UK medical device regulatory authority the MHRA has issued a Medical Device Alert (MDA) pertaining to the Ankle Evolutive System(AES) from French company Transystème-JMT Implants. The action follows the company’s issuance of a field safety notice last month which called for annual follow-up of all implantee patients due to the observed occurrence of so-called geodes, or subchondral cysts, resulting from localised osteolysis in association with the prosthesis.
The alert links neatly to recent calls for increasing reliance on registries and a heightened degree of post marketing surveillance, this alert coming about because of a review of the scientific literature by the British Orthopaedic Foot & Ankle Society (BOFAS), which indicates that this device displays a higher than expected frequency of osteolytic lesions. Although the reasons for these osteolytic lesions are currently unknown, the manufacturer has stopped distribution of this device until further clinical follow-up information becomes available.
The manufacturer has informed the MHRA that approximately 450 of these devices were implanted in the UK from 2002 to 2009 inclusive.
Responsible medical professionals are asked to identify patients implanted with AES total ankle replacement implants and in line with the original Field Safety Notice, follow up all patients at least annually. Clinicians are asked to consider CT scans for patients with increasing pain or X-Ray evidence of lesions, with more frequent follow up indicated for patients presenting with minor asymptomatic lesions.
Larger or multiple lesions may render patients candidates for surgical intervention which may include curettage with bone grafting or arthrodesis according to the Field Safety Notice.
The alert pertains to all lots of the product, unused inventory of which should be identified and quarantined for return to the manufacturer.
Interesting one this. A two minute search uncovers clinical evidence that these devices have been associated with osteolytic changes for some time, for example in this 2009 paper in which 37% of 130 consecutive cases showed radiographic evidence of such problems. What’s unclear is why this occurs, but perhaps even more interestingly, while the agencies cannot respond to every single piece of published clinical evidence, the data appear to suggest that this implant has fundamental issues potentially worthy of regulatory authority involvement before now.
Source: MHRA, JBJS(British)