Main Causative Factor in the Failure of the DePuy ASR and ASR XL Devices

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Size of the devices:
The role of the large-diameter ASR devices in males are linked with considerably lower metal ion levels in contrast to the BHR devices, proposing that under perfect in vivo conditions the ASR has a less wear rate than the BHR device (Underwood et al. 2011). Although, problems also occurred with the smaller hip resurfacing implants among women and small men. It was discovered that these implants did not lubricate as well, unlike the bigger implants and therefore they produced a large amount of metal debris and produced a very concentration of metal ions in the blood. (Cohen 2012).
Acetabular component:
The BHR hip device is more innovative than the ASR device as it has a hole used for wires to fix the introducer. The ASR device does not have this. (Underwood et al. 2011).

Positioning of the components:
The difference can be seen in the sub optimally positioned components within 10° of Lewinnek’s safe zone in the occurrence of edge loading and rate of wear in both the ASR and the BHR devices (Underwood et al. 2011).

Wear and inclination of the acetabular component:
A major positive correlation was seen between the wear and inclination of the acetabular component with the BHR device (p = 0.01) which was not seen with the ASR device (p = 0.6). This suggests either that the ASR devices have a higher wear rate at all inclinations or that the ‘safe zone’ that escapes edge loading is a lot thinner than that of the BHR device (Underwood et al. 2011).

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