Zimmer studies powerpoint


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Zimmer studies powerpoint

  1. 1. Artificial Knee Studies<br /> Zimmerman Reed, PLLP<br />
  2. 2. NexGen CR Problems<br />NexGen LPS-Flex Problems<br />NexGen Standard v. NexGen High Flex<br />NexGen MIS Problems<br />Introduction<br />
  3. 3. Problems with the NexGen CR Flex<br />Dr. Berger Study <br />
  4. 4. Dr. Richard A. Berger<br />Assistant Professor, Rush University Medical Center <br />Degree in mechanical engineering from MIT <br />Revolutionized hip and knee replacement surgery by developing a minimally invasive method of replacing knee joints<br />Full Disclosure: currently being investigated by the DOJ<br />Dr. Craig Della Valle<br />Assistant Professor, Rush University Medical Center <br />Board Certified - Orthopaedic Surgery<br />Awarded the Hip Society's Frank Stinchfield Award for his research<br />New York Times – The “Berger Study” AuthorsNew York Times June 19, 2010<br />
  5. 5. <ul><li>From 2002 to 2008 Dr. Berger was a consultant for Zimmer, training physicians on Zimmer’s Minimally Invasive Surgery (“MIS”) technique</li></ul>In 2005, Dr. Berger implanted the NexGen CR-Flex Porous into 125 patients<br />Over the next year, Dr. Berger found his patients reported uncommon pain relating to their NexGen knee<br />Berger Study Background<br />
  6. 6. In early 2006, Dr. Berger’s follow-up care revealed X-rays showing lines in some patients where the implant met the thigh bone, an indication that the device <br />was loose and had not fused <br />completely<br />Several of the loose knees<br /> eventually required early <br /> knee revision surgery<br />Berger Study Background<br />
  7. 7. As a result of the 2005-2006 experience, Dr. Berger, along with Dr. Della Valle, set up a study of 100 patients who received the NexGen CR-Flex Porous Knee<br />Berger Study <br />
  8. 8. <ul><li>Dr. Berger’s and Dr. Della Valle’s presented their results at American Academy of Orthopaedic Surgeons Conference in March 2010
  9. 9. Failure rate resulting in revision surgery reached 9%
  10. 10. Actual number of complications could be much higher as many patients (36%) showed signs of loosening but had not yet reached the level of revision surgery</li></ul>Berger’s Study Findings:<br />
  11. 11. “This component is still commercially available but should not be used for any patient.”  <br />Dr. Richard A. Berger <br />Rush Medical Center <br />Former Zimmer Consultant<br />Dr. Berger’s Conclusion:<br />
  12. 12. Problems with the NexGen LPS Flex<br />Loosening<br />
  13. 13. High incidence of loosening of the femoral component in legacy posterior stabilized-flex total knee replacement<br />H.S. Han, et al, Journal of Bone and Joint Surgery – British Edition, Vol 89-B, No. 11, Nov. 2007- Korea<br />Study Demographics:<br />47 patients<br />72 knees <br />44 women and 3 men<br />All NexGen LPS-Flex - no standard LPS<br />Study Goal: Analysis of high-flexion design for evidence of aseptic loosening and related pain<br />Han Study (2007)<br />
  14. 14. Patients did get better flexion then regular Total Knee Replacement (“TKR”) designed knees<br />111-165 degrees of knee flexion in LPS-Flex knee<br />Versus 110-120 degree of flexion in general TKA<br />BUT aseptic loosening was found at a higher rate in the LPS-Flex than regular TKR knees<br />38% of the knees (27) were loose<br /> at mean follow-up of 32 months <br />21% of the knees (15) were revised <br /> at mean of 23 months<br />Han Study (2007) Study Results<br />
  15. 15. Han Study (2007) – Specific Findings<br />All loosening at femoral component which migrated into a position of increased flexion<br />(i.e. additional flexion emanated from the fact that the knee was loose)<br />“Several [physicians] have expressed concern that relatively small gains in maximum knee flexion achieved by making changes in the design may substantially reduce the stability of the prosthesis and increase the stresses on the component.”<br />“[W]e have not previously experienced such a high rate of early loosening for any design of TKR.”<br />
  16. 16. Are High Flexion Activities after High-Flex Total Knee Replacement Safe?<br />Kang, S., Journal of Bone and Joint Surgery, British Edition, Vol 92-B, Issue SUPP_II, 322<br />Study Demographics:<br />72 knees were implanted<br />All were NexGen LPS-Flex<br />Study Goal: Determine the factors contributing to the high rate of aseptic loosening in LPS-Flex knees<br />Kang Study (2008)<br />
  17. 17. At a mean of 32 months, 27cases (38%) had shown the radiological findings of aseptic looseningaround the femoral components <br />At a mean of 32 months, 15 cases (21%) had beenrevised for the progression of component loosening and pain<br />Kang (2008) Results<br />
  18. 18. Three- to six-year follow-up results after high-flexion total knee arthroplasty: can we allow passive deep knee bending?<br />Cho, SD et al., Journal of Bone and Joint Surgery - British Volume, Vol 92-B, Issue SUPP_I, 131<br />Study Demographics:<br />218 knees<br />All with NexGen LPS-Flex<br />166 patients (22 males, 144 females)<br />Followed up for more than 3 years after TKA<br />Study Goals: Evaluate clinical and radiological follow up results of NexGen LPS-Flex<br />Cho Study (2010)<br />
  19. 19. While NexGen LPS-flex Knee satisfactorily improved ROM, it was associated with a relatively high incidence of early loosening of the femoral components<br />Indications of loosening were visible on radiographs of 30 knees (13.8%)<br />The mean time to loosening was 24 months<br />Eventually 7 knees required revision surgery (3.2%)<br />The mean time to final revision surgery was 49 months<br />Cho Study (2010) Results<br />
  20. 20. High Flex v. Standard<br />Flexion and Range of Motion<br />
  21. 21. Postoperative evaluation of the NexGen Legacy posterior stabilized LPS flex implants<br />Allen, DG, et al., La SocieteInternationale de Chiragie Orthopedic et de Traumalologic/La SocieteInternationale de Recherche Orthopedic et de Traumalological, XXII World Congress, San Diego 2002:542<br />Study Goal: Compared range of motion between patients implanted with the LPS knee and the LPS-Flex knee<br />Found no difference between the two replacement knees in regards to range of motion<br />Allen Study (2002)<br />
  22. 22. Range of motion of standard and high-flexion posterior stabilized total knee prostheses: a prospective randomized study<br />Kim, YH, et al., Journal of Bone and Joint Surgery, American Edition, 2005; 87:1470-1475<br />Study Demographics:<br />2 men<br />48 women<br />Each receiveda standard LPS prosthesis in one knee and a LPS high-flexion prosthesis in the other knee. <br />Study Goal: to compare the ranges of motion associated with standard andhigh-flexion posterior stabilized total knee prostheses in patientsmanaged with simultaneous bilateral total knee arthroplasty<br />Kim Study (2005)<br />
  23. 23. Authors found no difference between the eventual flexion of the two types of implanted knees<br />The knees with the standard LPS prosthesis had a mean range of motion of 135.8<br />The knees with the LPS-flex prosthesis had a mean range of motion of 138.6<br />Kim Study (2005) Results<br />
  24. 24. High Flexion Knee Designs: More Hype than Hope? In the Affirmative<br />Ritter, M., Journal of Arthroplasty, 21(4), Supp. 1 (2006)<br />Study Demographics: <br />4727 Total Knee Replacements<br />Various ages and genders<br />Using Biomet knee<br />Study Goal: Evaluated the range of motion after 4727 TKA<br />Ritter Study (2006)<br />
  25. 25. Range of motion after a TKA is dependant primarily upon preoperative range of motion; not device design<br />High-Flex designs may increase knee instability and possible wear<br />Ritter Study (2006) Conclusions<br />
  26. 26. Range of flexion after primary TKA: the effect of soft tissue release and implant design.<br />Amed, I, et al., Orthopedics, 2009 Nov; 32(11): 811.<br />Study reported no difference in range of movement between standard and high flexion variants of the NexGen LPS implants in a randomized controlled study.<br />Amed Study (2009)<br />
  27. 27. Clinical and radiological results of high flex total knee arthroplasty: a 5 year follow-up.<br />D. Wohlrab et al., Arch Orthop Trauma Surg (2009) (Germany) <br />Study Demographics:<br />30 patients received a LPS-Flex knee <br />30 received a LPS knee<br />Study Goal: Compare the clinical outcome and radiological results after TKR using a high flex design versus a standard design<br />Wohlrab Study (2009)<br />
  28. 28. Wohlrab Study (2009) ResultsLimited to no advantage of using a high flex knee instead of a regular knee at the end of a 5 year period.<br />
  29. 29. Comparison Between Standard and High-Flexion Posterior-Stabilized Rotating-Platform Mobile-Bearing Total Knee Arthroplasties<br />Choi, WC et al., Journal of Bone and Joint Surgery, American Edition, 2010; 92:2634-42<br />Study Demographics:<br />85 knee replacements using a standard prostheses design<br />85 knee replacements using a high-flexion prostheses design<br />Study Goal: Compare the outcomes of standard and high-flexion posterior stabilizing TKR<br />Choi Study (2010)<br />
  30. 30. Showed no significant differences between standard and high flexion posterior stabilized mobile bearing total knee prostheses<br />Average maximal flexion for the standard design was 128⁰<br />Average maximal flexion for the high-flex design was 130⁰<br />Choi Study (2010) Results<br />
  31. 31. Does the new generation of high-flex knee prostheses improve the post-operative range of movement?<br />Mehin, R., Journal of Bone and Joint Surgery, British Edition, Vol. 92-B, Issue 10, 1429-1434<br />Study Type: Metadata analysis of already published articles regarding standard TKR design and high-flex TKR design<br />Study Goal: Determine whether the high-flex knee prostheses provide increased movement over standard knee prostheses design<br />Mehin Study (2010)<br />
  32. 32. Analysis suggests that high-flex knee prostheses do not increase the post-operative maximum knee flexion compared with traditional implants<br />The weighted mean difference between the range of flexion between a standard design and a high-flex design was 2.1⁰<br />“Not only is [the difference] not statistically significant, but more importantly it is not clinically significant. Additional flexion of 2⁰<br /> . . . has no functional advantage to the patient.”<br />Mehin Study (2010) Results<br />
  33. 33. Comparison of standard and gender-specific posterior-cruciate-retaining high flexion total knee replacements: a prospective, randomized study <br />Kim, YH, et al., Journal of Bone and Joint Surgery, British Edition, 2010 May, 92(5): 639-45<br />Study Demographics:<br />85 women<br />Received LPS-Flex design in one knee and gender-specific LPS-Flex design in the other knee<br />Study Goal: Compare clinical and radiographic results in patients receiving a LPS-Flex or gender specific LPS-Flex prostheses<br />Kim Study (2010)<br />
  34. 34. Study found no difference in clinical and radiological results in female patients undergoing standard and gender-specific variants of the NexGen LPS-Flex prosthesis<br />Kim Study (2010) Results<br />
  35. 35. Problems with MIS Tibial<br />Loosening and Revision<br />
  36. 36. Presented by Dr. Steven H Weeden and Dr. Steven Boyd Ogden<br />Podium Presentation: Early Loosening of MIS Tibial Implants in Primary TKA<br />From 2005 to 2007 the authors performed 403 TKAs with a Zimmer MIS tibial component <br />Study Demographics:<br />All procedures were performed with a MIS technique, PS articulation, and cement<br />22 replacements did not have the modular stem component<br />381 replacements included a stem component<br />American Academy of Orthopaedic Surgeons Conference in March 2010<br />
  37. 37. The study reports a higher than expected rate of early loosening in cemented primary TKA with an MIS tibial component<br />The average time to diagnosis of loosening in this study is 2.6 yrs<br />The overall loosening rate was 5.2% (21 tibias of the 403)<br />Early Loosening of MIS Tibial Implants<br />
  38. 38. Of the MIS Tibias placed without a stem component, 5 tibias out of 22 failed (24%)<br />Of the MIS tibias placed with a stem component, 16 tibias out of 381 failed (4.2%)<br />Early Loosening of MIS Tibial Implants specifics<br />
  39. 39. The doctors recommendation: “the use of an MIS tibia without the use of a modular stem is not recommended secondary to a high rate of early loosening in primary TKA.” <br />Early Loosening of MIS Tibial Implants continued<br />
  40. 40. Early Aseptic Loosening with Precoated Low Profile Tibial Component: A Case Study<br />Foran, J.R.H., et al, Journal of Arthroplasty, published online January 14, 2011<br />Authors performed TKAs in 460 patients using the NexGen MIS Tibial Component<br />Authors experienced early loosening of the tibial component<br />The average time to diagnosis of loosening was 17 months<br />In addition, several additional patients show radiographic signs of pending failure<br />Foran Case Study<br />
  41. 41. Based on their experience with early aseptic loosening of the MIS Tibial Component, the authors report they will discontinue further use until the etiology of the high failure rate is able to be determined<br />Foran Case Study: Specific conclusions<br />