Pseudotumors in association with well-functioning metal-on-metal hip prostheses: a case-control study using three-dimensional computed tomography and magnetic resonance imaging

Patients with metal-on-metal articulation in trapeziometacarpal total joint arthroplasty may have elevated serum chrome and cobalt

Serum chrome and cobalt was measured in 50 patients with trapeziometacarpal total joint replacement with metal-on-metal articulation and compared with serum chrome and cobalt values in 23 patients with trapeziometacarpal total joint replacement with metal-on-polyethylene articulation. In 10 of 50 (20%) patients with metal-on-metal articulation, slightly elevated serum chrome or cobalt values were found compared with only one in 23 (4%) patients with metal-on-polyethylene articulation. All metal values were lower than accepted 'normal values' for metal-on-metal hip arthroplasty and so considered not to be a general health risk. However, the mean disabilities of the arm, shoulder and hand (DASH) score was 24 in patients with elevated serum chrome or cobalt compared with 10 in patients with normal metal values (p < 0.05) suggesting a local clinical effect of the elevated serum chrome or cobalt values. We recommend that patients with trapeziometacarpal total joint replacement with metal-on-metal articulation are followed with DASH score and radiological examination every 3-5 years and serum chrome and cobalt should be analysed in symptomatic cases to learn more about possible local complications leading to, or arising from, metal debris.

High prevalence of adverse reactions to metal debris in small-headed ASR™ hips

BACKGROUND

There has been increasing concern of metal-on-metal (MOM) hip replacements regarding adverse reactions to metal debris. Information regarding prevalence and risk factors for these adverse reactions is scarce.

QUESTIONS/PURPOSES

The primary purposes of our study were to determine (1) the prevalence of adverse reactions to metal debris among patients who received small-headed (< 50 mm) Articular Surface Replacement (ASR™) prostheses in hip resurfacing procedures or the ASR™ XL prostheses during THAs at our institution, and (2) the risk factors for adverse reactions to metal debris and if they are different in hip resurfacing replacements compared with THAs?

METHODS

Small-headed ASR™ prostheses were used in 482 operations (424 patients) at our institution. After the recall of ASR™ prostheses, we established a systematic screening program to find patients with adverse reactions to metal debris. At a mean of 4.9 years (range, 0.2-8.1 years) postoperatively, 379 patients (435 hips) attended a screening program, which consisted of clinical evaluation, whole blood cobalt and chromium measurements, and cross-sectional imaging.

RESULTS

At followup, 162 hips (34%) have been revised. The majority (85%) were revised owing to causes related to adverse reactions to metal debris. The 7-year survivorship was 51% for the ASR™ hip replacement cohort and 38% for the ASR™ XL THA cohort, respectively. Reduced cup coverage was an independent risk factor for adverse reactions to metal debris in both cohorts. High preoperative ROM, use of the Corail(®) stem, and female gender were associated with an increased risk of adverse reactions to metal debris only in patients undergoing THA.

CONCLUSIONS

Adverse reactions to metal debris are common with small-headed ASR™ prostheses. Risk factors for these adverse reactions differ between hip resurfacing procedures and THAs. Our results suggest a more complicated failure mechanism in THAs than in hip resurfacing procedures.

Current literature and imaging techniques of aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL)

Aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) are a recognized complication of metal-on-metal bearing hip prostheses. There is an impending concern regarding the future investigation and management of patients who have received such implants. The current literature is discussed, and the current guidelines for management of these patients in the UK are reviewed. The various imaging techniques available, such as computed tomography, metal artefact reduction magnetic resonance imaging, and ultrasound are discussed and evaluated with respect to the assessment of patients with suspected ALVAL. The histopathological findings are discussed with images of the tissue changes provided. Images of the radiological findings are also provided for all general radiological methods. ALVAL and its radiological presentation is an important issue that unfortunately may become a significant clinical problem.

Infection versus ALVAL: acute presentation with abdominal pain

A 52-year-old man underwent bilateral articular surface replacement (ASR) DePuy in June 2006. Following a right femoral neck fracture 4 days postoperatively, he underwent revision to a cemented C-stem DePuy, a taper sleeve adaptor and a 47 mm diameter cobalt chromium femoral head. The patient recovered well with satisfactory 5-year follow-up. In September 2011 the patient presented to the accident and emergency department with a 5-day history of feeling unwell with right lower quadrant pain. Examination of the right hip was unremarkable apart from painful adduction. Blood tests showed raised inflammatory markers and white cell count. MRI scan showed a right iliopsoas collection which appeared to communicate with the hip joint. The patient underwent a direct exchange of the right hip prosthesis. The intraoperative clinical picture was suggestive of atypical lymphocytic vasculitis and associated lesions. The patient recovered well and was discharged home. At his last clinic visit he was well and pain free.

Revision of metal-on-metal hip arthroplasty in a tertiary center: a prospective study of 39 hips with between 1 and 4 years of follow-up

BACKGROUND AND PURPOSE

Operative findings during revision of metal-on-metal hip arthroplasty (MOMHA) vary widely and can involve massive soft tissue and bone disruption. As a result, planning of theater time and resources is difficult, surgery is challenging, and outcomes are often poor. We describe our experience with revision of MOMHA and provide recommendations for management.

PATIENTS AND METHODS

We present the findings and outcomes of 39 consecutive MOMHAs (in 35 patients) revised in a tertiary unit (median follow-up time 30 (12-54) months). The patients underwent a preoperative work-up including CT, metal artifact reduction sequence (MARS) MRI, and blood metal ion levels.

RESULTS

We determined 5 categories of failure. 8 of 39 hips had conventional failure mechanisms including infection and impingement. Of the other 31 hips, 14 showed synovitis without significant disruption of soft tissue; 6 had a cystic pseudotumor with significant soft tissue disruption; 7 had significant osteolysis; and 4 had a solid pseudotumor. Each category of failure had specific surgical hazards that could be addressed preoperatively. There were 2 reoperations and 1 patient (2 hips) died of an unrelated cause. Median Oxford hip score (OHS) was 37 (9-48); median change (ΔOHS) was 17 (-10 to 41) points. ΔOHS was similar in all groups-except those patients with solid pseudotumors and those revised to metal-on-metal bearings, who fared worse.

INTERPRETATION

Planning in revision MOMHA is aided by knowledge of the different categories of failure to enable choice of appropriate personnel, theater time, and equipment. With this knowledge, satisfactory outcomes can be achieved in revision of metal-on-metal hip arthroplasty.

MR imaging of metal-on-metal hip prostheses

Metal-on-metal (MoM) hip arthroplasty was expected to provide benefits over metal-on-polyethylene systems. After widespread placement of MoM implants, outcomes have been disappointing. MoM implants are associated with higher serum levels of metal ions, adverse periarticular soft tissue reactions, and increased long-term failure rates. In light of these findings, it is crucial that patients with MoM implants be closely monitored for adverse effects. MR imaging is ideally suited for assessment of these patients and complements standard clinical evaluation and laboratory testing. This article reviews the background of MoM implants, emerging data on complications, strategies for using MR imaging, and MR imaging findings in patients with reaction to metal.

A comparison of two resurfacing arthroplasty implants: medium-term clinical and radiographic results

The objective of this study was to perform a medium-term analysis comparing the clinical and radiographic outcomes of the CONSERVE® Plus (C+) and Birmingham Hip Resurfacing (BHR) arthroplasty systems. 137 hips were included in each cohort, with a mean follow-up of 60.0 ± 14.2 months and 63.3 ± 3.5 months in the C+ and BHR cohorts respectively. Latest review UCLA and HHS scores showed statistically significant improvements when compared with preoperative scores for both cohorts. UCLA and SF-12 physical component outcome scores were significantly different (p<0.01 and p = 0.04, respectively). Median serum chromium and cobalt levels were significantly increased in the BHR cohort (p = 0.001). Both cohorts demonstrated excellent Kaplan-Meier 5-year survival rates (96.9% in the C+ cohort, and 96.4% in the BHR cohort). Overall both implants appear to perform well in the medium term.

Prevalence of adverse reactions to metal debris following metal-on-metal THA

The purpose of this study was to determine the prevalence of adverse reactions to metal debris (ARMD) following large-diameter metal-on-metal total hip arthroplasty. The authors examined the potential for using magnetic resonance imaging to screen for pseudotumors in 108 hips 2 years postoperatively. Serum cobalt and chromium concentrations were measured in 80 hips that underwent unilateral total hip arthroplasty. The authors considered pseudotumors and aseptic lymphocyte-dominated vasculitis-associated lesions to be ARMD and compared metal ion levels between hips with ARMD (ARMD group) with hips with no ARMD (non-ARMD group). Magnetic resonance imaging revealed pseudotumors in 9 patients (10 hips, 9%). Five of these 10 hips were symptomatic and underwent revision surgery. Two other patients underwent revision surgery due to symptomatic cup loosening with aseptic lymphocyte-dominated vasculitis-associated lesions. Ten patients (12 hips) had ARMD. Serum cobalt and chromium concentrations were significantly higher in hips with ARMD than hips without ARMD. Other factors, including age, body mass index, sex, clinical score, acetabular cup inclination angle, and femoral head diameter, were not significantly different between the groups. Elevated metal ion levels suggest that ARMD is associated with increased metal wear. Magnetic resonance imaging provides sensitive screening for pseudotumors following metal-on-metal total hip arthroplasty.

The painful hip

The differential diagnosis of the painful total hip arthroplasty (resurfacing or total hip) includes infection, failure of fixation (loosening), tendinitis, bursitis, synovitis, adverse local tissue reaction (ALTR) to cobalt-chromium alloys, and non-hip issues, such as spinal disorders, hernia, gynecologic, and other pelvic pain. Assuming that the hip is the source of pain, the first level question is prosthetic or non-prosthetic pain generator? The second level prosthetic question is septic or aseptic? The third level question (aseptic hips) is well-fixed or loose? ALTR is best diagnosed by cross-sectional imaging. Successful treatment is dependent on correct identification and elimination of the pain generator. Treatment recommendations for ALTR and taper corrosion are evolving.

Metal-on-metal total hip arthroplasty: do symptoms correlate with MR imaging findings?

PURPOSE

To determine the prevalence of magnetic resonance (MR) imaging abnormalities after metal-on-metal total hip arthroplasty and to determine whether presence of symptoms correlates with findings at MR imaging.

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the institutional review board, and informed consent was waived. MR imaging was performed with conventional sequences and a 1.5-T clinical imager in 192 hips (174 patients) evaluated during a 15-month period. Two observers retrospectively reviewed the images for the presence and size of pseudotumor, communication with the pseudocapsule, wall thickness, synovial hypertrophy, compartmentalization, solid components, foci of wall susceptibility, osteolysis, bone marrow edema, abductor muscle or tendon abnormality, and Anderson MR grade (normal, infection, or varying severity of metal-on-metal disease). These findings were compared between asymptomatic and symptomatic patients by using the Fisher exact test or the Wilcoxon-Mann-Whitney test, as appropriate.

RESULTS

Prevalence of pseudotumors per patient and per hip was 69% (120 of 174 patients, 132 of 192 hips). Bone marrow edema (present in six asymptomatic patients and 19 patients with pain, P < .01) and tendon tearing (present in five asymptomatic patients and 13 patients with pain, P < .05) were predictors of pain. Presence of symptoms was not correlated with presence (P = .4151) or size of pseudotumors. Anderson MR grade binarized into normal versus abnormal showed moderate agreement between readers (κ = 0.439) but was also not correlated with symptoms (P = .6648).

CONCLUSION

The presence of bone marrow edema and abductor tendon tears but not the presence or size of pseudotumor was associated with patient pain.