MEGASYSTEM C
Department of Oncological and Reconstructive Surgery CTO Florence Italy
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Eclectic Device Different Clinical Conditions
posttraumaticrevisiontumor
MEGASYSTEM C
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ModularityFrom a minimum of 5 cm
(revision surgery)
to the“en bloc” knee
&entire femur and tibia
(extensive tumor resection)
MEGASYSTEM C
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Modularity
Accurate length adjustment 1cm by 1cm( instead 2 by 2 )
1 cm
2cm
MEGASYSTEM C
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Further accomodationwith extension ring
in hip reconstructionsPDF created with pdfFactory Pro trial version www.pdffactory.com
Complete Hip Joint System
- hip arthroplasty
conventionalsnap fitfully retentive
- bypolar cup
- saddle prosthesis
MEGASYSTEM C
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üAntiversion - adjustable at surgery
MEGASYSTEM C
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Newendomodel
kinematic rotating hinge knee
MEGASYSTEM C
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Intraoperative changeable from rotational to total hinged knee without removing stems or joint components
Component for rotation and extension/flexion
Component forextension/flexion only
Assembly without extension between femur and tibia
MEGASYSTEM C
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MEGASYSTEM C
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Same system :3 Extensive revisions3 Resection arthroplasty3 Intercalary resections3 Resection arthrodesis
Conversionfrom arthroplasty
to arthrodesisfeasible at any time
without stem removal
MEGASYSTEM C
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Stem fixation
Interchange ability
cemented cementless
Older pt. Younger pt.Metastases Primary tumorsOsteoporotic Normal bonePrevious Rxth. NoneScheduled Rxth. NoneInadequate press fitt Adequate press fit
MEGASYSTEM C
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Rough Collar Ring
Cemented stem
MEGASYSTEM C
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enhanced scar tissueprevents
polyethilene debrismigration
at the interfacestem / inner cortex
“purse string effect”
MEGASYSTEM C
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Cementless fixation
Rough titanium trunco conical flanged stems (1 mm steps)
MEGASYSTEM C
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Cementless fixation
Two antirotational pegs
MEGAPROSTHESIS C
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The anchorage elements absorbs rotational forces acting on the intramedulary stem anchorage. This
assures a bone-safe transmission between the anchorage of the prosthesis and the bone
MEGASYSTEM C
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short coneconnection
MEGASYSTEM C
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Conventional megaprosthesis
Composite allograft- prosthesis
Ibrid solutions“encased grafts”
Implant Flexibility
MEGASYSTEM C
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MEGASYSTEM C
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Conventional megaprosthesis
Composite allograft- prosthesis
Ibrid solutions“encased grafts”
Implant Flexibility
MEGASYSTEM C
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üThe allograft allows a
normal distribution of
forces from implant to
host bone when union
has been achieved
Rationale for alloprosthesis
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Alloprostheses vs Megaprostheses:Outcome (10 years survival)
Alloprosthesis Megaprosthesis
Anract 77 noneZehr 76 58Capanna 85 83Robb -- 63Horowitz -- 67Urwin -- 94
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Alloprostheses vs Megaprostheses:Functional Results
Alloprosthesis Megaprosthesis
score limp can score limp can
Zehr 87 64 43 80 90 60
Anract 83 52 10 75 75 35
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Conventional megaprosthesis
Composite allograft- prosthesis
Ibrid solutions“encased grafts”
Implant Flexibility
MEGASYSTEM C
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Rationale for alloprosthesisReattachment of bone and muscles is feasable and effective
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osteosarcoma
MEGASYSTEM C
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osteosarcoma
MEGASYSTEM C
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allograft
conventional
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MEGASYSTEM C : “conventional” tibia
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MEGASYSTEM C : “conventional” tibia
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MEGASYSTEM C : tibial “ encased graft ”
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Chondrosarcoma involving the entire tibia with pathological fracture & closed nail fixation
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Osteoarticularwith
capsular repair
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5 years follow up
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Recurrent G. C. T.
extensivelyinvolving
the knee joint
MEGASYSTEM C : knee “ ibrid” implant
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Recurrent G. C. T.
extensivelyinvolving
the knee joint
MEGASYSTEM C : knee “ ibrid” implant
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SERIES OF PATIENTSTotal 297 cases
Department of Orthopaedics, Florence, Italyfrom june 2001 to july 2007
213 casesUniversity of Innsbruck, Austria
from maj 2002 to july 200760 cases
University of Hamburg, Germany24 cases
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SERIES OF PATIENTS297 cases
RECONSTRUCTION TYPE CASES
Proximal femur 130 (44%)
Distal femur 108 (36%)
Total femur 35 (12%)
Proximal tibia (sept. 2005) 10 (3.2%)
A-P composite of the knee 8 (3%)
Knee arthrodesis 5 (1.5%)
Intercalary resection of the femur 1 (0.3%)
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COMPLICATIONS297 cases
34 cases (11.4%)Type Florence Innsbruck Hamburg Tot.
Infection 14 1 2 17 (5.7%)Mechanical failure
6 1 - 7 (2.3%)
Dislocation 3 - 1 4 (1.3%)Loosening 2 1 - 3 (1%)Shaft perforation - 2 - 2 (0.6%)Prosthetic disconnection
1 - - 1 (0.3%)
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PROSTHETIC COMPLICATIONS
17 out of 297 cases ( 6 %)
Type Florence Innsbruck Hamburg Tot.
Cone breakage 6 1 - 7 (2.3%)Hip dislocation 3 - 1 4 (1.3%)Stem loosening 2 1 - 3 (1%)Shaft perforation - 2 - 2 (0.6%)Cone disconnection
1 - - 1 (0.3%)
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Mechanical failureFlorence experience
Total # %213 pts 6 2.8%493 cones 8 1.6%
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Further recent improvements
Modification on cone
slope obliquityshiftingstress
distributionmore at its basis
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Mechanical failurePersonal experience
Total # %Before 150 pts 5 3.3
322 cones 7 2.1
Total # %After 63 pts 1 1.5
171 cones 1 0.6PDF created with pdfFactory Pro trial version www.pdffactory.com
Further recent improvements
Transfixing screws for cone stability
were foundprudentialexcessive
tools
Elimination of any stress riser or week pointPDF created with pdfFactory Pro trial version www.pdffactory.com
Further recent improvements
• Full thicknesscone
with total contact• Removal of
transfixing screws
To avoid any stress riser or week pointPDF created with pdfFactory Pro trial version www.pdffactory.com
Further recent improvements :biomechanical tests
Disassembling forces :
6500 N without screw8000 N with screw
Very safe locking device
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Further recent improvements :biomechanical tests
Small screw grippingin a notch of the
collar
very effectivelocking device(up to 8000 N )in a safe area
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Further recent improvements :biomechanical tests3 points bending stresses :
3500 N 10 Hz 10,000,000 cycles
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ALLOGRAFT COMPLICATIONS
TYPE NUMBER EFFECT
PARTIAL RESORPTION &
FRACTURE
1 CASE(PROX FEM)
NO INFLUENCE ON FUNCTIONAL OUTCOME
PARTIAL RESORPTION
1 CASEREMOVAL AFTER 4 YEARS REVISION FOR COTYLOIDITIS
POST-TRAUMATIC EXTENSOR APPARATUS ELONGATION
1 CASE EXTENSOR LAG
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PRE RESORPTION & FRACTURE
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POST RESORPTION&
FRACTURE
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ALLOGRAFT COMPLICATIONS
TYPE NUMBER EFFECT
PARTIAL RESORPTION & FRACTURE
1 CASE(PROX FEM)
NO INFLUENCE ON FUNCTIONAL OUTCOME
PARTIAL RESORPTION 1 CASE
REMOVAL AFTER 4 YEARS REVISION FOR COTYLOIDITIS
POST-TRAUMATIC EXTENSOR APPARATUS ELONGATION
1 CASE EXTENSOR LAG
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