techniques in primary total knee arthroplasty

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 !