biomechanical essentials and studies first 12 years processes the femoral neck screw - prosthesis...

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


• 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


„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


• 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


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


• Thread causes an up to 30% Surface enlargement (Osseointegrationssurface) as compared to a conventional cementless stem prosthesis

• Thread = „bone inductor“

Osteological advantages I


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


1 year postoperative

Change of the femoral x-raymorphologyby the Spiron-prosthesis

1 year postoperative


Application of force of femoral neck prostehses

Extension trajectories

Sek. Pressure trajectories

Prosthesis as „capstone“of the trajectories

Pictures: Permedica, JUST-Prothese

Pressure trajectories


• 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


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


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


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


X-ray processes particularly cases: case 2 (2001)

2004 2007 2013

statement:

Femoral neck was damaged. Cerclage. No consequences


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


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


Example for Varus without lateral contact of the prosthesis

Varus-Position without lateral cortical contact operated permanent

1 y post op2 year post op


Example: Septic Early loosening (2002)

Pat. under Immunosuppression with rheumatoidarthritis with left sided early infect


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. 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


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


The investigation

In laboratory

The test machine


Results I

Terminal of the investigation:The fracture

Spiron Zweymüller


ResultStrength – Time-Diagram


Resultblue = Spiron; red = Zweymüller; white = without prosthesis

Vergleich Max. Prüflast, blau: Spiron-Prothese,rot: Zweymüllerprothese,gelb: ohne Prothese

0

1000

2000

3000

4000

5000

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


Result: Maximal stress at femur fracture

Mittelwert max. Prüflast

0,00

500,00

1000,00

1500,00

2000,00

2500,00

3000,00

3500,00

4000,00

4500,00

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


Elasticity of the system „Prosthesis in bone“ (Force in Newton vs. distance in millimeter)


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


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.


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


1. Are Femoral neck prostheses short stem prostheses?2. Are shortstem- und femoral neck prostheses

biomechanical equivalent?

Outstanding questions

Thank you for your attention!

biomechanical essentials and studies first 12 years processes the femoral neck screw - prosthesis...

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