290 likes | 332 Views
SPORT INJURIES AND BIOMECHANICS. ACL RUPTURE. ANATOMY. Intra capsular knee joint structure Length 38mm( 25 to 41mm) Width 10mm (7 to 12mm) Made up multiple collagen fibers Surrounded by synovial membrane envelope. ANATOMY.
E N D
SPORT INJURIES AND BIOMECHANICS ACL RUPTURE
ANATOMY • Intra capsular knee joint structure • Length 38mm( 25 to 41mm) • Width 10mm (7 to 12mm) • Made up multiple collagen fibers • Surrounded by synovial membrane envelope
ANATOMY • 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
BIOMECHANICS • Posterolateral bulky portion is tight in extension • Anteromedial bundle is tight in flexion • Ultimate tensile load :2160 +/- 157 N • Approx 85% resistance to anterior tibial displasment
Biomechanical 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 rupture • Common and severe injury particularly in compact sports as rugby • Usual mechanism of injury knee hyperextension or external rotation in flexion
AP 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 also Baratta et al 1988
Moment vs. time. Examples of quadriceps avoidance Devita et all 1998 Timony et all 1993
Load deformation curve Plastic Region Load Yield Point Ultimate Failure Point Elastic Region Deformation