Knee Flashcards
Bones of the Knee
Femur:
Tibia: Medial bears most of weight and has a larger surface area (most common area of arthritis)/Lateral side is receptacles for femoral condyles
Fibula: serves as the attachment for knee joint structures/doesn’t articulate with femur or patella/not part of knee joint/not weight bearing
Patella: sesamoid bone/imbedded in quad and patellar tendon/serves similar to a pulley in improving angle of pull, resulting in greater mechanical advantage in knee extension (lengths the wrench)
Knee articulations
Femoral condyles on tibial plateaus:
Patella with distal femurs:
Role of fibula
-Serves as the attachment for knee joint structures/doesn’t articulate with femur or patella/not part of knee joint/not weight bearing
-Biceps femoris inserts primarily on fibula head
-LCL (fibula) originates on lateral femoral condyle and inserts on fibular head
Role of patella in improving knee extensors
sesamoid bone/imbedded in quad and patellar tendon/serves similar to a pulley in improving angle of pull, resulting in greater mechanical advantage in knee extension (lengths the wrench)
What are the boney landmarks?
-Tibial tuberosity
-Gerdy’s tubercle
-Superior/inferior poles of patella
-Medial/lateral femoral condyles
-Upper medial surface of the tibia
-Head of the fibula
Tibial tuberosity
-Three vasti muscles if quadriceps originate on proximal femur and and insert on patellar superior pole
-Insertion is ultimately on tibial tuberosity via patella tendon
Gerdy’s tubercle
-IT band of TFL inserts on Gerdy’s tubercle
Superior/Inferior poles of patella
-Apex of patella is situated inferiorly
-Base forms the superior aspect of the bone
-Rectus femoris and vastus intermedius muscles insert at the superior pole of the body
-Patellar tendon originates from the inferior pole and inserts into the tibial tuberosity
Medial/Lateral femoral condyles
-Articulate on enlarged tibial condyles
Upper medial surface of the tibia
-Semi membranous inserts posteromedially on medial tibial surface
-MCL (Tibial) originates on medial aspect of upper medial femoral condyle and inserts in medial tibial surface and into medial meniscus
Head of fibula
-Biceps femoris inserts primarily on fibula head
-Serves as the attachment for knee joint structures/doesn’t articulate with femur or patella/not part of knee joint/not weight bearing
-Biceps femoris inserts primarily on fibula head
-LCL (fibula) originates on lateral femoral condyle and inserts on fibular head
Q-angle of knee
-Central line of pull for entire quadriceps runs from ASIS to the center of patella
-Line of pull of patella tendon runs from center of patella to center of tibial tuberosity
-Angle formed by the intersection of these two lines at the patella is the Q angle
-Normally angle will be 10 degrees for males and 20 degrees in females
-Generally, females have higher angles due to wider pelvis
Valgus and Varus stress
-Normally on frontal plane
-Valgus (knocked knees, cave in)
-Varus (bow legged, cave out)
Q-angle effect on ACL
-Higher Q angles generally predispose people in varying degrees to a variety of potential knee problems including patellofemoral syndrome (lateral patellar rubbing), and ligamentous injuries (ACL)
Medial/Lateral meniscus
-Cushion between bones for shock absorption
-Deepen tibial fossa to enhance stability
-Increase surface area to decrease stress
-Medial torn more often as MCL inserts into it/bigger because of stress
-Menisci may be torn in serval different areas from a variety of mechanisms (tears often occur due to significant forces during rotation (quick directional changes in running)
ACL
-One of the most common serious injuries to knee
-Mechanisms often involves noncontact rotary forces associated with planting and cutting, hyperextension, valgus collapse
-Get quad atrophy as a result and needs to be strengthened??
-Maintains anterior stability and rotary stability
PCL
-Not often injured
-Mechanism of direct contact with an opponent or playing surface
-Maintains posterior stability and rotary stability
LCL
-Infrequently injured because requires a varus stress which is difficult because it is protected by other leg
MCL
-Maintains medial stability by resisting valgus forces or preventing knee from being abducted
-Injuries occur commonly, particularly in contact or collision sports
-Mechanisms of teammate or opponent may fall against lateral aspect of knee or leg causing medial opening of knee joint and stress to medial ligamentous structures
Strengthening quads with ACL injury is not the best course of action
-Quads have been historically implicated in knee/injury disease as atrophy occurs once injured
-Therefore strengthening the quads given as treatment is wrong
-The quads crush the knee and strain the ACL when contracted, and can’t selectively activate quads
-If the knee hurts, look at the hip and ankle first
Anterior drawer/Posterior Drawer
-ACL test, but biased by hamstring
-PCL test by pulling on tibia
Lachman’s test
ACL special test with less hamstring influence (with flexion of knee)
Varus test
LCL test, grab ankle and place stress inside of knee to push knee out laterally
Valgus test
MCL test, grab ankle and place stress on outside knee
