Biomechanical essentials and studies First 12 years processes The Femoral neck screw - prosthesis type Spiron Mülheim a.d. Ruhr, B. Birkenhauer Stiftungsklinikum Mittelrhein, Location Boppard

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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 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 „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 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 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 Thread causes an up to 30% Surface enlargement (Osseointegrationssurfac e) as compared to a conventional cementless stem prosthesis Thread = „bone inductor“ Osteological advantages I

B. BirkenhauerCoST OP-Kurs Hüftgelenk Surface enlargement (Osseointegrationsurface) by Threaded sructure 2. 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 year postoperative Change of the femoral x-raymorphology by the Spiron-prosthesis 1 year postoperative

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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 First implantation Harris-Hip-Score (HHS) präop. 51 (24-76), n = 51 and increased after one year to HHS 1 : 94 ( ), n = 33 on 30 Patients B. Birkenhauer, H. Kistmacher, J. Ries, Zementfreie Schenkelhalsschraubenprothese Typ Spiron, Konzeption und erste klinische Ergebnisse, Der Orthopäde, 11/2004, year postop. Clinical results

B. BirkenhauerCoST OP-Kurs Hüftgelenk Followup of the implantations 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 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 X-ray processes particularly cases: case 1 (2001) Statement: Bone under the collar can resorb several milimeters without consequences, this meets also with the calculations

B. BirkenhauerCoST OP-Kurs Hüftgelenk X-ray processes particularly cases: case 2 (2001) statement: Femoral neck was damaged. Cerclage. No consequences

B. BirkenhauerCoST OP-Kurs Hüftgelenk X-ray processes standard cases: case 3 (2001) Statement: Picture proves, no negative bone rebuilding like with longer prostheses This meets also with the calculations

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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 Example for Varus without lateral contact of the prosthesis Varus-Position without lateral cortical contact operated permanent 1 y post op 2 year post op

B. BirkenhauerCoST OP-Kurs Hüftgelenk Example: Septic Early loosening (2002) Pat. under Immunosuppression with rheumatoid arthritis with left sided early infect

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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% 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 B. Ebbecke, Universiy Hanover Institute for constructional mechanic and numerical mechanic Numerical studies of Spiron – Prosthesis Results 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, 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, Nackenhorst, U. und Schröder, U. Numerische Simulation des beanspruchungsinduzierten Knochenumbaus am Beispiel endoprothetisch versorgter Femura. Bericht aus dem Institut für Mechanik, Hamburg, Ziefle, M. Numerische Untersuchungen der Druckscheiben Prothese. Zusammenfassung, Universität Hannover, Institut für Baumechanik und Numerische Mechanik, 2002 Further studies

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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 bone MS ID : Authors : Ulrich Wiebking, Björn Birkenhauer, Franziska Hühn, Christian Krettek and Thomas Gösling Journal : Acta Veterinaria Scandinavica 2007

B. BirkenhauerCoST OP-Kurs Hüftgelenk The investigation In laboratory The test machine

B. BirkenhauerCoST OP-Kurs Hüftgelenk Results I Terminal of the investigation: The fracture SpironZweymüller

B. BirkenhauerCoST OP-Kurs Hüftgelenk Result Strength – Time-Diagram

B. BirkenhauerCoST OP-Kurs Hüftgelenk Result blue = Spiron; red = Zweymüller; white = without prosthesis

B. BirkenhauerCoST OP-Kurs Hüftgelenk Result: Maximal stress at femur fracture Femora with Spiron Femora with Zwey- müller Natural Femur

B. BirkenhauerCoST OP-Kurs Hüftgelenk Elasticity of the system „Prosthesis in bone“ (Force in Newton vs. distance in millimeter)

B. BirkenhauerCoST OP-Kurs Hüftgelenk The „Helica“-Prosthesis in the veterinary medicine Due to the good biomechanical results of that investigation was the Spiron prosthesis under 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:

B. BirkenhauerCoST OP-Kurs Hüftgelenk 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 Indications Good bone quality Physiological hip joint geometry Biological age <65 BMI? (No previous surgery) good compliance Beware of arthritis with periarticular osteoporosis Approx max. 20% of hip replacement patients

B. BirkenhauerCoST OP-Kurs Hüftgelenk Are Femoral neck prostheses short stem prostheses? 2.Are shortstem- und femoral neck prostheses biomechanical equivalent? Outstanding questions

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