When metal hip replacements go wrong

Hip replacement surgery is very common, restoring mobility and quality of life to thousands every year in the UK. It is recognised to be the most cost effective for the NHS in returning patients to productive lives. The components wearing surfaces may be metal, ceramic or plastic, and will often last over 20 to 25 years, or even longer for some people. 
 

In 1997, metal on metal hip bearings first came on the scene, promoted particularly to younger candidates for surgery due to the components’ believed longevity. However, several years later previously unknown risks and unintended issues began to emerge.

Risks of metal debris soft tissue reaction

In the early 2000s, it was discovered that metal components may release metallic debris into the body, as they wear together.

Some recipients may develop an adverse reaction to metal debris (ARMD) (also known as metallosis) which untreated may lead to bone and/or tissue damage, eventual failure of the hip replacement and limited options for revision surgery if the damage is extensive. In the devastating cases we have seen, a patient may have no choice but to undergo a Girdlestone procedure (also known as an excision arthroplasty) where the ball and socket of the hip joint are removed, leaving future mobility severely restricted.

Between 2010 and 2017, guidance was issued by the Medicines and Healthcare products Regulatory Agency (MHRA) alerting hospitals and surgeons across the UK to these risks.

Current guidance requires recipients to be annually monitored through:

1. Oxford Hip score assessment, and
2. Blood chromium and cobalt tests, and / or
3. Radiology (by x-ray, CT or MRI)

Revision surgery should be considered if:

1. Imaging is abnormal, and / or
2. Blood metal levels are rising, and / or
3. Hip related clinical function or Oxford Hip score is deteriorating

Risks of mix and match metal hip replacements

It also emerged that some surgeons had been mixing and matching hip replacement components from different manufacturers. Between 2003 and 2013, 15% of total hip replacements (over 90,000) in England and Wales contained mixed metal on metal components.

The practice is often against manufacturer guidance. The majority of manufacturers state in their instructions for use that surgeons should only use components from the same manufacturer, otherwise they would be working “off label”.

There have been reports that use of a Birmingham or Finsbury Adept head and cup, with a Zimmer CPT stem has a higher failure rate than a standard hip with compatible components. The body of the stem has been found to corrode inside the femur, causing an adverse reaction to metal debris, and leading to severe damage to bone and soft tissue. This mixed manufacturer combination greatly increases the general risk of metallosis from metal hip replacements.[1]

Medical negligence claims

Medical negligence claims for mix and match hips or metal on metal hips may arise in the following circumstances:

Monitoring claims

Failure to monitor in line with applicable guidance may give rise to a medical negligence claim.

For example, by establishing:

1. Monitoring should have prompted treatment, such as revision surgery, and,
2. Failure to monitor resulted in further deterioration of the patient’s hip joint and/or failure of the hip replacement, such that,
3. The patient’s condition and prognosis is worse than if they had been treated earlier in line with appropriate standards of care

Mix and match claims

Implanting mix and match hip components may also give risk to a medical negligence claim.

Claims have been successfully settled against surgeons (and their NHS Trusts) who combined Birmingham heads and Finsbury Adept heads, with Zimmer CPT stems.[2]

Claimants have sought to establish liability on various grounds:

1. Surgical method itself was negligent – there was no need to use non-compatible components
2. Surgeon failed to obtain informed consent for the mix and match replacement
3. Surgeon created a new device by using a combination of components not intended by the manufacturers, without requisite authorisation under the Consumer Protection Act 1987

Conclusion

It is important patients are fully informed of the benefits and risks of surgical options available to them well before surgery and properly monitored to prevent bone and tissue destruction. Regular monitoring is advised in recognition that some patients will develop progressive soft tissue reactions to the wear debris associated with metal on metal articulations.

The majority of recipients of metal hip replacements in England, Wales and Northern Ireland continued to have well-functioning hips in 2017, according to the Metal on Metal Expert Advisory Group. However, it has been noted that that soft tissue necrosis may occur in both asymptomatic and symptomatic patients. Therefore, early detection through close monitoring should give a better revision outcome should this become necessary.

If you are concerned you may have experienced negligence in relation to your hip surgery and / or monitoring, you are welcome to contact us on +44 (0)20 7814 1200 or by email at enquiries@kingsleynapley.co.uk to discuss the matter further.