Introduction  

This document provides guidance for manufacturers of joint replacement implants. It outlines specific scenarios to consider when determining if an incident is reportable. You should read this document in conjunction with guidance on post market surveillance.  

The aim of this guidance is to complement the requirements of SI 2024 No.1368. You should read it in conjunction with this regulation. Device specific guidance does not replace or extend these requirements.  

What to report 

UK national regulations require manufacturers to notify the MHRA if: 

• they know of any malfunction or deterioration in the characteristics and/or performance of a joint replacement implant, as well as any inadequacy in the labelling or the instructions for use which might lead to, or might have led to, the death of a patient or to a serious deterioration in their state of health, including a clinically relevant increase in the duration of a surgical procedure, as defined by the operating surgeon 

• the joint replacement implant has been involved in any field safety corrective action connected with a deterioration in the characteristics or performance of an implant that could lead to the death or the deterioration in the state of health of a patient 

Reporting joint replacement revisions 

There are a number of reasons why joint replacement implants are revised. These include, but are not limited to: 

• infection of the operation site (septic loosening) 

• malpositioning or misalignment of one or more of the implant components during implantation 

• mechanical failure of one or more of the implant components, for example, fracture of hip stems or knee tibial trays, excessive wear of hip acetabular cups or knee tibial components 

• aseptic loosening of one or more of the implant components 

• associated anomalous soft tissue changes 

Revision of a joint replacement implant is a serious deterioration in a patient’s state of health since it necessarily requires surgical intervention to prevent permanent impairment of body function or permanent damage to body structure. 

However, only revisions where there has been an implant failure or deterioration of the implant, or anomalous local or systemic changes which may be related to the implant are reportable. 

Infection / misalignment / malpositioning 

We generally consider revisions carried out primarily because of infection or misalignment or malpositioning during implantation not to be malfunction or deterioration of the implant. They are not therefore usually reportable under the vigilance system.  

Misalignment or malpositioning are however reportable if they have occurred as a direct consequence of the design of the implant or of the design of the instrumentation intended to be used in conjunction with the implant. 

Mechanical failure 

We consider revisions carried out secondary to mechanical failure of the implant (however long it has been implanted) to be a malfunction or deterioration of the implant. They are therefore reportable unless there is clear evidence that the main cause of failure was not implant related. Examples of potentially non-reportable cases include, but are not limited to: 

• inappropriate implant selection 

• misalignment / malpositioning during implantation (unless such misalignment / malpositioning resulted as a direct consequence of the implant’s design) 

• failure of the cement to bone interface in cemented implants (this should be reported by the cement manufacturer) 

Aseptic loosening 

We consider revisions carried out primarily because of aseptic loosening within the expected life of the implant (as specified in the information supplied with the implant by the manufacturer) to be a malfunction or deterioration of the implant. They are reportable. If the expected life of the implant is not specified, revisions due to aseptic loosening within 10 years of primary implantation should be reported. 

Associated anomalous soft tissue changes 

Revisions carried out where there are surrounding anomalous soft tissue changes, including soft tissue necrosis, pseudotumours or pathological changes typical of hypersensitivity, should be reported, regardless of whether or not the implant is misaligned or malpositioned. There is presently an unestablished cause/effect relationship between these changes and joint failure and the MHRA thus considers them to be a malfunction of the implant for the purpose of vigilance. See advice from the MHRA expert advisory group on the biological effects of metal wear debris generated from hip implants. 

Blood metal ions and systemic changes 

There is a paucity of evidence concerning the relationship between blood metal ion concentrations and systemic changes or genotoxicity. Therefore, all systemic side effects associated with high blood metal ion concentrations, including those related to birth defects and malignancy should be reported for the purpose of vigilance. High blood metal ion concentrations in the absence of side effects or revision surgery do not need to be reported. 

Reason for revision not clear 

In some cases, the reason for revision may not be well defined, may involve a number of aetiologies, or may present novel or previously unrecognized factors. In these circumstances, the incident should be reported.