Limited need for screening of metal-on-metal hip resurfacing patients beyond 10 years of follow-up

Abstract

Background: National and international guidelines lack consistency on how to screen metal-on-metal (MoM) hip arthroplasty patients for adverse reactions to metal debris (ARMD). Long-term outcomes of MoM hip arthroplasty are scarce, hindering further development of such guidelines. We present the clinical, radiological and ARMD status of 158 cases of hip resurfacing with >10 years follow-up. Methods: A prospective analysis of a cohort of 298 consecutive hip resurfacing procedures was performed at a single institution. All patients underwent MARS-MRI scanning for pseudotumour screening at least once, regardless of symptoms. Implant survival and reasons for revision were analysed for all patients. Clinical, radiological and MARS-MRI results were analysed for 158 unrevised procedures with >10 years follow-up. Results: The implant survival was 85.9% at 14.5 years (95% CI, 81.9–90.6) with revision for all causes as endpoint and 92.3% with MoM disease-related revisions excluded (95% CI, 88.2–95.0). Of the 158 cases with >10 years follow-up, 1 had elevated metal ion levels, 29 had a stable C1 pseudotumour and 6 a stable C2 pseudotumour. All pseudotumours were observed within 3 years after initiating our intensified ARMD screening (2011), with no new pseudotumours observed after that period. Conclusions: We suggest that follow-up of MoM hip resurfacing patients beyond 10 years after surgery can be done with large intervals (i.e. every 5 years), and only earlier if a patient becomes symptomatic.

Ten-year results of a prospective cohort of large-head metal-on-metal total hip arthroplasty

“…6,12,[23][24][25] Other studies report that in asymptomatic patients with normal blood metal ion levels (< 2 μg/l) and normal ultrasound imaging, the risk of progression of ultrasound findings is small within five years of initial assessment. 26,27 Besides the local effect of metal debris, there are concerns about possible systemic toxic effects of elevated levels of metal ions found in large-diameter MoM THA. 28,29 Risk factors for elevated blood levels are malposition, taper issues, and prosthesis design.…”

“…Our study adds evidence to the hypothesis that elevated blood metal ion levels, as reported by several institutions, have poor discriminant ability in predicting pseudotumour formation. 26,27 In a study on MoM hip resurfacing, it was noted that the discriminatory capacity of cobalt alone was similar to cobalt and chromium combined, suggesting the limited utility of chromium ion levels. 34 It was recommended that the decision for revision surgery cannot be made based on blood metal ion values.…”

Median 10-year whole blood metal ion levels and clinical outcome of ReCap-M2a-Magnum metal-on-metal total hip arthroplasty

“…However, their implants were 2nd-generation Metasul implants and thus not directly comparable to our study ( 19 ). It has been suggested that beyond 10 years from surgery the appropriate follow-up interval for MoM hip resurfacing patients could be 5 years ( 4 ). Based on our data and these previous data we suggest that 5-year measurement interval for asymptomatic ReCap-M2a-Magnum patients may be sufficient in the future.…”

“…Reito et al have previously reported similar findings in their study of 154 ASR patients ( 25 ). It has been suggested that routine MARS-MRI imaging after 10 years of MoM hip implantation might not be beneficial ( 4 ).…”

“…The follow-up of these patients is important to recognise the failing implants, and also to identify and prevent systemic cobalt toxicity. Additionally, the long-term follow-up guidelines need to be updated to optimize the usage of limited healthcare resources ( 1 , 4 , 5 ).…”