A total of 397 hips were randomised to receive Metasul metal-on-metal (MoM), metal-on-conventional polyethylene (MoP) or ceramic-on-polyethylene (CoP) bearings using a cemented triple-tapered polished femoral component (MS-30). There were 129 MoM hips in 123 patients (39 male and 84 female, mean age 63.3 years (40.7 to 72.9)), 137 MoP hips in 127 patients (39 male and 88 female, mean age 62.8 years (24.5 to 72.7)) and 131 CoP hips in 124 patients (51 male and 73 female, mean age 63.9 years (30.6 to 73.8)). All acetabular components were cemented Weber polyethylene components with the appropriate inlay for the MoM articulation. Clinical evaluation was undertaken using the Harris hip score (HHS) and radiological assessments were made at two, five and seven years. The HHS and radiological analysis were available for 341 hips after seven years. The MoM group had the lowest mean HHS (p = 0.124), a higher rate of revision (p < 0.001) and a higher incidence of radiolucent lines in unrevised hips (p < 0.001). In all, 12 revisions had been performed in 12 patients: eight in the MoM group (four for infection, four for aseptic loosening, three in the MoP group (one each of infection, dislocation and pain) and one in the CoP group (infection). Our findings reveal no advantage to the MoM bearing and identified a higher revision rate and a greater incidence of radiolucent lines than with the other articulations. We recommend that patients with a 28 mm Metasul MoM bearing be followed carefully. Cite this article: Bone Joint J 2013;95-B:881–6

We report the clinical and radiological outcome at ten years of 104 primary total hip replacements (100 patients) using the Metasul metal-on-metal bearing. Of these, 52 had a cemented Stuehmer-Weber polyethylene acetabular component with a Metasul bearing and 52 had an uncemented Allofit acetabular component with a Metasul liner. A total of 15 patients (16 hips) died before their follow-up at ten years and three were lost to follow-up. The study group therefore comprised 82 patients (85 hips). The mean Oxford score at ten years was 20.7 (12 to 42). Six of 85 hips required revision surgery. One was performed because of infection, one for aseptic loosening of the acetabular component and four because of unexplained pain. Histological examination showed an aseptic lymphocytic vasculitis associated lesion-type tissue response in two of these. Continued follow-up is advocated in order to monitor the long-term performance of the Metasul bearing and tissue responses to metal debris

Second-generation metal-on-metal bearings have been used since the late 1980s as alternative bearings to eliminate aseptic loosening due to polyethylene wear. This study is the first with a long term follow-up for Meteasul, (Zimmer GmbH, Winterthur, Switzerland) metal on metal (MoM) hip replacement; in literature most of the studies have a mean follow-up of 7 years. Metasul showed better performances than other MoM couplings, with a low failure rate at long term follow-up and low revision rate for aspetic loosening. The aim of the present study was to evaluate the long-term results of a series of Metasul implanted between January 1993 and July 1997. 145 cementless THAs with a 28 mm Metasul articulation were performed in 114 consecutive patients. Implant survivorship was calculated and clinical and radiographic evaluations were performed on 93 hips still available for follow-up at a mean of 19 years postoperatively (43 hips are dead or lost to FU, 29, 6%). Nine hips (6.2%) were revised. The cumulative probability of survival of the overall implant at 19 years postoperatively with revision for any reason as the end point, was 0.937 (95% confidence interval, 0.888 to 0.985). The cumulative probability of survival of Metasul with revision for any reason as the end point, was 0.956 (95% confidence interval, 0.916 to 0.997). Clinical outcome has been evaluated with modified Harris Hip Score for 93 hips with an average of 88.8 points. Various degrees of radiolucencies and osteolysis were found proximally around the femoral components of 25 hips (20%). Most of the patients has normal serum levels of metal ions (Co and Cr), and no cases of systemic toxicity has been reported. Cementless Metasul THAs showed high probability of survival at 19 years postoperatively

Second-generation metal-on-metal bearings have been used since the late 1980s as alternative bearings to eliminate aseptic loosening due to polyethylene wear. The aim of the present study was to evaluate the long-term results of a series of Metasul (Zimmer GmbH, Winterthur, Switzerland) metal-on-metal total hip arthroplasty (THA). Between January 1993 and September 1996, 149 cementless THAs with a 28 mm Metasul articulation were performed in 111 consecutive patients. Implant survivorship was calculated and clinical and radiographic evaluations were performed on 82 hips still available for follow-up at a mean of 18 years postoperatively. Nine hips (6.0%) were revised. The cumulative probability of survival of the overall implant at 18 years postoperatively with revision for any reason as the end point, was 0.937 (95% confidence interval, 0.888 to 0.985). The cumulative probability of survival of Metasul with revision for any reason as the end point, was 0.956 (95% confidence interval, 0.916 to 0.997). Various degrees of radiolucencies and osteolysis were found proximally around the femoral components of 25 hips (20%). Cementless Metasul THA showed high survival at 18 years postoperatively

Introduction: Reintroduced in 1988, 28-mm metal-on-metal Metasul bearings had head sleeves and liner rim edge. It was modified in 1995 for the 2nd current design without sleeve and rim. Aim of this study was to address the fate if any of this modification. Material and methods: 100 consecutive Alloclassic cementless titanium 1ary THA with 28mm-Metasul bearings (22 with head sleeve of the 1st design) were prospectively studied (primary arthritis in 76% of hips, mean age 59.6 years). 2 Metasul components of 1st design were exchanged for dislocation. The remaining 98 THAs were reviewed after a 6-year average follow-up (range, 17–126 months). Results: Clinical results were graded excellent and good except for 3 patients Radiographically, wear was undetectable in the 97 bearings available for study. Post-operative cobalt level in whole blood was noted superior to the upper “normal” value (5 μg/L) for 16 THAs (3 of the 1st design, 13%). No significant relationship could be established between elevated blood Co level and any demographic or surgical data, including age (p = .61) and activity level (p = .44), except with radiographic aspect of a high anteversion of the cup, noted > 25° in 5 hips: incidentally 4 were of the 1st Metasul design (p = .0037). High dislocation rate (5%) could partly be explained by early impingement favoured by head sleeve and liner rim-edge. In 1 hip, despite excellent clinical result, posterior impingement with an extra-long sleeved head induced elevated Co level that leads to the bearing exchange. In another hip with Metasul head sleeve, the same mechanism induced femoral component aseptic loosening and osteolysis that was revised at 7.8 years. These 2 hips showed the higher Co levels of the series, up to 23.6 μg/L and 36 μg/L, respectively. The difference between revision rates of Metasul bearings of 1st (4/22, 17%) and current design (1/78, 1.3%) was significant (p =.008). At 8 year, survivorship of Metasul bearings from revision for any reason was 81.4% (95% CI, 57–93.5%) for the 1st design and 98.7% (81–99.9%) for the current design. No general toxic effect could have been detected thus far. Conclusion: In this personal experience, impingement due to metallic head sleeve has been the main cause of osteolysis, and Co level survey has shown to be a good indicator of Metal-on-Metal bearing behaviour. Obviously, Metasul head sleeve should have been avoided

Introduction. The Metasul articulation was introduced in the early 1990's. It comprises a 28mm forged, cobalt-chrome head and a forged metal inlay, set into the polyethylene element of the acetabular component. During the 1990's and early 2000's anatomic sized MoM articulations were re-introduced for hip resurfacing and stemmed implant designs. Adverse tissue reactions to metal debris and corrosion products subsequently led to a decline in MoM usage. Materials & Methods. Between January 1995 and December 1998, 133 hips underwent primary THR using the Metasul 28mm bearing. Patients were routinely sent an annual postal Oxford Hip Score (OHS) and radiographs were obtained from the second post-operative year. We have retrospectively reviewed the clinical and radiographic dataset following the 15 year follow-up time point. Results. At a mean follow-up of 16.6 years (range 15.5–19.2 years), the median OHS score at 15 years was 42 (range 7–48). OHS showed statistically significant improvements at all post-operative time points when compared to pre-operative scores (p= <0.001; CI 4.42–6.69). No significant decline in OHS score was observed following the 15 year follow-up. Nine hips were revised at a mean duration of 6.11 years (range 1.09–17.49). Worst case scenario Kaplan-Meier analysis, when lost patients were presumed revised, demonstrated an 84% (CI 0.77–0.90) survivorship at 15 years when revision for any cause was the endpoint. Aseptic loosening as the end point demonstrated an 88% survivorship (CI 0.81–0.93). One hip demonstrated femoral component migration of 2.7mm's but no component loosening's were observed. Discussion. In contrast to the problems reported for other MoM articulations, our study suggests that the 28mm diameter Metasul bearing provides good survivorship and outcome at a minimum of 15 years. No long-term joint stability issues were identified. We have not assessed serum metal ion levels or quantified metal debris generation. Our patients remain under surveillance

We report the review of performance and problems of Metasul Hip System with metallic sliding face during mean time of 11 years or longer. Subjects and methods: Twenty-three joints in 22 patients. 17 females and 5 males treated using cementless Metasul THA in our hospital from November of 1995 to April of 1998 were selected as subjects. The mean age at the time of surgery was 59 years, and disease included degenerative hip disease in 16 joints, femoral head necrosis in 5 joints, and rheumatoid arthritis in 2 joints. Mean follow-up period was 11 years and 3 months. We have investigated clinical results (JOA score), stem fixation by radiography (Engh), setting angle of socket, and presence or absence of osteolysis by CT, and the poor cases after surgery and problems were clarified. Results: Clinical results (JOA score) were improved from preoperative mean of 41.3 points to mean of 89.3 points at the time of investigation. Stem fixation examination by radiography (Engh) for bone ingrown resulted in 95% in ingrown and 5% in ingrown suspension, showing excellent fixation. The abduction angle of the socket was 38.8±4.5 degrees, and the anteversion angle was 14.6±7.7 degrees, revealing that precise surgery was conducted. There were no joints which showed loosening in stem or socket, but CT imaging showed osteolysis in 5 joints (22%) in the stem side and 12 joints (52%) in the acetabular side. Dislocation in Poly Liner occurred in 4 cases which needed revision surgery with accumulated survival rate of 82.6. Summary: When cementless Metasul Hip System was used, fixation of stem/metal shell was excellent, but there were problems in thickness and fixation of Poly Liner. Due to augmentation of activity, backside wear occurred, and osteolysis or dislocation of the liner was induced. THA System such as M2a which improves these defects using metallic liner may be promising hereafter

The main problem of modern total hip replacement is the reduction of wear debris. Hence, new tribological partners such as ceramic on ceramic, metal on highly crosslinked polyethylene and metal on metal have evolved. Of these new combinations metal on metal has the longest history. The early problems of high friction using a “micro-fit” between acetabulum and femoral head have been solved by introducing an optimal clearance between the head and the cup to allow for small deformations of the acetabulum during activities without locking. The annual wear rate of metal on metal combinations has been shown to be extremely low ranging from 2 to 5 micrometers/year only. A further advantage of Metasul may be the “wearing in of small scratches” as well as forgiving slight malpositions of the acetabulum, which is not the case in ceramic – ceramic combinations. However, Metasul should not be implanted in patients with renal failure or severe allergies. Metal-metail pairing has proven a valuable alternative in young and active patients over the last 10 years

Introduction: Total hip replacements (THR) with the first generation metal-on-metal articulation were abandoned in 1970s in favour of metal-on-polyethylene articulation. Osteolysis due to polyethylene wear particles renewed the interest in metal-on-metal articulations. The second generation had improved clearance, metal hardness and reproducible surfaces. We describe the 10-year outcome of 63 THR with Metasul metal-on-metal articulation. Methods: From 1995 to 1996, 86 patients (90 hips) underwent THR with Metasul articulation and cemented CF-30 femoral stem. Of these, 55 hips had a cemented Stuhmer-Weber-Allopro cup and 35 hips had an uncemented Allofit cup. Eleven patients (12 hips) died and five patients (6 hips) were not available for clinical evaluation. However all had been contacted and it was known that the hip was not painful and had not been revised. Nine patients were lost to follow up. Thirty nine hips in cemented group and 24 hips in uncemented group had clinical, radiological and Oxford hip score (OHS) at minimum of 10-years follow-up after the operation. Results: The minimum length of follow up was 10-years with an average of 10.8 years. The average OHS at 10 years for the cemented group was 23 (range 12 – 42) and for the hybrid group was 20.3 (range 12 – 37). Five out of 63 (8%) hips had revision surgery. Two revisions (3%) were performed because of infection, 1 was revised (1.5%) because of unexplained pain and suspected metallosis and 2 were revised (3%) for suspected aseptic acetabular cup loosening. Conclusion: In comparison with the outcome of first generation metal-on-metal bearing, the hips in our study had lower rate of revision due to acetabular wear and loosening. This is the first study to show that the Metasul articulation has good outcome over a 10-year period. The survivorship is 97% with aseptic loosening as the endpoint for revision surgery

The need for better durability and longevity in total hip arthroplasty in high demand patients is a constant challenge. For this purpose a metal-on-metal prosthesis with improved tribology was developed. Our early results of using this system are presented. Materials and Methods: From 1997 till present 68 Meta-sul hip arthroplasties were performed on 64 patients. 16 cases performed during 2001 were not included in the study due to short follow-up period. Of the remaining 52 cases, 39 were fully followed up (18 male and 21 female) and five were telephonically contacted. Six were lost to follow up and two died for reason not related to the THR. The average age at operation was 57y (27–77y), average height 163cm and average weight 79kg (50–180kg). 18 cases were left and 21 right sides. 4 patients had bilateral THR. There were 3 revision cases due to loosening of cemented cup and 3 post surgical hip procedures. The etiology of the hip pathology was OA in 23, AVN in 10, CDH in 3, two post surgical procedures and one Paget’s disease. The THR prosthesis system consisted of a Wagner type uncemented cup with a factory-assembled Metasul inlay. An uncemented collarless hydroxypaptite coated, Spotorno stem, with a modular 28mm head was used. Long stem was used in 3 cases and reinforcement cage in one. Additional screws (average of 3,4) were used for primary cup fixation. The anterolateral approach, laying either supine or on the side was performed. Average hospitalization time was 12 days. Full weight bearing was allowed as tolerated. Results: The average follow-up was 30 months. Average Harris Hip Score pre-operatively was 45 (15-74) and post-operatively 75 (15–99). Subjectively, 87% of the primary cases with various etiologies were satisfied with the outcome. The majority of patients had pain-free range of motion and returned to improved daily function. One technical intra-operative complication (false route) was resolved with immediate revision. Two patients required cerclage wiring due to a femoral crack. Immediate post-operative complications included 2 cases of persistent distal peroneal nerve palsy. Three cases of anterior dislocations were reduced and did not recur. A case of positive intra-operative culture was treated successfully with 6 weeks of intravenous antibiotic therapy. Late complications included one case of cup loosening and one of a painful hip with suspected infection that required revision with a cemented prosthesis. Radiographic examination included measuring of radiolucent lines around the femoral stem according to the zones described by Gruen et al. and acetabulum as described by DeLee and Charnley. No femoral radiolucent lines were found. Seven cases revealed partial ace-tabular radiolucent lines. Discussion: The Metasul metal-on-metal THR system was used so far with relatively satisfactory results in the early follow-up period despite the leaning curve. It is early to draw conclusions as to the superiority of this system over conventional metal-polyethylene bearing prosthesis. Long term follow-up studies are needed

Introduction: There has been a renewed interest in metal-on-metal articulation in hip joint Arthroplasty. The reason for having metal-on-metal articulation is to reduce the volume of wear particles that are produced with THR. The outcome of reduced particle formation will hopefully be reduced osteolysis. Methods: We reviewed the results of 139 primary hip arthroplasties (130 patients) performed using Metasul articulation and cemented Weber cup. Six patients were lost to follow-up leaving 133 hips (124 patients) for review with at least 5-year follow-up. The acetabular socket was the cemented Weber cup and Bone grafting of the acetabulum and application of a reinforcement ring was done where necessary. Cemented CF-30 femoral stem was used in all patients but one (PFMR). The study was conducted retrospectively based on the information collected from hospital notes and Orthocom database. Immediate post-operative films were seen to measure the cup and stem inclination and quality of cementing using the Barracks grading system. Results: There were 102 females and 22 males in the cohort. Mean age was 73 years (SD-7.46, range 58–86). Left to right hip ratio was 52:81. Most common Pre-operative diagnosis was Osteoarthritis (103) followed by Intracapsular fracture neck of femur (20). The average follow-up was 7.23 years (range 5–10.9). Mean pre-operative Harris hip score was 42.09 and mean post-operative hip scores were 90.01, 86.84, 87.42 and 84.63 at 1-year, 3-year, 5-year and final follow-up with the corresponding pain scores were 42.9, 41.84, 41.56 and 41.56 respectively. Only two hips were revised for aseptic loosening of the cup with a 93.4% implant survivorship at 12 years. There was no case of aseptic stem loosening. No untoward systemic effects were noted in the cohort. Discussion: We believe that in our study Metasul metal-on-metal articulation has shown satisfactory results with regards to aseptic loosening and reduction in osteolysis in medium-term

Aims: Do the short term results, histopathological þndings and metal ion concentration predict a better outcome of modern metal-on-metal Hip Resurfacings (BHR) in comparison with historic metal-on-polyethylene Resurfacings? Methods: Comparison of 241 BHR arthroplasties with a follow up from 6 months to 4 years with long time results of 305 WHR; of 7 BHR and 3 MetaSUL capsule tissue histologyñs and chromium and cobalt serum concentrations of 67 BHR patients and 32 patients after MetaSUL THR implantation. Results: We achieved mean Harris Hip Scores of 90–92 in our BHR series with no radiological signs of aseptic loosening and a revision rate of 1.7% after approx. 18 months in opposition to 8% of the WHR after 2 years. The BHR capsule tissue showed wear particles in only 2 of 7 cases in opposition to MetaSUL joints, where in every case wear particles were detectable. We found no statistical difference in metal ion serum levels between BHR and Meta-SUL joints. Conclusions: In our opinion the cementless press þt cup, the low wear metal-on-metal bearing and the conservative implantation technique of the BHR at least fundamentally improves the known disadvantages of the historic Resurfacings which may predict better long term results

Background: This study was undertaken to investigate the differences in the metal ion serum concentrations after implantation of a MetaSUL-THR and a Birmingham Hip Resurfacing in comparison to implant free subjects and to review the influence of factors, possibly influencing the wear behaviour of the articulation.

Methods: Serum levels of cobalt, chromium and molybdenum in 74 patients after primary implantation of a MetaSUL-THR and in 111 patients after BHR were compared with the levels found in 130 control subjects without implants. Serum ion concentration was determined by atomic absorption spectrophotometry. Furthermore, the correlation between serum ion concentration and in-situ time, implant size and cup inclination was studied.

Results: The chromium and cobalt concentrations of BHR-patients as well as the chromium concentration of bilateral MetaSUL-THR-patients, however, were significantly higher as the concentrations of patients with unilateral MetaSUL-THR and the control group. The molybdenum serum concentration was very similar in all investigated groups.

The chromium serum concentration in patients with unilateral MetaSUL-THR and in patients with BHR showed the highest level in the postoperative period from 7 to 12 months.

Analyses of the subgroups showed an association between higher cobalt serum levels and cup inclination greater than 50 in patients with unilateral MetaSUL-THR more than 12 months after implantation. A statistically significant negative correlation was detectable between implant size and chromium as well as cobalt serum concentration in BHR-patients studied more than 12 months after implantation.

Conclusions: Metal-on-metal bearings of large diameter result in a greater systemic exposure of cobalt, chromium and molybdenum ions than bearings of smaller diameter. It is not known to what extent the different levels are due to corrosion of the surfaces of the components or to the amount of wear particles produced.

The chromium concentrations were highest 7–12 months after operation, what may due to a running-in of the bearing like known from hip simulator studies.

Interestingly implant size and metal ion serum levels correlate negatively in the BHR-patients studied more than 12 months after implantation. That could be due to an existing fluid film lubrication in these bearings and may be caused by the thicker fluid film in bearings with greater radius.

We have updated our previous randomised controlled trial comparing release of chromium (Cr) and cobalt (Co) ions and included levels of titanium (Ti) ions. We have compared the findings from 28 mm metal-on-metal total hip replacement, performed using titanium CLS/Spotorno femoral components and titanium AlloFit acetabular components with Metasul bearings, with Durom hip resurfacing using a Metasul articulation or bearing and a titanium plasma-sprayed coating for fixation of the acetabular component. Although significantly higher blood ion levels of Cr and Co were observed at three months in the resurfaced group than in total hip replacement, no significant difference was found at two years post-operatively for Cr, 1.58 μg/L and 1.62 μg/L respectively (p = 0.819) and for Co, 0.67 μg/L and 0.94 μg/L respectively (p = 0.207). A steady state was reached at one year in the resurfaced group and after three months in the total hip replacement group. Interestingly, Ti, which is not part of the bearing surfaces with its release resulting from metal corrosion, had significantly elevated ion levels after implantation in both groups. The hip resurfacing group had significantly higher Ti levels than the total hip replacement group for all periods of follow-up. At two years the mean blood levels of Ti ions were 1.87 μg/L in hip resurfacing and and 1.30 μg/L in total hip replacement (p = 0.001). The study confirms even with different bearing diameters and clearances, hip replacement and 28 mm metal-on-metal total hip replacement produced similar Cr and Co metal ion levels in this randomised controlled trial study design, but apart from wear on bearing surfaces, passive corrosion of exposed metallic surfaces is a factor which influences ion concentrations. Ti plasma spray coating the acetabular components for hip resurfacing produces significantly higher release of Ti than Ti grit-blasted surfaces in total hip replacement

Introduction: Laboratory simulator and clinical retrieval studies of metal-on-metal (MOM) total hip replacements have shown that the metallic alloy, the femoral head radius, the clearance between the acetabular cup and femoral head and the cup thickness can influence the contact mechanics, the lubrication and the wear of the articulation. MOM hip resurfacing procedures have received significant attention recently. The purpose of the present study was to compare the contact mechanics between a MOM hip resurfacing implant and a MOM total hip replacement under identical conditions. Materials and Methods: A 50mm diameter DUROM. TM. MOM hip resurfacing prosthesis and a 28mm diameter Metasul. TM. MOM bearing system (Centerpulse Orthopedics, a Zimmer Company, Winterthur, Switzerland) were investigated. All implants were manufactured from wrought-forged high carbon cobalt chromium alloy (Pro-tasul 21WF. TM. ). The diameters of the DUROM. TM. femoral head and acetabular cup were 50mm and 50.145mm respectively, and the corresponding wall thickness of the acetabular component was around 4mm. The diameters of the Metasul. TM. femoral head and acetabular cup were 28mm and 28.12mm. Three-dimensional finite element models were created to simulate the contact between the bearing surfaces of both the femoral head and the acetabular cup fixed to a three dimensional anatomically positioned pelvic and femoral bone consisting of both cortical (with 1mm thickness) and cancellous regions. The load applied to both models was 3200N. Results: The maximum contact pressure at the bearing surfaces was found to be around 22MPa for the DUROM. TM. and the contact area between the femoral and acetabular components was predicted to be 237mm. 2. For the Metasul. TM. bearing under identical conditions, the maximum contact pressure and the contact area predicted were approximately 47MPa and 74mm. 2. respectively. Discussion: A large reduction in the contact pressure, which should improve overall tribological performances, was noted for the DUROM. TM. hip resurfacing prosthesis, as compared with the Metasul. TM. bearing. The main reasons for this reduction were the large diameter of the articulation and the small acetabular cup thickness of the DUROM. TM. system. In contrast, the Metasul. TM. bearing has a smaller head diameter, and relies on a polyethylene backing underneath the metallic cup inlay to reduce the contact pressure at the articulating surfaces

Metal-on-metal (MOM) bearings for artificial hip joints have attracted significant attention recently as a way of reducing wear and consequently wear particle induced periprosthetic osteolysis, which is the major cause of failure. One of the most widely used MOM total hip implants is the Metasul system (Zimmer GmbH), in which a thick polyethylene backing is used underneath the metallic inlay. The purpose of this study was to investigate the effect of the polyethylene backing on the transient lubrication under dynamic loading and velocity conditions representative of walking. A 28mm diameter Metasul bearing was analysed, and the predicted lubricant film thickness was compared with that for an all metallic cup. The predicted transient lubricant film thickness in the Metasul system was found to be significantly greater than the corresponding prediction from the all metal cup. Therefore it was concluded that the polyethylene backing may play an important role in the lubrication and overall tribological performance of the Metasul bearing system with a diameter of 28mm

The recent resurgence in the use of metal-on-metal bearings has led to fresh concerns over metal wear and elevated systemic levels of metal ions. In order to establish if bearing diameter influences the release of metal ions, we compared the whole blood levels of cobalt and chromium (at one year) and the urinary cobalt and chromium output (at one to three and four to six years) following either a 50 mm or 54 mm Birmingham hip resurfacing or a 28 mm Metasul total hip replacement. The whole blood concentrations and daily output of cobalt and chromium in these time periods for both bearings were in the same range and without significant difference

Purpose of the study: Long-term outcome of Charnley low-friction arthroplasty in young active patients is impaired worldwide due to wear of the polyethylene (PE) component and osteolysis. In the late eighties, reports of possible low wear with some former metal on metal total hip arthroplasties led to the reintroduction of metallic bearings. The aims of this work were to examine the rationale for using metal on metal bearings in primary total hip arthroplasty (THA) and report preliminary results obtained with cementless Metasul™-Alloclassic™ hips. Materials and methods: From January 1994 to March 1997, 64 cementless primary Alloclassic-THA (grit-blasted titanium SL stems and CSF treaded cups) with 28 mm Metasul bearings were performed. Mean age at surgery was 60 years (range, 36–73). Diagnoses were usual, mainly primary osteoarthrosis in 70 p. 100 of the hips. Two bearing surfaces were exchanged for late dislocation at 2.6 and 2.9 years. Thus, 62 hips in 58 active patients (4 bilateral) were reviewed after a minimum 2-year follow-up (mean 3.2 years, range 24–66 months). Results: Clinical results according to the Merle d’Aubigne and Charnley rating system were graded excellent or good in all 62 hips. Radiologically, calcar, atrophy and spot welds were noted in 93 p. 100 and 82 p. 100 of hips respectively. Proximal reactive and lucent lines and mild proximal stress shielding were observed in 8 p. 100 and 4.8 p. 100 of hips respectively. No osteolysis granuloma has thus far been observed in the vicinity of any component. Cobalt blood level remained normal, except in 6 cases due to occupational exposure (n = 1), possible impingement (n = 1) or an unknown cause (n = 4). All elevated cobalt levels (range 7 to 25 mg/l) were nevertheless far below the toxic limit. Discussion: Dislocation may be due either to the posterolateral surgical approach and/or early impingement with the first Metasul bearing design (head sleeve). Metasul acetabular component fixation is not restricted to only cementless metal-backing, unlike alumina-ceramic cups. The concern about the toxicity of metallic wear debris dissemination and the hematocarcinogenic risk must be taken into consideration as for any metallic THA. Follow-up is too short for the new polys for significant comparisons. Conclusion: Metal on metal tribology is well known in vitro and Metasul™ bearings have functioned in vivo for 12 years (120 000 Metasul hips worldwide) as was expected from laboratory tests. Obviously, this friction couple is not the unique answer to PE-wear and THA longevity, but, in light of current data, appears as a trustworthy solution available today

Introduction. There has been much discussion in the literature concerning the possible detrimental effects of metal ion circulating in the body after MOM THR. This study seeks to evaluate the differences in observed Co and Cr levels in blood after TKR and several popular THR options. Method. We compared chromium (Cr) and cobalt (Co) levels between three different hip replacement bearings and total knee replacements (TKR) over time. Blood samples were taken from patients who received metasul 28 mm (n=25), metasul 32 mm (n=25) and Durom (n=50) hip bearings and TKR (n=100), pre- operatively and post operatively at six, twelve and twenty-four month intervals. Blood samples were analysed for Co and Cr levels using ICPMS (Inductively coupled mass spectrometry) and reported as parts per billion. Results were compared using Kruskal-Wallis Test (nonparametric ANOVA). Results. No increase was seen in serum Co and Cr levels in TKR patients over time. There were statistically significant differences in Co levels between the TKR group and all bearing surfaces of THR (28, 32 mm and Durom), p<0.001 at two years. Cr levels were significantly higher (p<0.001) in Durom bearings vs TKR only at one year decreasing to p<0.01 at two years. Comparing ion levels over time in the hip group, only in the Durom cohort did serum Cr levels preop vs 12 and 24 months reach a statistical significance of p<0.001. For Co, all three bearings showed a statistically significant increment over time (p<0.01). Highest levels of ions were seen with the 28 mm bearings but comparison between the three THR bearings at two years showed no statistical difference in Cr or Co levels. Median blood Cr concentration did not exceed 1.6 ppb in any subgroup. All median Co concentrations were below 0.8ppb. Conclusions. Over a two-year period Co and Cr levels for TKR did not differ appreciably from preoperative levels. Both Cr and Co levels were only mildly elevated post THR for all bearings. Metasul 28 mm bearings require further follow-up as the Co levels were not seen to plateau at two years

Aims: A prospective multicentric study was carried out in patients having metal-on-metal METASUL components to check if the concentration markers of chromosomal damage (Sister Chromatid Exchanges (SCEñs) and Micronuclei (Mni) and that of Co, Cr, Ni and Mb in the body ßuids are affected by the implant of METASUL components within 6 months. Methods: 30 patients were enrolled homogeneous as to the exposition to mutagenic agents. Observation times were pre-op., 7 days, 2 months, 6 months; blood and urine samples were taken at each observation time, and the markers of chromosomal damage (blood) and the ion concentration (blood and urine) were measured. Results: measurements showed a 2-fold increase of Co in blood, a 10-fold increase of Co in urine, a 1.5-fold increase of Cr in the blood and a 3-fold increase of Cr in the urine at a follow-up of 6 months from the operation; the Ni blood concentration was also increased at the 7 day check-up. The study cohort did not show any modiþcation in the frequency of markers of chromosomal damage at any of the observation times. The amount of the SCEñs and Mni recorded at all the observation times did non correlate with each other nor with any of the ion levels measured in the blood and in the urine. Conclusions: the implant of prostheses with METASUL components determines an increase in the concentrations of mainly Co and Cr in blood and urine, but that this increase has no genotoxic effects on the peripheral lymphocytes in the selected group at a follow-up of 6 months