Adverse Reaction to Metal Debris from Biomet Metal Hip Arthroplasty


Research Title: Adverse Reaction to Metal Debris after ReCap-M2A-Magnum Large-Diameter Head Metal on Metal Total Hip Arthroplasty

Background and Purpose:

Adverse reaction to metal debris (ARMD) is a type of implant failure that can occur after metal-on-metal hip replacements. The symptoms of ARMD failure may include fluid collections around the hip, a build-up of soft tissue around the hip, and gluteal muscle necrosis (a condition where the cells of the gluteal muscles decompose, often causing a build-up of dead tissue).

The Biomet ReCap M2a Magnum was a very popular hip implant for patients receiving metal-on-metal total hip replacements between 2005 and 2012. This study aims to answer two questions: what are the warning signs that the ReCap-M2a-Magnum device might be failing due to ARMD? And how common it is for this device to fail?


This study focused on 74 patients (80 hips total) who received the Biomet ReCap-M2a-Magnum device between 2005 and 2006 in order to assess how common it is for this device to fail and what symptoms might indicate its failure. On average, patients were examined 6 years after receiving the implant. The researchers examined the patients by taking MRI scans, measuring levels of chromium and cobalt in the blood, filling out the Oxford hip score questionnaire, and conducting basic clinical examinations. Based on these measurements, implant failure was considered definite if elevated chromium or cobalt levels were above 10 µg/L and/or if there was a solid mass or fluid collection greater than or equal to 50 mm on the MRI scan. Implant failure due to ARMD was considered probable or possible if chromium or cobalt blood levels were above 5 µg/L or if the MRI revealed any collection of fluid or tissue.


In total, the implant had a definite failure in 11 of the 80 hips; three of the patients with definite failure required a revision operation. Another 32 hips were determined to have a probable or possible failure. This means that, overall, there was some degree of failure in 43 of the hips studied, and only 37 hips did not show symptoms of implant failure.

MRI scans also showed that 46 hips had developed a soft tissue mass or a collection of fluid.

Common symptoms or warning signs associated with definite implant failure include clicking in the hip, swelling of the hip, and a feeling that the hip is dislocated.


Failure of the ReCap-M2a-Magnum is common, and the researchers discourage doctors and patients from using this device.

Implant failure due to ARMD has many potential warning signs. Patients with definite failure experience clicking, swelling, and a feeling that the hip is dislocated. Another indicator of implant failure is a high level of chromium and cobalt in the patient’s blood. Additionally, MRIs may reveal fluid collections surrounding the hip, build-ups of soft tissue surrounding the hip, and gluteal muscle necrosis (a condition where the cells of the gluteal muscles decompose, often causing a collection of dead tissue) in patients with probable to definite failure. Patients who show small fluid collections in their MRI scans may not need a revision surgery immediately, but they should be followed up closely, even if they do not show any other symptoms of hip implant failure. In order to detect and diagnose implant failure, physicians must be sure to optimize the MRI scanner to reduce image distortions by metallic implants.


There is a lot of concern over the high failure rates of large-diameter head metal-on-metal total hip replacement implants like the ReCap-M2a-Magnum.

It is hard to tell when, exactly, revision surgery is needed. However, at the absolute latest, the revision surgery should be performed before the gluteal muscle cells start to deteriorate (before gluteal muscle necrosis occurs).

Patients with normal cobalt and chromium levels in their blood could still have ARMD, and high cobalt and chromium levels alone are not sufficient to diagnose implant failure due to ARMD. Therefore, screenings for ARMD must include more than just cobalt and chromium measurements.

ARMD is definite among patients with a soft tissue mass of any size. ARMD is either probable or definite in patients with fluid collections greater than or equal to 50 mm.


Mokka J, Junnila M Seppanen M Virolainen P, Polonen T, Vahlberg T, Matilla K, Tuominen E, Rantakokko J, Aarimaa V, Kukkonen J, Makela K.  Adverse reaction to metal debris after ReCap-M2A-Magnum large-diameter-head metal-on-metal total hip arthroplasty. Acta Orthopaedica 2013; 84 (6): 549-554

More Info About the Research

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