The Knee Joint Flashcards
Where degrees of freedom in the tibio femoral joint?
2 degrees of freedom
Flex / ext
IR / ER
What are the defining features of the medial condyle?
Larger & more distal
What are the defining features of the lateral condyle?
Smaller; more in line with femoral shaft
Projects more anterior
Where is the intecondylar notch/femoral sulcus
Which lip of the patella is larger?
Lateral lip is larger than the medial
What is the angle of the tibial plateaus?
7-10°
Which tibial plateau is longer?
Medial longer vs. lateral (AP)
What is the shape of the tibial plateau?
Shape concave
What do the inter-CON DY LAR tubercles do in the knee joint?
Engage in notch in full extension
Bony stability
What is considered normal physiologic valgus of knee?
Norm = 170°- 175°
What does physiologic valgus allow?
Allows equal loading in both compartments
What is genu valgus?
“knock knees”
< 170
What are the consequences of genu valgus?
Compressive forces on lateral side of knee and tensile forces on medial side
What is genu varus?
“bow legs”
> 180°
What are the consequences of genu varus?
Compressive forces on the medial side of the knee and tensile forces on the lateral aspect
What is the function of the knee joint capsule?
Restricts joint motion and provides proprioception
What is the close packed position of the joint capsule of the knee?
Full extension
What position of the knee allows the most volume in the joint capsule?
Semi flexed position
What are the posterior attachment to the joint capsule of the knee?
Condyles
What are the anterior/inferior attachments of the joint capsule of the knee?
Retinaculum
Patellar tendon
What is the superior attachment of the capsule of the knee?
Quadriceps tendon
What is the composition of the capsule of the knee?
Fibrous layer
Synovial layer
What does the synovial layer of the knee joint capsule due posteriorly?
it folds inward to surround cruciates
What are plicae? And how many are there?
Embryologic remnants of synovial septae
Potentially 4
Inferior, superior, medial, lateral
What is the anterior fibrous layer of the joint capsule also known as?
Extensor retinaculum
What are the Medial retinacular fibers?
MPFL & Medial patelleotibial ligament
What are the lateral retinacular fibers?
LPFL & lateral patelleotibial ligament
What is the lateral layer of the joint capsule reinforced by?
Reinforced by LCL, ITB and lateral patellar retinacular fibers
What is the medial side of the joint capsule reinforced by?
Reinforced by MCL, medial patellar retinacular fibers
What is the posterior medial corner of the fibrous layer of the joint capsule of the knee made of?
Where are the following?
What is the posterior lateral corner of the fibrous layer of the joint capsule of the knee made of?
Where are the following?
What does the posterior medial corner & posterior lateral corner of the knee capsule resist respectively?
Resist hyperextension and valgus and varus stresses respectively
What are the attachments of the IT band?
Attaches to the tibia via the iliotibial band and the patella via the patellofemoral ligament
What are the functions of the IT band?
Support anterolateral knee
With knee flexion, assists ACL in resisting anterior tibial translation
What cushions the IT band deeper to the tendon?
Fat pad rather than a bursa
can become inflamed and agitated leading to IT band syndrome
How many portions does the medial collateral ligament have?
Two portion superficial and deep
What is the primary restraint of the MCL
Valgus (0° & 25°)
60% at 0 and 80% at 25
Lateral rotation of tibia
What is the secondary restraint of the MCL?
ant tibial trans
Which of the four distinct ligaments of the knee has the greatest capacity for healing?
MCL, highly vascular
What is the primary restraint of the lateral collateral ligament?
Primary restraint
Varus (0° & 25°)
55% at 0 and 70% at 25 degrees
Which ligament is extra capsular in the knee?
LCL
What is the secondary restraint of the LCL?
Lateral rotation of tibia
What are the attachments of the ACL?
Anteromedial tibia to posteromedial LFC
What is the primary restraint of the ACL
Anterior tibial translation
Hyperextension
Rotary stability
Which ligament tension guides the arthrokinematics of the knee?
Anterior crusade ligament (ACL)
What is the ACL loaded with that play a protective role?
mechanoreceptors
What muscles place stress on the ACL?
quadriceps muscles
What is the most common ACL mechanism of injury?
Strong activation of the quad over a slightly flexed knee
Valgus collapse
Excessive ER of the tibia
What is another ACL mechanism of injury?
Hyperextension of the knee
What are the attachments of the posterior cruciate ligament?
Posterior tibia to medial femoral condyle