Serum Cobalt Research Articles

Pseudotumours, cobalt and clinical outcome in small head metal-on-metal versus conventional metal-on-polyethylene total hip arthroplasty.

Background:Metal-on-metal total hip arthroplasty (MoM THA) is associated with the formation of pseudotumours. Studies mainly concern pseudotumour formation in large head MoM THA. We performed a long-term follow-up study, comparing pseudotumour incidence in small head metal-on-metal (SHMoM) THA with conventional metal-on-polyethylene (MoP) THA. Predisposing factors to pseudotumour formation were assessed.Methods:From a previous randomised controlled trial comparing SHMoM (28 mm) cemented THA with conventional MoP cemented THA, patients were screened using a standardised CT protocol for the presence of pseudotumours. Serum cobalt levels and functional outcome were assessed.Results:56 patients (33 MoP and 23 MoM) were recruited after mean follow-up of 13.4 years (SD 0.5). The incidence of pseudotumours was 1 (5%) in the SHMoM THA cohort and 3 (9%) in the MoP THA cohort. Prosthesis survival was 96% for both SHMoM and MoP THAs. Serum cobalt levels did not exceed acceptable clinical values (<5 µg/L) whereas no differences in cobalt levels were detected at follow-up between both groups. Oxford and Harris Hip Scores were good and did not differ between SHMoM and MoP THA.Conclusions:This long-term follow-up study shows a low incidence of pseudotumour formation and good functional outcome in cemented head-taper matched SHMoM and MoP THA.

Comparing The levels of trace Elements in females with Diabetes Mellitus

Cumulative investigations have depicted that metabolic rate of some trace elements has altered in diabetes. This study is designed to illustrate the consequence of some trace element copper (Cu), iron (Fe), Cobalt (Co), zinc (Zn) and Zn/Cu ratio) in diabetic female patients with mellitus type 2 (n=60), type 1 (n=69) as compared to nondiabetic control subjects (n=35). The element levels have recorded by an atomic absorption spectrophotometer. The consequences of this paper have depicted that the mean magnitudes of Zn, Cu, in addition to Fe have significantly lessened in testers of diabetic patients than control subjects (p < 0.006, p < 0.000, p < 0.000) correspondingly, but no significances in serum cobalt. Serum Cu, Fe levels have been significant and lower in samples of type 1 diabetic patients than type 2 diabetic patients (p < 0.001, p < 0.005).

Relationship between pre-pregnancy body mass index and mineral concentrations in serum and amniotic fluid in pregnant women during labor

The aim of the study was to determine the correlations between body mass index (BMI) values before pregnancy and the concentrations of selected elements (Mg, Co, Cu, Zn, Sr, Cd, Ba, Pb, U, Ca, Cr, Al, Mn, V, Fe) in blood serum and amniotic fluid (AF) in pregnant women. Elemental analysis of serum and amniotic fluid in 225 Polish women (Caucasian/white) showed a relationship between the concentration of minerals in the above-mentioned samples and the pre-pregnancy BMI. Analysis of blood serum was performed by using ICP-MS and it demonstrated that iron concentration was significantly lower in overweight and obese women. Being underweight in pregnant women was associated with a significantly lower concentration of magnesium and cobalt in the blood serum. Both underweight and overweight women were associated with significantly lower concentrations of calcium and strontium in the blood serum. The concentration of cobalt was significantly higher in underweight women. The concentration of lead in the blood serum of overweight and obese women was significantly higher than in other groups. Analysis of the AF showed that the concentration of copper was significantly lower in overweight and obese women, and the concentration of manganese and vanadium significantly higher than in other groups of women. A deficiency in essential minerals and an excess of heavy metals in women may be associated with abnormal body weight and this is important in the etiopathogenesis of pregnancy and fetal development disorders.

Association between maternal and umbilical cord serum cobalt concentration during pregnancy and the risk of preterm birth: The Ma'anshan birth cohort (MABC) study

Cobalt is an essential trace element and has been suggested to be involved in oxidative stress and inflammatory responses. However, researches have paid little attention to the association between serum cobalt levels during pregnancy and the risk of preterm birth (PTB, <37 week of gestation). The purpose of this study was to determine the association between maternal and umbilical cord serum cobalt concentrations and the risk of PTB. A total of 2951, 3080, and 2698 serum samples were obtained from pregnant women in the first, the second trimester, and the umbilical cord blood, respectively. The tertile levels of ln-transformed cobalt were defined as low, medium and high levels for cobalt respectively. In our study, the rate of PTB (<37 weeks of gestation) was elevated in subjects with low cobalt levels in the first trimester of pregnancy (adjusted OR 1.61, 95% CI: 1.01, 2.58) and the second trimester of pregnancy (adjusted OR 1.62, 95% CI: 1.03, 2.54). The adjusted OR for PTB was 2.46 (95% CI: 1.34, 4.53) among subjects with low cobalt levels and 2.22 (95% CI: 1.19, 4.15) among subjects with medium cobalt levels in the umbilical cord serum. Our findings demonstrated that the lower levels in maternal and umbilical cord serum cobalt were associated with the increased the risk of PTB.

Serum Metal Ion Levels in Cementless Metal-On-Metal Total Hip Arthroplasty: Long-Term Follow-Up Trends

BackgroundLong-term trends in serum metal ion concentration after metal-on-metal (MoM) total hip arthroplasty (THA) are unclear. In most studies, serum metal ion levels increase initially and remain constant during follow-up. However, there are no previous studies that evaluate the metal ion level longitudinally at multiple intervals over the long term. Increasing metal ion levels during the long-term follow-up of patients who underwent cementless MoM THA has been seen, so this study investigated those trends. MethodsSeventy-one patients were followed for a minimum of 10 years (range, 10.0-18.6 years). All underwent unilateral THA with MoM bearings. Serum cobalt (Co) and chromium (Cr) levels were measured preoperatively and annually after surgery. Trends and differences in serum levels based on sex, mean age, body mass index, cup inclination, and implant selection were analyzed. ResultsWithin 5 years after the operation, the mean Co and Cr levels peaked postoperatively at 3-4 years (4.14 and 6.89 μg/L, respectively). Between 5 and 10 years postoperatively, the serum levels showed 2 tendencies. One group (62) showed a constant range, but a smaller group (9) showed increasing serum metal ion levels. The only factor which showed a difference between the 2 groups was body mass index (P = .030), which was lower in the increasing serum metal ion level group. ConclusionAt a medium-term to long-term follow-up period, serum Co and Cr levels are not always constant. This should be considered when seeing patients with MoM THA, and laboratory tests may be needed for long-term follow-up.

Revision total hip arthroplasty with metal on metal bearing for ceramic bearing fractures

BackgroundDue to concern of potential metallosis caused by residual microscopic ceramic particles, metal-on-metal (MoM) bearing is deemed undesirable in revision total hip arthroplasty (THA) for ceramic bearing fracture. We determined whether MoM bearing is suitable to be used in revision THA for ceramic fractures and also evaluated whether this treatment increases serum iron levels compared with MoM bearing revision THA for polyethylene failure. MethodsBetween 2006 and 2012, 22 patients underwent revision surgery using MoM bearing (28 mm femoral head in 18 hips and 32 mm in 4 hips) for ceramic bearing fracture and followed average 52.1 months. We assessed radiological parameter and functional outcome using Harris hip score (HHS) and WOMAC score. Also, serum cobalt (Co) and chromium (Cr) blood tests were performed and compared with the result obtained from age, sex- and follow-up duration-matched patients with MoM revision THA for failed polyethylene bearing. ResultsThe mean HHS improved from 60.6 preoperatively to 90.3 at final follow-up. There were no changes in cup position, progression of osteolytic lesions, and measurable wear of MoM bearing articulation at final follow-up radiographs. There was one case of recurrent dislocation after surgery, which was treated with greater trochanter distal advancement and one case of deep infection, which underwent two-stage revision. Mean serum Co level (1.7 vs. 1.4 μg/dl; p = 0.211) and Cr level (0.70 vs. 1.01 μg/dl; p = 0.327) showed no significant difference. ConclusionsMoM articulation with liner cementation into the acetabular cup along with total synovectomy can be chosen in revision surgery for ceramic fracture with good midterm follow-up. However, the use of MoM bearing is indicated when the stem and metal shell can be retained and ceramic on ceramic or ceramic on polyethylene bearing cannot be selected. Also long-term outcome needs to be further evaluated.

Abstract 17269: Incidence of Atrial Fibrillation in Patients With Cobalt and Chromium Containing Hip Arthroplasty

Background: Worldwide, approximately one million patients have had total hip arthroplasty with 35% being cobalt and chromium Metal-on-Metal (MoM) or Metal-on-Polythelene (MoP) implants. Animal models have suggested that cobalt and chromium can affect all chambers, but there seems to be an atrial predilection. There are several case reports of metal containing hip arthroplasty causing atrial arrhythmias but the true incidence of atrial fibrillation associated with metal hip arthroplasty remains undefined. Objective: We sought to determine the incidence of atrial fibrillation in patients with metal containing hip arthroplasty. We also examined the association between serum cobalt and chromium levels and arrhythmias in this cohort and all cause mortality. Methods: We retrospectively examined the records of patients from the Mayo Clinic total hip arthroplasty registry (Metal group - Metal-on-Metal: MoM and Metal-on-Polyethylene: MoP, Non-Metal group - Ceramic-on-Ceramic: CoC and Ceramic-on-Polyethylne: CoP) to obtain demographic data, comorbidities, laboratory, ECG, and echocardiographic data. Out of a total of 1756 patients, Cobalt and Chromium levels were available in 138 patients. Results: The mean age of patients with metal containing hip replacement was 50 years and were predominantly male. During a follow up period of 10 years, the incidence of atrial fibrillation in our study population was 8% in metal group compared to 2% (p=0.11) in non-metal group. There was no association between cobalt or chromium levels with the incidence of atrial fibrillation. All-cause mortality was significantly higher in metal group versus non-metal group (p=0.005). Conclusion: The incidence of atrial fibrillation was relatively more in patients with metal versus non-metal hip arthroplasty but there was no association of serum cobalt or chromium levels with incidence of atrial fibrillation in the subset of patients. In addition, all-cause mortality was significantly higher in the metal group suggesting potential toxic effects of metal containing hip arthroplasty.

Retrieval Findings of Recalled Dual-Taper Hips.

Background:The recent high-profile recalls of several dual-taper hip designs pose questions regarding why those designs perform poorly. We aimed to characterize taper damage in 1 recalled design to understand failure mechanisms to inform surgeons on which patients should be considered at risk of revision and when to revise.Methods:High-precision measurement equipment was used to characterize the metal loss from the neck-stem interface of 116 retrieved Rejuvenate femoral stems (Stryker Howmedica Osteonics) revised because of an adverse reaction to metal debris. Head-neck taper surfaces were also investigated, and clinical and laboratory data were examined.Results:The neck-stem junction of each implant was moderately to severely corroded and showed a characteristic wear pattern on both male and female taper surfaces. The severity of taper damage was positively correlated with time to revision (coefficient, 0.040 [95% confidence interval (CI), 0.028 to 0.051]; p < 0.0001) and with serum cobalt concentration (coefficient, 0.02 [95% CI, 0.01 to 0.02]; p < 0.0001) and serum chromium concentration (coefficient, 0.04 [95% CI, 0.009 to 0.070]; p = 0.0142).Conclusions:A forensic examination of the retrieved components that failed secondary to an adverse reaction to metal debris showed, in all cases, visible corrosion. Of the implant and patient factors investigated, we did not identify any predictors of corrosion. The severity of damage was found to increase with time; cobalt was significantly elevated over chromium.Clinical Relevance:Surgeons should scrupulously follow and consider revision for patients with this implant design to avoid extensive tissue excision. Blood metal ion tests may aid in identifying the mechanisms of taper corrosion.

Effect of an Acute Exercise Until Exhaustion on the Serum and Urinary Concentrations of Cobalt, Copper, and Manganese Among Well-Trained Athletes

The current information about the effect of physical exercise on the body concentrations of several minerals is still limited, both in the acute (short-term) and adaptive (long-term) responses. So, this manuscript aims, on the one hand, to assess the possible differences on basal levels of cobalt (Co), copper (Cu), and manganese (Mn) concentrations in serum and urine between athletes and sedentary participants and, on the other hand, to evaluate the effect of an acute progressive physical exercise until voluntary exhaustion on the serum and urinary concentrations of Co, Cu, and Mn. Two groups participated in this survey, one was formed by untrained, sedentary males (CG; n = 26), and the other group was constituted by national endurance (long and middle distances) athletes (AG; n = 21). All participants were from the same region of Spain. Participants of both groups performed a physical test on a treadmill, reaching voluntary exhaustion. Blood and urine samples of each participant were collected before and at after the tests. Once obtained and processed, the concentrations of Co, Cu, and Mn elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The differences in the studied variables were evaluated using a mixed model by means of an ANOVA and Bonferroni post hoc tests. In the comparison of the pre-test values between groups, the results showed that serum concentrations of Mn were significantly lower in CG than in AG (p < 0.01). In urine, Co and Mn levels were significantly higher among CG participants (p < 0.01) than among AG ones, while in the case of Cu, the values were lower (p < 0.01) in the CG than in the AG. Regarding the effects of the effort tests, no significant changes were found among the participants of the CG. It was observed that the serum concentrations of Co (p < 0.05) and Cu (p < 0.01) decreased after the test among the AG participants. Also, the results showed that there were no statistical differences in Co and Mn values (expressed in μg/g creatinine). However, the urinary post-test Cu concentrations were lower (p < 0.05) among AG participants. In basal conditions, serum concentrations of Mn were significantly lower in CG than in AG. In urine, Co and Mn levels were significantly higher among CG participants and Cu level was significantly lower in CG, a fact which may reflect adaptive responses to exercise. An incremental exercise to exhaustion in AG produces a decrease in Co and Cu serum concentrations, as well as in urinary excretion of Cu.

Trunnion corrosion in metal-on-polyethylene hip arthroplasty: a simple diagnosis and treatment?

To report our experience with trunnion corrosion following metal-on-polyethylene total hip arthroplasty, in particular to report the spectrum of presentation and determine the mean time to presentation. We report the presenting symptoms and signs, intraoperative findings, and early results and complications of operative treatment in nine patients with a mean age of 74 years (60 to 86). The onset of symptoms was at a mean of seven years (3 to 18) after index surgery. Patients presented with a variety of symptoms including pain, limp and rash. The preoperative mean serum cobalt level was 7.1 ppb (2.2 to 12.8) and mean serum chromium level was 2.2 ppb (0.5 to 5.2). Metal artifact reduction sequence (MARS) MRI showed fluid collection and possible pseudotumour formation in five hips, fluid collection in two hips, and synovitis/debris in one hip, with no MRI in one patient. Acetabular revision was performed in three patients, six patients underwent liner and head exchange only. The postoperative metal levels decreased in all patients: mean cobalt 0.5 ppb (0 to 1.8) and mean chromium 0.9 ppb (0 to 2.6) at a mean of five months (3 to 8) postoperatively. Seven patients had good pain relief and no complications at one year. There were two major complications requiring reoperation: acute infection at six weeks, for which the patient required two-stage reimplantation; and recurrent dislocation, for which the patient was revised to a dual mobility component. Trunnion corrosion in metal-on-polyethylene THA has a range of presenting symptoms, and may present later than previously described. A high index of suspicion is warranted, and serum cobalt and chromium levels are recommended for diagnosis. Patients should be counselled about possible postoperative complications. Cite this article: Bone Joint J 2018;100-B:898-902.

A Survey of the Prevalence of and Techniques to Prevent Trunnionosis.

Trunnionosis of total hip arthroplasty (THA) components has been an increasingly reported complication. Consensus is lacking regarding preventive practices and the overall incidence of trunnionosis. In this study, fellowship-trained adult reconstruction orthopedic surgeons were surveyed to identify expert opinions. A 25-question, web-based survey regarding trunnionosis incidence, prevention, and biomaterials was sent to 345 fellowship-trained adult reconstruction orthopedic surgeons in North America. The survey yielded 151 (43.8%) responses from surgeons with a mean of 11.97±9.49 years of experience. These surgeons believe that the material composite of the head-neck junction is the most important contributor to trunnionosis. They often choose a ceramic head with a metal alloy stem to reduce trunnionosis. They more commonly impact the femoral head 3 times than once. Fifty-one percent believe that trunnionosis leads to THA failure for between 0% and 2% of all THA revisions, whereas 48.3% believe that the failure rate is greater than 2%. More than half (53.6%) of these surgeons recommend a revision THA if a patient's serum cobalt level is greater than 10 µg/L, regardless of symptom presence. The incidence of trunnionosis appears to be increasing due to changes in implants and/or an increased awareness of the problem, with 48.3% of these surgeons believing that trunnionosis is the primary cause of THA failure for more than 1 in 50 patients. Some suggested preventive measures include cleaning and drying the trunnion, using ceramic femoral heads, matching THA components, and adding titanium sleeves on well-fixed stems that are retained during revision surgery. [Orthopedics. 2018; 41(4):e557-e562.].

An Early Report of the Use of a Modular Dual Mobility Articulation in Revision Acetabular Reconstruction

BackgroundInstability remains one of the main problems after revision hip surgery. The aim of this study was to review the clinical, radiological, and patient-reported outcomes with the use of modular dual-mobility articulation for revision acetabular reconstruction and investigate the risk of fretting corrosion by measuring serum trace metal ion levels. MethodsSixty consecutive patients with a minimum of 24-month follow-up after the insertion of a modular dual-mobility (Stryker, Mahwah, NJ) cup at the time of revision hip surgery were identified. Follow-up included clinical and radiological patient review and functional outcome measures, and a subset of patients had their metal ion (cobalt and chromium) levels checked. ResultsAt the most recent follow-up, 5 patients had died, 3 patients have been revised because of ongoing instability, and 3 patients have had revision surgery due to infection. Overall functional outcome (mean Western Ontario and McMaster Universities Osteoarthritis Indexfunction 76, University of California, Los Angeles 5.6, mean Oxford 74.7, Short Form-12 physical 41.6/mental 53.3) and overall pain relief (mean Western Ontario and McMaster Universities Osteoarthritis Index pain score 78.3) scores were good. The mean satisfaction score was 78 of 100. The median serum trace metal chromium and cobalt levels at the most recent follow-up were 0.4 µg/L (range 0.1-6.1 µg/L) and 0.42 µg/L (range 0.21-9.42 µg/L), respectively. The survival with revision as the end point was 90%. ConclusionsDual-mobility cups with modularity represent an excellent option for the patient having revision hip surgery at high risk of instability. This series presents good patient-reported outcome measures and a low complication and revision rate.

Femoral offset found not to affect metal ion levels in metal-on-metal total hip arthroplasty.

Failure to restore femoral offset in metal on polyethylene total hip arthroplasty (THA) causes polyethylene wear and aseptic loosening. To our knowledge, no study to date has investigated the relationship between femoral offset and wear in metal-on-metal (MOM) THA. In this study, we investigated the relationship between femoral offset and wear by measuring circulating metal ion levels in MOM THA. In this retrospective study, we identified patients who had undergone MOM THA with the ASR XL system (DePuy International Ltd., Leeds, UK). Femoral offset was measured using anteroposterior radiographs, and circulating metal ion levels (cobalt and chromium) were recorded. In total, 95 patients were included (68 males and 27 females). The mean age at the time of surgery was 64.9. Mean time from surgery to blood sampling was 15.4months. No statistically significant relationship was found between femoral offset and cobalt (p = 0.313) or chromium (p = 0.401) ions. It is known that failure to restore femoral offset during THA can lead to high rates of wear in metal-on-polyethylene articulations. In our study, no statistically significant relationship was found between femoral offset and serum cobalt or chromium ions. This study adds to the information available to surgeons regarding factors that increase wear in metal-on-metal total hip arthroplasty.

Long-term results of metal on metal total hip arthroplasty in younger patients (

IntroductionMetal on Metal (MoM) hip arthroplasty saw a new era of popularity with development of its second generation bearing surfaces, in the first decade of this century. However, by the end of that decade, concerns had been raised due to metal debris related complications.We aimed to determine the survival of MoM stemmed hip replacement in younger population. We also studied the rate of revision related to adverse reaction to metal debris (ARMD) along with reviewing the clinical and radiological progress of MoM hip arthroplasty in younger age (<55 yrs) group. Patients & MethodsThis is a retrospective cohort study of patients 55 yrs old or younger, who had metal on metal (MoM) hip arthroplasty for osteoarthritis. We had 109 procedures performed on 90 patients with a mean follow up of 10 years. All patients were reviewed as per MHRA guidelines in planned follow-up clinics. Data analyses were performed using SPSS. ResultsSurvival of implant in our younger cohort was 88.1% at a mean age if 10 years, with revision for any cause as an endpoint. Most of the patients were happy with the outcome of their hip replacement as they were able to perform activities of daily living and work without compromise. Mean Oxford hip score was 43.Altogether, there were 12 revisions, 7 of these were for metallosis and associated symptoms. Average time to revision was 7 years. Other analysis revealed mean acetabular cup inclination angle to be 49 degrees but no significant correlation was found between this angle and serum metal ion levels. Serum Chromium and Cobalt levels were significantly higher in revision group. DiscussionMetal on metal hip arthroplasty prime popularity time has gone. In younger population, although revision rates are higher, the surviving implants give a very good outcome in terms of patient satisfaction. Most of the patients report a desired outcome of ‘forgotten hip’.

Serum Metal Levels in Maxillofacial Reconstructive Surgery Patients: A Pilot Study

The aim of this pilot study was to assay metal concentrations in the serum of patients who had undergone dental implant placement, orthognathic surgery using rigid metal fixation plates and screws, and total temporomandibular joint replacement (TMJ TJR). Thirty patients were identified and included in this pilot study. Sixteen patients (9 men and 8 women), with an average age of 44years (range, 19 to 79yr), provided informed consent to participate and were divided into 3 study groups with 4 patients in each (group 1, orthognathic surgery; group 2, TMJ TJR; and group 3, dental implant placement). A control group consisted of volunteers without any implanted metallic devices. Blood samples for serum metal analysis were obtained and analyzed in accordance with the standardized collection and testing protocols used at the Trace Metal Analysis Laboratory of the Department of Orthopedic Surgery at the Rush University Medical Center (Chicago, IL). All control participants had levels below the normal reference range for all serum markers assessed. In the orthognathic group, 1 patient had an increased serum cobalt level. In the TMJ TJR group, 1 patient had an increased serum cobalt level and another patient had an increased serum chromium level. In the dental implant group, 1 patient had an increased serum titanium level and another had increased serum levels of titanium and chromium. This is the first study to report on the release of metal into the bloodstream in patients with different maxillofacial implanted metallic objects. The results raise questions regarding the types and magnitude of metal released from maxillofacial reconstruction devices and their potential long-term local and systemic effects. Future large-scale prospective studies involving serial measurements in homogeneous groups of patients could further elucidate the impact of these findings.

Sensitivity and Specificity of Metal Ion Level in Predicting Adverse Local Tissue Reactions Due to Head-Neck Taper Corrosion in Primary Metal-on-Polyethylene Total Hip Arthroplasty

BackgroundThere is increasing concern regarding the occurrence of adverse local tissue reactions (ALTRs) in metal-on-polyethylene (MoP) total hip arthroplasty (THA) patients due to mechanically assisted crevice corrosion at the head-neck modular taper junction. The utility of metal ion levels in evaluating MoP patients with head-neck taper has not been fully characterized. This study aimed to investigate the sensitivity and specificity of serum metal ions as a predictor of ALTR in MoP THA patients. MethodsA total of 62 MoP THA patients in 2 cohorts were investigated: (1) ALTR on metal artifact reduction sequence magnetic resonance imaging (n = 43) and (2) without ALTR on metal artifact reduction sequence magnetic resonance imaging (n = 19). Receiver-operating characteristic curve was constructed to determine the sensitivity and specificity using different metal ion thresholds and the optimal metal ion cutoff values. ResultsThe presence of ALTR was associated with significantly higher cobalt (8.9 ng/mL vs 0.3 ng/mL, P < .001), chromium (2.26 ng/mL vs 0.21 ng/mL, P < .001), and Co/Cr ratio (5.9 vs 2.0, P < .001). The sensitivity and specificity for cobalt (1 ng/mL) was 95% and 94% and for Co/Cr ratio (2) was 83% and 72%, respectively. ConclusionsAlthough metal ion levels alone should not be relied on as the sole parameter to determine revision surgery, serum cobalt level of >1 ng/mL (1 ppb) and Co/Cr ratio >2 thresholds provide evidence-based practical information for surgeons when interpreting metal ion levels in MoP THA patients for clinically relevant head-neck taper corrosion.

The Fate of Elevated Metal Ion Levels After Revision Surgery for Head-Neck Taper Corrosion in Patients With Metal-on-Polyethylene Total Hip Arthroplasty

BackgroundElevated metal ion levels have been associated with the presence of adverse local tissue reactions in patients with metal-on-polyethylene (MoP) total hip arthroplasty (THA) secondary to corrosion at head-neck taper junction. Patients are frequently concerned with their elevated systemic metal ion levels. This study investigated the rate of decline of serum cobalt and chromium ion levels after revision surgery. MethodsA total of 39 patients with MoP THA were revised because of the presence of symptomatic adverse local tissue reactions on magnetic resonance imaging with elevated serum metal ion levels. The time between initial implantation of MoP THA (index surgery) and revision surgery was considered the duration of metal exposure. The prerevision measure of ion level was considered the intensity of exposure. Prerevision median serum Co and Cr levels, as well as revision serum Co/Cr ratio, were reported. ResultsThe median serum levels of cobalt and cobalt-to-chromium ratio significantly decreased from prerevision levels of 8.2 μg/L (0.2-56.1 μg/L) and 5.6 μg/L (0.1-53.3 μg/L) to 3.1 μg/L (0.2-14 μg/L) and 1.7 μg/L (0.4-3.8 μg/L) at postrevision (P < .01), respectively. The rate of decline of Co was 0.45% per day during the first month. For chromium, the rate of decline was slower with 0.08% per day during the first month. ConclusionAt 3 months after revision surgery, cobalt and chromium ion levels declined by 34% and 8% of prerevision level, respectively. This study provides evidence-based practical information for surgeons to provide MoP THA patients when considering revision surgery for head-neck taper corrosion.

Outcomes after revision of metal on metal hip resurfacing to total arthroplasty using the direct anterior approach.

Function after revision total hip arthroplasty (THA) in failed metal-on-metal (MoM) hip resurfacing arthroplasty (HRA) is variable, but post-operative complication rates are reportedly high. We hypothesized HRA conversion to THA using the direct anterior approach (DAA) would be associated with optimal outcome. Seventeen MoM-HRAs in 15 patients (seven males, eight females) were revised through the DAA. The mean age was 45years (28-59yrs). The most common indications for revision were aseptic loosening of the acetabular component or of the femoral component and femoral neck fracture. In 16 hips, a conversion to a ceramic-on-ceramic (CoC) (13 hips) or to a metal-on polyethylene (MOP) (2), or to a large-head MoM (1) THA was done. An isolated femoral revision was done in one hip. After 6.7 ± 3years, no hip had required a re-revision. The Postel-Merle d'Aubigne (PMA) functional score improved from 9 (4-14) to 16 (12-18) (p < 0.001). An intra-operative fracture of the greater trochanter (one hip) and dysesthesia of the lateral femoral cutaneous nerve (four hips) were reported. Mean serum chromium concentration decreased from 33.2μg/L (11.8-62μg/L) pre-operatively to 5.8μg/L (0.4-35.5μg/L) post-operatively (p < 0.001), and mean serum cobalt concentration decreased from 35.8μg/L (6.3-85.5μg/L) to 4.7μg/L (0.26-25.7μg/L) (p = 0.003). Revision of failed MoM-HRA using the DAA resulted in an acceptable clinical outcome, no specific complication and no further surgery. A consistent decline in serum ion levels may be expected following HRA conversion to THA.

Serum Concentrations of 15 Elements Among Helicobacter Pylori-Infected Residents from Lujiang County with High Gastric Cancer Risk in Eastern China.

Helicobacter pylori (H. pylori) infection can interfere with the absorption of most elements, and the variations of some element levels are related to the incidence of gastric cancer. However, there have been conflicting results concerning the influence of H. pylori infection on serum element levels. The present study aimed to compare the serum element concentrations of H. pylori-infected local residents with uninfected residents from Lujiang County with high gastric cancer risk in Eastern China. We used data and serum samples from the H. pylori screening-survey program which was a cross-sectional study. We took 155 samples randomly from the screening survey, identified 74 H. pylori-positive residents and 81 H. pylori-negative residents by a serological test. The serum concentrations of 15 elements (calcium, magnesium, iron, zinc, selenium, copper, molybdenum, chromium, cobalt, nickel, lead, cadmium, mercury, arsenic, and aluminum) were determined using inductively coupled plasma mass spectrometry. Serum cobalt was found at higher levels in the H. pylori-infected residents than the H. pylori-uninfected residents (0.246 vs 0.205μg/L, P = 0.022), but no statistically significant differences in the serum levels of other elements were found. This is the first study to report the serum concentrations of 15 elements and their relationships with the infection status of H. pylori among local residents from Lujiang County with high gastric cancer risk. Although the International Agency for Research on Cancer has classified cobalt and other soluble cobalt salts as possibly carcinogenic to human beings, our results may provide a clue to the relationships between cobalt, H. pylori, and gastric cancer.

Pseudotumor in metal-on-metal hip arthroplasty: a comparison study of three grading systems with MRI

ObjectivePseudotumors, a well-known complication of metal-on-metal total hip arthroplasty (MoM THA), are well identified on metal artifact-reducing sequences magnetic resonance imaging (MARS-MRI). Several MRI grading systems are described in the orthopedic literature, but their validity is unknown in large clinical studies. Our study was undertaken to describe the classification of pseudotumors in a preselected cohort divided into high- and low-risk patients, using three pseudotumor grading systems applied on MARS-MRI, and to determine the interobserver reliability of the grading systems.Patients and methodsA retrospective study was performed on 377 consecutive patients (240 MRI scans) treated with an M2a-38 and Taperloc stem combination (Biomet, Warsaw, IN, USA). Patients were divided into a high-risk and a low-risk group based on previous published risk factors. Two observers determined the presence of pseudotumors using three different pseudotumor grading systems for classifying MARS-MRI results.ResultsThe prevalence of pseudotumors as determined with MARS-MRI was 59% in our high-risk group, 0% in the low-risk group and 43% in the control group. Serum cobalt values were increased in the high-risk group. The kappa values of the Anderson, Hauptfleisch and Matthies grading system scores were 0.43, 0.44, and 0.49 respectively.ConclusionsHigh-risk patients are at a high risk for pseudotumor development. No pseudotumor development was found in low-risk patients. Interobserver reliability scored best with the Matthies system, but all three grading systems showed only a moderate agreement.