MISMATCHED HIP REPLACEMENT COMPONENTS.

As well as bringing claims in relation to the DePuy ASR hip replacement and the AES ankle replacements, Pryers are now investigating the practice of mixing and matching hip components.

Pryers Solicitors have recently been instructed by a patient in Cheltenham who was fitted with a head and cup made by Finsbury and a stem made by Zimmer.  She was fitted with this combination again on her other hip 6 months later.

Unfortunately, within 2 years, she began to suffer from significant pain in both hips and was found to have developed large pockets of fluid on both hips.  The components had worn out and failed at the junction between the head and the stem, releasing metal debris into the tissue around the joint and into her blood.

She has undergone two operations to remove the components so far, but it is likely she will require another operation in the next couple of months.

Why is mismatching components a bad idea?

Hip stems, which are long pieces of titanium that go into the thigh bone, have a tapered section on the top.  The ball of the joint is a separate piece, made of a cobalt-chromium alloy, which has a tapered hole on the back.  For the head to fit securely onto the stem, the tapers must be exactly the same.  Any tiny difference in the taper angle, even a fraction of a degree, will probably result in early failure of the joint.

The problem can be clearly seen in the illustration below.

Mis-Matched Hip Replacement JointMis-Matched Hip Replacement Joint

Pryers work with some of the world’s leading orthopaedic and engineering experts and through this work, we know that taper angles are all slightly different between manufacturers.

Components from different manufacturers must not be used together and the products’ instructions for use specifically warn against doing so.

Another problem with mismatched components is that they are completely untested.  Normally, a manufacturer puts its components through an exhaustive testing process using simulators and they have protocols for monitoring and following up their hip components once fitted to patients.  However, no manufacturer would test how their component works when paired with a product from another brand.  Therefore, when a surgeon mixes brands, he cannot have any idea at all how well they will work or how long they will last.  It is unlikely that patients are told that the combination of components they are to receive are incompatible and untested.

Moreover, there is absolutely no clinical advantage to using an unmatched set of components.

If you are in the Cheltenham area and have suffered a failure of your hip replacement, please contact Richard Starkie or a member of his team at Pryers.

Tel: 0800 316 0166

Email: hips@pryers.co.uk

Our team of experts have a wealth of experience dealing with medical negligence compensation claims.