(Παρουσίαση στο Πανευρωπαϊκό Συνέδριο Ορθοπαιδικής Χειρουργικής & Τραυματιολογίας, Μαδρίτη/ Ισπανία 2010). PASSIVE ROBOTICS IN TOTAL KNEE ARTHROPLASTY. PRELIMINRY RESULTS. EFFORT CONGRESS, MADRID/SPAIN 2010

1. S.ALEVROGIANNIS, MD, PhD.
CONSULTANT ORTHOPAEDIC SURGEON
2ND Orth. Dept.251 General Air Force
Hospital, Athens/GR.
G. A. SKARPAS, MSc, PhD
8TH Orth. Dept., General Hospital
“Askepieion Voulas”, Athens-GR.
11th EFORT CONGRESS
MADRIT 2010

2. Knee Pain Patient Population: Underserved and
Growing
•The Population is Aging
-Age 55+, peak knee pain
candidates, will grow 3 times
the average rate of the U.S.
population
-Reaching 96 million by 2020
•Obesity Rates are Rising
-In 2000, 31% of the adult
U.S. population had a BMI of
30
-Estimated rise to 40% by
2010

3. Major Healthcare Trends
•Patient – Centric Healthcare
 Increase in Internet education
 Increase in Direct to Consumer
Marketing
 Patients desire superior high
tech CAOS/ Robotic Solutions
•Early outcomes Robotic
Surgery
 Improved accuracy
 Repeatability
 Enabling: minimally
invasive surgery
 Next frontier is
orthopedics

4. Patients Desires in Knee
Surgery
 No Lifestyle Change
 Latest Technology
 No Hospitalization-
Short Rehab
AAOS
 No pain
Survey
 Long Term Solutions
© MAKO Surgical Corp. 2009

5. TKA Gold Standard For
Surgeons
• Total Knee Arthroplasty (TKA) considered Gold Standard for
degenerative joint disease
• John Insall, M.D. – Father of Modern TKA
• Proven long term survivorship 90% out 15 years
• One of the most successful procedures in modern medicine
Limitations
• Highly invasive
• Requires extensive rehabilitation
• Addresses late stage osteoarthritis (OA)
• Often over utilized due to lack of equally successful / predictable
alternatives, (UKA)
• Aggressively removes healthy cartilage when treating early stage
OA
• Per Duke University Study: 88-92% of men and women
respectively decline Total Knee / Hip Arthroplasty .

6. Limitations of Instruments
 Improper cutting block pin to bone alignment
 Vibration of blade can cause deflection & skiving
 Learning curve with instrumentation
 Pins can be a stress riser to bone
 Intramedullary alignment guides (standard for femur)
are invasive and can cause pulmonary emboli upon
tourniquet release
 Extramedullary alignment relies on the palpation of
bony landmarks underneath varying thicknesses of soft
tissue
 Requires larger incisions

7. TKA outcomes have been shown to be dependent
on implant positioning and alignment
With conventional techniques:
 Limited preoperative planning (templates, x-ray)
 Instrumentation does not provide consistent
alignment
 Instrument cutting guides do not always deliver
precise resection (blade skiving)
 Requires large, sufficient size incision to inserts jigs
 Jigs require pinning, thus there is more bone
disruption

8. AIM OF THE STUDY
 To present our
preliminary results,
using Navigation for
TKR.

9. EARLY NAVIGATION SYSTEMS

10. WHAT IS CAS ?
A NEW TECHNIQUE:
 Navigation
 Passive Robotics
 Joint Surgery
 Bridging the gap between
TKR and technology
 Bringing More Treatment
Options

11. Move to Kinematics
 Klee is the Software for evaluation of
joint kinematics developed on the basis
of surgeon’s requirements to help the
surgeon to analyze laxity values during
the standard kinematics evaluation
which are performed several times
during the surgical procedure.
 In particular Klee addresses the
standard kinematics tests executed
before and after arthroplasty
interventions to evaluate parameters
such as the anterior-posterior (AP), the
rotational laxity, the internal/external (IE)
and varus/valgus (VV), and let the
surgeon to define , to acquire and
investigate further references.
 Klee quantifies the kinematics
parameters and displays the knee
position when they are performed, and
therefore supports the surgeon to
reproduce more precisely the same
kinematics tests before and after the
reconstruction for interventions such as:
ACL, TKR,THR.

12. ΤΕCHNIQUE
CAS surgery, made simple
 VOYAGER platform combines
surgeon’s experience with accuracy
and visualization features of
computer technology.
 VOYAGER provides the surgeon
with improved information of
surgical tools position related to
patient’s anatomy, in order to
significantly decrease positioning
errors and to obtain better long-
term results.
 The use of VOYAGER platform
allows to reduce the learning curve
of surgical interventions and to
decrease surgical times.

13. ΤΕCHNIQUE
Simplicity is the key of
success
 Mirò is the software
for total knee
arthroplasty.
 Even the surgical
instrumentation has
been designed
focusing on accuracy
and minimally
invasive surgery.

15. ΤΕCHNIQUE
Surgical sequence:
 This surgical sequence has been studied to
obtain at once both the maximum precision and
an easy recovering of any unsatisfactory
situations.
 The tibial resection gives the surgeon a good
benchmark to perform the femoral cuts, and
more room to operate in the femoral part.
 To leave the chamfers as the last cuts, allows a
much more precise measurement of the
articular gap, and a much easier recutting, if any
is needed.
 A functional system of augmentations of the trial
balance helps the surgeon to select the correct
thickness of the insert.
 At any stage, the surgeon may verify the
articular alignment with a metal rod inserted in
the proper eyelets present in most of the
instrumentation parts.

16. ΤΕCHNIQUE
Every patient is different
 The unique bone visualization method of
VOYAGER, combines the enhanced
information given by bone morphing and the
registration speed of imageless navigation
systems.
 Only few points are required to define patients’
specific anatomy, which is represented in a
clear way to avoid any possible misleading
information.
 In each step the congruency of the patient's
data are verified with the anatomical database
of the system.
 Implant positioning can be planned
considering the soft tissue envelope through
the ligament balance screen.
 A well balanced knee means long term results
and patients’ satisfaction.

17. ΤΕCHNIQUE
Accuracy
 Particular attention was
bend to the design of
surgical instrumentation.
 Only one hand is
necessary to hold firmly
the cutting guide in the
exact position, while
drilling for fixation.
 During the positioning of
the cutting guide the
VOYAGER interface
warns the surgeon with a
red frame if it is
exceeding the tolerance

18. PROSTHESES

19. PROSTHESES
Trekking knee system includes:
 Τwo femoral components: CR component (Cruciate Rataining)
which provides for the preservation of the posterior cruciate
ligament and PS component (Posterior Stabilized) which instead
provides for its removal
 Τwo tibial components for rotating and fixed inserts
 Τibial inserts for mobile plate and inserts for fixed plate
 Ρatellar components
 Both the femoral components CR and PS and the fixed and
mobile tibial components are also available in the uncemented
version, with a VPS (Vacuum Plasma Spray) treated TiCoat

20. PROSTHESES
 The TREKKING mobile bearing tibial components are manufactured in a
CoCrMo alloy by micro fusion and machining.
 The plate of the mobile model is mirror-polished to reduce the back-side
wear and provided with a central hole to accommodate the UHMWPE
insert peg. For a better anatomical congruency, the keel comes in five
different sizes.
 The posterior plate slope is 0° and allows for a better insert mobility.
 The TREKKING MBH tibial plate system includes a 3 mm plate for
considerable bone sparing.
 Moreover, a finite element method (FEM) has been used to design the
keel in such a way that an optimal mechanical strength is ensured.
 Components are available in cemented and uncemented versions with a
VPS treated (Vacuum Plasma Spray) TiCoat surface.

21. PROSTHESES
 The TREKKING MBH System features a rotating insert in a mirror-
polished tibial plate and an articular surface perfectly congruent with the
corresponding surface on the femoral component.
 The Trekking mobile bearing knee system has three main advantages:
• Reduced polyethylene wear, thanks to an optimised articular contact area.
• Improved implant function: each movement is accommodated by a different
joint. Moreover, each surface has been specifically designed for a
dedicated movement, thus considerably improving both wear
performance and joint function.
• Tibial plate rotation is a less critical parameter, since optimal alignment can
be naturally reached by the bearing.
 The mobile bearing knee system is indicated in relatively young and
active patients with good ligaments.

22. PROSTHESES
 The TREKKING CR cemented femoral
component is manufactured in a CoCrMo
alloy.
 It is a Posterior Cruciate retaining system
and therefore indicated in patients with
ligaments in good conditions.
 Components are available in cemented and
uncemented versions with a VPS treated
(Vacuum Plasma Spray) TiCoat.

23. PROSTHESES
 The fixed TREKKING System provides for a
technique to fix the insert to the tibial plate
consisting in notches on the tibial component
that fit with the stainless steel wire spring of the
insert itself.
 This system, beside granting a perfect fixation
of the two components, minimizes the backside
wear of the polyethylene insert, that can be
compared to the wear rate of the articular
surface, as recognized by several scientific
works.

24. KNEES
Material
RIGHT
20
LEFT
15
 35 patients (35 knees)
 Mean age 73 years (60 – 82)
 W: 23, M : 12
 KNEES: L:15/R:20 ΦΥΛΟ
 Mean height 167cm
MEN
 ΒΜΙ: 34 ( 61% OVERWEIGHT) 12
 1ST TKR
 FOLLOW UP: 1 year
 PRE-OP score KSS: 40+13(26-53)
WOMEN
23

25. Aetiology for operation
ΟΑ:30
RΑ:2
Post.Traumatic:2
PVNS:1

26. METHOD
 Same surgeon
 Standard anterior midline approach/medial
parapatellar exposure of the joint
 Clean theater-vertical laminar airflow
system
 Special cutting guides-templates, lateral
release
 Antibiotics-Anticoagulants

27. OPERATIVE PLANNING VIA
NAVIGATOR-assembling the
sensors

29. PRE-OP MEASUREMENT

30. TIBIA

31. TIBIA

32. FEMUR

33. FEMUR

34. FEMUR

35. FEMUR

36. IMPLANT CHECK

37. FINAL ALIGNMENT

38. FINAL RESULT

39. POST-OP X-RAY

40. POST-OP
 Cool Pads
 Drain-autotransfusion for 2 days
 Antibiotics -3 days
 LMWH-35 days
 Early Mobilization
 FROM + Special Rehab. Protocol
 PWB: 2nd post-op day
 FWB: 30 days
 Hospitalization :6 days(5– 10 )

41. RESULTS
 No major complications were seen.
 Follow-up at 6 and 12 months post-op.
 No presence of radiolucent zones (very
early).
 Special tests for flexion-pain-well being
all excellent.

42. KNEE FUNCTION
KNEE PATIENT Pt POST-OP
FLEXION PRE-OP 1080 (80-1250)
920( 70-1150)
< 700 3 _
70-890 15 _
90-1080 14 11
> 1100 3 24

43. KNEE FUNCTION
CLIMBING STAIRS PTs PRE-OP PTs POST-OP
NORMAL 3 25
CLIMBING UP NORMAL- 7 8
CLIMBING DOWN WITH HELP
CLIMBING UP AND DOWN
15 2
WITH HELP
CLIMBING UP WITH HELP- 8 -
CLIMBING DOWN
IMPOSSIBLE
TOTAL IN COMPETENCE 2 -

44. KNEE FUNCTION
WALKING PTs PRE-OP PTs POST-OP
ONLY AT HOME 19
< 10 BLOCKS 7 5
> 10 BLOCKS 9 8
WITHOUT 0 22
LIMITATION

45. RESULTS
 KSS Score : 40 pre-op./ 70 at 6 m.p.o/
95 at 12 m.p.o.
 Knee Sore : 35-67-98.
 Function score: 43-75-99.
 Knee Pain Score:
Pre-op
Severe pain 69,2%/ Moderate 21%/
Mild 5,6%/ No pain 4,2%
Post-op
Painless 68,7%/ Mod 6.55%/ Mild 24.3%

46. Results
 Caplan-Mayer Survey: All prostheses
survived 1 year post-op uneventfully.
 Tibio-femoral axis: 0-5 Valgus 52.4%
0-5 Varus 36.4%

47. CONCLUSIONS
 Clinical and radiological results equal to international literature.
 The MIRO software is an innovative tool for computer assisted surgery.
 Navigation TKR by SAMO is time sparing and allows shorter learning
curve.
 Only crucial measurements and values are evaluated during the
procedure, anatomically.
 Less intraoperative bleeding and less risk for fat embolism-no
intramedullary guides.
 There is always the option for conventional TKR.
 Minimal invasive-instrumentation of same mentality-same cutting block
for both bones.
 For sure a greater number of cases and mid- and long-term follow
up is needed in order to prove the efficacy of the method.

48. THANK YOU