TOTAL HIP REPLACEMENT:

Transcription

1 THR Prosthesis Design TOTAL HIP REPLACEMENT: PROSTHESIS DESIGN FEATURES JESS JOHNSTON & MELINDA ZIETH History of Hip Prosthesis Joint Replacement Registry Implant Design Technology & Future History and Evolution of Hip Replacement John Charnley Osteolysis At the time thought to be cement disease First full hip replacement in the 1960 s Built a biomechanical lab for testing and production His research demonstrated the need for low friction Stainless steel and Teflon were first products used Teflon cup failed after 1 year (granulomas as not biocompatible) Charnley s assistant recommended UHWMPE THR bonded with bone cement 5 years of implantation successful years then began to fail (osteolysis) Was thought to be cement.. 1

2 Now Instruments 1980 onwards 1990 onwards Material and instruments have changed significantly from 1960 s till now 2000 onwards Total Hip Implants Today The Australian Joint Registry Today s construct: Cup (often uncemented) Poly liner highly crosslinked OR Ceramic liner The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) is an initiative of the Australian Orthopaedic Association (AOA). The AOANJRR was established in 1999 becoming fully national in mid The purpose of the AOANJRR is to improve and maintain the quality of care for individuals receiving joint replacement surgery. Information on hip, knee, shoulder, elbow, wrist, ankle and spinal disc replacement is collected from all hospitals in Australia undertaking joint replacement surgery. Ceramic head OR Metal head Cemented Stem OR Uncemented stem 2

3 The Joint Registry The Joint Registry Other Joint Registries: Patient demographics UK Sweden (first in 1975) Norway NZ Some Points to Note: All the registries record slightly different outcomes The Australian Joint Registry records to Revision (Failure) Australian Registry has VERY high compliance making it very sensitive eg: ASR The Joint Registry Reason for Revision and which component Most commonly used and revision rates at odd year intervals 3

4 Findings by Diagnosis, and potential change to suit patient demographic Implant Design Prosthesis/combinations identified with higher than normal revision rates Components Total Hip: - Acetabular Shell & Liner - Femoral Stem & Head 4

5 Surgical Technique - Posterior Surgical Technique - Dislocate the hip joint - Osteotomy of the femoral head Surgical Technique Acetabular Preparation Surgical Technique Acetabular Preparation - Ream Acetabulum - Gradual size increase of diameter of hemispherical reamers 56mm at Periphery 54mm Hemispherical Reaming Diameter 5

6 Surgical Technique Acetabular Preparation Acetabular Fixation Cemented - Grooves on cup to improve fixation with cement - Requires cement to aid fixation to bone 45 Degrees Abduction & Degrees Anteversion Acetabular Fixation Acetabular Liner Options Uncemented: - Porous surface for fixation to bone Polyethylene - Neutral - Hooded - Constrained Hydroxyapatite (Calcium Phosphate Mineral) Cancellous Bone Structure Titanium Ceramic 6

7 Femoral Stem Preparation Offset & Leg Length Open Femoral Canal Broach Femur Incrementally Trial Neck & Head Offset - Centre of head to axis of femur - Tension on abductors & ext rotators Leg Length Offset Offset & Leg Length - Increased offset can create excess tension in the abductors & trochanteric bursitis - Decreased offset can affect the efficiency of the abductors Femoral Head options - Increasing neck lengths in 3-4mm increments - Increases Length and offset due to angle Offset High Offset Standard Offset Leg Length 7

8 Femur Implants Stem Design Options Insert Final Femoral Stem & Head Uncemented Cemented How does a surgeon choose an implant??? Revision Hip Prosthesis - Acetabular Revision Hip Prosthesis - Acetabular 8

9 4/09/2017 Revision Hip Prosthesis Femoral Hemiarthroplasty #NOF Technology & Future of Hip Arthroplasty Computer Navigation - Computer Navigation - Robotic Surgery - Custom planning and implant design Use of intraoperative trackers on instrumentation to communicate with a computer for: - Acetabular Cup Positioning - Leg Length & Offset 9

10 Robotics 3D Case Planning 3D Case Planning Custom Implant 10

11 Custom Acetabular Implants Custom Acetabular Implant Custom Acetabular Implant Oncology Custom Implants Post-Operative X-Ray Proposal Implant 11

12 Questions?? 12