PCL BALANCING IN TOTAL KNEE ARTHROPLASTY

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PCL BALANCING IN TOTAL KNEE ARTHROPLASTY

• Mark A. Snyder, M.D.
• Wellington Orthopaedics and
• Sports Medicine
• Cincinnati. Ohio

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PCL FUNCTION

• Provides 95 of total restraint to posterior
  displacement of the tibia on the femur
• Tensile forces increase with knee flexion
• Tibiofemoral translation (roll back) occurs
  during knee flexion which benefits
• Posterior clearance
• Increased quadriceps moment arm

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PCL RETENTION IN TKA

• BENEFITS
• The intact PCL in the total knee provides for
  more normal function, especially in
  stair-climbing.
• Tibiofemoral shear forces are favorably shared by
  the PCL which may protect the bone-implant
  interface.

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PCL RETENTION IN TKA

• DISADVANTAGES
• More challenging surgical exposure
• Interferes with ease of collateral balancing,
  particularly in severely deformed knees
• Low tibiofemoral conformity in CR knees, coupled
  with a tight PCL may lead to accelerated poly
  wear.

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THE DEBATE GOES ON!

• At long term follow-up, there is no difference in
  implant survivorship between CR and PS knee
  arthroplasties.
• Several studies report no difference in
  functional scoring.

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IS THERE GENERAL AGREEMENT?

• If you are going to use
• a cruciate-retaining
• prosthesis, consider
• Excluding severe varus, valgus, and flexion
  deformities
• Avoiding either an excessively tight or lax PCL
• In short, know how to
• balance the PCL!

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THE EXCESSIVELY TIGHT PCL

• Limited flexion
• Excessive posterior poly contact stress and shear
  forces due to exaggerated rollback
• Rocking movement of the tibial component may
  precipitate loosening, especially in uncemented
  cases.

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THE EXCESSIVELY LAX PCL

• Flexion instability
• Pagano, CORR, 1998
• May occur in the CR total knee with prior
  patellectomy
• Laskin, JBJS, 1995
• Possible increase in poly wear due to cyclic
  sliding
• Walker, ORS, 1991
• PCL deficiency can occur in rheumatoid patients
  with recurrent synovitis
• Laskin, CORR, 1997

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FLEXION INSTABILITY (Pagnano)

• Clinical Features
• Persistent pain
• Sense of instability
• Recurrent effusions
• Pes and retinacular tenderness
• Posterior drawer sign
• Above average range of motion

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THESE CLINICAL FEATURES PREDICT THE NEED FOR PCL
BALANCING

• Limited preoperative range of motion
• Flexion contracture
• Varus and valgus deformities that require
  collateral balancing (tight side releases)

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WHICH SURGICAL TECHNIQUES LEAD TO A TIGHT FLEXION
SPACE?

• Posterior osteophytes not removed
• Overstuffing which either too large a femoral
  component or posterior malposition of the femoral
  component
• A tibial cut in extension

Posterior malposition resulted in greater
functional problems than did the anterior notch.
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TIGHT FLEXION SPACE

• Increasing the thickness of the tibial poly after
  collateral balancing in severe deformities
• Any joint line elevation
• More proximal femoral cut (flexion contracture)
• Tibial resection level exceeded by tibial
  component thickness

Tibial joint line elevation so severe that
flexion is limited
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BEFORE GIVING ANY THOUGHT TO PCL RECESSION

• Optimal technique
• Remove deforming osteophytes
• Perform soft tissue releases
• Align the AP axis of the femoral component to the
  AP axis of the femur
• Whiteside, CORR, 1995
• Match bone resection with implant thickness in
  extension and flexion

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WHAT ARE THE SIGNS OF PCL IMBALANCE?

• If too lax
• The tibial trial surface can be pulled out from
  underneath the femoral component at 90 degrees
  of flexion.
• The patella must be reduced to prevent false
  positive laxity
• The poly insert must be dished to prevent false
  positive laxity
• Scott, JOT, 1996

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PCL TOO TIGHT

• You will observe
• Tibial component lift off in flexion
• Increased femoral rollback in flexion with
  posterior 1/3 contact rather than mid 1/3 contact
  of the tibiofemoral articulation

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HOW TO BALANCE (RECESS) THE TIGHT PCL

• Before placing the trial
• components, tease
• adherent fibers off the
• upper portion of the
• back slope of the posterior tibial spine.
• Remove impinging
• osteophytes from around
• the PCL both on the
• femoral and tibial side.

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HOW TO BALANCE (RECESS) THE TIGHT PCL

• With the trial components in place, partially
  release the PCL fibers off the tibial spine 2 to
  3 mm at a time. Recall that the PCL inserts over
  2 cm of the proximal tibia.
• Retest the trial arthroplasty in flexion to
  observe for lift off and/or excessive rollback.

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HOW TO BALANCE (RECESS) THE TIGHT PCL

• If excessive rollback
• occurs after greater
• than 10 mm of release,
• then consider other
• measures.

Excessive rollback after 10mm release
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PCL PERFORATION

• With the knee in
• flexion, use the bovie or
• 11 blade to perforate
• the anterolateral fibers
• of the PCL
• Palpate the PCL to see if it can be deflected 1
  to 2 mm.
• With the patella reduced, observe for lift off or
  excessive rollback .
• If PCL integrity is in
• question, used a dished
• insert.

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TIBIAL SPINE BONE BLOCK OSTEOTOMY

• Cut only the bone, not the periosteum
• Trim proud bone
• Palpate for degree of PCL laxity
• With the patella reduced, observe for lift off or
  excessive rollback.
• You may need a dished insert.

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IF THE FLEXION SPACE IS STILL TOO TIGHT

• Resect more tibial plateau.
• Increase the posterotibial slope, though no
  greater than 10 degrees.
• Remove additional posterior femoral condylar bone
  to downsize the femoral component.
• Fully release/resect the PCL and convert either
  to a more congruent insert or a PS arthroplasty,
  if available.

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IS PCL BALANCING SAFE?

• When compared with normal cadaveric specimens,
  the PCL recessed arthroplasty specimens
  demonstrated
• No significant increase in AP laxity
• No significant increase in varus/valgus laxity
• Arima, CORR, 1998
• KT-1000 arthrometric testing did not reveal a
  difference between PCL recessed and nonrecessed
  total knees in a bilateral arthroplasty setting.
• Worland, J Arthroplasty, 1997

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IS PCL BALANCING SAFE?

• 500 Consecutive Genesis II TKA with greater than
  one
• year follow-up
• 456 cruciate-retaining implants
• 313 with PCL balancing
• 267 with greater than 5mm release
• 54 with PCL perforation/bone block
• All with dished insert
• No flexion instability
• No posterior subluxation/dislocation
• 282/313 with flexion gt 120 degrees irrespective
  of limited pre-op flexion
• 304/313 with flexion gt110 degrees

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THANK YOU
PCL recession/perforation needed after using a
thicker poly insert for a corrected valgus
deformity of almost 20 degrees