What’s New in Knee
Replacement
Kenneth D. Kleist, M.D.
HealthPartners Medical Group
Regions Hospital
St. Paul, MN
Goals of Knee Replacement
• Improve the quality of life
by improving pain and
function while maintaining
range of motion and
avoiding complications.
• 85% of Knee replacement
patients say they would
have the surgery again.
Trends
What is a joint replacement?
What is a partial knee
replacement?
Minimally Invasive Surgery
• No good consensus on what this means
– Less skin incision
– Less tendon/muscle splitting and damage
– ??? More rapid recovery
• Certainly there are benefits
– Cosmetic, psychological, blood loss, recovery
• Bottom Line
– Need to have pieces put in right!
– Long-term survival of the joint is most
important
Approach
• Medial Parapatellar
• Mini-Medial
Parapatellar
• Mid Vastus
• Sub Vastus
• Quad Sparing
Pain Control and Rehabilitation
Protocols
• Regional Anesthesia increasing
– Spinal or Epidural Anesthesia
– Femoral Nerve Blocks
– Pre-op Medicines
– Pain Catheters, continuous or on
demand
– Local anesthetic intra-operatively
– Cryocuff for icing
– Long-Acting Narcotics
– Less Intravenous narcotics
– Pain as a vital sign
Better Nausea Control
• Much more focus
– Regional Anesthesia Helps
– Multimodal approach
• Less intravenous narcotics
• Scopolamine patches
• Odansetron
• Prochlorperazine
• Metoclopramide
Post-operative Physical Therapy
• Early mobility is helpful
– Continuous Passive Motion
(CPM) the night of surgery
• Start at high flexion right
away
• Set goals for range of
motion
– Up on your feet the first
post-operative day
– Discharge on the third postoperative day
– Transition from walker to
cane to nothing
How much flex is enough?
• High flexion implants
– Theoretically allow higher range of motion
• Traditional Implants 125, maybe 135 degrees
• Some now up to 155 Degrees
– Caution: High flexion does not mean you definitely will
get better motion.
– Setting Expectations is Important
• Best predictor is pre-op motion
• Knee will not be normal.
– Can make the surgery slightly easier by removing
extra bone
– Can provide additional implant options.
Gender Specific
• 3 anatomical shape differences
– Females are narrower
– They have a different angle the
knee cap glides through
– They have thinner area at the
front of the bone
• Most companies now address this
in some way
– Shape change
– Sizing
Mobile Bearing TKA
• Rotating Platform
– Plastic liner rotates in the metal
– May decrease wear
– May improve motion
– May allow fudge factor
– However may also increase wear.
– More difficult to insert plastic
Highly Crosslinked Polyethylene
• Relatively New
– Not as accepted as in the hip
• Goal is to reduce wear
– Still long-term questions
about mechanica strength to
fracture resistance and
delamination
– Not common used by most
surgeons yet except in
limited cases
• Very young patient
Other Alternative Bearings
• New approaches to
femoral components
– Ceramics
– Oxidized Zirconium
Computer Navigation
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Still Controversial
May improve overall alignment
May improve the accuracy of sizing
Possible it may improve long term outcome
Increases time
“Garbage In, Garbage out”
May place you at a minimal risk for fracture
Awaiting long-term data
Direct to Consumer Marketing
Current State of Patient’s Decision
Making in Today’s Market!
• The best advice is to
have a discussion with
your surgeon.
• Balancing Act
– Patients needs/desires
– Surgeon training,
experience, and skill