Week 5 Lecture 5A - Tibiofemoral Joint Flashcards
Passive Restraints
ACL
Primary stabilizer of knee
What motions does it limit?
Restraint to (anterior/posterior) translation of tibia on femur
In extension, limits (varus and valgus/anterior to posterior) stress
Limits (hyperflexion/hyperextension), tibial rotation (IR/ER)
No ACL – knee is not stable
anterior; varus and valgus; hyperextension;
Passive Restraints - ACL
Anterior drawer test - (30/90) degrees
Lachman’s test - (30/90) degrees
90; 30
Biomechanics of the ACL
ACL Anteromedial Bundle Loose in (Flexion/Extension) Taut in (Flexion/Extension) (A/P/Rotary) stability
Posterolateral Bundle
Taut in (Flexion/Extension)
Loose in (Flexion/Extension)
(A/P / Rotary) stability
Anterior drawer test targets the (anteromedial/posterolateral) bundle.
Lachamn’s test targets the (anteromedial/posterolateral) bundle.
extension; flexion; A/P; extension; flexion; rotary; anteromedial; posterolateral
Passive Restraints
PCL
Limits what motion?
Limits (anterior/posterior) translation of tibia on femur
Bulk of PCL is taut in (flexion/extension)
Plays some role with control of (varus and valgus/anterior to posterior) forces
posterior; flexion; varus and valgus
Passive Restraints
PCL
Limits what motion?
Limits (anterior/posterior) translation of tibia on femur
Bulk of PCL is taut in (flexion/extension)
Plays some role with control of (varus and valgus/anterior to posterior) forces
posterior; flexion; varus and valgus
Passive Restraints
MCL
Limits what motion? Primary restraint against (varus/valgus) stress Taut in (flexion/extension)
valgus; extension
Passive Restraints
LCL
Limits what motion?
Primary restraint against (valgus/varus) stress
Taut in (flexion/extension)
varus; extension
MENISCAL FUNCTIONS
Primary Functions
Load Distribution
Shock Absorption
TOTAL MENISCECTOMY - Increase contact pressure x 230%
Joint Stability:
(Superior/inferior / Varus/Valgus)
Anterior / Posterior
Varus/Valgus;
Menisci
Movement
Medial < Lateral
(3 mm vs 9 mm)
MM more firmly attached to tibia and medial capsule and MCL
(Lateral/Medial) torn more often
Medial
Ligaments?
ACL/PCL
Ligaments?
ACL/Meniscus (shear force)
Unhappy triad
Ligaments?
PCL - tibia moving in a posterior direction
Ligaments?
PCL
Ligaments?
MCL. Meniscus?
Ligaments?
LCL
ACL Mechanism of Injury
Noncontact: 70-80% Landing, cutting, change of direction foot planted, (EROT/IROT) femur on tibia dynamic (varus/valgus) (hyperflexion/hyperextension)
Contact
Direct impact to knee
(valgus/varus) force
IROT; valgus; hyperextension; valgus
