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Custom endoprotesi - Progettazione personalizzata Protesi di caviglia

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6° Presentazione del workshop finale del progetto Custom Implants

Custom-Endoprotesi

Le superfici articolari affette da gravi degenerazioni sono sostituite da endoprotesi artificiali. L’attuale limitatissimo numero di taglie disponibili ingenera importanti problemi tra la protesi e l’osso ospitante, che porta spesso al fallimento della sostituzione. Con i nuovi strumenti a disposizione (immagini biomedicali, software di ricostruzione, modelli biomeccanici, ecc.) e la recente tecnologia di stampa-3D si sono progettate nuove protesi articolari personalizzate per la caviglia.

Principali settori indirizzati: Farmaceutico, biomedico, chimico, biologico, ingegneria tissutale, clinico

Sito web del progetto: www.custom-implants.it

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Custom endoprotesi - Progettazione personalizzata Protesi di caviglia

  1. 1. Progettazione, validazione e stampa 3D in leghe metalliche di endoprotesi per piccole articolazioni Laboratorio Analisi del Movimento Istituto Ortopedico Rizzoli
  2. 2. CUSTOM IMPLANTS 2 Total Ankle Replacement (TAR) Severe pain (*2M), end-stage osteoarthritis with motion limitation (*50K) Ankle Fusion (Arthrodesis) Total Ankle Replacement (TAR) Ankle fusion and current TARs are inadequate to solve the problem * Numbers refer to USA market only
  3. 3. CUSTOM IMPLANTS 3 Cement fixation Bone resection Original CoR changed Osteolysis Impingement Loosening (90-95%) Subsidence Infection Instability Edge loading Salvage/revision Malleolar fracture Polyethylene wear and dislocation Subsidence Instability Impingement Infection Vascularity Bone removal Syndesmosis fusion Non- delay-union Groove at articulation Long pegs, cortical window Screw-based fixation Stress-shielding Flat-Ti & Nat-Ta Earlier complications Sizing Back to conforming 2-comp.. Lateral access Back to constrained.. Back to cement.. Cumbersome operative technique.. Leardini et al. GIOT 2007; Giannini et al. Foot Ankle Surg 2000 Pioneers ‘70 Classics ‘80 Modern ‘90 Current 2000 Total Ankle Replacement (TAR)
  4. 4. CUSTOM IMPLANTS 4 TAR: the articular surfaces Polyethylene Metal components
  5. 5. CUSTOM IMPLANTS 5 Design of TAR components from a novel experimental investigation of the morphology of the ankle articular surfaces Imaging Segmentation & 3D Rendering 3D Geometrical Analysis Design & Manufacturing of Artificial Surfaces Testing: 3D kinematic and kinetic analysis CAOS & EFAS Best Paper Awards (2016)ankles (vitro/vivo) TAR design: anatomical approach
  6. 6. CUSTOM IMPLANTS 6 F C L CM B1 B2 A1 A2 Lateral Sphere Medial Sphere Tibia/Fibula Segment Talus/Calcaneus Segment Fixed Sphere CaFiL TiCaL C Parenti-Castelli, Leardini et al., Med Bio Eng Comp 2007; J Biomech 2009  Two ligament fibres  Three rigid contacts: A. 2 sph-pla at Ti-Ta, 1 sph-pla at Ta-Fi B. 3 sph-sph  3D mathematical description of passive kinematics TAR design: functional approach
  7. 7. CUSTOM IMPLANTS 7 TAR design: functional approach
  8. 8. CUSTOM IMPLANTS 86 in-vitro implantation (‘99–’02), and about 1200 patients (Jul ‘03 – May ‘16) TAR design: anatomical-functional approach
  9. 9. CUSTOM IMPLANTS 9 Custom design Imaging Biomech. MODELS: anatomical Motion analysis funct/anat functional Bones Ligaments Kinematics D E S I G N D E S I G N d i m e n s i o n Surgical/clinical options: • position • shoulder/gutter • fixation elements • material • cement / coating • transverse plane • chamfers • insert • cutting blocks? D E S I G N f i n a l …modelling both ankles?! Liverani et al. Materials and Design 2016
  10. 10. CUSTOM IMPLANTS 10 Imaging  Selection of best imaging technique:  CT based imaging: - Standard CT (no soft tissue) - Dual-Energy CT (enhancement of soft tissues) - ConeBeam CT (3D and soft tissue, real joint loading)  MRI based imaging: - 1.5 T MRI - 3.0 T MRI
  11. 11. CUSTOM IMPLANTS 11 Design of reference markers detectable by CT & MRI rigidly fixed on relevant anatomical structures via plaster HARD MARKER with centered cavity filled with a CRYSTAL JELLY BALL hermetically closed to prevent from drying out Imaging
  12. 12. CUSTOM IMPLANTS 12 MRI 3T T2 FS CBCT Imaging Regular CT Tissue 1 Standard CT Dual Energy CT Basal 1 Dual Energy CT
  13. 13. CUSTOM IMPLANTS 13 3D modelling and registration
  14. 14. CUSTOM IMPLANTS 14 SURFACE-TO-SURFACE ANALYSIS Bone-cartilage registration via best fitting method CBCT+3T Standard CT+1.5T Standard CT+3T CBCT+1.5T ConeBeam CT + 3T MRI • LESS OVERLAPPING • GREATER HOMOGENEITY tibiatalus 3D modelling and registration
  15. 15. CUSTOM IMPLANTS 15 DIFFERENCES IN ANATOMICAL PARAMETERS BETWEEN IMAGING TECHNIQUES 3D modelling and registration Siegler S et al, Clin Biomech, 29(1):1-6, 2014. Talus MED D(mm) LAT D(mm) ANT D(mm) ANT CENTR D(mm) CENTR D(mm) POST CENTR D (mm) POST D(mm) CT STANDARD 39.5 33.8 85.3 70.7 59.4 76.2 85.2(-) CBCT 40.0 36.1 62.0 121.7 86.3 75.9 50.1(-) DUAL ENERGY CT 42.5 36.9 45.3 92.1 62.3 74.2 80.8 (-) CT STANDARD +COR 1.5T 45.5 36.0 146.8 76.6 91.9 60.3 68.8(-) CT STANDARD +SAG 1.5T 41.3 35.1 87.0 95.9 120.5 69.7 114.6 (-) CT STANDARD + CUBE 3T 39.2 31.9 128.0 106.2 91.2 83.7 63.9 DUAL ENERGY CT +COR 1.5T 48.5 39.1 68.2 75.2 94.9 67.3 64.9 DUAL ENERGY CT +SAG 1.5T 51.5 41.3 77.4 95.8 127.0 65.5 51.6(-) DUAL ENERGY CT + CUBE 3T 41.3 35.6 106.2 103.9 102.4 70.3 48.7 CBCT+COR 1.5T 57.9 41.6 89.4 81.6 90.8 99.0 61.9 CBCT+SAG 1.5T 53.6 45.0 136.0 95.0 139.4 73.6 (-) 39.1 (-) CBCT + CUBE 3T 48.7 39.3 118.9 100.5 99.7 85.9 86.8
  16. 16. CUSTOM IMPLANTS 16 TAR design: virtual planning
  17. 17. CUSTOM IMPLANTS 17 TAR design: virtual planning
  18. 18. CUSTOM IMPLANTS 18 BOX (size M) Custom-sized BOX components + 10% SCALING of TAR components TAR design: virtual planning
  19. 19. CUSTOM IMPLANTS 19 TAR: implant-bone interface Polyethylene Metal
  20. 20. CUSTOM IMPLANTS 20Osseointegration Chemistry & biocompatibility Implant-bone interface material Core material - metals (e.g. CoCr, Ti alloys, Mg alloys) - ceramics (Zr and Al based) - metals (CoCr, Ti alloy, Tantalum) - Calcium-phosphate based (biomimetic coating, e.g. hydroxyapatite) - biotolerant (distance osteogenesis) - bioinert (contact osteogenesis) - bioreactive (stimulating bone ingrowth) “A direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant.” Branemark (1985) Stress-shielding Topography - surface roughness (10-50 micron) - micron-scale and nano-scale (1 – 100nm) Surface treatments - sand-blasting - plasma sprying - electropolishing
  21. 21. CUSTOM IMPLANTS 21 Novel implant-bone interface
  22. 22. CUSTOM IMPLANTS 22 Trabecular bone model microCT – femoral bone TopviewSideview Density = 17% Trabecular thickness = 150um Trabecular Separation = 670um Acknowledgement : Laboratorio di Tecnologia Medica (IOR)
  23. 23. CUSTOM IMPLANTS 23 Regular unit cells CIRCULAR CROSSING-ROD Acknowledgement: CIRI-MAM (UniBO)
  24. 24. CUSTOM IMPLANTS 24 Regular unit cells porous scaffoldsTopviewSideview SPHERICAL Density-matched regular geometries CIRCULAR CROSSING-ROD Implant-to-bone control interface
  25. 25. CUSTOM IMPLANTS 25 From STL to CrCo samples Selective Laser Melting (CIRI-MAM, UniBO) 9 x 9mm CoCr samples
  26. 26. CUSTOM IMPLANTS 26 Mechanical characterization (ISO 13314, ASTM E9-09)
  27. 27. CUSTOM IMPLANTS 27 Geometrical validation Circular lattice hole diameter Crossing-rod strut dimension Mean (SD) [µm] 761 ± 26 225 ± 27 STL nominal [µm] 800 200 Error [%] - 4.9 % + 12.7 % Optical microscope
  28. 28. CUSTOM IMPLANTS 28 SEM: round samples Geometrical validation Acknowledgement: Università Politecnica delle Marche
  29. 29. CUSTOM IMPLANTS 29 SEM: trabecular samples Geometrical validation
  30. 30. CUSTOM IMPLANTS 30 T0: 24 h T2: 2 weeks Biocompatibilitycircularcrossing-rodtrabecularcontrol top sidetop Acknolwedgement: laboratorio BITTA (IOR)
  31. 31. CUSTOM IMPLANTS 31 Biocompatibility
  32. 32. CUSTOM IMPLANTS 32 SEM: round samples + cells Biocompatibility
  33. 33. CUSTOM IMPLANTS 33 SEM: trabecular samples + cells Biocompatibility
  34. 34. CUSTOM IMPLANTS 34 Final remarks • Manufacturing: CoCr 3D porous structures are feasible via SLM • Mechanical properties: similar to those of human bone  (stress-shielding reduction) • Biocompatibility: osteoblast-like cells proliferation and viability is good on all geometries • Results need to be confirmed in-vivo
  35. 35. CUSTOM IMPLANTS 35 Prototype of custom ankle prosthesis via selective laser melting (CIRI-MAM, UniBO)
  36. 36. CUSTOM IMPLANTS 36 Grazie per l’attenzione Ing. Alberto Leardini [leardini@ior.it] Ing. Claudio Belvedere [claudio.belvedere@ior.it] Ing. Paolo Caravaggi [paolo.caravaggi@ior.it] Laboratorio Analisi del Movimento, Istituto Ortopedico Rizzoli

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