Medical alert advises follow-up of patients with metal-on-metal hip implants

The alert warns that some patients will develop progressive soft tissue reactions to metal-on-metal hip implants

The advice, published by the agency on 29 June, warns that soft tissue necrosis may occur in both asymptomatic and symptomatic MoM patients.

It states: ‘The majority of patients with MoM hip replacements currently have well-functioning hips. However, some patients will develop progressive soft tissue reactions to the wear debris associated with MoM articulations.’

The follow-up investigations could include MRI or ultrasound scan, and isolated fluid collection, the agency says.

‘Crucial’ role of physiotherapy

Physiotherapists could be vital to the early detection of problems with MoM implants, said Katie Monnington, a specialist hip physiotherapist at the Royal National Orthopaedic Hospital NHS Trust in Stanmore, north London.

Mrs Monnington, a member of the Association of Trauma and Orthopaedic Chartered Physiotherapists (ATOCP), told Frontline: ‘MoM hips can in the first instance, silently damage and impair the muscular stability system around the hip joint.

‘Physiotherapists play an important role in detecting these early muscle problems, which can create challenges for rehabilitation and should be investigated with an MRI scan.

‘And if an MoM hip is revised, post-operative physiotherapy is crucial to target the deep muscular stability system and to ensure that best muscle patterning and patient function can be achieved.’

Alister Hart, a consultant orthopaedic surgeon and director of research at the hospital, backs a multidisciplinary approach and spoke at an ATOCP meeting earlier year.

Professor Hart told Frontline that ongoing work at the London Implant Retrieval Centre aims to improve outcomes for hip implant patients.

‘We are establishing a better understanding of painful hip replacements and analysing prostheses that are removeddue to complications from MoM hips,’ she said.

‘This research, together with close multidisciplinary working, will facilitate how we best manage these patients.’

Improved outcomes for revision surgery

Despite the agency’s alert, data shows that patients who require metal-on-metal hip revision surgery are experiencing better outcomes in the UK than they did five years ago.

This is according to a new study carried out by researchers at the University of Oxford and funded by Arthritis Research UK and the Orthopaedics Trust.

The study examined data from the National Joint Registry covering 2,535 metal-on-metal hip replacement patients who required revision surgery after experiencing abnormal reactions to metal.

It found that outcomes following revision for MoM patients are now similar to the outcomes in patients with other types of hip replacement undergoing revision surgery.

Researchers behind the study suggest the change may be due to an increase in experience among surgeons.

Author: Robert Millett