Taskforce Report on Implant Retrieval

Wolfgang Klauser MD, Patrick Sussmann MD,

and Timothy Wright, PhD

III International Society of Orthopaedic Centers MeetingBologna, Italy May 1, 2010

Goal

Foster research collaboration through the utilization of orthopaedic implant retrieval analysis as a means to answer research questions common to participating ISOC members

Specific Aims

1. Identify timely, high impact research questions centered around device technology for which retrieval analysis can lead to clinically useful answers

Specific Aims

2. Survey ISOC members who are retrieving implants to determine available numbers of implants and availability of demographic, clinical, and radiographic data

Specific Aims

3. Establish necessary policies for conducting collaborative research

a. Oversight and selection of projects b. Material transfer agreementsc. Authorship policyd. Data ownershipe. Data/implant transfer and

coordination

Specific Aims

4. Survey ISOC members for available resources a. Information technologyb. Methodologies for retrieval analysis c. Experimental design/statistical

analysesd. Funding

Specific Aims

5. Conduct pilot project(s) as demonstration of the effectiveness of the collaborative process

Suggestions for Pilot ProjectsMetal-on-metal bearings for THA and hip resurfacing• Much is known of wear and surface damage mechanisms for

metal-on-polyethylene bearings, but the resurgence of metal-on-metal bearings has received little clinical evaluation on the basis of retrieval analysis

• Surgical and patient factors hypothesized to contribute to rapid wear and pseudotumors, but variation in performance (as observed on retrieved implants) in response to variations in these factors has not been established

• What are the modes of wear and surface damage in metal-on-metal bearings?

• How are the presence and severity of these modes affected by patient, surgical, and design factors?

Suggestions for Pilot ProjectsRotating platform versus fixed bearing TKA• Rotating platform TKAs were intended in part to reduce wear

by allowing two conforming bearings• A recent study by one ISOC member (HSS) showed

considerable wear at both bearing surfaces, suggesting that reduced wear is not being achieved

• What is the relation between rotating platform surface damage and actual wear (i.e., do damaged surfaces necessarily mean considerable material has been worn away)?

• How do rotating platform designs compare to similar fixed bearing designs in terms of surface damage and wear to the femorotibial articulating surfaces and in terms of total damage and wear?

Suggestions for Pilot ProjectsRotating platform versus fixed bearing TKA• Rotating platform TKAs were intended in part to reduce wear

by allowing two conforming bearings• A recent study by one ISOC member (HSS) showed

considerable wear at both bearing surfaces, suggesting that reduced wear is not being achieved

• What is the relation between rotating platform surface damage and actual wear (i.e., do damaged surfaces necessarily mean considerable material has been worn away)?

• How do rotating platform designs compare to similar fixed bearing designs in terms of surface damage and wear to the femorotibial articulating surfaces and in terms of total damage and wear?

Suggestions for Pilot ProjectsRotating platform versus fixed bearing TKA• Rotating platform TKAs were intended in part to reduce wear

by allowing two conforming bearings• A recent study by one ISOC member (HSS) showed

considerable wear at both bearing surfaces, suggesting that reduced wear is not being achieved

• What is the relation between rotating platform surface damage and actual wear (i.e., do damaged surfaces necessarily mean considerable material has been worn away)?

• How do rotating platform designs compare to similar fixed bearing designs in terms of surface damage and wear to the femorotibial articulating surfaces and in terms of total damage and wear?

Survey of Retrieval ResourcesRegistry information technology

• Software/web-based solutions• Links to patient registries

Methodologies for retrieval analysis• Surface and geometric analysis

- Damage grading/damage mapping- Light and scanning electron microscopy- Profilometry- Laser scanning- Micro-computed tomography

• Histological grading• Radiographic review• Chemical and physical characterization

- Density- Infrared spectroscopy- Differential scanning calorimetry

Funding

• Institutional commitments (CEOs)• Federal/Int’l grant proposals and contracts• Commercial contracts• Philanthropy/Foundations