Il progetto si inserisce nel campo della chirurgia personalizzata di precisione e in particolare nella realizzazione in stampa 3D di protesi in leghe metalliche e in polietilene per la chirurgia protesica sostitutiva (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 vogliono progettare 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 Presentazioni e video: cerr.eu/what-s-going-on/357-materiali-dei-seminari-disponibili-online

1. 31/10/2017
1
Design e stampa 3D di protesi
personalizzate per la caviglia
Ing. Alberto LEARDINI, Ing. Claudio Belvedere, Ing. Paolo CARAVAGGI
Laboratorio Analisi del Movimento
Istituto Ortopedico Rizzoli
CUSTOM IMPLANTS 2
Total Ankle Replacement
Severe pain (*2M), end-stage osteoarthritis with motion limitation (*50K)
AnkleFusion TotalAnkle Replacement (TAR)
Both ankle fusion and current day TARs are inadequate in addressing the problem
* NumbersrefertoUSA marketonly, notworldwide
CUSTOM IMPLANTS 3
Total Ankle ReplacementGeneration: Pioneers ‘70 Classics ‘80 Modern ‘90 Current 2000
Smith ICLH Newton TPR Mayo TNK Agility Bue-Papp STAR ESKA AES Salto Alpha HintegraMobility TopezEclipse SaltoTal Taric CCIevol
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 articulat
Long pegs, cortical
window
Screw-based
fixation
Stress-shielding
Still Flat-Ti & Nat-
Ta?
Earlier
complications
Sizing
Backto conforming
2-comp?!
Lateral access?!
Backto
constrained?!
Backto cement?!
Cumbersome
operative
technique!
Leardini et al. GIOT 2007; Giannini et al. Foot Ankle Surg 2000
CUSTOM IMPLANTS 4
Disegno anatomo-funzionale
Plantarflexion DorsiflexionNeutral
Post Ant
Leardini Clin Biomech 2001; Med Bio Eng Comp 2001, 2002
CUSTOM IMPLANTS 5
Disegno anatomo-funzionale
Max Do
CaFi
TiCa
IC
In 6 in-vitro implantation(‘99–’02), and in about1200patients (Jul ‘03– May‘16)
Max Pl
CUSTOM IMPLANTS 6
Disegno funzionale
F
CL CM
B1
B2
A1
A 2
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 mathematicaldescription of passivekinematics
A
B

2. 31/10/2017
2
CUSTOM IMPLANTS 7
Disegno funzionale
CUSTOM IMPLANTS 8
Disegno anatomico
• A new TAR design with articulating surfacegeometry
representinga paradigm shift from the “Common knowledge”.
2. Lateralapex
• Main features:
1. Truncated non-symmetriccone
3. Saddle shaped
Claims, close to normal:
• JointKinematics
• Load Transfer
• Loadingof ligaments
• Behavior under functional
and extremeloads
Expectedbenefits:
• Reduced wear
• Reduced rates of failure
CUSTOM IMPLANTS 9
Disegno anatomico
Image- and experimental- based study of the morphology of the articular surfaces,
in natural and prosthetic ankle joint
CT Imaging
Segmentation &
3D Renderings
3D Geometrical
Analysis Design & Manufacturing
ofArtificial Surfaces
Testing: 3D Kinematics and Kinetics Analyses
CAOS & EFAS Best Paper Awards!, June 2016ankles (vitro/vivo) CUSTOM IMPLANTS 10
Progettazione personalizzata
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
s
n
e
d
Surgical/clinical
options:
•position
•shoulder/gutter
•fixationelements
•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
CUSTOM IMPLANTS 11
Scansioni ed immagini
Best selection, including possible combinations, among imaging devices at IOR:
CT based tech:
- Standard CT (no soft tissue)
- Dual-Energy CT (enhancement of soft tissues)
- ConeBeam CT (new technology, 3D and soft tissue, … loading!)
MRI based tech:
- 1.5 T MRI
- 3.0 T MRI
CUSTOM IMPLANTS 12
Scansioni ed immagini
to create reference markers well detectable in CT & MRI via material combination
rigidly fixed on relevant anatomical structures via plaster
HARD MARKER
with centered cavity…. ….Filled with a
CRYSTAL JELLY BALL…. ….and hermetically closed
to avoid possible drying.

3. 31/10/2017
3
CUSTOM IMPLANTS 13
Scansioni ed immagini
Regular CT Tissue 1Regular CT Tissue 1
Dual Energy CT Basal 1Dual Energy CT Basal 1
MRI 3T T2 FSMRI 1.5T cartilage new CBCT
CUSTOM IMPLANTS 14
Modellazione e registrazione
CUSTOM IMPLANTS 15
Disegno e progettazione
CUSTOM IMPLANTS 16
Disegno e progettazione
CUSTOM IMPLANTS 17
Interfaccia impianto-osso
Polyethylene
component
CUSTOM IMPLANTS 18
titolo
Osseointegration
Topography
Chemistry& biocompatibility
Bone-implant interface material
Corematerial
- 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)
- surface roughness (10-50 micron)
- micron-scale and nano-scale (1 – 100nm)
- biotolerant (distance osteogenesis)
- bioinert (contact osteogenesis)
- bioreactive (stimulating bone ingrowth)
Surface treatments
- sand-blasting
- plasma sprying
- electropolishing
“A direct structural and functional connection between ordered, living
boneand the surface of a load-carrying implant.”
Branemark (1985)
Stress-shielding

4. 31/10/2017
4
CUSTOM IMPLANTS 19
Interfaccia impianto-osso
CUSTOM IMPLANTS 20
CUSTOM IMPLANTS 21
‘Trabecular bone model’
microCT– femoralbone
TopviewSideview
Density = 17%
Trabecular thickness = 150um
Trabecular Separation = 670um
Acknowledgement : Laboratorio di Tecnologia Medica (IOR)
CUSTOM IMPLANTS 22
Dal .STL al modello CrCo
Selective Laser Melting
CUSTOM IMPLANTS 23
Test tossicità e osteogenesi
T0: 24 h T2: 2 weeks
rounddiagonaltrabecularspherical
top sidetop
Acknolwedgement: laboratorio BITTA (IOR)
CUSTOM IMPLANTS 24
Indagine SEM: campione
“round”

5. 31/10/2017
5
CUSTOM IMPLANTS 25
Indagine SEM: campione “round” +
cellule
CUSTOM IMPLANTS 26
Indagine SEM: campione “trabecolare”
CUSTOM IMPLANTS 27
Indagine SEM: campione
“trabecolare” + cellule
CUSTOM IMPLANTS 28
Prototipo di interfaccia
impianto-osso: protesi di caviglia
Selective Laser Melting (CIRI-MAM, UniBO)
CUSTOM IMPLANTS 29
Sviluppi futuri …
Cloud
Services
3DP Fabrication!
Specialised Research /
Design Centre #i
Specialised Research /
Design Centre #N
Specialised Research /
Design Centre #1
T rad. Fabrication #1
T rad. Fabrication #N
T rad. Fabrication #j
CUSTOM IMPLANTS 30
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 AnalisidelMovimento,Istituto Ortopedico Rizzoli