Unicondylar sled knee prosthesis - risk of early wear

(Waldemar Link GmbH & Company.KG) Consider annual review of patients for up to 5 years after implantation, including X-rays to detect progression of bearing wear. (MDA/2014/018)

CAS deadlines

Action underway: 4 June 2014, action complete: 12 June 2014

Note: These deadlines are for systems to be in place to take actions and not for the completion of patient follow-up and testing.


Unicondylar sled knee prosthesis

Image of Unicondylar sled knee prosthesis.

Unicondylar sled knee prosthesis

Metal-backed tibial plateau Endo-Model® 7mm

Manufactured by Waldemar Link GmbH & Co. KG

Catalogue numbers: 15-2030/01, 15-2030/05 and 15-2030/09.

The metal-backed tibia plateau consists of a UHMWPE (plastic) part attached to a cobalt-chromium alloy (metal) plate. The total height of the tibial plateau is 7 mm.


Risk of early wear of the ultra high molecular weight polyethylene (UHMWPE) plastic part of the tibial plateau of this device.

In August 2013 Waldemar Link issued a Field Safety Notice informing clinicians that they had received reports of wear of the plastic part of the metal-backed tibial plateau Endo-Model® 7mm.
The manufacturer has informed the MHRA that the affected products have now been discontinued.

A total of 9 cases of wear of the plastic part of the device were reported to the manufacturer from outside of the UK. The implant failures occurred between 6 months and 5 years after implantation and analysis of the returned explants showed significant plastic wear. A definitive root cause for the wear events has not been determined by the manufacturer.

Wear of the plastic part of the plateau could lead to pain and stiffness. The debris generated by the wear could cause osteolysis, requiring device revision. In instances where wear leads to metal-on-metal contact, the resulting wear debris may lead to soft tissue damage requiring device revision.

442 devices were distributed in the UK between 2003 and 2013.

The MHRA is issuing this Medical Device Alert to ensure that clinicians are aware of this issue and consider appropriate follow up of patients implanted with affected devices.


  • Identify patients implanted in the last 5 years with these devices.
  • Consider annual review of patients for up to 5 years after implantation, including X-rays* to detect progression of bearing wear.
  • Retain explanted devices to facilitate investigation by the manufacturer.
  • Report all adverse events to the MHRA and to Waldemar Link.

  • In all cases, the benefit of ionising radiation screening should be weighed against the risks from radiation exposure on an individual patient basis, in line with the requirements of The Ionising Radiation (Medical Exposure) Regulations 2000

Action by

  • Medical directors
  • Orthopaedic departments
  • Orthopaedic surgeons
  • Staff involved in the management of patients with joint replacement implants


This MDA has been sent to:  

  • Clinical commissioning groups (CCGs)
  • Care Quality Commission (CQC) (headquarters) for information
  • HSC trusts in Northern Ireland (chief executives)
  • Local authorities in Scotland (equipment coordinators)
  • NHS boards and trusts in Wales (chief executives)
  • NHS boards in Scotland (equipment coordinators)
  • NHS England area teams for information
  • NHS trusts in England (chief executives)

Onward distribution

Please bring this notice to the attention of relevant employees in your establishment. 
Below is a suggested list of recipients.

CAS and SABS (NI) liaison officers for onward distribution to all relevant staff including:

  • CSSD
  • Medical directors
  • Orthopaedic clinics
  • Orthopaedic surgeons
  • Orthopaedic theatres
  • Risk managers

Independent distribution

Establishments registered with the Care Quality Commission (CQC) (England only) 
This alert should be read by:

  • Hospitals in the independent sector
  • Independent treatment centres

Please note: CQC and OFSTED do not distribute these alerts. Independent healthcare providers and social care providers can sign up to receive MDAs directly from the Department of Health’s Central Alerting System (CAS) by sending an email to: safetyalerts@dh.gsi.gov.uk and requesting this facility.

Manufacturer contact

Dr Thomas Mehler
Waldemar Link GmbH & Co. KG

Tel: +49 (0)40 53995-305
Email: t.mehler@linkhh.de


If you have any comments or feedback on this Medical Device Alert please email us at: dts@mhra.gov.uk


If you are in England, please send enquiries about this notice to the MHRA, quoting reference number MDA/2014/018 or 2013/008/029/081/002

Technical aspects

Ms Bayode Adisa or Ms Michelle Kelly
Medicines & Healthcare Products Regulatory Agency
Floor 4
151 Buckingham Palace Road
London SW1W 9SZ
Tel: 020 3080 7223 or 7145
Fax: 020 8754 3965

Email: bayode.adisa@mhra.gov.uk or michelle.kelly@mhra.gov.uk

Clinical aspects

Dr Neil McGuire or Dr Camilla Fleetcroft
Medicines & Healthcare Products Regulatory Agency
Floor 4
151 Buckingham Palace Road
London SW1W 9SZ
Tel: 020 3080 6800 or 6097
Fax: 020 8754 3965

Email: neil.mcguire@mhra.gov.uk or camilla.fleetcroft@mhra.gov.uk

How to report adverse incidents

Please report via our website: Reporting adverse incidents involving medical devices
Further information about CAS can be found on the CAS website 

Northern Ireland

Alerts in Northern Ireland will continue to be distributed via the NI SABS system.

Enquiries and adverse incident reports in Northern Ireland should be addressed to:

Northern Ireland Adverse Incident Centre
Health Estates Investment Group 
Room 17, Annex 6, Castle Buildings
Stormont Estate
Tel: 02890 523 704
Fax: 02890 523 900

Email:  NIAIC@dhsspsni.gov.uk


All requests regarding return, replacement or modification of the devices mentioned in this alert should be directed to the relevant supplier or manufacturer.

Other enquiries and adverse incident reports in Scotland should be addressed to:

Incident Reporting and Investigation Centre
NHS National Services Scotland
Gyle Square 
1 South Gyle Crescent
EH12 9EB
Tel: 0131 275 7575
Fax: 0131 314 0722

Email:  nss.iric@nhs.net
Incident Reporting and Investigation Centre 


Enquiries in Wales should be addressed to:

Improving Patient Safety Team
Medical Directorate 
Welsh Government 
Cathays Park
CF10 3NQ
Tel: 029 2082 5801

Email:  Haz-Aic@wales.gsi.gov.uk

Download documents

Medical Device Alert: Unicondylar sled knee prosthesis manufactured by Waldemar Link GmbH & Co. KG (MDA/2014/018) (99Kb)

Published 17 December 2014