Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

I assist guided verilast knee replacement


Published on

  • Be the first to comment

  • Be the first to like this

I assist guided verilast knee replacement

  1. 1. I-Assist guided Verilast Knee replacement Durable knee replacement for young patients Dr.A.K.Venkatachalam FRCS, M.Ch Orth, DNB Orth, MS Orth E
  2. 2. Patient details • Ms. PM from Gujarat • 32 years • Suffering from Avascular necrosis of Right knee • Had consulted several surgeons elsewhere. • Had advanced damage to the knee with bone loss from the lower end of the thigh bone • Was unable to walk without support for few preceding years. • Underwent I Assist guided Verilast Knee replacement in September 2014. E
  3. 3. Key concepts in this presentation • I –Assist • Verilast knee– What is it? How does it reduce wear? • How I-Assist and Verilast combine to lower wear and increase durability in young patients? E
  4. 4. 1. What is the I-Assist? • It is a Personalized guidance system designed to assist the surgeon in positioning a total knee arthroplasty implant components intra operatively. • It uses surgical instruments and position sensors to determine alignment axes in relation to anatomical landmarks • To thus precisely position alignment instruments & implant components relative to these axes. E
  5. 5. I Assist components – 4 pods initially, now only 2 pods. E
  6. 6. What is inside it? • It consists of 4 half palm sized pods with electronic apps like • Wi-Fi found in smart phones. • Gyroscope found in air planes. • The electronic sensors inside calculate the alignment. The blinking lights on the display face indicate the correct position. • Red light means improper position and Green light means proper position. E
  7. 7. How does it work? • It is inserted into the bones of the knee joint itself. E
  8. 8. How does it work? • After connecting it to the knee the surgeon moves the femur (thigh bone) in 13 different positions and the tibia ( leg bone) in 4 positions. • It calculates the position by the electronic devices inside it. • The surgeon makes fine adjustments so that red lights turn to green. • Blinking green lights indicate zero percent error. • The surgeon can proceed to cut the bone confident that his cuts will be perfectly aligned. • He can then finally place the implant components in the correct alignment achieved and validated in the previous steps. E
  9. 9. Advantages • It guides the surgeon to get perfectly aligned cuts intra operatively. • It gives zero error cuts and again validates it in the next step. • Thus the surgeon gets the right fit during the surgery itself. • This ensures that the implant components are positioned perfectly in correct alignment. • Surgeon focusses his eyes in the operating field itself and not take his eyes away. • It thus saves time. E
  10. 10. What does it differ from? • Patient specific instrumentation • Computer assisted knee replacement E
  11. 11. Alignment in Knee replacement • It is one of the factors that ensures long life of the implant. • A proper alignment means the implant is perpendicular to the ground. • Mal aligned knee replacements tend to wear out sooner than normal. • Even experienced surgeons can make errors in placement of the components. Mal-aligned car tyre Wear on the inside E
  12. 12. Properly aligned Knee replacements Implant is perpendicular to the ground E
  13. 13. Why do young patients need a knee replacement ? • Rheumatoid arthritis (common) • Post traumatic arthritis (common in India and developing countries • Avascular necrosis (rare) E
  14. 14. Less than 65 years 12 % 65 – 75 years 10 % 75 years 4 % Total knees fail more often in young patients Age and failure rates Robertsson, Thesis Lund 2000 , Swedish arthroplasty registerE
  15. 15. Why ? Young patients wear away their total joints more • than their older colleagues • Wear is proportional to usage. • Young patients walk on average up to 50% more than older patients. • Usage leads to increased poly wear • Poly wear leads to aseptic loosening Patient age Average of steps/year < 60 years 1200,00 > 60 years 800,00 Age & activity after THR/TKR E
  16. 16. Problems of knee replacement in young • Previous two slides indicates that there is a higher risk of failure in young patients and they may require a revision within 10 years • We also know that the Redo operation will be technically a difficult operation than the primary. Result also will be inferior. E
  17. 17. How to prolong the life of a knee replacement in a young patient ? • The surgeon can do a TKR with a prosthesis that wears out slowly. • Use of materials, techniques, activity modification can lead to better implant survivorship. E
  18. 18. Prosthetic life prolongation Wear is an issue. Steps to reduce wear • Bearings- alternate bearings like oxidized zirconium. • Poly ethylene – X LP poly, anti oxidants, thickness. • Accuracy of component placement- ? Navigated surgery E
  19. 19. Options for change • Change femoral counter-face ( Oxidized zirconium instead of routine Cobalt Chrome ) • Change Poly insert ( XLPE) Combination is known as Verilast knee. E
  20. 20. Oxidised Zirconium • Meets requirements for ideal TKR • Smoother • ↓ Coefficient of friction • More scratch resistant • Less wear against both conventional and highly cross linked poly ethylene. E
  21. 21. What is it? • Zirconium- metallic element • Zirconia- ceramic • Zr-2.5 Nb Metallic alloy • Super heating zirconium to 500+°C in Oxygen presence • Surface transformation into zirconia ( ceramic oxide) • Chemically bonded ceramic oxide surface 5μ thick Ceramic Oxide Original Surface Air 500oC Oxygen Diffusion Oxygen Enriched Metal Metal Substrate E
  22. 22. Oxidized Zirconium properties • It is a metal component • Thin layer of ceramic like material that is part of its innate structure. This is not a coating. • Ceramic oxide is 5 μ thick • Biocompatibility is excellent, matches titanium • Very low coefficient of friction vs Cobalt chrome. • Extremely abrasion resistant. • Hard like ceramic • Equivalent strength properties to Cobalt chrome. • Adverse to chipping that can occur at insertion and over time. • Lack of Nickel allergy. E
  23. 23. Wear properties of Oxidized zirconium • Oxidized zirconium reduces volumetric wear by upto 89% in an abraded environment when compared to Cobalt Chrome E
  24. 24. Oxidized Zirconium- Best of both worlds (Ceramic & Metal) • Strength of Cobalt chrome • Low coefficient and scratch resistance of ceramic • Non brittle as the ceramic layer is part of the innate structure. • Decrease wear is the main advantage.4900 less volumetric wear. • 160 times smoother. E
  25. 25. Verilast Knee E
  26. 26. Verilast CR knee • Femoral component made of Oxidized Zirconium • Plastic insert made of Cross linked poly ethylene (XLPE) • Cruciate retaining or CR knee removes less bone than other knee. E
  27. 27. Verilast knee has the potential to last 35 years • Potential has to be harnessed by perfect alignment. E
  28. 28. I Assist + Verilast knee • Gives perfect alignment during surgery itself. • Alignment along with durable materials like Zirconium and Cross linked poly-etheylene increases life of a knee replacement to 35 years. • No need for future revision surgery in young patients. E
  29. 29. What is innovative in my procedure? • Earlier Verilast knee was implanted with an earlier smart tool called “ Visionaire” patient specific instruments from the same company. • Patient specific instruments manufacturing take time. • Technique is operator dependent. • Also used with Computer navigation – Surgeon has to keep shifting his gaze from the operating field to the computer and back. • This is the first time that it is used with a user friendly I –Assist smart tool. • I-Assist and Verilast belong to different companies. • This is the first time that high end products from different companies have been combined to hopefully give a high end durable product. E
  30. 30. Thank you E