Serum metal ion levels after second-generation metal-on-metal total hip arthroplasty

Introduction  

Metal-on-metal bearings for total hip arthroplasty are increasing in popularity. However, metal ion toxicity, metal hypersensitivity, and metal carcinogenicity are the causes concern for patients with metal-on-metal hip replacement. We investigated serum levels of cobalt and chromium ions in patients with successfully implanted second-generation metal-on-metal total hip arthroplasty (THA) using PINNACLE-A (DePuy, Warsaw, IN, USA).     

Serum metal ion concentrations after unilateral vs bilateral large-head metal-on-metal primary total hip arthroplasty

It is unknown if the presence of bilateral well-functioning large-head metal-on-metal (MOM) total hip arthroplasties (THAs) leads to higher serum metal ion concentrations than unilateral MOM THA. Elevated levels (chromium, 17 μg/L; cobalt, 19 μg/L) have been associated with poorly functioning MOM THA with metallosis. Fourteen patients having undergone bilateral and 25 patients having undergone unilateral large-head primary MOM THA were compared. Harris Hip Scores, University of California Los Angeles activity scores, radiographs, serum creatinine, and serum cobalt and chromium levels were obtained. Only cobalt ion levels were significantly higher in the bilateral group than in the unilateral group (1.8 μg/L vs 1.0 μg/L, P = .029). Comparatively, this magnitude is clinically rather low because ion levels did not approach those associated with metallosis in either group. We conclude that although patients with well-functioning bilateral MOM THA may have slightly higher cobalt levels, neither cobalt nor chromium levels approach those seen in poorly functioning MOM THA with metallosis.     

Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations

Background and purpose — Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival.

Patients and methods — 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome.

Results — 15-year implant survival was similar in both groups (MoM 96% [95% CI 88–100] versus MoP 97% [95% CI 91–100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5?μg/L) compared with the MoP cohort (0.4?μg/L, p < 0.001) and the mean chromium concentration was double in the MoM (2.2?μg/L) compared with the MoP cohort (1.0?μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93?μmol/L versus MoP 92?μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts.

Interpretation — This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.     

Long-term follow-up and metal ion trend of patients with metal-on-metal total hip arthroplasty

Purpose

Long-term studies are required to support the use of metal-on-metal (MoM) bearings in total hip arthroplasty (THA) given the concern about systemic metal ion release and reports of adverse local soft tissue reactions. The purpose of this study was to report the seven to 13-year clinical, radiographic, and metal ion results in patients following MoM THA.

Methods

We studied 163 prostheses after second-generation MoM THA between July 1997 and November 2003. Cobalt and chromium metal ions were collected using whole and analysed by inductively-coupled plasma-mass spectrometry.

Results

The mean follow-up was 8.87 years (range, 7–13 years). Four hips (2.5 %) were revised. The Kaplan-Meier survivorship was 91.3 % for revision for all causes, and 97.5 % when excluding the hips revised for a manufacturer’s defect. Median whole blood cobalt levels peaked at a value of 2.87 μg/L at four years (p < 0.0001 vs. pre-operative) and subsequently decreased to 2.0 μg/L after nine years (p = 0.002 vs. four years). Median chromium levels maximally increased up to 0.75 μg/L after five years (p < 0.0001 vs. pre-operative) and tended to decrease thereafter to values of 0.56 μg/L after seven years.

Conclusions

This seven to 13-year follow-up study indicates that the clinical and radiological results following MoM THA are satisfactory with low revision rates. Cobalt and chromium ion levels peaked at four and five years, respectively, and gradually decreased thereafter.     

Painful metal-on-metal total hip arthroplasty

Two patients were evaluated for the possibility of hypersensitivity to a Metasul articulation (Centerpulse, Austin, Tex) coupled with total hip arthroplasty. Serum was tested with a lymphocyte proliferation assay, and the capsular tissues from the hip were examined for perivascular lymphocytes. The diagnosis of hypersensitivity to Metasul could not be confirmed in these patients, and ultimately, the painful hip arthroplasties were felt to be caused by a combination of musculoskeletal problems.     

Serum metal ion concentration: comparison between small and large head metal-on-metal total hip arthroplasty

The purpose of this study was to compare serum metal ion concentrations (chromium and cobalt) in 3 groups, 2 with metal-on-metal articulations and a control metal-on-polyethylene group. Forty-six patients with good to well-functioning hips were recruited for the study. Serum ion levels of all patients were drawn, and Harris Hip Score, University of California, Los Angeles activity score, and radiographs were performed. Serum chromium concentrations were significantly lower in the large head group compared with the small head group (P = .013). There was no difference in the cobalt concentrations between the 2 groups (P = .087). There was a significant difference between both metal-on-metal groups when compared with controls for both chromium and cobalt levels (P = .0005 and P = .0004, control vs small; P = .001 and P = .0001, control vs large, respectively).     

Cobalt and chromium ion release after large-diameter metal-on-metal total hip arthroplasty

Seventy-five patients underwent unilateral metal-on-metal total hip arthroplasty using a large-diameter head. Serum levels of cobalt and chromium were determined. Significant increases in both cobalt and chromium were observed at 3 months (cobalt, 1.4 μg/L; chromium, 1.4 μg/L) compared with preoperative values (P < .001). At 1 year, the median cobalt and chromium levels were 2.3 and 2.1 μg/L, respectively, and the levels had increased significantly compared with 3 months (P < .001). There were no significant differences between levels of either metal at 1 or 2 years (cobalt, 2.3 μg/L; chromium, 1.6 μg/L). Pseudotumor occurred in 2 hips. Patients with large-diameter metal-on-metal total hip arthroplasty had higher circulating metal ion levels at 3 months and 1 year, with no additional significant increases at 2 years.     

Revision total hip arthroplasty for metal-on-metal failure

Metal-on-metal (MoM) arthroplasty systems became popular in the early-2000s due to presumed advantages of improved wear characteristics and superior stability. However, subsequent reports of abnormal soft-tissue reactions to MoM implants and national registry data reporting high failure rates raised concerns. Early outcomes of revision total hip arthroplasty (THA) for adverse reaction to metal debris (ARMD) were poor, leading to development of surveillance programs and a trend towards early revision surgery. Patients with MoM arthroplasties require surveillance, comprehensive history and physical examination, imaging with ultrasound or magnetic resonance imaging (MRI), and laboratory evaluation including metal ion levels. Operative strategies for revision THA vary from exchange of modular components to extensive debridement and reconstruction with revision components. Surgeons should be aware of the increased risks of dislocation and infection following revision THA for ARMD. However, there is growing evidence that early revision surgery prior to extensive soft tissue destruction results in improved outcomes and decreased re-operation rates. It is estimated that >1 million MoM articulations have been implanted, with a large proportion still in situ. It is imperative to understand the aetiology, presentation, and management strategies for these patients to optimise their clinical outcomes.     

Management of failed metal-on-metal total hip arthroplasty

The theoretical advantages of metal-on-metal (MOM) bearing couples in total hip arthroplasty (THA) have been recently balanced by concerns regarding adverse local and systemic effects. Higher than anticipated early revision rates have been reported by several joint registries. Failed MOM hips present with a spectrum of symptoms and findings and traditional methods of failure must be considered in addition to the failure modes that appear to be unique to the MOM bearing couple. Metal hypersensitivity and soft tissue immune reactions remain incompletely understood and require careful ongoing study. The tools available to evaluate MOM THAs and the indications for revision surgery remain to be defined. Outcomes following revision of MOM hips appear to depend on appropriate evaluation, early identification, and appropriate surgical management.     

Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study

Introduction  

Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring a large diameter metal head coupled with a polycarbonate-urethane liner.     

Serum cobalt levels after metal-on-metal total hip arthroplasty

BACKGROUND: Systemic cobalt dissemination from the Metasul Co-28Cr-6Mo-0.2C metal-on-metal total hip prosthesis has been demonstrated in the first year after implantation. The aim of this prospective study was to monitor the serum cobalt concentrations in patients during the first five years after total hip arthroplasty with a metal-on-metal articulation. METHODS: A total hip arthroplasty was performed without cement in 100 consecutive patients who had either unilateral osteoarthritis or unilateral osteonecrosis. Fifty patients were randomized to be treated with a metal-on-metal articulation, and fifty patients, with a ceramic-on-polyethylene bearing. The femoral stem was made of a Ti-6Al-7Nb alloy, and the threaded acetabular cup was made of commercially pure titanium. Blood samples were taken before the operation and at multiple time-points for five years after the operation. Serum cobalt concentrations were measured with use of atomic absorption spectrometry. RESULTS: In the metal-on-metal group, the median serum cobalt concentration was 1 micro g/L at one year after surgery and 0.7 micro g/L at five years. The median of the serum cobalt concentrations measured from three to twelve months did not differ from the median of subsequent measurements, with the numbers available. The median serum cobalt level in the control group of patients treated with the ceramic-on-polyethylene articulation was below the detection limit at all time-points. CONCLUSIONS: Systemic cobalt release from Metasul metal-on-metal articulations was demonstrated throughout the five-year study period. The median serum cobalt concentrations were found to be slightly above the detection limit and remained in a constant range. The serum cobalt concentrations did not reflect a so-called run-in wear period of the metal-on-metal articulations.     

Metasul非骨水泥金属对金属全髋关节置换随访报告

[目的]探讨Metasul非骨水泥金属对金属全髋关节假体在人工全髋关节置换术中的应用效果.[方法]对本科于2003年8月-2005年12月行Metasul非骨水泥金属对金属人工全髋关节置换术25例(30髋)患者进行了随访.包括临床评估和放射学评估,并检测血铬浓度和肾功能情况.[结果]23例28髋获得随访,平均随访3.6年(2.5～4.8年).患者的平均Harris评分由术前的49.5分提高到末次随访时的93.4分.3髋(11.5%)形成透亮带;1髋股骨形成局灶性骨溶解.1例术中坐骨神经受损,2.5年后除趾背伸肌力较弱外其他均完全恢复.1例糖尿病患者血糖未控制理想,术后4年发生假体周围感染但X线检查未见松动迹象.无一术后发生脱位、股骨骨折等并发症.末次随访时平均血铬浓度为0.82 μg/L(0.020～0.140 μg/L),较正常参考值(0.007、0.109)无明显升高,未发现因血铬浓度升高导致的肾功能损害和癌症、白血病等恶性疾病.[结论]Metasul非骨水泥金属对金属全髋关节假体在人工全髋关节置换术中的效果令人满意,但有必要做进一步随访,以了解与金属对金属关节置换有关的任何不良反应.     

Cobalt and chromium concentrations in patients with metal-on-metal and other cementless total hip arthroplasty

We measured the cobalt and chromium concentrations in the serum and urine of 32 patients with current designed metal-on-metal total hip arthroplasty and 43 patients with conventional metal on ultrahigh molecular weight polyethylene (UHMWPE) cementless total hip arthroplasty. The results of our study showed that the serum and urine chromium concentrations increased in 37.5% and 90.6%, respectively, of 32 patients with well-fixed metal articulation (the mean values were 0.09 microg/dl and 2.2 microg/l, respectively) and also increased in 28.6% and 85.7%, respectively, of 7 patients who received metal-on-UHMWPE articulation with loosened acetabular component or stem made of Co/Cr alloy (the mean values were 0.06 microg/dl and 1.6 microg/l, respectively). On the other hand, the serum and urine cobalt concentrations were below the detection limit in all patients.     

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

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

Large-diameter metal-on-metal cementless total hip arthroplasty in the elderly

To evaluate the clinical effectiveness and complications of large-diameter metal-on-metal prostheses, particularly in the elderly, we performed cementless total hip arthroplasty (THA) using metal-on-metal prostheses with large-diameter femoral heads (mean, 45 mm) in 59 patients (average age, 75.1 years) between January 2004 and December 2005. All procedures were performed using a posterolateral approach and spinal anesthesia. Average follow-up was 65 months. Pre- and postoperative Harris Hip Scores and SF-36 questionnaire results were recorded for all patients to evaluate the level of pain relief, improvement in physical function, and changes in quality of life. Postoperative radiographic images were used to document areas of osteolysis and probable aseptic loosening. Average preoperative Harris Hip Score was 36.1±5.7, compared to 69.4±8.3 at last follow-up (P<.01). Average preoperative SF-36 score was 33.6±7.4, compared to 71.8±6.4 at last follow-up (P<.01). There were no dislocations, aseptic loosening, or revisions. Our findings suggest that metal-on-metal cementless prostheses with large-diameter femoral heads in THA can produce satisfactory results with good durability, a low rate of dislocation and aseptic loosening, and a low incidence of revisions in the short term. The benefits of this technique for elderly patients, especially those with weak muscle power and reduced cognitive function, include avoidance of severe cement-injection complications and early functional recovery.     

Adverse reaction to metal debris after ReCap-M2A-Magnum large-diameter-head metal-on-metal total hip arthroplasty

Background and purpose The clinical findings of adverse reaction to metal debris (ARMD) following large-diameter-head metal-on-metal total hip arthroplasty (LDH MoM THA) may include periarticular fluid collections, soft tissue masses, and gluteal muscle necrosis. The ReCap-M2a-Magnum LDH MoM THA was the most commonly used hip device at our institution from 2005 to 2012. We assessed the prevalence of and risk factors for ARMD with this device.

Methods 74 patients (80 hips) had a ReCap-M2a-Magnum LDH MoM THA during the period August 2005 to December 2006. These patients were studied with hip MRI, serum chromium and cobalt ion measurements, the Oxford hip score questionnaire, and by clinical examination. The prevalence of ARMD was recorded and risk factors for ARMD were assessed using logistic regression models. The mean follow-up time was 6.0 (5.5–6.7) years.

Results A revision operation due to ARMD was needed by 3 of 74 patients (3 of 80 hips). 8 additional patients (8 hips) had definite ARMD, but revision was not performed. 29 patients (32 hips) were considered to have a probable or possible ARMD. Altogether, 43 of 80 hips had a definite, probable, or possible ARMD and 34 patients (37 hips) were considered not to have ARMD. In 46 of 78 hips, MRI revealed a soft tissue mass or a collection of fluid (of any size). The symptoms clicking in the hip, local hip swelling, and a feeling of subluxation were associated with ARMD.

Interpretation ARMD is common after ReCap-M2a-Magnum total hip arthroplasty, and we discourage the use of this device. Asymptomatic patients with a small fluid collection on MRI may not need instant revision surgery but must be followed up closely.     

No association between serum metal ions and implant fixation in large-head metal-on-metal total hip arthroplasty

Background — The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris.

Patients and methods — 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28–68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density.

Results — At 1–2 years, mean total translation (TT) was 0.04 mm (95% CI: –0.07 to 0.14; p = 0.5) for the stems; at 2–5 years, mean TT was 0.13 mm (95% CI: –0.25 to –0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1–2 and 2–5 years. At 2–5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < –1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)).

Interpretation — Most cups and stems were well-fixed at 1–5 years. However, at 2–5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the fixation of hip components in large-head MoM articulations at medium-term follow-up.     

Recurrent intrapelvic cyst complicating metal-on-metal cemented total hip arthroplasty

Spontaneous intrapelvic masses causing vascular compression raise the suspicion of a neoplasm or infection. We present a patient who developed a recurrent intrapelvic cyst 14 years after a McKee-Farrar total hip arthroplasty which presented as acute onset of lower limb swelling, threatening the vascularity of the limb. This cyst recurred three times, and the patient finally needed revision total hip arthroplasty. The most probable cause of the recurrence was the cement and metal wear debris. Such cysts have been described in the literature, but to the best of our knowledge, this is the only report that describes it complicating a metal-on-metal prosthesis. Received: 27 September 1999