MAUDE Adverse Event Report: STRYKER GMBH SLIDING CORE, UHMPWE,7MM; PROSTHESIS, KNEE, FEMOROTIBIAL, UNICOMPARTMENTAL, SEMI-CONSTRAINED, METAL/POLYME

Catalog Number	400141F
Medical Device Problem Code	Fracture (1260)
Health Effect - Clinical Code	No Information (3190)
Date of Event	03/19/2019
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
Once the investigation has been completed any additional information will be reported in a supplemental report.
Event or Problem Description
Sliding core broke after 6 years.After revision, debridement and implantation of a new sliding core were performed.
Additional Manufacturer Narrative
The reported event could be confirmed.Since the operative reports and x-rays were provided, the opinion of stryker's medical expert was requested.After analysis of the documents, they stated: "revision surgery after ankle replacement is not uncommon.Unfortunately it is more common than in hip and knee.Probably the wear and tear in the ankle is higher, also because of the complex movement in the ankle.The polyethylene core is exchanged after fracturing most often, but some surgeons replace it if revision is needed (also for other components) just to place a newer generation polyethylene core in the ankle.This is mainly done because these surgeons do acknowledge the higher wear on the ankle prosthesis.In this case an earlier intervention was not necessary of course.Looking at the literature, the mean time for polyethylene core fractures to occur is around 5 years, however the range is wide from just over 1 year to 10 years.In this case it was 6 years.I do not see a clinical or surgical explanation for the occurrence of this polyethylene core fracture." the device inspection revealed the following: the component is fractured in two halves perpendicularly to the sliding groove.A large zone of the sliding core is highly deformed, most probably due to an unbalanced repartition of the mechanical forces on the implant during the 6 years of implantation.This discrepancy in mechanical loading could be one of the reasons the material broke due to fatigue "faster".The ankle joint with a star implant is a complex mechanism of motion and is dependent upon proper alignment.A misalignment to this ankle joint complex system affects the interactions between metal and poly and causes degradation of the poly and visual wear on the metal.As a conclusion, according to our medical expert, no obvious clinical or surgical root cause can be noticed from the documents provided.However, patient related factors could explain the accelerated fatigue and wear of the device.Indeed, even a slight inadequate repartition of mechanical forces could have affected the devices lifespan.As a reminder, the ifu clearly reminds the users that: "appropriate selection, placement and fixation of the star ankle components are critical factors which affect implant service life." a review of the device history was not possible because the lot number was not communicated.No corrective actions are required at this time.A review of the labeling did not indicate any abnormalities.No indications of material, manufacturing or design related problems were found during the investigation.If any further information is provided, the investigation report will be updated.
Event or Problem Description
Sliding core broke after 6 years.After revision, debridement and implantation of a new sliding core were performed.

• Brand Name: SLIDING CORE, UHMPWE,7MM
• Common Device Name: PROSTHESIS, KNEE, FEMOROTIBIAL, UNICOMPARTMENTAL, SEMI-CONSTRAINED, METAL/POLYME
• Manufacturer (Section D): STRYKER GMBH; bohnackerweg 1; postfach; selzach 2545 ; CH 2545
• MDR Report Key: 8487670
• Report Number: 0008031020-2019-00350
• Device Sequence Number: 2798475
• Product Code: NTG
• UDI-Device Identifier: 00886385026930
• UDI-Public: 00886385026930
• Combination Product (Y/N): N
• Initial Reporter Country: CH
• PMA/510(K) Number: P050050
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Device Implanted Year: 2013
• Device Explanted Year: 2019
• Reporter Type: Manufacturer
• Report Source: health professional
• Initial Reporter Occupation: Physician
• Type of Report: Initial,Followup
• Report Date (Section B): 05/03/2019

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Operator of Device: Lay User/Patient
• Device Catalogue Number: 400141F
• Device Lot Number: UNKNOWN
• Was Device Available for Evaluation?: Device Returned to Manufacturer
• Date Returned to Manufacturer: 04/11/2019
• Initial Date Received by Manufacturer: 03/19/2019
• Supplement Date Received by Manufacturer: 04/11/2019
• Initial Report FDA Received Date: 04/05/2019
• Supplement Report FDA Received Date: 05/03/2019
• Is This a Single-Use Device that was Reprocessed and Reused on a Patient? (Y/N): No
• Patient Sequence Number: 1
• Outcome Attributed to Adverse Event: Required Intervention
• Patient Age: 75 YR
• Patient Weight: 75