pseudotumor to Synovial Sarcoma in a Failed Metal-on-Metal Total Hip Arthroplasty

Adverse local tissue reaction (ALTR) from the release of chromium and cobalt ions in metal-on-metal total hip arthroplasty (MoM THA) is a well-reported complication, but there is little evidence suggesting that this inflammatory reaction causes malignancy. We present a 69-year-old female with MoM THA who developed synovial sarcoma (SS). She underwent mass resection and revision THA. Postoperative pathologic analysis revealed the unanticipated diagnosis of SS. She subsequently underwent chemotherapy, sarcoma resection, and endoprosthetic reconstruction. We hypothesize that the SS developed from an ALTR in the setting of failed MoM THA. Given the paucity of data on possible malignant transformation of an ALTR to SS, we advise surgeons to consider potential malignancies when diagnosing ALTR in the setting of failed MoM THA bearings.

Ultrasonographic assessment of magnetic growing rods overestimates the lengthening of the thoracic spine compared to radiographs in early-onset scoliotic patients

PURPOSE

Magnetic growing rods (MGRs) are one of the most common procedures to treat early-onset scoliosis (EOS). Radiographic examinations (X-ray) or ultrasonographic (US) assessments are used to evaluate the lengthening of the rods. X-ray exposes patients to radiation, while the US has not been validated and may be affected by the radiologist's ability to assess elongation. The research question of the present study is to compare the difference between US and X-ray growth assessments in EOS patients treated with MGRs.

METHODS

The study enrolled 65 patients consecutively from July 2011 to July 2022. Noninvasive lengthening was performed every four months, and X-ray follow-up was performed at different intervals. An experienced radiologist assessed the mean US rod elongation per session. The mean elongation/session of T2-T12 and T2-S1 was calculated, and the results were compared using an independent t-test.

RESULTS

The mean age at operation was 8.8 ± 2 years, and the mean follow-up was four ± two years. The average rod elongation assessed by the US was 3.1 ± 0.1 mm. The average rod elongation evaluated by X-ray was 1.2 ± 2.9 mm (T2-T12) and 1.8 ± 1.9 mm (T2-S1). The difference between the values measured by US and X-ray was statistically significant in the T2-T12 group (p < 0.05) and not significant in the T2-S1 group (p = 0.34).

CONCLUSIONS

This is the most extensive single-center study comparing US and X-ray data for MGRs in EOS patients. US overestimates thoracic spine elongation compared to X-ray. US elongation analysis could be appropriate in long thoracolumbar curves.

Patients treated by magnetic growing rods for early-onset scoliosis reach the expected average growth

INTRODUCTION

Magnetic controlled growing rods (MCGRs) are one of the most common procedures to treat early-onset scoliosis (EOS). One of the major concerns is that patients treated with MGCR do not reach an adequate height with MGCR. The present study has one of the largest sample sizes of EOS patients treated by MGCR. This study aims to demonstrate the efficacy of the treatment with MGCR in EOS patients, comparing our results with the estimated growth.

METHODS

Patients were consecutively enrolled from July 2011 to July 2022. The same surgical equipe performed all the procedures. The mean length of the patients was assessed by X-ray (T2-T12 and T2-S1 distance) by a team of expert radiologists. The estimated growth by Dimeglio was compared with the mean elongation obtained by year.

RESULTS

65 patients were included. 16 patients underwent final surgery. In group 1, patients reached a growth of 3.6 ± 8.7 mm (T2-T12) and 9.6 ± 27.6 mm (T2-S1). In group 2, patients grew 5.4 ± 5.7 mm (T2-T12) and 9 ± 9 mm (T2-S1).81% of the estimated elongation during the treatment was obtained during the first surgery. The difference between Dimeglio's estimated growth and the value obtained by MGCR was -4.3 ± 8.7 mm(T2-T12) and -12.3 ± 12.2 mm (T2-S1) in group 1 (p < 0.001) and -1.1 ± 4.2 mm (T2-T12) and -6.6 ± 6.0 mm (T2-S1) in group 2 (p = 0.001).

CONCLUSIONS

MGCR patients reached and overlapped the growth target according to the score by Dimeglio. However, the value of growth tended to reduce over the years. Lastly, obtaining the most significant elongation possible at the first surgery is mandatory, comprising 81% of the total value.

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

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

No increased risk of cancer associated with metal-on-metal or ceramic-on-ceramic procedures compared to other bearing surfaces in patients with total hip arthroplasty: A nationwide linked registry cohort analysis of 167,837 patients

OBJECTIVES

Studies have identified increased cancer risk among patients undergoing total hip arthroplasty (THA) compared to the general population. However, evidence of all-cause and site-specific cancer risk associated with different bearing surfaces has varied, with previous studies having short latency periods with respect to use of modern Metal-on-Metal (MoM) bearings. Using the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) linked to Australasian Association of Cancer Registries data, our aim was to evaluate risk of all-cause and site-specific cancer according to bearing surfaces in patients undergoing THA for osteoarthritis and whether risk increased with MoM bearings.

METHODS

Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated by comparing number of observed cancer cases to expected number based on incidence rate in the Australian population. All-cause and site-specific cancer rates were calculated for all conventional stemmed THA (csTHA) and resurfacing THA (rsTHA) procedures performed for osteoarthritis. Cox proportional hazards models were used to compare cancer rates for MoM, ceramic-on-ceramic (CoC) and resurfacing procedures with a comparison group comprising metal-on-polyethylene (MoP) or ceramic-on-polyethylene (CoP) procedures.

RESULTS

There were 156,516 patients with csTHA procedures and 11,321 with rsTHA procedures for osteoarthritis performed between 1999 and 2012. Incidence of all-cause cancer was significantly higher for csTHA (SIR 1.24, 95% CI 1.22-1.26) and rsTHA (SIR 1.74, 95% CI 1.39-2.04) compared to the Australian population. For csTHA, there was no significant difference in all-site cancer rates for MoM (Hazard Ratio (HR) 1.01, 95%CI 0.96-1.07) or CoC (HR 0.98, 95%CI 0.94-1.02) compared to MoP and CoP bearings. Significantly increased risk of melanoma, non-Hodgkins lymphoma, myeloma, leukaemia, prostate, colon, bladder and kidney cancer was found for csTHA and, prostate cancer, melanoma for rsTHA procedures when compared to the Australian population, although risk was not significantly different across bearing surfaces.

CONCLUSIONS

csTHA and rsTHA procedures were associated with increased cancer incidence compared to the Australian population. However, no excess risk was observed for MoM or CoC procedures compared to other bearing surfaces.

(Bio)Tribocorrosion in Dental Implants: Principles and Techniques of Investigation

Tribocorrosion is a current and very discussed theme in tribology and medicine for its impact on industrial applications. Currently, the phenomena are mainly oriented to the biological environment and, in particular, to medical devices such as hip prostheses, dental implants, knee joints, etc. The term tribocorrosion underlines the simultaneous action of wear and corrosion in a tribocouple. It has a non-negligible effect on the total loss of contact materials and the potential failure of the bio-couplings. This overview aims to focus firstly on the basic principles of prosthesis tribocorrosion and subsequently to describe the techniques and the analytical models developed to quantify this phenomenon, reporting the most relevant results achieved in the last 20 years, proposed in chronological order, in order to discuss and to depict the future research developments and tendencies. Despite considerable research efforts, from this investigation come many issues worthy of further investigation, such as how to prevent or minimize tribocorrosion in biological tribopairs, the development of a consolidated protocol for tribological experiments in corrosive environments joined with new biomaterials and composites, the possibility to achieve more and more accurate theoretical models, and how to be able to ensure the success of new implant designs by supporting research and development for the management of implant complications. The above issues certainly constitute a scientific challenge for the next years in the fields of tribology and medicine.

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.

What is the Level of Evidence Substantiating Commercial Payers' Coverage Policies for Total Joint Arthroplasty?

BACKGROUND

The prevalence of total joint arthroplasty (TJA) in the United States has drawn the attention of health care stakeholders. The payers have also used a variety of strategies to regulate the medical necessity of these procedures. The purpose of this study was to examine the level of evidence of the coverage policies being used by commercial payers in the United States.

METHODS

The references of the coverage policies of four commercial insurance companies were reviewed for type of document, level of evidence, applicability to a TJA population, and success of nonoperative treatment in patients with severe degenerative joint disease.

RESULTS

282 documents were reviewed. 45.8% were primary journal articles, 14.2% were level I or II, 41.2% were applicable to patients who were candidates for TJA, and 9.9% discussed the success of nonoperative treatment in patients who would be candidates for TJA.

CONCLUSION

Most of the references cited by commercial payers are of a lower level of scientific evidence and not applicable to patients considered to be candidates for TJA. This is relatively uniform across the reviewed payers. The dearth of high-quality literature cited by commercial payers reflects the lack of evidence and difficulty in conducting high level studies on the outcomes of nonoperative versus operative treatment for patients with severe, symptomatic osteoarthritis. Patients, surgeons, and payers would all benefit from such studies and we encourage professional societies to strive toward that end through multicenter collaboration.

An integrated benefit-risk assessment of cobalt-containing alloys used in medical devices: Implications for regulatory requirements in the European Union

In 2017, the European Union (EU) Committee for Risk Assessment (RAC) recommended the classification of metallic cobalt (Co) as Category 1B with respect to its carcinogenic and reproductive hazard potential and Category 2 for mutagenicity but did not evaluate the relevance of these classifications for patients exposed to Co-containing alloys (CoCA) used in medical devices. CoCA are inherently different materials from Co metal from a toxicological perspective and thus require a separate assessment. CoCA are biocompatible materials with a unique combination of properties including strength, durability, and a long history of safe use that make them uniquely suited for use in a wide-range of medical devices. Assessments were performed on relevant preclinical and clinical carcinogenicity and reproductive toxicity data for Co and CoCA to meet the requirements under the EU Medical Device Regulation triggered by the ECHA re-classification (adopted in October 2019 under the 14th Adaptation to Technical Progress to CLP) and to address their relevance to patient safety. The objective of this review is to present an integrated overview of these assessments, a benefit-risk assessment and an examination of potential alternative materials. The data support the conclusion that the exposure to CoCA in medical devices via clinically relevant routes does not represent a hazard for carcinogenicity or reproductive toxicity. Additionally, the risk for the adverse effects that are known to occur with elevated Co concentrations (e.g., cardiomyopathy) are very low for CoCA implant devices (infrequent reports often reflecting a unique catastrophic failure event out of millions of patients) and negligible for CoCA non-implant devices (not measurable/no case reports). In conclusion, the favorable benefit-risk profile also in relation to possible alternatives presented herein strongly support continued use of CoCA in medical devices.

Global diversity in bearings in primary THA

Choice of articulating materials, head size and the design of the articulation will become decisive for the long-term performance of a total hip arthroplasty (THA) and especially in terms of risk for dislocation and wear-related problems. Here we account for common alternatives based on available studies and the evidence that can be derived from them.Metal or ceramic femoral heads articulating against a liner or cup made of highly cross-linked polyethylene and ceramic-on-ceramic articulations have about similar risk for complications leading to revision, whereas the performance of metal-on-metal articulations, especially with use of big heads, is inferior. The clinical significance of problems related to ceramic-on-ceramic articulations such as squeaking remains unclear. With use of current technology ceramic fractures are rare.Large femoral heads have the potential to increase the range of hip movement before impingement occurs and are therefore expected to reduce dislocation rates. On the other hand, issues related to bearing wear, corrosion at the taper-trunnion junction and groin pain may arise with larger heads and jeopardize the longevity of THA. Based on current knowledge, 32-mm heads seem to be optimal for metal-on-polyethylene bearings. Patients with ceramic-on-ceramic bearings may benefit from even larger heads such as 36 or 40 mm, but so far there are no long-term reports that confirm the safety of bearings larger than 36 mm.Assessment of lipped liners is difficult because randomized studies are lacking, but retrospective clinical studies and registry data seem to indicate that this liner modification will reduce the rate of dislocation or revision due to dislocation without clear evidence of clinically obvious problems due to neck-liner impingement.The majority of studies support the view that constrained liners and dual mobility cups (DMC) will reduce the risk of revision due to dislocation both in primary and revision THA, the latter gaining increasing popularity in some countries. Both these devices suffer from implant-specific problems, which seem to be more common for the constrained liner designs. The majority of studies of these implants suffer from various methodological problems, not least selection bias, which calls for randomized studies preferably in a multi-centre setting to obtain sufficient power. In the 2020s, the orthopaedic profession should place more effort on such studies, as has already been achieved within other medical specialties, to improve the level of evidence in the choice of articulation when performing one of the most common in-hospital surgical procedures in Europe. Cite this article: EFORT Open Rev 2020;5:763-775. DOI: 10.1302/2058-5241.5.200002.

A prospective study on cancer risk after total hip replacements for 41,402 patients linked to the Cancer registry of Norway

BACKGROUND

Concerns have been raised that implants used in total hip replacements (THR) could lead to increased cancer risk. Several different materials, metals and fixation techniques are used in joint prostheses and different types of articulation can cause an increased invasion of particles or ions into the human body.

METHODS

Patients with THR registered in the Norwegian Arthroplasty Register during 1987-2009 were linked to the Cancer registry of Norway. Patients with THR due to osteoarthritis, under the age of 75 at time of surgery, were included. Standardized incidence ratios (SIR) were applied to compare cancer risk for THR patients to the general population. Types of THR were divided into cemented (both components), uncemented (both components), and hybrid (cemented femoral and uncemented acetabular components). To account for selection mechanisms, time dependent covariates were applied in Cox-regression, adjusting for cancer risk the first 10 years after surgery. The analyses were adjusted for age, gender and if the patient had additional THR-surgery in the same or the opposite hip. The study follows the STROBE guidelines.

RESULTS

Comparing patients with THR to the general population in Norway we found no differences in cancer risk. The overall SIR for the THR-patients after 10 years follow-up was 1.02 (95% CI: 0.97-1.07). For cemented THR, the SIR after 10 years follow-up was 0.99 (95% CI: 0.94-1.05), for uncemented, 1.16 (95% CI: 1.02-1.30), and for hybrid 1.12 (95% CI: 0.91-1.33). Adjusted Cox analyses showed that patients with uncemented THRs had an elevated risk for cancer (hazard ratio: HR = 1.24, 95% CI: 1.05-1.46, p = 0.009) when compared to patients with cemented THRs after 10 years follow-up. Stratified by gender the increased risk was only present for men. The risk for patients with hybrid THRs was not significantly increased (HR = 1.07, 95% CI: 0.85-1.35, p = 0.55) compared to patients with cemented THRs.

CONCLUSIONS

THR patients had no increased risk for cancer compared to the general population. We found, however, that receiving an uncemented THR was associated with a small increased risk for cancer compared to cemented THR in males, but that this may be prone to unmeasured confounding.

A heavy metal baseline score predicts outcome in acute myeloid leukemia

Despite abundant epidemiological data linking metals to leukemia and other cancers, baseline values of toxic and essential metals in patients with leukemia and the clinical impact of these metals remain unknown. Thus, we sought to quantify metal values in untreated patients with acute myeloid leukemia (AML) and controls and determine the impact of metal values on AML patients' survival. Serum samples from patients with untreated AML and controls at Hospices Civils de Lyon were analyzed and compared for trace metals and copper isotopic abundance ratios with inductively coupled plasma mass spectrometry. Survival analysis was performed as a function of metal values, and a multi-metal score was developed for patients with AML. Serum samples were collected from 67 patients with untreated AML and 94 controls. Most patients had intermediate-risk cytogenetics (63.1%) without FLT3 internal tandem duplication mutations (75.6%) or NPM1 mutations (68.1%). Most metal values differed significantly between AML and control groups. Patients with lower magnesium and higher cadmium values had the worst survival rates, with only 36% surviving at 6 months (P = .001). The adverse prognostic effect of this combination was maintained on multivariate analysis. Based on this, we developed a novel metal score, which accounts for multiple relative abnormalities in the values of five toxic and five essential metals. Patients with a higher metal score had significantly worse survival, which was maintained on multivariate analysis (P = .03). This baseline metal scoring system was also prognostic when we applied it to a separate population of front-line AML patients.

Are dual mobility cups associated with increased metal ions in the blood? Clinical study of nickel and chromium levels with 29 months' follow-up

INTRODUCTION

Dual mobility cups have become the implant of choice for older patients with a high risk of dislocation. However, to our knowledge, no study has explored the possibility of metal ion production with these implants that incorporate a polyethylene-on-metal bearing. This led us to conduct a prospective study to determine whether use of a dual mobility cup is accompanied by increased levels of nickel and chromium in the blood.

HYPOTHESIS

Use of a dual mobility cup is accompanied by an increase of nickel and chromium levels in the blood.

METHODS

Between 2012 and 2015, 16 consecutive patients were enrolled in the study. They underwent primary hip arthroplasty with a ceramic Biolox™ head (CeramTec, Plochingen, Germany), Corail™ titanium alloy stem (DePuy Synthes, Saint Priest, France) and a Novae™ dual mobility cup (SERF, Décines-Charpieu, France) consisting of 19% chromium (Cr) and 13-15% nickel (Ni). Patients who had other potential sources of nickel or chromium in their body (joint implants, dental implants, etc.) were excluded. The blood levels (μg/L) of nickel and chromium were measured preoperatively and at 2 years' follow-up by an independent laboratory (Biomnis) using inductively coupled plasma mass spectrometry. The upper limits set by the laboratory were<0.87μg/L for chromium and<1.0μg/L for nickel. AP and lateral X-rays of the pelvis were taken preoperatively and at each postoperative follow-up visit to look for signs of loosening. The Postel-Merle-d'Aubigné (PMA) score was determined preoperatively and at each postoperative follow-up visit. Surgical revision procedures for any cause were also documented.

RESULTS

The mean follow-up was 29 months [13-39]. Preoperatively, blood nickel ion levels were measured in 7 patients; they were below 1μg/L in 6 patients (86%) and at 1.5μg/L in 1 patient (14%). The mean preoperative chromium ion levels (n=7) was 0.2μg/L [0-0.8μg/L]. Postoperatively, all 16 enrolled patients had their blood ion levels checked at a mean follow-up of 29 months. The nickel ion levels averaged 1.69±1.49 [0.2-5.6] (with 4/16 having>2μg/L and 12/16>1μg/L) and the chromium ion levels averaged 0.5±0.11 [0.4-0.7] (with no patients>0.7μg/L). There were no signs of loosening or osteolysis on the follow-up radiographs. The mean PMA score at 2 years was 17.8 [17,18].

CONCLUSION

We found that dual mobility cups generate increased nickel but not chromium ions in the blood. The levels measured are comparable to those for other orthopedic implants such as spine implants. The clinical consequences of these increased levels are not known. Nevertheless, there were no clinical or radiological signs of loosening, although the follow-up was only 2 years.

LEVEL OF EVIDENCE

IV, Cohort study.

Midterm risk of cancer with metal-on-metal hip replacements not increased in a Finnish population

Background and purpose - Metal-on-metal (MoM) total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA) have been widely used during the early 21st century. We assessed the midterm risk of cancer of patients treated with modern MoM hip implants compared with patients with non-MoM hip implants and the general Finnish population with special interest in soft tissue sarcomas and basalioma due to the findings of our previous report. Patients and methods - All large-diameter head MoM THAs and hip resurfacings performed in Finland between 2001 and 2010 were extracted from the Finnish Arthroplasty Register (10,728 patients). Patients who underwent conventional THA formed the non-MoM reference cohort (18,235 patients). Data on cancer cases up to 2014 were extracted from the Finnish Cancer Registry. The relative risk of cancer in the general population was expressed as the ratio of observed to expected number of cases, i.e., standardized incidence ratio (SIR). Poisson regression analysis was used to compare the cancer risk between the cohorts. The mean follow-up was 7.4 years (1-14) in the MoM cohort and 8.4 years (1-14) in the non-MoM cohort. Results - The overall risk of cancer in the MoM cohort was comparable to the general Finnish population (SIR 0.9, 95% CI 0.9-1.0). Risk of basalioma in the MoM cohort was higher than in the general Finnish population (SIR 1.2, CI 1.1-1.4) and higher than in the non-MoM cohort in the stratified regression analysis (RR 1.2, CI 1.0-1.4, p = 0.02). The SIR of soft-tissue sarcoma in the MoM cohort was 1.4 (CI 0.6-2.8); the incidence was same as in the non-MoM cohort. Interpretation - Metal-on-metal hip implants are not associated with an increased overall risk of cancer during midterm follow-up.

Risk of cancer after primary total hip replacement: The influence of bearings, cementation and the material of the stem

Background and purpose - Despite the increasing number of total hip replacements (THRs), their systemic influence is still not known. We have studied the influence of specific features of THRs-the bearing surface, the use of bone cement and the material of the stem-on the cancer incidence. Patients and methods - In a retrospective cohort study we identified 8,343 patients with THRs performed at Valdoltra Hospital from September 1, 1997 to December 31, 2009. Patient data were linked to national cancer and population registries. The standardized incidence ratios (SIR) and Poisson regression relative risks (RR) were calculated for all and specific cancers. Results - General cancer risk in our cohort was comparable to the population risk. Comparing with population, the risk of prostate cancer was statistically significantly higher in patients with metal-on-metal bearings (SIR =1.35); with metal-on-polyethylene bearings (SIR =1.30), with non-cemented THRs (SIR =1.40), and with titanium alloy THRs (SIR =1.41). In these last 3 groups there was a lower risk of hematopoietic tumors (SIR =0.69; 0.66 and 0.66 respectively). Risk of kidney cancer was significantly higher in the non-metal-on-metal, non-cemented, and titanium alloy groups (SIR =1.30; 1.46 and 1.41 respectively). Risk of colorectal and lung cancer was significantly lower in the investigated cohort (SIR =0.82 and 0.83, respectively). Risk for all cancers combined as well as for prostate and skin cancer, shown by Poisson analysis, was higher in the metal-on-metal group compared with non-metal-on-metal group (RR =1.56; 2.02 and 1.92, respectively). Interpretation - Some associations were found between the THRs' features, especially a positive association between metal-on-metal bearings, and specific cancers.

Short-term Outcomes of Ceramic Coated Metal-on-Metal Large Head in Total Hip Replacement Arthroplasty

Purpose

This study characterizes the short-term outcomes of ceramic coated metal-on-metal (MoM) large head total hip arthroplasty (THA) in prospectively selected patients aged 70 to 75 years.

Materials and Methods

Eighteen patients (18 hips) between the ages of 70 and 75-years old with THA using ceramic-coated MoM large heads between June 2014 and December 2014 were evaluated. We prospectively selected patients younger than 70 years for bipolar hemiarthroplasty and older than 75 years for conventional THA. There were one case of osteoarthritis, 8 cases of femur neck fracture, and 9 cases of intertrochanteric fracture. All patients underwent clinical and radiological follow-up at 6 weeks, 6 and 12 months, and every year postoperatively. The mean duration of follow-up was 24.2 months (range, 18–34 months).

Results

The average Harris hip score at the final follow-up was 81.0, except one case which was ultimately converted to conventional THA due to acetabular cup loosening. Radiographically, mean acetabular cup inclination was 45.8°(range, 38–56°) and anteversion was 20.1° (range, 11–25°). The average femoral head size was 48.7 mm. All stems were neutral-positioned except 1 varus-positioned stem. There was 1 case of a soft tissue infection, 3 patients complained of persistent groin pain, and no dislocations occurred.

Conclusion

Ceramic coated large MOM articulation (ACCIS) have many complications: cup loosening, groin pain, which can lead to fatal outcomes in the elderly patients. Especially in patients with communicated intertrochanter fracture (AO 31-A22, 23), careful attention should be paid to the choice of surgical option.

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.

Synchrotron analysis of human organ tissue exposed to implant material

BACKGROUND

Orthopaedic implants made of cobalt-chromium alloy undergo wear and corrosion that can lead to deposition of cobalt and chromium in vital organs. Elevated cardiac tissue cobalt levels are associated with myocardial injury while chromium is a well-established genotoxin. Though metal composition of tissues surrounding hip implants has been established, few investigators attempted to characterize the metal deposits in systemic tissues of total joint arthroplasty patients.

METHODS

We report the first use of micro-X-ray fluorescence coupled with micro-X-ray absorption spectroscopy to probe distribution and chemical form of cobalt, chromium and titanium in postmortem samples of splenic, hepatic and cardiac tissue of patients with metal-on-polyethylene hip implants (n = 5).

RESULTS

Majority of the cobalt was in the 2+ oxidation state, while titanium was present exclusively as titanium dioxide, in either rutile or anatase crystal structure. Chromium was found in a range of forms including a highly oxidised, carcinogenic species (CrV/VI), which has never been identified in human tissue before.

CONCLUSIONS

Carcinogenic forms of chromium might arise in vital organs of total joint arthroplasty patients. Further studies are warranted with patients with metal-on-metal implants, which tend to have an increased release of cobalt and chromium compared to metal-on-polyethylene hips.

Analysis of Explanted Magnetically Controlled Growing Rods From Seven UK Spinal Centers

STUDY DESIGN

Analysis of explanted MAGnetic Expansion Control (MAGEC) growing rods.

OBJECTIVE

To analyze explanted MAGEC rods used in management of early onset scoliosis and identify the mode of failure in such cases.

SUMMARY OF BACKGROUND DATA

Magnetically controlled growing rods are increasingly used as the option of choice for early onset scoliosis. However, being more complex than conventional growing rods they are perhaps more likely to succumb to multifarious failure modes. In addition, metallosis has been reported around failed MAGEC rods.

METHODS

Explanted MAGEC rods from seven UK spinal centers were obtained for independent analysis. Thirty-four MAGEC rods, from 18 children, explanted for reasons including failure of rod lengthening and maximum rod distraction reached, were cut open to allow internal components to be evaluated and assessed.

RESULTS

Externally, all MAGEC rods showed localized marks, which were termed "growth marks" as they indicated growth of the rod in vivo, on the extending bar component. After cutting open, titanium wear debris was found inside all 34 (100%) MAGEC rods. Ninety-one percent (31/34) of MAGEC rods showed measurable wear of the extending bar, towards the magnet end. Substantial damage to the radial bearing was seen inside 74% (25/34) of MAGEC rods while O-ring seal failure was seen in 53% (18/34) of cases. In 44% (15/34) of MAGEC rods the drive pin was fractured but this was felt to be an effect of rod failure, not a cause.

CONCLUSION

The combination of high volumes of titanium wear debris alongside O-ring seal damage likely accounts for the metallosis reported clinically around some MAGEC rods. Based on this explant data, a failure mechanism in MAGEC rods due to the natural off axis loading in the spine was proposed. This is the largest data set reporting a complete analysis of explanted MAGEC rods to date.

LEVEL OF EVIDENCE

4.

Modularity in Total Hip Arthroplasty: Benefits, Risks, Mechanisms, Diagnosis, and Management

Modular implants are currently widely used in total hip arthroplasty because they give surgeons versatility during the operation, allow for easier revision surgery, and can be adjusted to better fit the anatomy of the specific patient. However, modular implants, specifically those that have metal-on-metal junctions, are susceptible to crevice and fretting corrosion. This can ultimately cause implant failure, inflammation, and adverse local tissue reaction, among other possible side effects. Surgeons should be aware of the possibility of implant corrosion and should follow a set of recommended guidelines to systematically diagnose and treat patients with corroded implants. Ultimately, surgeons will continue to use modular implants because of their widespread benefits. However, more research is needed to determine how to minimize corrosion and the negative side effects that have been associated with modular junctions in total hip arthroplasty. [Orthopedics. 2017; 40(6):355-366.].

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.

Magnetically controlled growing rods in the treatment of early-onset scoliosis

The MAGnetic Expansion Control (MAGEC) system is used increasingly in the management of early-onset scoliosis. Good results have been published, but there have been recent reports identifying implant failures that may be associated with significant metallosis surrounding the implants. This article aims to present the current knowledge regarding the performance of this implant, and the potential implications and strategies that may be employed to identify and limit any problems.

We urge surgeons to apply caution to patient and construct selection; engage in prospective patient registration using a spine registry; ensure close clinical monitoring until growth has ceased; and send all explanted MAGEC rods for independent analysis.

The MAGEC system may be a good instrumentation system for the treatment of early-onset scoliosis. However, it is innovative and like all new technology, especially when deployed in a paediatric population, robust systems to assess long-term outcome are required to ensure that patient safety is maintained.

Cite this article: Bone Joint J 2017;99-B:708–13.

Cobalt toxicity in humans-A review of the potential sources and systemic health effects

Cobalt (Co) and its compounds are widely distributed in nature and are part of numerous anthropogenic activities. Although cobalt has a biologically necessary role as metal constituent of vitamin B₁₂, excessive exposure has been shown to induce various adverse health effects. This review provides an extended overview of the possible Co sources and related intake routes, the detection and quantification methods for Co intake and the interpretation thereof, and the reported health effects. The Co sources were allocated to four exposure settings: occupational, environmental, dietary and medical exposure. Oral intake of Co supplements and internal exposure through metal-on-metal (MoM) hip implants deliver the highest systemic Co concentrations. The systemic health effects are characterized by a complex clinical syndrome, mainly including neurological (e.g. hearing and visual impairment), cardiovascular and endocrine deficits. Recently, a biokinetic model has been proposed to characterize the dose-response relationship and effects of chronic exposure. According to the model, health effects are unlikely to occur at blood Co concentrations under 300μg/l (100μg/l respecting a safety factor of 3) in healthy individuals, hematological and endocrine dysfunctions are the primary health endpoints, and chronic exposure to acceptable doses is not expected to pose considerable health hazards. However, toxic reactions at lower doses have been described in several cases of malfunctioning MoM hip implants, which may be explained by certain underlying pathologies that increase the individual susceptibility for Co-induced systemic toxicity. This may be associated with a decrease in Co bound to serum proteins and an increase in free ionic Co²⁺. As the latter is believed to be the primary toxic form, monitoring of the free fraction of Co²⁺ might be advisable for future risk assessment. Furthermore, future research should focus on longitudinal studies in the clinical setting of MoM hip implant patients to further elucidate the dose-response discrepancies.

Metal in Total Hip Arthroplasty: Wear Particles, Biology, and Diagnosis

Total hip arthroplasty (THA) has been performed for nearly 50 years. Between 2006 and 2012, more than 600,000 metal-on-metal THA procedures were performed in the United States. This article reviews the production of metal wear debris in a metal-on-metal articulation and the interaction of cobalt and chromium ions that ultimately led to a dramatic decline in the use of metal-on-metal THA articulations. Additionally, the article reviews mechanisms of metal wear, the biologic reaction to cobalt and chromium ions, the clinical presentation of failing metal-on-metal articulations, and current diagnostic strategies. Further, the article discusses the use of inflammatory markers, metal ion levels, radiographs, metal artifact reduction sequence magnetic resonance imaging, and ultrasound for failed metal-on-metal THA procedures. When adopting new technologies, orthopedic surgeons must weigh the potential increased benefits against the possibility of new mechanisms of failure. Metal-on-metal bearings are a prime example of the give and take between innovation and clinical results, especially in the setting of an already successful procedure such as THA. [Orthopedics. 2016; 39(6):371-379.].

Serologic and radiographic outcome of total hip arthroplasty with CoCr modular neck at mid-term follow-up

PURPOSE

The aim of this study is a radiographic evaluation and to determine serologic values of chromium and cobalt in the blood and urine of patients who have been implanted with a Stryker^® ABG II Modular Neck and see if there is correlation with the features of prosthesis and patients.

METHODS

The study involves the collection of data from patients operated on for total hip model with the ABG II Modular Neck with a minimum follow-up of 1 year.

RESULTS

We evaluated 22 patients who underwent implantation of a hip prosthesis with modular neck in CoCr. Of these, the average Cr in the blood was 0.63 μgL^-1 (range 0.1-2.15 μgL^-1), the average of Co in the blood was 3.50 μgL^-1 (range 0.62-7.78 μgL^-1), the average Cr in the urine was 1.24 μgL^-1 (range 0.48-2.21 μgL^-1), and the average Co in urine was 14.22 μgL^-1 (range 3.3-31.2 μgL^-1). None of these patients had undergone revision surgery.

CONCLUSIONS

Our study seems to indicate that the restoration of offset and age are correlated with the release of metal ions, although the correlation is weak and needs better methodological studies and a greater number of patients to confirm this hypothesis.

STUDY TYPE

Case series Level of Evidence 4.

Lessons learnt from metal-on-metal hip arthroplasties will lead to safer innovation for all medical devices

Metal-on-metal bearings were re-popularised in the late 1990s with the introduction of modern hip resurfacing. Large diameter (LD) metal-on-metal (MoM) hips became more prevalent and have been the least successful group of hip implants ever used. They were rapidly adopted from 2004 until the British Hip Society stopped their use in 2012. Well functioning MoM hip results (including the BHR and Metasul) are hidden in the mire of poor results from the group of all MoM bearings.We have reviewed what happened and we make 3 observations. Firstly, collaboration between surgeons and then between surgeons and other disciplines, first identified and then solved the clinical management problems. Secondly, the problems with MoM hips occurred because hip simulation was inadequate at predicting performance in patients. They gave no indications of the biological effects of wear in the human environment. Lastly, retrieval of failed implants was essential to understanding why failure occurred.These lessons must never be forgotten and must form the basis by which new or altered implants are introduced and how they should be monitored. This will enable safer innovation for patients, surgeons and manufacturers. The problems with MoM hips will not have been in vain.

The biological response to orthopaedic implants for joint replacement: Part I: Metals

Joint replacement is a commonly performed, highly successful orthopaedic procedure, for which surgeons have a large choice of different materials and implant designs. The materials used for joint replacement must be both biologically acceptable to minimize adverse local tissue reactions, and robust enough to support weight bearing during common activities of daily living. Modern joint replacements are made from metals and their alloys, polymers, ceramics, and composites. This review focuses on the biological response to the different biomaterials used for joint replacement. In general, modern materials for joint replacement are well tolerated by the body as long as they are in bulk (rather than in particulate or ionic) form, are mechanically stable and noninfected. If the latter conditions are not met, the prosthesis will be associated with an acute/chronic inflammatory reaction, peri-prosthetic osteolysis, loosening and failure. This article (Part 1 of 2) is dedicated to the use of metallic devices in orthopaedic surgery including the associated biological response to metallic byproducts is a review of the basic science literature regarding this topic. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2162-2173, 2017.

Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis

IMPORTANCE

There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA).

OBJECTIVE

To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA) compared to patients with non-metal-on-metal articulations (non-MOM THA) after primary total hip arthroplasty.

DATA SOURCES

Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied.

STUDY SELECTION

Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD) were calculated with random effect models. Meta-regression was used to explore modifying factors.

MAIN OUTCOMES AND MEASURES

Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA.

RESULTS

Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI) [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more), the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM) than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as moderate according to the CLEAR-NPT (for non-pharmacological trials) and Cochrane risk of bias Table.

CONCLUSIONS AND RELEVANCE

Meta-analysis suggests there may be an increased long-term risk of mortality and revision surgery for patients with MOM THA compared to patients with non-MOM THA.

REGISTRATION

PROSPERO 2014:CRD42014007417.

Cobalt deposition in mineralized bone tissue after metal-on-metal hip resurfacing: Quantitative μ-X-ray-fluorescence analysis of implant material incorporation in periprosthetic tissue

Most resurfacing systems are manufactured from cobalt-chromium alloys with metal-on-metal (MoM) bearing couples. Because the quantity of particulate metal and corrosion products which can be released into the periprosthetic milieu is greater in MoM bearings than in metal-on-polyethylene (MoP) bearings, it is hypothesized that the quantity and distribution of debris released by the MoM components induce a compositional change in the periprosthetic bone. To determine the validity of this claim, nondestructive µ-X-ray fluorescence analysis was carried out on undecalcified histological samples from 13 femoral heads which had undergone surface replacement. These samples were extracted from the patients after gradient time points due to required revision surgery. Samples from nonintervened femoral heads as well as from a MoP resurfaced implant served as controls. Light microscopy and µ-X-ray fluorescence analyses revealed that cobalt debris was found not only in the soft tissue around the prosthesis and the bone marrow, but also in the mineralized bone tissue. Mineralized bone exposed to surface replacements showed significant increases in cobalt concentrations in comparison with control specimens without an implant. A maximum cobalt concentration in mineralized hard tissue of up to 380 ppm was detected as early as 2 years after implantation. Values of this magnitude are not found in implants with a MoP surface bearing until a lifetime of more than 20 years. This study demonstrates that hip resurfacing implants with MoM bearings present a potential long-term health risk due to rapid cobalt ion accumulation in periprosthetic hard tissue. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1855-1862, 2017.

Systemic cobalt toxicity from total hip arthroplasties

Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging.

The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation.

The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity.

This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties.

Take home message: Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications.

Cite this article: Bone Joint J 2016;98-B:6–13.

Does chronic raise of metal ion levels induce oxidative DNA damage and hypoxia-like response in patients with metal-on-metal hip resurfacing?

Metal-on-metal hip resurfacing (MOM-HR) represents a viable alternative to traditional arthroplasty. Nevertheless, in MOM coupling both metal nanoparticles and ions are released, whose toxicity remains a matter of concern. We investigated whether 'endogenous' chronic exposure to cobalt and chromium induced a state of oxidative stress, DNA damage and a hypoxia-like response in patients with well-functioning MOM-HR. Twenty-two patients with unilateral MOM-HR were recruited at long-term. Twenty-one osteoarthritic subjects were enrolled for comparison. Serum ion levels were measured and correlated with 8-hydroxydeoxyguanosine and circulating-free-DNA, as markers of oxidative DNA damage. Moreover, the hypoxia-inducible factor-1α, marker of hypoxic state, was evaluated. Ion concentrations were found to be 5-to-15 times higher in MOM-HR patients than in presurgery subjects (p < 0.001); circulating-free-DNA, 8-hydroxydeoxyguanosine, and hypoxia-inducible factor-1α levels were not significantly different between groups and did not correlate with ion levels. Analyzing the results according to gender, MOM-HR males had higher 8-hydroxydeoxyguanosine levels (p = 0.01) compared with MOM-HR females. Similarly, circulating-free-DNA values were higher in males than females, even if this difference did not reach statistical significance. This research is the first that attempted to investigate the long-term effects of ion dissemination in subjects with well-fixed MOM implants. A significant correlation between biomarkers increase and ion levels was not demonstrated. Nevertheless, both circulating-free-DNA and 8-hydroxydeoxyguanosine showed a tendency to increase in MOM-HR males. Further studies with a larger sample size should be performed to detect the clinical relevance of biomarkers increase especially in younger subjects, where a chronic moderately elevated exposure has to be faced. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 460-466, 2017.

Pseudotumor formation and serum ions after large head metal-on-metal stemmed total hip replacement. Risk factors, time course and revisions in 706 hips

INTRODUCTION

The incidence and natural course of pseudotumors in metal-on-metal total hip arthroplasties is largely unknown. The objective of this study was to identify the true incidence and risk factors of pseudotumor formation in large head metal-on-metal total hip arthroplasties.

MATERIALS AND METHODS

Incidence, time course and risk factors for pseudotumor formation were analysed after large femoral head MoM-THA. We defined a pseudotumor as a (semi-)solid or cystic peri-prosthetic soft-tissue mass with a diameter ≥2 cm that could not be attributed to infection, malignancy, bursa or scar tissue. All patients treated in our clinic with MoM-THA's were contacted. CT scan, metal ions and X-rays were obtained. Symptoms were recorded.

RESULTS

After median follow-up of 3 years, 706 hips were screened in 626 patients. There were 228 pseudotumors (32.3 %) in 219 patients (35.0 %). Pseudotumor formation significantly increased after prolonged follow-up. Seventy-six hips (10.8 %) were revised in 73 patients (11.7 %), independent risk factors were identified. Best cutoff point for cobalt and chromium was 4 μg/l (68 and 77 nmol/l).

CONCLUSIONS

This study confirms a high incidence of pseudotumors, dramatically increasing after prolonged follow-up. Risk factors for pseudotumors are of limited importance. Pain was the strongest predictor for pseudotumor presence; cobalt chromium and swelling were considered poor predictors. Cross-sectional imaging is the main screening tool during follow-up.

Metal-on-metal hip surface replacement

Metal-on-metal resurfacing of the hip (MoMHR) has enjoyed a resurgence in the last decade, but is now again in question as a routine option for osteoarthritis of the hip. Proponents of hip resurfacing suggest that its survival is superior to that of conventional hip replacement (THR), and that hip resurfacing is less invasive, is easier to revise than THR, and provides superior functional outcomes. Our argument serves to illustrate that none of these proposed advantages have been realised and new and unanticipated serious complications, such as pseudotumors, have been associated with the procedure. As such, we feel that the routine use of MoMHR is not justified.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):17–21.

Anaplastic large cell lymphoma (ALCL) and breast implants: breaking down the evidence

Systemic anaplastic large cell lymphoma (ALCL) is a distinct disease classification provisionally sub-divided into ALCL, Anaplastic Lymphoma Kinase (ALK)(+) and ALCL, ALK(-) entities. More recently, another category of ALCL has been increasingly reported in the literature and is associated with the presence of breast implants. A comprehensive review of the 71 reported cases of breast implant associated ALCL (iALCL) is presented indicating the apparent risk factors and main characteristics of this rare cancer. The average patient is 50 years of age and most cases present in the capsule surrounding the implant as part of the periprosthetic fluid or the capsule itself on average at 10 years post-surgery suggesting that iALCL is a late complication. The absolute risk is low ranging from 1:500,000 to 1:3,000,000 patients with breast implants per year. The majority of cases are ALK-negative, yet are associated with silicone-coated implants suggestive of the mechanism of tumorigenesis which is discussed in relation to chronic inflammation, immunogenicity of the implants and sub-clinical infection. In particular, capsulotomy alone seems to be sufficient for the treatment of many cases suggesting the implants provide the biological stimulus whereas others require further treatment including chemo- and radiotherapy although reported cases remain too low to recommend a therapeutic approach. However, CD30-based therapeutics might be a future option.

The imaging prevalence of osteolytic metastasis or multiple myeloma presenting as a periprosthetic lucency in the hip

OBJECTIVE

The purpose of this article is to determine how often a malignant process presents as a lucency near a hip prosthesis, and to classify the frequency and distribution of differential diagnoses of these lytic lesions, and to determine their disposition.

MATERIALS AND METHODS

Hip and pelvis imaging examinations obtained from January 1998 to June 2008 were text searched (1,164,560 reports) to identify patients with hip prostheses (3508 patients); the records were then searched and individually reviewed to identify periprosthetic lucency (2036 reports; 176 patients). The most likely cause for the lucency, as determined by the interpreting radiologist, was recorded. Malignancy was confirmed in all cases. Malignancy was excluded by biopsy for some patients but by clinical follow-up or at the time of revision, if performed, for most patients. Prevalence rates and 95% CIs were calculated.

RESULTS

The overall prevalence of periprosthetic lucency was 5.02%. The prospective diagnoses suggested included loosening or infection (37.5%), degenerative cysts (19.3%), metastases (23.3%), multiple myeloma (14.8%), and metastasis of previously unknown malignancy (3.4%). The prevalence of metastases or multiple myeloma near a hip prosthesis was 1.54%; however, each of these patients had a known prior diagnosis of bone metastases, multiple myeloma, or primary bone malignancy.

CONCLUSION

Among the 2036 examinations with periprosthetic lucency, there were no instances of new malignancy, metastasis, or myeloma. These results suggest that it is statistically unlikely that a lucency near a hip prosthesis represents the first presentation of malignancy or metastases, regardless of how large or aggressive it may appear on imaging.

Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland

BACKGROUND AND PURPOSE

Metal-on-metal hip implants have been widely used, especially in the USA, Australia, England and Wales, and Finland. We assessed risk of death and updated data on the risk of cancer related to metal-on-metal hip replacements.

PATIENTS AND METHODS

A cohort of 10,728 metal-on-metal hip replacement patients and a reference cohort of 18,235 conventional total hip replacement patients were extracted from the Finnish Arthroplasty Register for the years 2001-2010. Data on incident cancer cases and causes of death until 2011 were obtained from the Finnish Cancer Registry and Statistics Finland. The relative risk of cancer and death were expressed as standardized incidence ratio (SIR) and standardized mortality ratio (SMR). SIR/SIR ratios and SMR/SMR ratios, and Poisson regression were used to compare the cancer risk and the risk of death between cohorts.

RESULTS

The overall risk of cancer in the metal-on-metal cohort was not higher than that in the non-metal-on-metal cohort (RR = 0.91, 95% CI: 0.82-1.02). The risk of soft-tissue sarcoma and basalioma in the metal-on-metal cohort was higher than in the non-metal-on-metal cohort (SIR/SIR ratio = 2.6, CI: 1.02-6.4 for soft-tissue sarcoma; SIR/SIR ratio = 1.3, CI: 1.1-1.5 for basalioma). The overall risk of death in the metal-on-metal cohort was less than that in the non-metal-on-metal cohort (RR = 0.78, CI: 0.69-0.88).

INTERPRETATION

The overall risk of cancer or risk of death because of cancer is not increased after metal-on-metal hip replacement. The well-patient effect and selection bias contribute substantially to the findings concerning mortality. Arthrocobaltism does not increase mortality in patients with metal-on-metal hip implants in the short term. However, metal-on-metal hip implants should not be considered safe until data with longer follow-up time are available.

Alternative bearing surfaces in total hip arthroplasty

Total hip arthroplasty continues to be one of the most effective surgical procedures currently available. The longevity of this otherwise very successful procedure is compromised by the wear of the bearing surface. In recent years, great advances have been made in the design of bearing surfaces that poise to offer extended performance to these artificial joints. The purpose of this review is to discuss the recent technologic advances in bearing surfaces and offer an insight to the potential benefits and concerns with the alternative bearing surfaces.

Is second generation metal-on-metal primary total hip arthroplasty with a 28 mm head a worthy option?: a 12- to 18-year follow-up study

To determine whether MoM THA with a small head is still worthy of use, we investigated survivorship, complications, and factors influencing failure. Of 149 consecutive patients (195 hips), 141 (180 hips) of mean age 43 (19-55) years were available for review at a mean of 14.4 years postoperatively. Survivorship for cup revision for any cause was 97.8% at 18.4 years postoperatively. Nine hips generated complaints of groin pain; six showed periacetabular osteolysis, one had pain without radiological change, and two were diagnosed as symptomatic pseudotumors. Four of six hips with periacetabular osteolysis or aseptic loosening were revised. Surgery- and patient-related factors had no effect in results. Our results are encouraging, however, further study will be necessary to determine the incidence and fates of pseudotumors after MoM THA with a small head.

The Effect Of Different Bearing Surfaces On Metal Ion Levels In Urine Following 28 Mm Metal-On-Metal And 28 Mm Metal-On-Polyethylene Total Hip Arthroplasty

Background and Aims:

Recent advancements in manufacturing technology have enabled more precise tolerances and surface finishes using metal-on-metal bearing surfaces in total hip arthroplasty. The aim of this study was to compare the level of metal ions in urine after implantation of a 28-mm metal-on-metal bearing manufactured from high-carbon wrought alloy and a 28-mm metal-on-polyethylene bearing.

Material and Methods:

A total of 92 total hip arthroplasty patients were prospectively randomized into two groups: those receiving metal-on-metal bearings and those receiving metal-on-polyethylene bearings. Chromium, cobalt, and molybdenum ion levels in urine were measured preoperatively and at 1 year and 2 years postoperatively.

Results:

In the metal-on-polyethylene group, there was a slight increase in mean chromium and cobalt concentrations at 2-year follow-up compared to the preoperative level (p = 0.02 for both chromium and cobalt). In the metal-on-metal group, there was a 15-fold increase in chromium and a 26-fold increase in cobalt at 2-year follow-up compared to the preoperative level (p < 0.001 for both chromium and cobalt). However, the quantity of chromium and cobalt in urine from the metal-on-metal group was not higher at 2-year follow-up than at 1-year follow-up (p = 0.5 and p = 0.6, respectively).

Conclusions:

The 28-mm metal-on-metal bearings yield chromium and cobalt concentrations in urine that can be higher than those recommended for occupational exposure. However, our results also indicate that a steady state in wear and ion production using metal-on-metal total hip arthroplasty can occur.

Poor short term outcome with a metal-on-metal total hip arthroplasty

Metal-on-metal (MoM) bearings for total hip arthroplasty (THA) have come under scrutiny with reports of high failure rates. Clinical outcome studies with several commercially available MoM THA bearings remain unreported. We evaluated 78 consecutive MoM THAs from a single manufacturer in 68 patients. Sixty-six received cobalt-chrome (CoCr) monoblock and 12 received modular titanium acetabular cups with internal CoCr liners. Femoral components were titanium with modular necks. At average 2.1 years postoperatively, 12 THAs (15.4%) demonstrated aseptic failure (10 revisions, 2 revision recommended). All revised hips demonstrated capsular necrosis with positive histology reaction for aseptic lymphocytic vasculitis-associated lesions/adverse local tissue reactions. Prosthetic instability following revision surgery was relatively common. Female gender was a strong risk factor for failure, though smaller cups were not. Both monoblock and modular components fared poorly. Corrosion was frequently observed around the proximal and distal end of the modular femoral necks.

Fracture of ceramic bearing surfaces following total hip replacement: a systematic review

Ceramic bearing surfaces are increasingly used for total hip replacement, notwithstanding that concern is still related to ceramic brittleness and its possible mechanical failure. The aim of this systematic review is to answer three questions: (1) Are there risk factors for ceramic component fracture following total hip replacement? (2) Is it possible to perform an early diagnosis of ceramic component failure before catastrophic fracture occurs? (3) Is it possible to draw guidelines for revision surgery after ceramic components failure? A PubMed and Google Scholar search was performed and reference citations from publications identified in the literature search were reviewed. The use of 28 mm short-neck femoral head carries an increased risk of fracture. Acetabular component malposition might increase the risk of ceramic liner fractures. Synovial fluid microanalysis and CT scan are promising in early diagnosis of ceramic head and liner failure. Early revision is suggested in case of component failure; no consensus exists about the better coupling for revision surgery. Ceramic brittleness remains a major concern. Due to the increased number of ceramic on ceramic implants, more revision surgeries and reports on ceramic components failure are expected in the future. An algorithm of diagnosis and treatment for ceramic hip failure is proposed.

Cumulative revision rate is higher in metal-on-metal THA than metal-on-polyethylene THA: analysis of survival in a community registry

BACKGROUND

Metal-on-metal (MOM) THA bearing technology has focused on improving the arc of motion and stability and minimizing wear compared with traditional metal-on-polyethylene (MOP) bearing couples. It is unclear whether this more costly technology adds value in terms of improved implant survival.

QUESTIONS/PURPOSES

This study evaluated Kaplan-Meier survival, revisions for dislocation, and cost of MOM THA compared with metal-on-cross-linked polyethylene (MOXP) THA in a community joint registry, with subset analysis of the recalled Depuy ASR™ implant.

METHODS

All MOM THAs (resurfacings excluded) performed between January 2002 and December 2009 were included (n = 1118) and compared with a control group of MOXP THAs (n = 1286) done during the same time. Analysis was performed to compare age, gender, cost of implant, length of stay, year of index procedure, diagnosis, head size (< 32 mm versus ≥ 32 mm), revision and revision reason for both groups. Analysis at a mean of 3.6 years was done using Wilcoxon rank sum tests, Pearson's chi-square tests, Kaplan Meier methods, and Cox regression.

RESULTS

The cumulative revision rate (CRR) was higher in MOM implants than in MOXP implants (MOM CRR = 13%; MOXP CRR = 3%). MOM implants were three times as likely to be revised as MOXP implants after adjustment for age, head size, and year of procedure. The recalled DePuy ASR™ implant was six times as likely to be revised as other MOM THAs. After removing the ASR™ implants from analysis, survivorship of MOM implants was not better than that of the MOXP hips.

CONCLUSIONS

During the study time, MOM THAs showed inferior survival to MOXP THAs after adjusting for age, head size, and year of procedure. Longer followup is necessary to see whether MOM THAs add value in younger patient groups.

The effect of femoral head size on functional outcome in primary total hip arthroplasty: a single-blinded randomised controlled trial

We conducted a prospective single-blinded randomised controlled trial to compare the functional and quality of life outcomes in two groups of patients between 60 and 80 years of age undergoing THR; the first receiving a small head (28-32 mm) metal on polyethylene (MoP) articulation, and the second receiving a large head (44-54 mm) metal on metal (MoM) articulation. We recruited 49 patients and randomised them into one of the two groups (22 MoP and 27 MoM). The results demonstrated no statistical difference in any of the assessed functional outcomes at any follow-up point (p>0.05). There were no dislocations or revisions in either group. Although it has been suggested that large head MoM articulations in THA offer superior stability and function, our results suggest that small head MoP articulations can achieve comparable ROM, function and quality of life at short-term follow-up.