Week 2

• Age 55 or over • Isolated tenderness of the patella (no bone tenderness of the knee other than the patella) • Tenderness at the head of fibula • Inability to flex knee to 90 degrees • Inability to weight bear immediately and in the casualty department (4 steps= unable to transfer weight twice onto each lower limb regardless of limping)

Non-contact (80%) • Valgus stress with knee in ext rotation AND near EROM extension • Deceleration with an attempt to change direction • Forced hyperextension Contact -Mechanisms = valgus force to knee

Biomechanical: Knee valgus Anterior tibial shear Tibial IR or ER Lateral trunk motion Dynamic foot pronation GRF Neuromuscular: Relative hamstring recruitment Hip abduction strength Limb and trunk proprioception Gender: Female 2X8 more at risk Anatomical: High BMI Femoral notch width Generalised or specific joint laxity Prior injury

• Stance foot kept closer to the body’s midline • Torso kept upright and rotated toward the desired direction of travel • Increased knee flexion angles • Control of lateral sway -Hip neuromuscular control (isometric hip abduction & ER independantly predict future ACL injury)

• Low knee effusion • Less episodes of knee instability(self reported) • High IKDC scores(self reported knee function) Low pain low TSK 11 score Higher quadriceps peak torque Less pre/post surgical change in Tegner score(self reported physical activity) • = biggest indicator ACL injury has 3x greater risk of OA after AC treated with recon than contralateral healthy knee

Hyperextension 1 posterior capule torn/stretched 2.ACL 3.PCL O’donoghues /unhappy triad/Valgus knee force with knee in slight flexion • Classic presentation: 1. Superficial MCL then Deep MCL 2. Tear of medial meniscus- via pull of MCL on attachment to medial meniscus 3. Rupture of ACL • can also result in # of lateral tibial condyle • Alternative veiw 1. Superficial MCL then deep MCL 2. Tear of lateral meniscus - compression shearing as lat compartment dislocates posteriorly 3. Rupture of ACL VARUS FORCE TO THE KNEE- uncommon contact MOI • Lateral collateral ligament • ACL tear • Tear of fibres to popliteus • Fracture of medial tibial condyle • Lateral meniscus tear

Patient heard crack/pop.snap Felt knee go in and out Initial intense pain Rapid hot effusion within 2 hours Hemoarthrosis = 80% chance of ACL tear PE -Exclude PCL & #'s -lachman’s, anterior draw, pivot shift -X-ray for associated bony injury (tibial spine avulsion, postero-lateral tibial plateau injury)

• Posterior sag test - Stability tests (posterior draw, reverse Lachman’s)

Tender on palpation Lack of knee extension Nil or minimal swelling Positive to valgus testing (pain, gapping, altereded end feel) Pain & stiffness with extension & twisting

Nil-minimal swelling Lateral joint line tender on palpation loss of terminal extension Positive varus stress test (pain, gapping, altered end feel)

Falling on tibia/blow to tibia forcing it backwards Football tackle Dashboard injury Forced knee hyperextension injury with foot plantarflexed Hyperextension ( as complication of ACL rupture)

Superficial MCL -Primary restraint to VALGUS loads in all degrees of knee flexion • primary restraint to ER of tibia • secondary restraint to Anterior tibial translation

Valgus force with knee slighly flexed(odonoghues triad) (MCL only) Valgus force with knee extended (Posterio medial capsule also torn) if more severe ACL may also be affected

• primary restraint to Varus forces at knee • Restraint to IR of tibia Very uncommon Varus stress to the knee( direct blow to anteromedial tibia)

• With knee flexion the menisci elongate posteriorly • lateral moves more than medial • Medial more vulnerable to injury

1 low energy mechanism twist on flexed knee ( tib ER + knee valgus) in degenerative middle aged pop 2 High energy mechanism Twisting involved in sport Male>female , medial >lateral 3 associated with other injury Lateral meniscus with ACL injury> result of compression/sheering forces as lateral compartment dislocates posteriorly Medial meniscus with MCL injury> via pull of MCL on attachment to medial meniscus

Load transmission & shock absorbtion Joint congruity enhanced Stability enhanced Joint lubrication Articular cartilage nutrition Proprioception

S/E patient age catching or locking can usually weight bear through pain Effusion around joint line( mild & slow) P/E Pain with loaded deep flexion loss of end range extension with springy end feel hamstring spasm and acute locking joint line tenderness Pain with varus/valgus stress tests Pain & clicking w - mcmurrarys test flex ext w varus/valgus -thelasy test -eges test MRI non invasive gold standard

SnOUT: sensitivity high a neg test willl rule the disorder out (low risk of false negative) SpIN Specificity high a pos test will rule the disorder in (low risk of false positive)