Modular to Monoblock: Difficulties of Detaching the M2a-MagnumTM Head Are Common in Metal-on-metal Revisions

Abstract

Background Modern hip implants typically feature modular heads, which allow for easy exchange and removal from the femoral stem at the time of revision. However, owing to fretting, corrosion, or cold welding, the modular head may be difficult or impossible to separate from the underlying trunnion, especially if the implant has titanium interfaces between the head and the stem. We have repeatedly encountered difficulty removing the titanium sleeve adapter in the M 2 a-Magnum TM implant. Although the manufacturer warns about this complication and cases with these difficulties have been reported to the United States FDA, we believed this topic is important to study, because the frequency of difficulties in head removal is unknown and the complications related to this event have not been characterized. Although the global use of metal-on-metal implants in THAs has decreased dramatically during the last several years, many thousands remain in service and therefore still might require revision. It is crucial to be prepared with special tools, including a femoral head extraction tool and diamond saw. The patient has to be informed of the possibility of a more extensive operation than preoperatively planned. Level of Evidence Level III, therapeutic study.123 Clin Orthop Relat Res (2016) 474:1999-2005 DOI 10.1007/s11999-016-4774-7 Clinical Orthopaedics and Related Research ® A Publication of The Association of Bone and Joint Surgeons® stem revision owing to difficulties with head removal.

Systematic Screening of Adverse Reactions to Metal Debris after Recap-M2A-Magnum Metal-on-Metal Total Hip Arthroplasty

“…The reasons for revision were not assessed in the study by Bosker et al (13); however, we agree that the early detection of pseudotumors is important because if revision surgery is performed in patients before substantial soft tissue damage has occurred, the outcome is likely to be better. Furthermore, many of the ReCap-M2a-Magnum THA revisions in our clinic were complicated by cold-welded femoral heads and adapters, which is a unique feature of this device (28).…”