TECHNIQUES IN PRIMARY TOTAL KNEE
ARTHROPLASTY: Balancing !
Douglas E. Padgett, M.D.Adult Reconstruction and Joint Replacement
Hospital for Special SurgeryNew York, New York
DISCLOSURESDISCLOSURES
None Related to the topic of this presentation
Consultant: Mako, Stryker
AAHKS: Board Member
Success in TKR
Basic tenets of Dr. John Insall:– TKR should be
thought of as a soft tissue operation
– Failure to address the soft tissue envelope will result in:
Pain
Stiffness
Laxity
“Thinking is the hardest work there is, which is the probable reason so few engage in it “
Henry Ford
American entrepreneurr
FAILURE IN TKR
Often can be traced back to original patho-anatomy
Varus knee– Preop: Tight medial side– Trial Components: knee
noted to be tight medially– Additional tibia resected– Result: knee “books open”
medially
Failure in TKR:The Valgus Knee
Complex patho-anatomy
Rotation often difficult to discern
Effect of deficiency of posterolateral condyle upon landmarks
Insufficient lateral side release: results is unstable arthroplasty
The Happy TKR
THE VARUS KNEE
BALANCING THE VARUS KNEE:May be straight forward
Items for consideration:– Fixed versus flexible
– Tightness:Flexion
Extension or both !
– Osteophytes
– Bone Loss– Subluxation and or
effect upon rotation
The Varus Knee:At times, a surgical challenge
APPROACH TO THE VARUS KNEE
Standard medial parapatella approachSharp dissection onto the proximo-medial tibiaDissection interval above the pes but below the joint lineSubperiosteal elevation
The Varus Knee
Remove all osteophytes
STOP !!!– Assess ligamentous /
soft tissue tightness before proceeding
RELEASE OF THE FIXED VARUS KNEE
TIGHTNESS IN EXTENSION– Posterior ½ of the
superficial MCL is primary factor
– Anteromedial capsule can also contribute
RELEASE OF THE FIXED VARUS KNEE
Tightness in Flexion– Anterior ½ of the
superficial MCL– Semi-membraneossus
and posteromedial capsule are tight
FIXED VARUS KNEE:FLEXION
Check gap symmetry (medial and lateral sides)– Release anterior
portion of superficial MCL
Flexion space should not be excessively tight (I prefer some ability to translate forward)
FIXED VARUS KNEE: EXTENSION
Sequential subperiosteal elevation of posterior portion of superficial MCLEnsure symmetry medial and lateral sidesKnee must come to full extension !
ROLE OF BONE RESECTION EFFECT UPON BALANCING
While majority of balancing is soft tissue in nature:– tibial resection in
coronal plane (varus-valgus) will effect soft tissues
– Femoral rotation clearly affects soft tissue tension especially in flexion
BALANCING THE VALGUS KNEE
THE VALGUS KNEE
Fixed vs correctable
Associated bone loss
Tightness:– Flexion ?– Extension ?– Both ?
Status of MCL
STEP #1: EXPOSURE / RESECTION
Medial parapatella
Minimal medial side release
Tibial resection:– Minimal cut
perpendicular to shaft
Femoral resection:– I favor 2-3 degrees off
of femoral line
FLEXION SPACE RELEASES
Laminar spreader is the best device
Pie-crusting of the posterolateral capsule and arcuate complex
Leave the popliteus intact if possible.– Can result in flexion
instability in varus
EXTENSION SPACE RELEASE
Tight structures:– ITB– Posterolateral capsule
Pie-crusting technique with SLOW gradual releases work best in my hands.
FINAL PRODUCT:Ligament balance: M=L
Gap Balance: Flexion=Extension
THE VALGUS KNEE
Adhering to the concept of sequential releases, majority of knees can be corrected with the use of additional constraint from the articulation.
THE FLEXION CONTRACTED KNEE
THE FLEXION CONTRACTED KNEE
Considerations:– Definition: 15 degrees
or greater loss of extension
– ? Length of contracture
– Status of skin, prior incisions
– Neurologic exam
THE FLEXION CONTRACTED KNEE
Deformity
Bone loss
Patella height
THE CONTRACTED KNEE:Surgical Technique
May require extensile approach if knee is stiff
Start with standard resection
Remove all osteophytes
THE CONTRACTED KNEE:Soft Tissue Work
PCL recession if using CR knee
Posterior capsular release
Posterior capsular stripping up to level of gastroc
THE FLEXION CONTRACTED KNEE: Bone Resection
Optional distal femoral cut
Effectively decrease the extension space
? How much can you take ?– DO NOT
COMPROMISE COLLATERALS !!
If unstable: constraint
THE CONTRACTED KNEE:POSTOP CARE
Emphasis on extension
No pillows under knee
Pain control
Dynamic splinting but watch the skin !!
Role for manipulation is not clear!
TOTAL KNEE ARTHROPLASTY
RECURVATUM
RECURVATUM
Seen predominantly in neuromuscular diseases:– Polio
– Neuropathic joints
– Spinal cord patients
Can occasionally be seen in rheumatic conditions
RECURVATUM:Options
Hyperextension up to 20 degrees:– Attempt to “overstuff”
the extension space– Must balance the
temptation to leave the knee with a flexion contracture:
If recurvatum is due to quad weakness, flexion contracture will lead to knee giving out !
RECURVATUM
Use of distal femoral augmentation– Will tighten the
extension space while not affecting the flexion space
Limits of distal femoral augments:– 10-15 mm– Usually require use of
femoral stems
RECURVATUM
Posterior stabilized implants are preferred
Less constraining implants may lead to instability
RECURVATUM
Reliance upon standard implants will lead to excessive anterior polyethylene impingement
Wear and or loosening is clearly a consequence
RECURVATUM:The larger deformities
In instances where there is more than 20 degrees of recurvatum: consider a more constrained implant with an extension stopDO NOT RELY UPON STANDARD CONDYLAR DESIGNS !!
Primary TKR:Summary
Understanding of pathoanatomy crucial
Correction of deforming forces is vital to successful outcome
Know the limits of your prosthetic implant
THANK YOU FOR YOUR ATTENTION !
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