This document discusses implant selection considerations for revision total knee replacement (TKR) surgery. It begins by outlining common causes for revision TKR such as aseptic loosening and polyethylene wear. Key challenges in revision TKR are managing bone defects from osteolysis, compromised soft tissues, and restoring proper limb alignment. Implant options discussed include metaphyseal sleeves and stems to provide fixation in bone defect zones, as well as augmentations. Constraint levels from unconstrained to fully constrained implants are reviewed. Clinical cases demonstrate approaches for addressing instability, significant bone loss, and peri-prosthetic fractures in revision TKR.

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

10. .

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

14. CLASSIFICATION OF SOFT TISSUE DEFECTS :-
4. MCL and LCL ABSENT
• Rotating Hinge Implant

15. Bone Defect Zones for Revision TKR

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

21. Sleeves v/s cones
Fixation and Augmentation
Both Augmentation only

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 .

24. Femoral augments
Handed distal femoral
augments
•4mm
•8mm
•12mm
•16mm
Posterior femoral
augments
•4mm
•8mm

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.

29. Types of implants
 Unconstrained
 Semi constrained
 fully constrained

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.

34. Clinical cases and discussion

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

46. THANK YOU