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Biomechanical essentials and studies
First 12 years processes
The Femoral neck screw -
prosthesis type Spiron
Mülheim a.d. Ruhr, 12.04.2013B. BirkenhauerStiftungsklinikum Mittelrhein, Location Boppard
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Content
• The development of Spiron-Prosthesis• Biomechanical backgrounds• Clinical results and studies
-12-years processes- Figuring of incorrect implatations
• - Prvention of OP-fails
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
• Self cutting conical (proximal cylindrical) Screw
• Rotationsproof design• No modular concept• No Left- / Right-variants• Bonit-coated, rough blasetd
titanium alloy for cementless fixation
Prosthesis design
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
„Father“„Mother“
DSP nach Huggler u. Jacob,Bild: Sulzer Orthopedics
Problem of the DSP: often „long suffering period“ of the pateints, lug pain (???),Suspicion: too low Osseointegrationsurface
„Child“
Conceptional development
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
• Proximal-cortical and distal and distal spongiose anchorage by conical screw body
• Verified good load distribution even with strength components vertical to the implant axis
ill.: Allopro. Allospine posterior, technichal information biomechanical investigations. Sulzer Medica. 1999: 3
Pedicalscrew priciple
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
On a conical base body the vertical effective load will transfered consistentto the implant => Prevention of punctual bear maximation
ill.: Allopro. Allospine posterior, technichal information biomechanical investigations. Sulzer Medica. 1999: 2
Load distribution at the conical screw
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
• Thread causes an up to 30% Surface enlargement (Osseointegrationssurface) as compared to a conventional cementless stem prosthesis
• Thread = „bone inductor“
Osteological advantages I
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
1. Surface enlargement (Osseointegrationsurface) by Threaded sructure2. Bone induction on protuding prosthesis-structures using the example of revisionsstem SL on Wagner
Histolog. Pictures used from: Schenk, Wehrli: Zur Reaktion des Knochens auf eine zementfreie SL-Femur-Revisionsprothese, Orthopäde (1989)
Osteological advantages II
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
1 year postoperative
Change of the femoral x-raymorphologyby the Spiron-prosthesis
1 year postoperative
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Application of force of femoral neck prostehses
Extension trajectories
Sek. Pressure trajectories
Prosthesis as „capstone“of the trajectories
Pictures: Permedica, JUST-Prothese
Pressure trajectories
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
• First implantation 08.02.2001• Harris-Hip-Score (HHS) präop. 51
(24-76), n = 51 and increased after one year to HHS1: 94 (86-100), n = 33 on 30 Patients
• B. Birkenhauer, H. Kistmacher, J. Ries, Zementfreie Schenkelhalsschraubenprothese Typ Spiron, Konzeption und erste klinische Ergebnisse, Der Orthopäde,11/2004, 1259-1266
1 year postop.
Clinical results
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Followup of the implantations 2001-2003
Running followup of the patients with minimum 10 years-process • n = 48
• substract out (censored) loss: 3• 2 cases of death, 1 periprothetic Fractures after fall
• Not censored loss: 4• 2 aseptic early loosening (Implantation fail)• 2 Early infects (1 Immunsuppr. Patient)
• Precental survival rate after 10(-12) years: 91,2%
• Running evaluation by „HipDo-patient interview sheet“ for assessment of the result quality after min. 10 years with good to very well long term evaluation of patients
• For Comparison: SP2-survival rate after10(-13) years: 93 % (Lubinus, P.: Die SP2-Schaft Endoprothese, Frankfurter Orthopädie Symposium, November 2005)
* Copyright: Orthopädische Klinik Dortmund, K. Buckup
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
The „disillusionment“
Abstract out of the
A) Australian Hip-prothesesregister 2011
B) schwedish Hip-prothesesregister 2010
Statement
Both register shows that cementless endoprostheses in younger patient have worse survival rates than in older patients
Reason: higher stress!
Furthermore it‘s interesting that cemented supplies shows a very good success!
Ergo: If there is now revision problem, (older patients) a cemented implantation is a very welel working supply
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
X-ray processes particularly cases: case 1 (2001)
2002 2004 2009
Statement:
Bone under the collar can resorb several milimeters without consequences, this meets also with the calculations
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
X-ray processes particularly cases: case 2 (2001)
2004 2007 2013
statement:
Femoral neck was damaged. Cerclage. No consequences
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
X-ray processes standard cases: case 3 (2001)
2005 2008 2012
Statement:
Picture proves, no negative bone rebuilding like with longer prostheses
This meets also with the calculations
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Example of a early loosending at varus and lateral contact
1 Months 5 Months 7 Months
1 year
before Revison
Statement: Avoid Lateral Contact
If it still appears already intraoperative change to standard stem
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Example for Varus without lateral contact of the prosthesis
Varus-Position without lateral cortical contact operated permanent
1 y post op2 year post op
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Example: Septic Early loosening (2002)
Pat. under Immunosuppression with rheumatoidarthritis with left sided early infect
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
What are the central statements?
• Contact the lateral Spiron should be avoided: - too shallow angle with lateral contact is always wrong - but too steep angle with lateral contact works (But not recommended!)
• Don't choose Spiron too thin; Spiron length is not so critical. There Spiron is much to suggest that it is good if the Spiron still has some distance to the opposite cortex.
• If loosening were observed, this was in the first 2 years. No loosening at 2 years post-op
• If the implantation failure "lateral" contact out of the study expects to get a survival rate of 96.8% 10-12 years *
• The HHS is remarkably good at Spiron patients.• Bone condition for a revision is excellent. Calculations for bone remodeling are consistent with X-ray processes. • Application of Spiron useful for patients who are still experiencing revisions. In the older age standard hips and
also cements supplies are meaningful.
* For reasons of simplicity, the prostheses were summarized by 10 to 12 years in a group
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
B. Ebbecke, Universiy HanoverInstitute for constructional mechanic and numerical mechanicNumerical studies of Spiron – ProsthesisResults of bone remodelling by Spiron-prosthesis:Density distribution in biological balance, 2003
Ebbecke, B. Knochenwachstum - Endlich verständlich. Zusammenfassung, University Hanover, Institut für Baumechanik und Numerische Mechanik, 2003. Nackenhorst, U. Ein effizientes Finite Element Verfahren zur Simulation des beanspruchungsstimulierten Knochenwachstums. Tagungsband des Workshops ”Die Methode der Finiten Elemente in der Biomedizin, Biomechanik und angrenzenden Gebieten”, Ulm, 1997. Nackenhorst, U. und Schröder, U. Numerische Simulation des beanspruchungsinduzierten Knochenumbaus am Beispiel endoprothetisch versorgter Femura. Bericht aus dem Institut für Mechanik, Hamburg, 1997. Ziefle, M. Numerische Untersuchungen der Druckscheiben Prothese. Zusammenfassung, Universität Hannover, Institut für Baumechanik und Numerische Mechanik, 2002
Further studies
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Study for comparative primary stability 2005
• In collaboration with the animal medical school and the MHH Hannover Medical School (Department of Trauma Surgery), a Investigation of the femurs of shepherds carried out:
• 3 groups (same age, same size, similar bone quality):
• 15 femurs without prosthesis• 15 femurs with Spiron• 15 femurs with cementless
standard stem type "Zweymüller”
Article title: Less motion in bone/prosthesis interface by the new uncemented short-stem prosthesis Spiron(R) in dog boneMS ID : 1648004516228708 Authors : Ulrich Wiebking, Björn Birkenhauer, Franziska Hühn, Christian Krettek and Thomas GöslingJournal : Acta Veterinaria Scandinavica 2007
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
The investigation
In laboratory
The test machine
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Results I
Terminal of the investigation:The fracture
Spiron Zweymüller
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
ResultStrength – Time-Diagram
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Resultblue = Spiron; red = Zweymüller; white = without prosthesis
Vergleich Max. Prüflast, blau: Spiron-Prothese,rot: Zweymüllerprothese,gelb: ohne Prothese
0
1000
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3000
4000
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6000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Hundefemora
Kra
ft i
n N
ew
ton
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Result: Maximal stress at femur fracture
Mittelwert max. Prüflast
0,00
500,00
1000,00
1500,00
2000,00
2500,00
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3500,00
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Femora mit Spiron-Prothese Femora mit Zweymüller-Prothese Femora ohne Prothese
Kra
ft F
in
New
ton
Femora with Spiron
Femora with Zwey-müller
Natural Femur
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Elasticity of the system „Prosthesis in bone“ (Force in Newton vs. distance in millimeter)
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
The „Helica“-Prosthesis in the veterinary medicine
Due to the good biomechanical resultsof that investigation was the Spiron prosthesisunder a new name directly Introduced in the veterinary medicine.
Hach, V., Delfs,G.: Initial experience with newly developed hip endoproethesis; Vet Comp Orthop Traunatol 2009; 22: 153-158
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Result
A major factor of the primary stability is the preservation of the elasticity of the bone. But a stem prosthesis increases elasticity and stiffens the proximal femur. A femoral neck prosthesis can maintain the elasticity of the proximal femur.
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
Indications
• Good bone quality• Physiological hip joint
geometry• Biological age <65• BMI?• (No previous surgery)• good compliance• Beware of arthritis with
periarticular osteoporosis• Approx. 15 - max. 20% of
hip replacement patients
B. BirkenhauerCoST OP-Kurs Hüftgelenk 12.04.2013
1. Are Femoral neck prostheses short stem prostheses?2. Are shortstem- und femoral neck prostheses
biomechanical equivalent?
Outstanding questions
Thank you for your attention!