SPORT INJURIES AND SPORT INJURIES AND BIOMECHANICSBIOMECHANICS

ACL RUPTURE

ANATOMYANATOMY

Intra capsular knee joint structureLength 38mm( 25 to 41mm)Width 10mm (7 to 12mm)Made up multiple collagen fibersSurrounded by synovial membrane

envelope

ANATOMYANATOMY

Femoral proximal attachment :postero- lateral corner of inter condylar notch

Tibial distal attachment : front and lateral of anterior tibial spine

Two bands: small anteromedial and a larger posterolateral portion

BIOMECHANICSBIOMECHANICS

Posterolateral bulky portion is tight in extension

Anteromedial bundle is tight in flexionUltimate tensile load :2160 +/- 157 NApprox 85% resistance to anterior tibial

displasment

Maximum laxity in 30 deg Maximum laxity in 30 deg flexionflexion

Biomechanical characteristicsBiomechanical characteristics

ACL does not remain an isometric or constant length structure

Unsectioned ACL :2-5mm anterior translation at full extension 5-8 mm at 30 deg flexion by application 100N anterior force

ACL ruptureACL rupture

Common and severe injury particularly in compact sports as rugby

Usual mechanism of injury knee hyperextension or external rotation in flexion

AP instabilityAP instability

7-9 mm of increased translation (100N anterior force)

Supporting structures in ACL rupture: iliotibial band 24% medial capsule 22% lateral capsule 20% MCL 16% LCL 12%

Quadriceps and hamstrings in a certain degree alsoBaratta et al 1988

Moment vs. time. Examples of quadriceps avoidanceDevita et all 1998 Timony et all 1993

Matt Gaudet 2000Matt Gaudet 2000

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An

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subjects

normal

injured

Load deformation curveLoad deformation curve

Deformation

Load

Elastic Region

Plastic Region

Yield Point Ultimate

Failure

Point

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