Score Knee Prosthesis

Safety alert - higher than expected revision rate when used without patella resurfacing

24 March 2015

Consumers and health professionals are advised that Amplitude Australia, in consultation with the TGA, has issued a safety alert for its Score Knee Prothesis due to a higher than expected revision rate for these implants when used without resurfacing the patella. In addition the alert notes that Score knee replacements using cementless fixation have a higher revision rate than when they are used with cemented fixation.

Knee implants can be used in a variety of configurations. Implants can be used "cemented" in which an adhesive helps to hold them in place against both the femur and tibia or "cementless" in which no adhesive is used. Another option is to use a "button" to "resurface" the back of the patient's patella and keep it from potentially rubbing against the implant as the knee bends.

Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) Report 2014 show that the revision rate for the Score Knee Prosthesis when used without a patella button is higher than the revision rate of other knee implants being used in Australia. The revision rate of cemented Score Knee Prosthesis implants is substantially lower than the rate seen after cementless fixation.

Information for consumers

Amplitude Australia has contacted surgeons who have used Score Knee Prosthesis implants advising them of the issues outlined above.

If you have had a knee replacement and experience long-term pain, instability and/or decreased range of motion, or if you have any questions or concerns, please contact your surgeon or the hospital where the surgery was undertaken.

Information for health professionals

Patients who have had a knee replacement and who have any questions or concerns about the above issue should be referred to their surgeon or the hospital where the surgery was undertaken.

Information for orthopaedic surgeons

Amplitude Australia has contacted surgeons who have used the Score Knee Prosthesis implant, providing further information about the above issue.

Representatives from Amplitude Australia will follow up with each individual surgeon to arrange a discussion about its recommendations for management of the patella component.

Surgeons are advised to be alert to these issues.

Additional information

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An AOANJRR analysis compiled in September 2014 indicates that the Score Knee Prosthesis revision rate is significantly higher for cases where no patella button is implanted at the time of primary surgery, regardless of the fixation strategy employed. In comparison, the revision rate of cemented Score Knee Prosthesis implants when the patella button is used is low compared to other knee implants. The revision rate of cementless Score Knee Prosthesis implants when the patella button is used is not materially different than that of other implants.

Table 1. AOAJNRR analysis of Score revision rates

  Cumulative % revision at 1 Year (95% conf. limits) Cumulative % revision at 2 Year (95% conf. limits)
Cemented, patella used 0.0 (0.0, 0.0) 0.9 (0.1, 6.4)
Cemented, no patella 2.1 (0.5, 8.0) 2.1 (0.5, 8.0)
Cementless, patella used 0.4 (0.1, 2.7) 2.5 (1.0, 5.9)
Cementless, no patella 1.9 (1.1, 3.4) 3.9 (2.5, 6.0)
Other total knee 1.0 (1.0, 1.1) 2.1 (2.1, 2.2)

In October 2014 the AOAJNRR annual report indicated that only the cementless version of the Score implant was experiencing higher than expected revision rates, with 47 revisions from 1182 primary procedures. The reported revision rate was 1.48 revisions per 100 observed years and a cumulative percent revision rate of 6.5 at 5 years. The revision rate of all other knee implants in the annual report was 0.70 revisions/100 observed years, or 2.8% at 3 years and 3.8% at 5 years.

Reporting problems

Consumers and health professionals are encouraged to report problems with medical devices. Your report will contribute to the TGA's monitoring of these products. For more information see the TGA Incident Reporting and Investigation Scheme (IRIS).

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medical device.