Lecture 1 - Introduction

Question 1

Overview of DePuy ASR hip case

Answer 1

Metal on metal hips recalled in 2010, 2016 settlement of class action for $250m without admission of liability

Question 2

Cause of the problem with the DePuy ASR hip case

Answer 2

Acetabular cup design (more shallow) increased edge loading, increasing risk of wear

Question 3

How was the problem with the DePuy ASR hip identified?

Answer 3

Increased revision rate and associated metallosis with wear on the metal components(37.1% at 7 years compared to 14% for other implants)

Question 4

Overview of the J&J vaginal mesh case

Answer 4

700 patients begun class action claiming injury from vaginal mesh implants used to treat pelvis floor problems

Question 5

Adverse events reported in the J&J vaginal mesh case

Answer 5

Erosion of mesh through the vagina, mesh contraction causing pain, bleeding, organ perforation, urinary problems, recurrent prolapse

Question 6

Regulatory approval of the J&J vaginal mesh case

Answer 6

• Approved via 510k, usually used for hernia repair to support clinical testing (is it the same?)
• Reclassified from class II to III in 2016, meaning PMA is required
• A trial was stopped early due to several patients experiencing complications

Question 7

Overview of PIP breast implants case

Answer 7

Produced from industrial grade silicone filler

Question 8

Cause of problems associated with PIP breast implant case

Answer 8

Lack of traceability documentation in this material, was eventually demonstrated to not be toxic or carcinogenic

Question 9

How were the problems with PIP breast implants identified?

Answer 9

Double the rupture rate of other implants, but deemed to not be due to the silicon grade

Question 10

Overview of bioresorbable vascular scaffold case

Answer 10

New implanted drug eluting stent used to open blocked coronary arteries, manufactured by Abbott (fully absorbed by body within 3 years)

Question 11

Problems with the bioresorbable vascular scaffold

Answer 11

Found to be linked to elevated rate of major cardiac adverse events compared to other metallic stents (e.g heart attacks ofr clots)

Question 12

Future of bioresorbable vascular scaffolds

Answer 12

• Improved results may be seen using a scaffold specific surgical strategy including vessel preparation and sizing the stent both pre and post dilation
• Stent is thicker than similar models, questions of whether this affects flow properties
• Smaller vessels should be avoided, with trials continuing to the 3 year mark

Question 13

Overview of the Vitek TMJ implant case

Answer 13

• Disc which replaces fibrocartilage joint in the skull which was approved for use in 1983
• In accordance with substantial equivalence (prior to restrictions requiring manufacturers to prove safety and efficacy)
• Associated with catastrophic failures including bone resorption and pain
• FDA revoked approval many lawsuits and manufacturer went broke (TMJ implants reclassified as class III in 1993)

Question 14

Material used in Vitek TMJ implants

Answer 14

• Silasitc implants had been deemed not appropriate for long term use and was discontinued for use in TMJ implants by the end of the 1980s
• Demonstrated fragmentation, perforation and deterioration in a high load environment
• The Vitek implant was made of proplast, with teflon film laminated to PTFE and aluminium oxide

Question 15

Problems associated with Vitek TMJ implants

Answer 15

Giant cell reaction to the material induced bone resorption and pain as well as degeneration of parts of the skull

Question 16

Causes of problems with Vitek TMJ implant

Answer 16

1. Lack of background research - Teflon has been abandoned for use in total hip replacements in 1960s due wear particles causing inflammatory response
2. Lack of product validation testing - reliance on substantial equivalence to a device used prior to regulatory standards existed
3. Animal studies - Limited studies, with reports of failure in 1984 leading to studies on dogs which showed the teflon layer being completely worn after a few months and particles triggering bone erosion