INTERNATIONAL ARTHROPLASTY SYMPOSIUM

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INTERNATIONAL ARTHROPLASTY SYMPOSIUM

• REVISION ACETABULAR

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Frank R. Ebert, MDAssistant Chief Department of
Orthopædics

• The Union Memorial Hospital
• Baltimore, Maryland

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Classifications

• AAOS
• Engh and Glassman
• Chandler and Penenberg
• Paprosky
• Gross

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Paprosky Classification Type I

• Supportive rim
• No bone loss
• No migration

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Acetabular Deficiencies
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Paprosky ClassificationType II

• Distorted hemisphere
• Intact supportive columns
• lt than 2 cm superomedial or lateral migration

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Acetabular Defiencies
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Paprosky ClassificationType II

• II a superomedial
• II b superolateral (no superior dome)
• II c medial only

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Acetabular deficiencies

• Contained Cavity defect are managed with
  morsellized allograft that is impacted in the
  cavity

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Paprosky ClassificationType III

• Superior migration greater than 2 cm
• Severe ischial and medial osteolysis

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Acetabular Deficiencies
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Paprosky ClassificationType III A

• Kohlers line intact
• 30 to 60 of component supported by bone graft
• Bone loss 10 oclock to 2 oclock

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Acetabular Deficiencies

• Global contained cavity defect including medial
  wall are managed with impacted morsellized graft

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Paprosky ClassificationType III B

• Kohlers line not intact
• More than 60 of component supported by bone
  graft
• Bone loss 9 oclock to 5 oclock

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Acetabular Deficiencies
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Acetabular Deficiencies

• Major column or segmental defect will require
  restoration of bone stock by major column
  allograft

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Gross ClassificationAcetabular Deficiencies THR

• Type I Contained
• Type II Noncontained
• Type II a Shelf/minor column
• lt50 of cup coverage
• Type II b Major column
• gt50 loss of cup contact loss of
  1 or both columns

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Treatment Options

• Structural Allograft
• Modified Cups
• Reinforcement Rings
• Impaction Grafting
• Trabecular Metal

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Structural Allograft
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Structural Allograft

• 1976 Harris started to use fresh frozen femoral
  heads in revisions
• Early results encouraging
• Later high rates of cup migration with bipolar or
  threaded components

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Structural Allograft

• Large combined and major column defects
• Few reconstructive options
• 20 cases bulk frozen femoral heads uncemented
  cups, follow-up 2 years 30 acetabular failure

Pollock F.H. J. Arthroplasty 1992
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Structural Allograft

• 27 cases 16 femoral head and 11
  distal femoral grafts
• uncemented cups
• 4 year follow-up 44 loose
• gt 50 graft cup contact increased
  failure rate

Hooten J.P. JBJS (Br) 1996
48 hips distal femoral grafts uncemented
cups 5 failure at 6.1 years
Paparosky W.G. Instr Course Lect 1996
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Structural Allograft
147 revisions 5.7 years follow-up fresh frozen
femoral heads uncemented cups 100 graft union
0 loosening
Paparosky, W.G. J Arthroplasty 1994

1. hips minor column defects5 loosening 5-12
   years

Gross A.C. Instr Course Lect 1996
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Structural Allograft

• 70 hips 16.9 years follow-up 62 cup
  supported by allograft 60 failure
• No failures if lt 30 cup supported by
  graft

Shinar A.A. JBJS 1997
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Structural Allograft Conclusions

• Conclusions
• Success depends on these factors
• Graft union/congruency
• Bone stock restoration
• Acetabular component stability Uncemented gt60
  host bone
• Cemented lt 60 host bone
• Good functional outcome

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Treatment Options

• Modified Cups

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Modified Cups

• Attempting to negate the need for bone
  grafts
• Well established that at least 50 host bone
  to cup contact required to prevent early
  failure
• Usually inferior bone is host accompanying
  a superior defect

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Modified Cups

• Roof Defects
• Jumbo Cups
• Expand the walls to incorporate large cup
• Press fit may be minimal therefore screws used to
  secure cup
• Concerns about removing more host bone
• Anterior Column can be sacrificed for placement

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Acetabular Deficiencies
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Modified Cups

• Oblong or Bilobed Cups
• Acetabulum becomes oblong with superior defect
• Oblong cups can achieve good host contact and
  press fit
• Central liner is seated inferiorly reestablishing
  COR

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(No Transcript)
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Modified Cups
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Modified Cups Results
No long term studies 30 cups follow-up 6 years
no loosening
Cameron H.U. Orthop Clin North Am 1998
Oblong cups 64 cases follow-up 44 months3
radiological loosening
Newman M.A. Orthop AAOS 1997
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Modified Cups
Capture Cup-Constrained Socket In revision
surgery soft tissues may be distorted, scarred or
absent May decide to use constrained
socket Reduces range of motion Increased neck
poly contact increases wear debris
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TRILOGY CONSTRAINED LINER
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• ProblemSoft-tissue laxity Extreme range of
  motionDislocationAbsence of abductor muscles as
  a result of multiple revisionsPatient paralysis

Solution 2Liner with a locking mechanism that
restrains the femoral head
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Treatment Options

• Reconstruction Rings

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Reconstruction Rings

• Reconstruction can be combined with particulate
  graft
• Rings must be securely fixed to pelvis
• Appropriate sized polyethylene cup cemented into
  ring in correct position
• Must not reference cup position to ring

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Reconstruction Rings

• First rings were cemented to the pelvis
• Theory was to spread the area of contact force
  and decrease incidence of migration
• Failed rapidly

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Reconstruction Rings
In general two types a) Fixation to ilium alone
(Muller, Ganz)
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Reconstruction Rings
b) Ilium and ischium fixation (Burch-Schneider)
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Reconstruction Rings Results

• Only short and midterm follow-up
• 68 Hips 51 had combined segmental and
  cavitary defects follow-up 2-5 years
• 3 radiographic loosening no revisions

Fuchs, M.D. Orthop Clin North Am, 1988
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Reconstruction Rings

• Muller Rings
• 46 Muller rings follow-up 5 years 10.8 failure

Rosson, J.J. JBJS (Br) 1992
55 Muller rings follow-up 10 years 20 failure
Zehtner, M.K.J. J.Arthroplasty 1994
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Reconstruction Rings

• Burch-Schneider
• 42 hips combined deficiencies follow-up 5 years
  24 failure rate

Berry D.J. et al JBJS (Br) 1994
28 hips follow-up 3 years 14 failure rate
Peters C.J. J.Arthroplasty 1995
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Acetabular Deficiencies
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Reconstruction Ring Fixation
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Acetabular Deficiencies
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Reconstruction Rings

• Consider in following circumstances
• Severe combined segmental and cavitary defects
• Poor bone quality not able to support uncemented
  cup
• Little biological activity left in bone i.e.,
  pelvic irradiation

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Treatment Options

• Impaction Grafting

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Impaction Grafting Results
60 revision hips 37 cavitary and 23
combined defects Follow-up 10-15 years 90
survival Schreurs B.W. et al, JBJS (Br) 1998

• hips mixed defects follow-up 5 years
  11.4 failed
• Slooff, T.J.J.H., CORR 1996

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Impaction Grafting

• Because morsellised bone cancellous thought to
  incorporate rapidly into host
• Cement, mesh and solidly impacted graft give good
  initial stability

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Trabecular Metal

• Excellent tool for revision surgery
• Host Bone support is probably around 30 to 40
• Can act as internal plating system to deal with
  pelvic dicontinuity

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Trabecular Metal

1. Revision cup obviates the need to drill through
   the trabecular metal USER FRIENDLY
2. Larger Head sizes make it ideal when concerns
   about dislocation exist
3. Early Clinical results are excellent- Mayo Series

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Conclusions

1. Results very surgeon dependent
2. Many centers have developed a technique that
   works for them
3. Results depend on multiple patient factors
   i.e., patients functional demands

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Thank You
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Defiencies
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Acetabular Deficiencies
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Acetabular deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Structural Allograft

• Centers modified their use of allografts
• Many switched to distal femoral or male femoral
  head allografts
• Techniques were improved

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Structural Allograft

• Massive acetabular defects
• Whole acetabular defects
• Cemented cups survival superior to uncemented
• 20 Hips follow-up 32 months 2 Failures
  for infection

Paprosky W.G., Instr Course Lect 1996
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Structural Allograft Results
Large segmental defects in T.H.A. 29 cases
superior deficiency loss of at least 30
coverage, Follow-up 3.5 years 17 failed Jasty
M. Orthop Clin North Am, 1987
30 hips graft supporting up to 60 cup 47
failure at 10 years Kwong, L.M. H Arthroplasty
1993
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Structural Allograft

• First used for protrusio acetabulæ in 1971
• 1973 Harris suggested use for acetabular
  reconstruction
• Femoral heads were used to reconstruct superior
  segmental defects

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Structural Allograft

• Large segmental and minor column defects
• 31 bipolar revisions femoral head
  allografts supporting 33-50 cup 2.4 years
  follow-up 50 complete failure

Wilson M.G., JBJS (Am) 1989
Threaded cups 18 cases follow-up 2.5 years 72
loose cups, 22 severe graft lysis
Hoikka V. Acta Orthop Scand 1993
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Modified Cups

• Porous coats weak in tension better in
  compression
• Even if have superior graft support only requires
  minimal resorption to remove any structural
  support
• Some reports of failure at cup porous coating
  interface

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Modified Cups

• The design required the cup to be vertical
• Polyethylene liner 15º offset means poly bears
  weight
• The upper defect may not include the whole depth
  of the acetabulum must remove more host bone

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Modified Cups

• Bilobed cups have advantages when bone removed to
  seat upper lobe leaves ridge which resists upward
  motion
• Lower lobe requires 15º anteversion upper lobe
  would sit proud posteriorly if it were in the
  same plane

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Modified Cups

• The lower cup is at 15 or 20º adduction compared
  to upper liner can have offset
• Most cups press fit however authors use
  supplementary screws
• Bone graft placed through screw holes.

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Modified Cups
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ZCA CONSTRAINED CUP
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• ProblemSoft-tissue laxity Extreme range of
  motionDislocationAbsence of abductor muscles
  as a result of multiple revisionsPatient
  paralysis

Solution 3Modified ZCA cup that provided
snap-fit constraint of femoral head
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TRILOGY OBLIQUE LINER
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SolutionRotate liner face and ID out to gain
additional version and soft tissue tension

• ProblemMal-Positioned Shell

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TRILOGY OBLIQUE LINER
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• Change acetabular version lateralization and
  translation of the femoral head

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TRILOGY OBLIQUE LINER
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Posterior
Anterior
Anterior

• Correcting total version (coronal view)

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TRILOGY ECCENTRIC LINER
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80mm liner
56mm liner
7.0mm

• ProblemSuperior head migration

SolutionShift center of joint rotation back to
normal
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Global Contained Cavitary Defect
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Recon Ring with All-Poly Cup
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Acetabular Revision

• Zimmer Mid-Atlantic
• Sales Meeting
• January 2004

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Acetabular Revision

• I Simpósio Internacional Combinado de Artroplastia

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Acetabular Deficiencies
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Acetabular Deficiencies
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Acetabular Deficiencies
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Reconstruction Rings

• Conclusions
• In USA limited to situations in which porous
  coated implants have high failure rates
• Incidence decreasing as Jumbo cups become more
  popular

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Reinforcement and Reconstruction Rings
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Reconstruction Rings

• Modern designs screwed to the pelvis
• Fixed mainly to the ilium but some to the ischium
• Polyethylene cup cemented into socket

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Structural Allograft

• 27 cases 16 femoral head and 11 distal
  femoral grafts
• uncemented cups 4 year f.u. 44 loose
• gt 50 graft cup contact increased
  failure rate

Hooten J.P. JBJS (Br) 1996
48 hips distal femoral grafts uncemented
cups 5 failure at 6.1 years
Paparosky W.G. Instr Course Lect 1996
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Structural Allograft alt version(s)
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Reinforcement Ring Insertion
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Reinforcement Ring Fixation
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Reinforcement Ring FixationAP VIEW
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Recon Ring with All-Poly CupAP View
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TRILOGY REVISION ACETABULAR PROJECT
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• Project Goal Develop a system of acetabular
  components that will provide a variety of options
  to address Joint instability Bone
  deficiencies

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TRILOGY REVISION ACETABULAR PROJECT INSTABILITY
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ZCA Constrained Liner
Oblique Liner
Eccentric Liner
Constrained Liner
Large Head Liner