Purpose of Study:. To look at the difference in metal ion levels using Ceramic on Metal (COM) and Metal on Metal (MOM) bearings in Total Hip Replacements, comparing the results between well placed and poorly placed cups. Methods:. Metal ion levels using the ICP-MS method of assay have been studied as part of a prospective randomised trial between 4 different bearing combinations. The ion levels have been raised in the COM and MOM bearings. Metal ions are not raised in the Ceramic on Ceramic (COC) and Ceramic on X linked Poly(COP) bearings, showing that no other material in the study prosthesis aside from the bearing surfaces contribute to raised ion levels. Cup inclination and cup anteversion has been measured in all patients. Results:. At 3 year follow-up the Cobalt and Chrome levels are significantly lower with the COM bearing than the MOM bearing when both well and poorly placed cups are included, and seem to be returning to normal pre-operative levels. Taking cups put in in Lewinnik's safe zones, then the Chrome levels are similar between the two bearings, but the Cobalt levels remain raised in the MOM bearing. Conclusion:. Cobalt and Chrome levels are significantly lower in COM bearings than MOM bearings when cups are not placed in the ideal position. This represents an added advantage in the use of COM bearings as compared to MOM bearings

Metal on Metal coupling in total hip replacement has been widely used since many years. After the rebirth of resurfacing a new trend to use very large diameter metal-metal coupling with standard stem prostheses has been started. New prostheses, old and new problems. We analyze first failures with new large diameter metal on metal coupling. The analysis focused on seven early failures of large diameter metal-metal prostheses (two resurfacing and five cementless prosthesis with XL head) over the first series of 350 cases (100 resurfacing and 250 cementless) in the first year. Synovial fluid aspiration have been performed in all failed patients searching for metal ions and bacterial proliferation. Moreover, prosthetic component positioning was also studied as a possible primum movens of these failures. Some failed patients underwent epicutaneous patch test for skin reaction to metal. One resurface prosthesis failed as a result of an vascular necrosis and conseguent fracture of the femoral neck and revealed a moderate increment in metal ion concentration in blood and synovial fluid obtained at time of revision. One resurface prosthesis failed as a result of an infected metallosis with a huge intraabdominal mass and revealed a huge increment in metal ion concentration in blood, addominal and synovial fluid. This patient underwent a lumbotomy to evacuate the abdominal retroperitoenal mass before prosthesis removal for a two step procedure. Out of the five failures of metal on metal cementless prosthesis with XL head four were the result of aseptic loosening and one was the result of a low grade infection discovered at coltures after revision surgery. Three showed clear metallosis caused by wrong positioning (more than 50° of cup inclination). All of these three presented an articular noise and elevated blood and sinovial fluid metal ion concentration. The fourth patient with aseptic loosening had a good component positioning but demonstrated an epicutanous allergic reaction to Cobalt. Also one of the three patients with metallosis resulted allergic to Cobalt. The blood and sinovial metal ion values were always elevated but particularly high in patients with cup inclination over 50°. Large head metal on metal prostheses demonstrated a higher percentage of early failure in our experience. They are very sensible to positioning. Blood and sinovial metal ion determination helps to promptly diagnose a bad metal on metal prosthetic functioning. A more accurate analysis about the different metals available on the market and their resistance to edge wear should not be delayed any further

Cemented total hip arthroplasty yields reliable results in short to medium term studies, but aseptic loosening remains a problem in long-term follow up, especially in young and active patients. Aseptic loosening has been related to wear, and in order to minimize wear various alternatives to the traditional metal on polyethylene have been proposed. Both ceramic on polyethylene (COP) and metal on metal (MOM) have been shown to produce less wear than metal on polyethylene (MOP). In order to study the effect of the bearing, we have utilized identical stems and cups while comparing the different bearings. Methods and material. 396 hips were randomized to MOP, COP or MOM using a cemented triple tapered polished stem (MS-30; Sulzer Orthopedics) with a cemented polyethylene cup (Weber; Sulzer, Orthopedics) and a 28 millimeter head. For the MOP and COP articulations, a all-polyethylene cup was used with a Protasul™ metal head or a Sulox™ alumina head, whereas a polyethylene cup with metal insert was used for the MOM articulations (Weber Polyethylene Cup with Metasul™ Insert) with a Metasul™ metal head. Harris Hip Score (HHS) and radiological evaluation was performed after two, five and seven years. Ethical approval was obtained. Results. HHS was available for 338 hips after seven years. The HHS in the MOP group (116 hips) was 93.7 (SD 9.0), 93.5 in the COP group (112 hips) (SD 8.8), and 91.0 (SD 13.4) in the MOM group (110 hips). Radiographic evaluation was available for 335 hips. Radiolucencies around the stem larger than one millimeter were found in five of 115 MOP hips, seven of 111 COP hips and in seven of 110 MOM hips. Periacetabular radiolucencies identified as larger than one millimeter were found in none of the 116 MOP hips, five of the 112 COP hips and in 19 of the 110 MOM hips. Ten revisions were performed. In the MOP group there were three revisions (infection, dislocation, pain); one in the COM group (infection), and six in the MOM group (three infections, two aseptic loosening and one septic loosening). Discussion. Clinically, the three bearing types perform equally well at seven years, and there are few signs of impending failure for the stem. However, there are an alarmingly high proportion of cups showing signs of loosening. Two hips have been revised in the MOM group for aseptic loosening as opposed to none in the two other groups, which adds to the concern. The MOM articulation used in this study should be monitored closely for signs of aseptic loosening

Introduction. It is well-known that wear debris generated by metal-on-metal hip replacements leads to aseptic loosening. This process starts in the local tissue where an inflammatory reaction is induced, followed by an periprosthetic osteolysis. MOM bearings generate particles as well as ions. The influence of both in human bodies is still the subject of debate. For instance hypersensitivity and high blood metal ion levels are under discussion for systemic reactions or pseudotumors around the hip replacement as a local reaction. The exact biopathologic mechanism is still unknown. The aim of this study was to investigate the impact of local injected metal ions and metal particles. Material and Methods. We used an established murine inflammation model with Balb/c mice and generated three groups. Group PBS (control group, n=10) got an injection of 50µl 0.1 vol% PBS-suspension, Group MI (Metal-ion, n=10) got an injection of 50µl metal ion suspension at a concentration of 200µg/l and Group MP (Metal-particles, n=10) got an injection of 50µl 0.1 vol% metal particle suspension each in the left knee. After incubation for 7 days the mice were euthanized and the extraction of the left knee ensued. Followed by immunhistochemical treatment with markers of inflammation that implied TNFα, IL-6, IL-1β, CD 45, CD 68, CD 3, we counted the positive cells in the synovial layer in the left knees by light microscopy, subdivided into visual fields 200× magnified. The statistical analysis was done with Kruskal-Wallis test and a post hoc Bonferroni correction. Results. The Group with metal particles showed significantly elevated inflammatory markers (TNFα, IL-6, IL-1β, CD 68, CD 45) compared to all other groups. Interestingly, CD 3 as a marker for T-lymphocytes showed no increased levels in all groups. The metal ion group showed significant elevated CD 45 expressions compared to the control group. Conclusion. The results clearly demonstrate that especially metal wear particles lead to an intensive inflammatory reaction. The tissue formations in the metal particle group show an osseous destructive behavior in previously demonstrated results, comparable to pseudotumors. But, in this study, the expression of the immunohistological markers CD 3, CD 45 and CD 68 indicate that the tissue consists of leucocytes and macrophages, whereas lymphocytes could not be detected. This might be due to an acute inflammatory reaction, whereas the adaptive immune response by T-lymphocytes seems not (yet) to be activated. Overall it must be stated that solid metal wear particles are responsible for local inflammatory reactions, whereas it is still unknown whether wear particles corrode in vivo and release a potentially high level of locally toxic metal ions

Introduction and Aims: Polyethylene wear continues to be the most significant issue following total hip arthroplasty (THA), leading to the current increase in use of alternative bearing surfaces. We performed a prospective, randomised, blinded clinical trial comparing metal versus polyethylene bearing surfaces in patients receiving THA. Method: Forty-one patients were randomised to receive a metal (23) or a polyethylene (18) insert with identical femoral and acetabular components. Patients were evaluated pre-operatively at three, six, 12 months and annually thereafter, including an evaluation of erythrocyte and 24-hour urine cobalt, chromium and titanium metal ion levels, validated outcome measures (WOMAC, SF-12, Harris Hip Score) and radiographs. Results: No patients were lost to follow-up. One patient died of unrelated causes. At an average 4.4 (range 3.3–5.1) years follow-up there were no differences in any outcome measures or radiographic findings. Patients receiving metal liners had significantly elevated metal ion measurements. At the latest follow-up erythrocyte cobalt levels were seven times elevated (median 1.2μg/l (metal) Vs 0.18μg/l (poly), p< .001). Urine cobalt levels were 41 times elevated (median 11.9μg/day (metal) Vs 0.29μg/day (poly), p< .001) and urine chromium levels were 14 times elevated (median 4.9μg/day (metal) Vs 0.36μg/day (poly), p< .001). Erthrocyte chromium, titanium and urine titanium were not significantly different between groups. As well, contrary to previous reports, there was not a significant trend towards decreasing ion levels over time. Conclusion: In this prospective randomised blinded clinical trail comparing metal to polyethyle bearing surfaces, both cobalt and chromium ion levels were significantly elevated in the blood and urine of the patients randomised to receive the metal on metal THA

Introduction: Local problems of metal on metal (MOM) hip arthroplasty such as pseudotumours, neck thinning and osteolysis maybe related to concentrations of cobalt and chromium ions in the synovial fluid. There is little reported on these values. Our aim was to determine the range of metal ion levels in synovial fluid, and to investigate the relationship between these samples and simultaneous blood samples. Methods: Synovial fluid and whole blood samples were taken from 30 consecutive patients at the time of revision surgery for a painful MOM hip. Aspirated fluid was not visibly contaminated with blood. Impants were in situ for a mean period of 31 months. All had normal renal function. Samples were analysed using ICP mass spectrometry and compared with 10 samples from patients without implants. Results: The mean (and range) of synovial fluid metal ion levels were 1965 ug/l (30 to 13618) and 6265 ug/l (11 to 81630) for Cobalt and Chromium respectively. There was a good correlation between synovial and blood levels for both cobalt (R=0.65, p = 0.0001) and chromium (R = 0.59, p = 0.006). Discussion and Conclusion: Metal ions in synovial fluid from MOM hips are generated from wear of the bearing surfaces, the correlation with blood metal ion levels, shown in this study, suggest that blood levels may be used as surrogate marker for hip wear rate. Our range of synovial fluid metal ion levels may be useful for those conducting in vitro studies on the biocompatibility of MOM hips

Objectives. Alarm over the reported high failure rates for metal-on-metal (MoM) hip implants as well as their potential for locally aggressive Adverse Reactions to Metal Debris (ARMDs) has prompted government agencies, internationally, to recommend the monitoring of patients with MoM hip implants. Some have advised that a blood ion level >7 µg/L indicates potential for ARMDs. We report a systematic review and meta-analysis of the performance of metal ion testing for ARMDs. Methods. We searched MEDLINE and EMBASE to identify articles from which it was possible to reconstruct a 2 × 2 table. Two readers independently reviewed all articles and extracted data using explicit criteria. We computed a summary receiver operating curve using a Bayesian random-effects hierarchical model. Results. Our literature search returned 575 unique articles; only six met inclusion criteria defined a priori. The discriminative capacity of ion tests was homogeneous across studies but that there was substantial cut-point heterogeneity. Our best estimate of the “true” area under curve (AUC) for metal ion testing is 0.615, with a 95% credible interval of 0.480 to 0.735, thus we can state that the probability that metal ion testing is actually clinically useful with an AUC ≥ 0.75 is 1.7%. Conclusion. Metal ion levels are not useful as a screening test for identifying high risk patients because ion testing will either lead to a large burden of false positive patients, or otherwise marginally modify the pre-test probability. With the availability of more accurate non-invasive tests, we did not find any evidence for using blood ion levels to diagnose symptomatic patients. Cite this article: M. Pahuta, J. M. Smolders, J. L. van Susante, J. Peck, P. R. Kim, P. E. Beaule. Blood metal ion levels are not a useful test for adverse reactions to metal debris: a systematic review and meta-analysis. Bone Joint Res 2016;5:379–386. DOI: 10.1302/2046-3758.59.BJR-2016-0027.R1

Aims. Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA). Methods. Studies were identified by searching electronic databases: Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Embase, from their inception to November 2020, for studies evaluating TKA patients with metal hypersensitivity/allergy. All studies reporting on diagnosing or managing metal hypersensitivity in TKA were included. Data were extracted and summarized based on study design, study population, interventions and outcomes. A practical guide is then formulated based on the available evidence. Results. We included 38 heterogeneous studies (two randomized controlled trials, six comparative studies, 19 case series, and 11 case reports). The evidence indicates that metal hypersensitivity is a rare complication with some histopathological features leading to pain and dissatisfaction with no reliable screening tests preoperatively. Hypoallergenic implants are viable alternatives for patients with self-reported/confirmed metal hypersensitivity if declared preoperatively; however, concerns remain over their long-term outcomes with ceramic implants outperforming titanium nitride-coated implants and informed consent is paramount. For patients presenting with painful TKA, metal hypersensitivity is a diagnosis of exclusion where patch skin testing, lymphocyte transformation test, and synovial biopsies are useful adjuncts before revision surgery is undertaken to hypoallergenic implants with shared decision-making and informed consent. Conclusion. Using the limited available evidence in the literature, we provide a practical approach to metal hypersensitivity in TKA patients. Future national/registry-based studies are needed to identify the scale of metal hypersensitivity, agreed diagnostic criteria, and management strategies. Cite this article: Bone Jt Open 2021;2(10):785–795

During the past fifty years metal hip implants have been used in orthopaedics. While these implants are considered biologically inert, several studies indicated that prosthetic implants could release metal ions following wear. The aim of this study was to evaluate serum and urine concentrations of metal ions in patients treated with hybrid surface replacement of the hip. Co, Cr, Mn, Mo, and Ni in the serum and urine of 14 patients and 19 controls were quantified by Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). A Spectrometer ELEMENT (Finnigan MAT, Bremen, Germany) was used at the following resolution: 98Mo, 100Mo, (m/D;m = 300); 52Cr, 53Cr, 55Mn, 59Co, 60Ni, (m/D;m = 3000). The internal standard method (In) was applied to correct the random fluctuations of the signal. Indium was added to the sample solutions so as to reach a final concentration of 1 ng mL-1. Limits of Detection were calculated on the basis of the 3=555; criterion for 10 replicate measurements of solutions containing dilute pooled blood serum and dilute pooled urine, and recovery was obtained by quantifying the analytes of interest in spiked serum and urine. Recoveries of the elements ranged between 94.6% (serum Cr) and 118% (urine Ni). Data support the assumption that the concentrations of Co and Cr (the major components of the alloy) are substantially higher in serum and urine of patients than in those of controls while for the other elements no specific trend could be observed. Actually there isn’t any explanation on the possible biological consequences related to the increase of the metal ions levels although many hypothesis have been made. Further studies are thus mandatory to clarify this pattern

Introduction: Several studies have shown the presence of cobalt (Co) and chromium (Cr) ions in blood, urine, and organs of patients after THA using Co-Cr alloy-based implants. Even though it is well known that exposure to heavy metals may lead to significant alterations in human sperm morphology and motility, less is known on the effect of Co and Cr on semen parameters after metal on metal (MOM) hip replacement. Methods: Semen was collected form 10 patients between 41 and 49 years old (mean=45.9±3.0 years) by masturbation after 2–3 days of abstinence. The time of implantation varied from 1 to 9 years (mean=5.1±3.9 years). Samples were collected in a sterile container and examined within 1h after ejaculation for morphology, motility, and number of sperm cells following standard criteria. All patients were doing well at their follow-up visits (Harris Hip Score=94±4; UCLA activity a score=7±1) and no sign of osteolysis was observed on X-rays. Co and Cr concentrations were measured in both the seminal plasma and in the blood of patients by inductively coupled plasma-mass spectroscopy (ICP-MS). Results: results showed that the levels of Co in the seminal plasma and the blood of the patients were not statistically different. However, the level of Cr was significantly lower in the seminal plasma than in the blood of the patients. The ejaculate volume (2.1 ±0.6 ml), the sperm density (66±53 x 106), the total sperm count (151±75 x 106/ml), the pH (8), and the percentage of normal morphology (46±18%) were in the range of the WHO criteria for fertile population and also in the range of reference patients in the city of measurements. However, the viability was lower than that observed in a fertile population without prosthesis (41±19%). Conclusions: results of the present study strongly suggest that both Co and Cr ions crossover to the semen but that their concentrations were too low to significantly affect sperm parameters of young patients with MM prosthesis. Further longitudinal studies are however necessary to conclusively determine the effect of metal ions from MM prosthesis on sperm parameters

Aims: Measure serum chromium (SrCr) and cobalt (SrCo) and urine chromium (UCr) levels in patients with metal on metal surface arthroplasty of the hip. Methods: Ion levels were measured prospectively in 22 patients implanted with the Conserve Plusª (Wright Medical, TN) CoCr hip resurfacing. There were 15 males and 7 females with an average age of 49 years (range 28 Ð 62 yr). Serum and urine samples were collected using strict anti-contamination techniques pre-operatively and at 3, 6 and 12 months using graphite furnace atomic absorption spectrophotometry. Results: All postoperative metal levels were increased compared to their pre-operative levels. SrCr and SrCo values are at their highest at 3 months post operative and then begin to decrease. UrCr although elevated at 3 and 6 months postoperatively compared to the preop values, the levels continued to increase after the 6-month interval. These values are approximately 4-fold, 7-fold and 3-fold higher in SrCr, UrCr and SrCo, respectively, compared to the values seen in a group of patients with well functioning conventional metal (CoCr) on polyethylene total hips at 84 months postoperative measured by our group. Conclusions: The present levels are 2-fold lower in both SrCr and UrCr and 3-fold lower in SrCo than a group of patients with older generation surface arthroplasties reported previously by our group, suggesting improved manufacturing techniques and material properties have resulted in reduced component wear and generation of wear particles. 12 and 24 month data are currently being collected and analyzed

Introduction:. The clinical significance of serum metal ion levels alone in patients with stemmed MoM hip arthroplasty remains uncertain. This study aims to measure the metal ion levels in patients with unilateral and bilateral hip arthroplasty to see whether or not the patients with bilateral hips have higher metal ions. Patients and Methods. All the patients with bilateral MoM hip arthroplasty were identified from the research database. These patients were then matched with those in a similar age group who had a unilateral hip arthroplasty, but same University of California Los Angeles (UCLA) activity score. The UCLA activity scores along with other hip scores have been previously gathered for all the patients. Both sets of patients then had measurement of serum cobalt and chromium levels. The results were analyzed and compared. Results:. There were a total of 53 patients with bilateral hips and 53 matched patients with unilateral hips. The average serum Cobalt and Chromium levels were 34 nmol/L (range <10–76) and 23 nmol/L (range <10–104) respectively in the bilateral group; and 14 nmol/L (range <10–45) and 21 nmol/L (range <10–57) in the unilateral group. Given that the MHRA (UK) threshold levels deemed clinically significant are 120 nmol/L and 135 nmol/L for Cobalt and Chromium respectively; the results obtained here are not clinically significant. Conclusions:. One would normally expect, with mathematical reasoning, a patient with bilateral hip arthroplasty to have higher serum metal ion levels than a patient with unilateral arthroplasty. However, this study goes to show that it is not the case

Introduction. Cemented stems have shown 90–100% survivorship when coupled with polyethylene acetabular component. This study aims to compare cemented stem behaviour in combination with large metal on metal (MOM) vs. metal on poly (MOP) bearings. Patients and Methods. 100 patients were recruited into a single centre RCT (we required 40 in each group for power .90 to confirm stem subsidence of >0.5mm at 2 years; p< 0.05). Recruits were randomized to MOP (28mm) or MOM femoral heads with CPCS cemented femoral stem. Assessments included X-rays (AP pelvis), Harris Hip Scores, blood metal ion levels and patient questionnaires (WOMAC, SF-36, satisfaction questionnaire). Evaluations were done pre-operatively and 3, 12 and 24 months post operatively; blood metal ion measures at 1 year. Results. There were 50 patients in each arm of study matched for age (64 ± 8.5) and BMI (29.04 ±5.5). There was no difference in femoral stem subsidence at 2 years 1.34 (±1.3) and 1.4 (±1.2) mm for MOM and MOP respectively (p=0.88). There was significant improvement in HHS from pre-op to 3 months: 41 to 87 for MOM and 44 to 86 for MOP (p=0.00). This was maintained with no difference between groups at 2 years (p=0.74). Similar pattern was seen for WOMAC and SF-36 scores for both groups at 2 years (p>0.05). Increased blood Cobalt and Chromium levels were observed in 17% and 0% for MOM and MOP group. MOM group reported better patient satisfaction for overall (91% vs. 79%), pain relief (82% vs 66%) and improvement in ADL activities (94% vs.70%) at 2 years. Conclusions. There were no significant differences between groups for stem behavior, clinical and patient reported outcomes. Despite higher patient satisfaction reported by MOM patients, increased metal ion levels had raised concerns regarding the use of MOM bearings with cemented stems for primary THR

Introduction: The advantages of metal on metal bearings (MoM) include improved wear characteristics and lower dislocation rate. Metal sensitivity and Aseptic Lymphocyte Dominated Vasculitis Associated Lesion (ALVAL) reaction are becoming increasingly recognised. The BOA has recently issued a statement regarding MoM bearings. They suggested that any revisions for symptoms of pain and soft tissue reaction should be reported to the MHRA and histological specimens forwarded to the Stanmore Retrieval Centre. Methods and results: We report four patients (all females), who presented with late dislocation of a large diameter MoM bearing (three following total hip replacements and one following resurfacing). They all made good initial recovery with complete relief of pain. They developed pain around groin between one and two years following the surgery. Inflammatory markers were normal. MRI/Ultrasound scanning showed the presence of cystic lesions around the hip. They all presented with relatively late dislocation (26 months to six years). At exploration there was a large joint effusion with necrosis and detachment of the abductors. A characteristic finding was an avascular bare trochanter stripped free of any soft tissues. Histology showed a predominantly histiocytic response in keeping with the findings of Willert and Pandit. Discussion: In the absence of any obvious causes for dislocation, one should have a high index of suspicion for the possibility of metal hypersensitivity causing joint effusion, muscle necrosis and thereby leading to instability due to the progressive periosteal and soft tissue erosion. These patients should be considered for early revision of the bearing surface to prevent further damage to the muscle and bone. If the abductors are completely detached a more constrained type of bearing should be used to improve the stability. To the best of our knowledge this is the first report of this unusual complication following MoM bearings

Despite advancements, revision rates following total ankle replacement (TAR) are high in comparison to other total joint replacements. This explant analysis study aimed to investigate whether there was appreciable metal particulate debris release from various contemporary TARs by describing patterns of material loss. Twenty-eight explanted TARs (9 designs: 3 fixed and 6 mobile bearing), revised for any reason, were studied. The articulating surfaces of the metal tibial and talar components as well as the polyethylene insert were assessed for damage features using light microscopy. Based on the results of the microscopic analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy was performed to determine the composition of embedded debris identified, as well as non-contacting 3D profilometry. Pitting, indicative of material loss, was identified on the articulating surfaces of 54% of tibial components and 96% of talar components. Bearing constraint was not found to be a factor, with similar proportions of fixed and mobile bearing metal components showing pitting. More cobalt-chromium than titanium alloy tibial components exhibited pitting (63% versus 20%). Significantly higher average surface roughness (Sa) values were measured for pitted areas in comparison to unpitted areas of these metal components (p<0.05). Additionally, metallic embedded debris (cobalt-chromium likely due to pitting of the tibial and talar components or titanium likely from loss of their porous coatings) was identified in 18% of polyethylene inserts. The presence of hard 3. rd. body particles was also indicated by macroscopically visible sliding plane scratching, identified on 79% of talar components. This explant analysis study demonstrates that metal debris is released from the articulating surfaces and the coatings of various contemporary TARs, both fixed and mobile bearing. These findings suggest that metal debris release in TARs may be an under-recognised issue that should be considered in the study of painful or failed TAR moving forwards

Summary. The M2a-38. tm. metal on metal total hip arthroplasty showed a high incidence of pseudotumors and an unexpected high revision rate in our thoroughly screened cross sectional cohort. Introduction. After the revival of the metal on metal (MoM) bearing in total hip arthroplasty (THA) at the beginning of this century, there are now serious questions about this type of bearing. The advantage of large head MoM bearing is the increase in range of motion and stability. In our institution the choice was made for 38 mm heads. During the last few years concerns have been raised about the relationship of MoM bearing and elevated serum cobalt and chromium ion levels, their local and systemic toxicological effects and the incidence of local tumorous masses (pseudotumors). Are these findings applicable for all MoM bearings or are there also product specific issues. We present the outcome of a cementless MoM THA using a 38mm head in a unique consecutive series of 377 THA who were performed in our institution. Patients and Methods. All 351 patients (377 THA) with a cementless MoM THA (M2a-38. tm. , Biomet Inc, Warsaw, IN, USA, and Taperloc® stem, Biomet UK, Bridgend) between 2008 and 2011 were evaluated. All patients were analyzed by a physical exam, serum levels of cobalt and chromium and an interview to determine if there were any complaints. An MRI of the hip was made if patients reported pain during physical activity, allergies to metals, serum cobalt or chromium ion levels ≥ 5 ppb or if the inclination of the acetabular component was more than 50 degrees. Nine patients deceased, three were lost to follow up and four already underwent a revision before the screening. We analyzed 361 hips with an average follow up of 30 (range 2–58) months. The average preoperative age was 63 years (41–88). Results. 219 patients with 235 THA (65%) reported no complaints. Median cobalt level in patients with complaints was 6.6 (0.2–173) ppb and in the group without complaints 3.7 (0.2–27.3) ppb. Median chromium level in patients with complaints was 5.0 (0.1–134) ppb and in the group without complaints 3.7 (0.2–27) ppb. On the 226 performed MRI scans, 56 pseudotumors were diagnosed and described using the Anderson classification (9 C1, 41 C2 and 5 C3). 71 hips had been revised after a mean follow of 30 months (range 0.2–50 months). Reasons for revision were because of pain, raised metal ions and a pseudotumor in 28; pain and raised metal ion levels in 15; aseptic loosening of the acetabular or femoral component in 11; raised metal ions and a pseudotumor in 7; combination of luxations, luxation feelings and fractures in 5; infections in 3 and for other reasons in 2. Conclusion. The short-term results of the THA with a 38mm head metal on metal articulation are higher compared with other MoM bearings. They show a revision rate of 7% and 10% in the Australian and England register. In other peer reviewed literature we find a revision rate between 0–13% after five years. We also observed a high incidence of elevated serum levels of metal ions, pseudotumors and an unexpected high early revision rate

Objectives. Several studies have reported elevated blood cobalt (Co) and chromium (Cr) concentrations in patients with total knee replacements (TKRs). Up to 44% of tissue samples taken from patients with failed TKRs exhibit histological evidence of metal sensitivity/ALVAL. In simulated conditions, metal particles contribute approximately 12% of total wear debris in TKR. We carried out this investigation to determine the source and quantity of metal release in TKRs. Design and Methods. We analysed 225 explanted fixed-bearing TKRs (Attune, Genesis II, NexGen, PFC, and Vanguard) revised for any indication. These were analysed using peer-reviewed [coordinate measuring machine (CMM)] methodology to measure the volumetric wear of the polyethylene (PE) bearing surfaces and trays. The trays were analysed using 2D profilometry (surface roughness-Ra) and light microscopy. Histological and blood metal ion concentration analyses were performed in a sub-sample of patients. Results. The median (IQR) PE wear rate was 14 (6 to 20) mm. 3. /year. Microscopic examination of the superior surface of trays exhibited pitting on 132 (59%) of trays. There was a statistically significant (p<0.05) increase in Rvk on the pitted area of trays for each design, indicating material removal from the pits compared to the unpitted area. The inferior surface of 116(51%) of trays displayed polishing, indicative of abrasive wear. The median(range) Co and Cr concentrations were 2.5µg/l (0.2–69.4) and 1.7µg/l (0.5-12.5) respectively in 40 patients. Of the tissue samples examined in 30 patients, 6 had at least “mild”-ALVAL infiltrate. All corresponding “ALVAL” explants were found to be pitted and/or show evidence of loosening of the tray. Conclusion. This study provides further evidence that CoCr release in TKR appears to be an under-appreciated cause of adverse clinical outcomes. The generation of metal particles was predominantly from the metal tray, which may explain elevated metal ions after TKRs, despite no direct metal-on-metal contact

The objective of this study was to investigate how a new customizable light-curable osteosynthesis method (AdFix) compared to traditional metal hardware when loaded in torsion in an ovine phalanx model. Twenty-one ovine proximal phalanges were given a 3mm transverse osteotomy and four 1.5mm cortex screws were inserted bicortically on either side of the gap. The light-curable polymer composite was then applied using the method developed by Hutchinson [1] to create osteosyntheses in two groups, having either a narrow (6mm, N=9) or a wide (10mm, N=9) fixation patch. A final group (N=3) was fixated with conventional metal plates. The constructs were loaded in torsion at a rate of 6°/second until failure or 45° of rotation was reached. Torque and angular displacement were measured, torsional stiffness was calculated as the slope of the Torque-Displacement curve, and maximum torque was queried for each specimen. The torsional stiffnesses of the narrow, wide, and metal plate constructs were 39.1 ± 6.2, 54.4 ± 6.3, and 16.2 ± 3.0 Nmm/° respectively. All groups were statistically different from each other (p<0.001). The maximum torques of the narrow, wide, and metal plate constructs were 424 ± 72, 600 ± 120, and 579 ± 20 Nmm respectively. The narrow constructs were statistically different from the other two (p<0.05), while the wide and metal constructs were not statistically different from each other (p=0.76). This work demonstrated that the torsional performance of the novel solution is comparable to metal fixators. As a measure of the functional range, the torsional stiffness in the AdhFix exceeded that of the metal plate. Furthermore, the wide patches were able to sustain a similar maximum toque as the metal plates. These results suggest AdhFix to be a viable, customizable alternative to metal implants for fracture fixation in the hand

Introduction. The aim of this study is to report the results of Revision hip arthroplasty using large diameter, metal on metal bearing implants- minimum 2 year follow up. Methods. A single centre retrospective study was performed of 22 consecutive patients who underwent acetabular revision surgery using metal on metal bearing implants between 2004 and 2007. Birmingham hip resurfacing (BHR) cup was used in all patients - monoblock, uncemented, without additional screws in 16 cases and cemented within reinforcement or reconstruction ring in 6 cases. Femoral revisions were carried out as necessary. Results. There were 16 men and 6 women with a mean age of 71 years (51-83). Revision surgery was performed for aseptic loosening in 10, infected primary hip arthroplasty in 8, infected Hemiarthroplasty in 1 and Peri-prosthetic fracture with loosening in 3 patients. A 2-stage revision was performed for all infected hips. One patient died and the remaining 21 patients had clinical and radiological assessment at a mean 35 months (24-60). The mean Harris hip score was 75 (23-98) with 50% good to excellent results. Only 1 patient had further revision to a proximal femoral replacement and constrained cup in 2 stages for recurrent infection at 24 months. There were 2 recurrent infections (both revised for septic loosening) and 1 non-union of trochanteric osteotomy. There were no dislocations in the group. No radiological loosening of implants or metal ion complications have been seen at last follow up. Conclusions. We believe this is the first reported series on the use of large diameter metal on metal bearing surfaces for revision hip arthroplasty. Our series shows satisfactory short to medium term results in this complex group of patients with no component loosenings, despite monoblock cups and no dislocations

Background. Previous studies have suggested that the modular junction of metal on metal (MoM) total hip replacements (THR) is an important source of metallic debris. Methods. We carried out a prospective study using custom techniques to analyse one of the largest collections of failed contemporary MoM devices in the world. All explants from patients who had suffered adverse reactions to metal debris (ARMD) were included in this study. These explants included: 82 36mm THRs, and 147 resurfacing head THRs and 140 resurfacing arthroplasties from several manufactures. Volumetric wear analysis of the bearing surfaces and taper junctions was carried out using a coordinate measuring machine. The relationships between total metallic loss and metal ion concentrations and the macroscopic and histological tissue appearance of THR patients were compared to those in resurfacing patients. Mann Whitney test for non-parametric data was used to assess significant differences between groups. Results. Resurfacing explants retrieved from patients who had suffered ARMD were found to have significantly higher median rates of volumetric wear than the THRs (10.16 versus 2.25mm. 3. /yr (p < 0.001)). Total volumetric material loss from taper junctions ranged from 0.01 to 21.55mm. 3. When volumetric taper wear was combined with bearing surface wear in the THR patients this total rate of material loss was still significantly less than in the resurfacing patients 2.52 versus 10.16mm. 3. /yr (p < 0.001)). Despite this, macroscopic tissue destruction and extent of ALVAL infiltration was found to be significantly greater in the THR patients. Conclusion. Taper debris appears to more readily stimulate a destructive immune cascade than debris from primary bearing surfaces. This cascade can culminate in catastrophic tissue necrosis when blood metal ion concentrations appear normal. MHRA guidance should distinguish clearly between MOM THRs and resurfacings