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Implant Selection In Revision T.K.R
1. IMPLANT SELECTION IN REVISION TKR
DR. MURTUZA RASSIWALA,
DNB RESIDENT,
DEPARTMENT OF ORTHOPAEDICS AND TRAUMATOLOGY,
UNIQUE SUPER SPECIALITY CENTRE, INDORE
2. INTRODUCTION
Total knee replacement surgery is a successful
operation for advanced arthritis of the knee.
However ,the components can wear or loosen causing
pain , swelling and instability, which may limit the
joint mobility.
Revision knee replacement surgery involves the
removal of all worn or damaged knee components and
replacement with new artificial components.
3. Indications for revision TKR
Aseptic loosening of implants
[ most common cause 40-50 % ]
Patellar Complication [5-20%]
Polyethylene wear [10-15%]
Instability [8-12%]
Infection [6-10%]
4. Challenges in revision TKR
While in primary TKR, bone is the friend of
the surgeon, and the defects are relatively small ;
in revision TKR Bone itself is changed by
1.) infection,
2.)osteolysis due to polyethylene wear or
3.)mechanical damage due to loosening of a
component.
5. Challenges in revision TKR
Bone Defects :-
Osteolysis is caused by polyethylene wear. The
wear particles contribute to the bone defects called
as “particle disease”.
Most patients undergoing revision TKR are old &
suffer from basic diseases like RA/OA and
osteoporosis. Hence the bone stock is already
compromised & quantitatively small.
6. Challenges in revision TKR
Soft Tissue :-
soft tissue may offer even more difficult problems
a) What was the original incision & how was the soft
tissue handling?
b) What is the cause of instability –
i. Over release
ii. Under release
7. Challenges in revision TKR
Alignment:-
If ligaments are present, they must be correctly
tensioned and balanced by choosing the correct
prosthesis size and correctly positioning it.
In many cases, constraint WILL NOT be necessary
If the ligaments have failed, a constrained implant still
needs perfect alignment.
8. General principles for revision TKR
Clarify the cause of failure.
Use adequate surgical exposure
Restore limb alignment
Achieve soft tissue balance
Use correct implant
Restore the joint line
Obtain a good Range of motion
9. JOINT LINE
Definition: The joint line is the articulating surface of the
femoral component in extension, flexion and all points in
between.
Anatomical Landmarks:
One finger above the fibula head
One finger below the inferior patella pole
30 mm distal to the medial femoral epicondyle
12-16 mm distal to the femoral attachment of the PCL
Old meniscus scar
Re-establishing the correct joint line is paramount in achieving
good functional outcome in revision knee replacement
11. CLASSIFICATION OF SOFT TISSUE DEFECTS :-
1. LCL ABSENT
• Align the knee
• Brace for 3 months
post op to restore
lateral stability
• Posterior stabilized
implant
12. CLASSIFICATION OF SOFT TISSUE DEFECTS :-
2. PCL ABSENT
• Assure
flexion/extension
space balanced
• Posterior stabilized
implant
13. CLASSIFICATION OF SOFT TISSUE DEFECTS :-
3. MCL ABSENT
• Reconstruct MCL and
brace post op
• Rotating Hinge
Implant
16. Metaphyseal Sleeves
Based on the principal of zonal fixation:
1. If the zone 1 is sufficient, bone quality is overall
good, alignment and ligament balance
reconstructed, a stemless fixation can be an
option.
2. Sleeves should be used with stems if the zone 1 is
compromised.
3. In case, a tibial stem is used, the diameter should
be 14mm or less, in order to make removal easier.
17. Metaphyseal Sleeves
Fixation in zone 2.
Made of Titanium with sintered beads of 50
to 80 % porosity on surface .
Morse taper fixation so no cement required .
Axial as well as Rotationally stable.
Wolf’s law induces bone growth on the
surface
Indications for Metaphyseal Sleeves
New level of immediate fixation
Management of severe bone loss
Stability of construct controlling flexion gap and
the joint line
Uncemented fixation
18. Problems
Radiolucent lines (needs followup ….).
Intraoperative fracture.
How “In the god’s name will you remove a well fixed
sleeve .”
19. Till now largest series and longest follow up
• 121 pts
• 196 sleeves
• 3.6 years follow up .
• Good outcome .
20. Tantalum cone
Tantalum as a metal has
high volumetric porosity (70–80%)
low modulus of elasticity (3 MPa)
high friction characteristics
Hence uniform load distribution .
No stress shielding.
Also has less bacterial adherence
22. Tibial stems
Designed for intramedullary
load sharing and press-fit with
excellent stability
•Bypass cortical defects
Fluted Tibial Rods
•Lengths 75, 115, and 150mm
•Cemented Stems
•Lengths 30 and 60mm
standard
•Tapered 90, 120, 150mm
•Diameter -13mm Only
23. Role of tibial stem
Support for implants
Fixation stability
Distribution of shear stress
Reduction in bone cement stress
When defect is more than 5mm after
the tibial cut .
25. Tibial Step Wedges
Sizes 1-6
•Thicknesses 5, 10, and
15mm
•May be downsized relative
to tray
•Universal –for use on
medial, lateral, or both
sides
Note: If you use a tibial
wedge you can NOT use a
tibial sleeve
26. Wedge v/s block
Block augmentation
better than wedge in
strain distribution,
tensile deformation rate,
compression deformation
rate, and shear
deformation rate.
Wedge better than block
in removal of less bone .
27. The chart below shows the recommended implant systems using the
Engh Bone Defect Classification System and ligament stability in the
patient’s joint.
30. Fully Constrained Implants
Here the tibial and femoral components are linked to each
other,like in a hinge.
advantage- stable implant,does not require much bony
and ligamentous support.
Use- tumour and revision tkr surgery
Disadvantage- supra physiological forces produced causes
implant and bone wear
Eg- Walldius, Shiers, Guépar, Kinematic rotating hinge.
31. Fully Constrained Implants
Constraint should only be used in revision TKR after
the principles of extension , flexion gap and medial
and lateral collateral ligament balancing are
performed
As little constraint as possible should be used
If stability cannot be obtained , only then , progressive
levels of constraint should be tested and used in the
construct.
32. Un Constrained Implants
Opposite of fully constrained implants
Not mechanically limited in their movements, but rely
on conforming joint surfaces and soft tissue guidance.
Very low constraint forces during entire joint motion
arc.
Eg- Modular type-Marmor, Lotus, Savastano
polycentric type (for unicompartmental knee
arthroplasty)
33. Semi constrained implants
Semi-constrained implants have near physiologic
constraint and are divided into -
posterior cruciate ligament-preserving,
posterior cruciate ligament sacrificing
Many prostheses fall into this category, including the
geomedic, anametric, total condylar, kinematic,
Kodama-Yamamoto, ceramic devices and others.
35. CASE 1 : Instability
Pre revision AP and lateral x rays
showing assymetric polyethylene
wear and major proximal tibial
and femoral lysis.
History
A 68 year old female presents 6 years
after left TKR.
Investigations
•All blood parameters are normal.
• Joint aspiration negative.
•Plain X-rays reveal significant
osteolysis of lateral tibial plateau and
femoral metaphysis.
•Asymmetric bearing wear is noted
suggestive of polyethylene bone
granuloma.
•The stabilised ‘plus’ bearing is
indicative of poor balance at the
initial primary TKR.
36. Problem
Excessive constraint, in an unbalanced knee, leading
to early polyethylene wear and bone lysis.
At explantation bone loss will inevitably be greater
than pre-operative films indicate once the granuloma
have been removed to healthy bone.
What would you do?
Simple bearing exchange or full revision?
How would you achieve fixation?
How would you reconstruct the bone defects?
How much constraint will be needed at revision?
37. SOLUTION
A full revision is required to
reconstruct bone defects and
achieve secure fixation.
We used 2 zone fixation
(metaphyseal sleeve in
zone 2 and stems in zone 3).
The sleeves also provide
secure reconstruction and
load the metaphysis to
regenerate bone stock
(Wolff’s Law).
By re-establishing the joint
line in extension and flexion,
the ligaments can be balanced
and reduced constraint is
needed (from stabilised plus
to PS).
38. CASE 2 : Bone Loss
Pre operative AP and LATERAL
X-Rays showing significant
osteolysis and bone loss
History
Male age 85 had a successful
left TKR 10 years earlier,
presents with increasing
discomfort and swelling.
Investigations
Examination reveals collateral
pseudo-laxity secondary to
loosening and subsidence of
the tibial and femoral
components.
X-rays confirm significant tibial
and femoral lysis. All blood
parameters are normal and
joint aspirate was negative.
39. Problem
Significant bone loss secondary to polyethylene
wear.
Revision TKR will need to address problems of bone
reconstruction, implant fixation and ligamentous
balance.
What would you do?
Revise to cemented stems and a rotating hinge
implant?
Reconstruct with metal / bone graft block augments
and diaphyseal engaging stems?
Use metaphyseal sleeves to achieve bone
reconstruction and implant fixation?
Use porous metal reconstruction cones to overcome
bone loss and use cemented fixation?
Arthrodesis?
40. SOLUTION
Post revision AP and
LATERAL X-Rays showing
metaphyseal sleeve tibial
reconstruction
In this case both
reconstruction and implant
fixation were achieved
using metaphyseal sleeves
supported by uncemented
stems.
Bone reconstruction
allowed the joint line to be
re-established such that
ligament balance allowed a
posterior stabilised mobile
bearing.
41. Why not the other options?
Porous cones and cemented stems would also be an
acceptable but more complicated option.
Metal / bone graft block augments and diaphyseal
stems provide a less reliable reconstruction and
fixation compared to other methods.
A cemented stem, rotating hinge would achieve a
satisfactory outcome but is unnecessary, as is
arthrodesis.
42. CASE 3: Peri- Prosthetic Fracture
AP and LATERAL X-Rays at
presentation showing
displaced,non united
supracondylar femur fracture
History
Female age 84, fell at home and
sustained a supracondylar
fracture above a well functioning
TKR.
Initial management was
conservative but after 8 weeks
the position was deemed
unacceptable, the fracture un-
united and the patient referred
for further management.
Investigations
Examination confirmed a
painful non-united distal
femoral fracture. X-rays revealed
a displaced, mal-rotated
fracture. All blood parameters
were normal.
43. Problem
Displaced type 2 femoral supracondylar peri-
prosthetic fracture with delayed presentation.
What would you do?
Continue non-operative management and anticipate
bone union, then mobilise?
Open reduction and internal fixation?
Revision knee replacement to reconstruct and bypass
the fracture?
Distal femoral replacement?
44. SOLUTION
Post revision AP and
LATERAL X-Rays at 12 month
review showing restored
femoral alignment and
fracture union
In view of the patients age,
unacceptable position and
non-united fracture, revision
to a rotating hinge using
metaphyseal sleeves to
reconstruct and provide
satisfactory fixation was
performed.
Immediate full weight
bearing post-revision was
possible.
45. Take home message
Diagnosis-must be sure
“REVISE” – do not repeat
Use revision implants
Complete revision
Build the knee from the tibia
Femur controls the tissue tension and joint line
Rotating hinge for gross instability and bone loss