JISRF STUDY GROUP
Tissue Sparing Implant™ (TSI™) Total Hip Stem Designs
PARTICIPANTS
The following is the list of participants in JISRF's Study Group on Tissue Sparing Implant™ Total Hip Stem Designs. This will be an ongoing study and findings will be added to the results below as they become available.
| Aram, Tony, MD, Fairfax, VA, USA |
Lombardi, Adolph, MD, Columbus, OH, USA |
| Berend, Keith, MD, Columbus, OH, USA |
Mackel, Audley, MD, Cleveland, OH, USA |
| Brazil, Declan, PhD, NSW, Au |
Manktelow, Andrew, PHD, Nottingham, England |
| Bruce, Warwick, MD, NSW, Au |
McCarthy, Joseph, MD, Boston, MA, USA |
| Bryant, Charles, MD, Oklahoma City, OK, USA |
McPherson, Ed, MD, LA, CA, USA |
| Cameron, Hugh, MD, Toronto, Canada |
McTighe, Timothy, Dr. H.S. (hc), Chagrin falls, OH, USA |
| Campbell, David, MD, South Australia, Au |
Nevins, Russell, MD, Las Vegas, NV, USA |
| Clarke, Ian, PhD, Loma Linda, CA, USA |
Rubin, Lee, MD, Waterbury, CT, USA |
| Clyburn, Terry, MD, Houston, TX, USA |
Samuels, Lewis, MD, Canada |
| Donaldson, Thomas, MD, Loma Linda, CA, USA |
Schmidt, Frank, MD, Cody, WY |
| Drinkwater, Chris, MD, Rochester, NY, USA |
Schutte, H. Del, MD, Charleston, SC, USA |
| Froimson, Mark, MD, Cleveland, OH, USA |
Smith, Evert, PHD, Bristol, England |
| Goldberg, Victor, MD, Cleveland, OH, USA |
Stulberg, S. David, MD, Chacigo, IL, USA |
| Hannoford, Peter, MD, NSW, Au |
Swank, Mike, MD, Cinnicitti, OH, USA |
| Harrison, John, MD, NSW, Au |
Sydney, Sam, MD, Baltimore, MD, USA |
| Jones, Richard E., MD, Dallas, TX, USA |
Tkach, Tom, MD, OKC, OK, USA |
| Keggi, John, MD, Waterbury, CT, USA |
Trick, Larry, MD, San Antanio, TX, USA |
| Keggi, Kristaps, MD, Waterbury, CT, USA |
Turnbull, Allen, MD, NSW, Au |
| Kennon, Robert, MD, Waterbury, CT, USA |
van der Rijt, Adrian, MD, Wagga Wagga, Au |
| Keppler, Louis, MD, Cleveland, OH, USA |
Vaughn, Bradley, MD, Ralegih, NC, USA |
| Kyle, Richard, MD, Minneapolis, MN, USA |
Walter, Brad, MD, Thomasville, GA, USA |
| Leslie, Cris, MD, Columbia, MO, USA |
Whitewell, Duncan, MD, Oxford, England |
| Liebelt, Ralph, MD, Durham, NC, USA |
Woodgate, Ian, MD, NSW, Au |
Each participant received a Certificate of Membership from the Executive Director of JISRF.
RESULTS
 Tissue Sparing Implant™ (TSI™) Total Hip Stem Designs
There is a current trend towards using short stems for Total Hip Arthroplasty (THA). This is exciting because there is a distinct advantage in preserving bone and soft tissue. Minimal utilization of bone stock is vital given the fact that revision hip surgery may be required in the future.
Preclinical tests such as mechanical fatigue, finite element analysis and photo-elastic techniques are used to design bone conserving stems that can be effective and potentially increase long term outcomes as compared to some of the conventional femoral stems. There is growing interest from total hip surgeons that this procedure is a more conservative approach to current re-surfacing designs and techniques by preserving more soft tissue and bone in the acetabulum.
 Historically, surgeons such as Freeman, Whiteside and Pipino identified the mechanical advantage of retaining the femoral neck. Freeman and Whiteside have advocated conventional stem length where as, Pipino has been a strong advocate of short curved stems. Pipino has argued for tissue (hard & soft) preservation for a number of years and is now beginning to be recognized for his 20 plus years of solid work.
A number of bone conserving hip joints have been developed and have been used instead of conventional femoral stems. First generation stems include Munting, Weber- Huggler Thrust Plate, Stratech, Spiron, Spotorno and the Mayo.
Second generation stems such as the Silent, Proxima, McMinn, Proximal Epiphyseal Replacement (PER), CFP (Pipino) are now in use.
The risk of some short stems is perforation of the cortical bone, stress shielding and bone loss with a faith driven belief in some that metaphyseal fit and fill alone will suffice for stability ignoring the hoop and mechanical strength of the proximal neck and superior (intact) digital fossa bone flowing in to the greater trochanter.
 The Newest Design Concept: TSI™ Stems
The MSA™ and ARC™ Stems have been designed with a unique lateral T-back design to maximize torsional stability and ease of insertion. A modular neck is used with this new stem design allowing fine tuning of joint mechanics including version length and offset and the potential ability to check on cup alignment to stem more accurately. A novel proximal conical flare provides for off loading of compressive forces stimulating the medial calcar.
Since this is a curved stem design there is significant protection of the lateral soft tissue structures along with less bone removal. Keeping the lateral bone and soft tissues intact provides a natural barrier to migration of particular debris, less blood loss and less force required to rehab the hip.
A choice of bearing surface may be used providing versatility over the limitations of hip resurfacing, (currently limited to MOM).
Development of TSI™ Stem Design and Technique
| Doctors John Keggi, Kristaps Keggi, and Louis Keppler reviewing surgical technique at Yale Medical University Cadaver Laboratory. |
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| Design and technique clearly demonstrate tissue preserving benefits of the TSI™ Stem. |
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Additional Cadaver Studies
Additional studies recently performed by Dr. Sam Sidney, at The Anatomy Board University of Maryland, confirmed the previous cadaver work.
Collaboration Worldwide
The work involved has been a worldwide effort from FEA modeling, engineering, review of x-rays, design review, development of surgical techniques and clinical evaluation.
Hundreds of x-rays were review both in Australia, Canada and the United States. Participating in this process acknowledgment goes out Doctors Peter Hannaford, John Harrison, Allen Turnbull, Ian Woodgate of Australia, Hugh U. Cameron, of Canada, Louis Keppler, John Keggi, Kristaps J. Keggi, Robert Kennon, and S. David Stulberg from the United States.
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FEA modeling was performed by three different scientist. Declan Brazil, PhD from Australia, Kevin Ong, PhD from Exponent, Philadelphia, PA and Edward Cheal, PhD, Omnilife Science, Raynham, MA.
All modeling demonstrated favorable bone remodeling and fatigue characteristics of this novel device. |
Evaluations of instrumentation, trial stems and final implants have been carried out successfully.
Design and technique have provided for a simple stem design (five sizes) with novel features that offer significant implant-to-bone stability, ease of surgical approach, reproducible techniques, and impressive short term clinical outcomes.
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March 2008 AAOS Poster Exhibit "A New Approach To Neck Sparing THA Stem" (requires Acrobat).
The Design Rationale of the ARC™ Stem (requires Acrobat).
