Hamelynck Kj. Stability Of The Knee, A Dynamic Concept

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