Depuy | ASR Hip Resurfacing | Which Medical Device

Description

From Which Medical Device

The Articular Surface Replacement (ASR) hip resurfacing from DePuy was introduced in July 2003, at around the same time as a number of other hip resurfacing devices. It was marketed as having the advantages of a reduced diametrical clearance (said to reduce wear) and a sub-hemispherical cup which allowed a larger range of movement before impingement occurred. The device had a narrower stem than the Birmingham Hip Resurfacing (BHR), and therefore some surgeons believed it was more suitable for smaller sized patients.
The socket had a Porocoat surface for bone integration and the bearing surfaces were high carbon content, cobalt chromium alloy.

Joint registry data from the United Kingdom and Australia subsequently showed that the ASR was associated with a relatively high rate of revision when compared with some other devices (notably the Birmingham Hip Resurfacing (BHR)). The 6th annual report of the UK National Joint Registry showed a strong statistical correlation between the device implanted and the risk of revision (3 year revision rates: ASR 7.5%; Conserve 7.4%; BHR 3.3%; p<0.0001). A single surgeon series appeared to show early failures particularly associated with smaller sizes (Nargol et al in 2010).

A Medical Device Alert (MDA/2010/044) was issued on 25th May 2010 by the UK MHRA for DePuy ASR ™ acetabular cups following reports of higher than anticipated rates of revision. The alert recommended that follow up systems were put in place for patients with implanted devices, and that devices should be implanted in accordance with manufacturer’s instructions (revised in 2008). These instructions emphasise the need to obtain a cup inclination angle of between 40 and 45 degrees, although even with navigation, this degree of accuracy would likely have been difficult to obtain.

The device was withdrawn from sale in 2010.

Read our roundup of hip resurfacing devices.