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STABILITY OF THE KNEE A dynamic concept
KJ Hamelynck
Amsterdam/Roma
Stability of the knee, a dynamic concept
“Why are total knee arthroplasties failing today?” Peter F. Sharkey, MD; William J. Hozack, MD; Richard H. Rothman, MD, PhD; Shani
Shastri, MD; Sidney M. Jacoby, BA
Clinical Orthopaedics and Related Research, november 2002 pag 7-14
Stability of the knee, a dynamic concept
“Current etiologies and modes of failure in total knee arthroplasty revision”
Kevin J. Mulhall, Hassan M. Ghomrawi, Sean Scully, John J. Callighan,
Khaled J. SalehClinical Orthopaedics and Related Research 446, pg 45-50, 2006
Stability of the knee, a dynamic concept
Stability of the normal knee
• intrinsic stability . geometry of surfaces . menisci• extrinsic stability . ligaments . posterior capsula
Stability of the knee, a dynamic concept
Forced internal/external rotation
Blankevoort et al., J Biomech 1988
moment
3
external rotation
-3
moment [Nm]
internal rotation
-30º
30º
Stability of the knee, a dynamic concept
Flexion and internal/external rotation
External rotation
Internal rotation
Flexion160º140º120º100º80º60º40 º-20º 20 º
-30º
-20º
-10º
10º
20º
30º
Blankevoort et al., J Biomech 1988
Stability of the knee, a dynamic concept
Flexion and internal/external rotation
Blankevoort et al., 1988; Van Kampen, thesis 1987
External rotation
Internal rotation
Flexion160º140º120º100º80º60º40 º-20º 20 º
-30º
-20º
-10º
10º
20º
30º
Stability of the knee, a dynamic concept
Flexion & rotation during gait
M.A. Lafortune et al., J Biomech 1992
Stability of the knee, a dynamic concept
External rotation
Internal rotation
Flexion80º60º40 º-20º 20 º
-20
-10º
10º
20º
Flexion & rotation during gait
M.A. Lafortune et al., J Biomech 1992
Swing phase
Toe off
Heel strike
Stance phase
Stability of the knee, a dynamic concept
The envelope of passive motion
External rotation
Internal rotation
Flexion160º140º120º100º80º60º40 º-20º 20 º
-30º
-20º
-10º
10º
20º
30º
Swing phaseStance phase
M.A. Lafortune et al., J Biomech 1992
Stability of the knee, a dynamic concept
Forces conducted through the ligaments
802010020Stair descending
60102756Stair ascending
602060100Ramp descending
1001514015Ramp climbing
50208040Level walking
LCLMCLPCLACL
Stability of the knee, a dynamic concept
Stability of the knee
compressive, torsional and shear forces loading forces are between 2 and 7x body weight during adl-activities
force
Stability of the knee, a dynamic concept
Stability of the knee
• ligaments are prividing some stability
• muscle force and gravitational forces are providing the real stability
• ligaments become recruted when motion tries to exceed the limits of the envelope of passive motion
Stability of the knee, a dynamic concept
Stability of the normal knee
• muscle force
Stability of the knee, a dynamic concept
How do ligaments work ?
• propriocepsis
Stability of the knee, a dynamic concept
What happens during total knee replacement ?
• articular surfaces removed• cruciate ligaments resected
> the knee de-stabilized
What happens if further release of a collateral ligament is performed ?
Stability of the knee, a dynamic concept
After total knee replacement
what happens with the collateral ligaments ?
Stability of the knee, a dynamic concept
Without well functioning ligaments
> the amount of proprioceptiv information diminished
> the envelope of passive motion widened
> disturbance of dynamic stabilization !
More intrinsic constraint makes it worse !!!
Stability of the knee, a dynamic concept
To create good stability of the replaced knee
> maintain the collateral frame !> don’t perform release of a collateral ligament !
Think about the dynamic stability of the knee