8 - Knee Joint Flashcards
What are the articulations of the knee joint?
The knee joint has 2 articulations
> femur and tibia (tibiofemoral)
> femur and patella (patellofemoral)
> the fibula is NOT involved in the knee joint
What joints are included in the joint cavity of the knee joint?
Both the tibiofemoral and patellofemoral joints
What kind of joint is the knee joint and what does it allow?
A hinge joint - mostly allows flexion and extension
What does the locking mechanism of the knee allow?
The locking mechanism means when the leg/knee is fully extended the muscle energy to maintain a straight leg like when walking/standing is reduced
What way is the patella moved during movement?
- the quad muscles are the muscles that act on the patella
- patella generally moves superiorly and inferiorly to extend the leg
- the quad muscles are on an angle from ASIS so they also pull the patella LATERALLY (Q angle)
What is the Q angle?
The line of pull the patella is on due to the quadricep muscles compared to the line it wants to be on (directly up to acetabulum)
How big is the Q angle?
14 degrees in males
17 in females
> the bigger the carrying angle and so bigger the hips, the more likely lateral dislocation is
How does the patella sit in the femur?
The distal femur has a groove inbetween the 2 condyles and the patella has a corresponding on its deep side
What about the patella/femur is important in preventing dislocation?
People with a flat distal femur and patella allows the patella to move more; the contour of the distal femur and patella is important in keeping the patella in place
How can you tell which side of the body the distal femur is from?
The lateral condyle projects further forward/anteriorly to protect the patella from dislocating laterally
Important features of the femur and tibia
- tibial tuberosity (where patella tendon inserts)
- tibial plateau
- femoral condyles
- femoral epicondyles
Where does the patella sit?
Anteriorly on the femur attached superiorly to the quadriceps tendon and there is a ligamentous tissue connecting the patella to the tibial tuberosity (patellar tendon)
What connects the patella to the tibial tuberosity?
The patellar tendon - ligamentous tissue that is more like a tendon
What attaches laterally to the tibial tuberosity?
The iliotibial band
The patella is a … bone. Why is this significant?
Sesamoid bone. It sits WITHIN the tendon of a muscle, protecting it from rupturing
> if there was no sesamoid bone here the FORCES and FRICTION that occurs over the distal femur and tendon when bending/straightening would cause the tendon to rupture
The patella acts as part of the …
Quadriceps mechanism and so can be thought of as a continuation of the muscle so the ligamentous tissue acts as a tendon
What is the primary function of the the collateral ligaments of the knee?
Act as knee stabilisers
Where do the collateral ligaments attach?
> They run down the medial and lateral sides of the knee.
Where does the Medial Collateral Ligament (MCL) run?
> medial femoral epicondyle to the medial tibia (behind pes anserinus)
broad ligament that posteriorly attaches to the JOINT CAPSULE and MEDIAL MENISCUS
as it attaches to these other structures when you injure MCL you often injure other structures
stops VALGUS malignment of the knee
What does MCL prevent?
Valgus knee malalignment
Describe the lateral collateral ligament (LCL)
> runs from lateral femoral epicondyle to fibula head
compared to the MCL the LCL is more discrete and does NOT adhere to other structures
means the LCL is less prone to damage
prevents VARUS
the ITB attaches more anteriorly; may be why the ligament is more discrete?
What collateral ligament is more prone to damage?
The Medial Collateral Ligament. Attached to more structures (joint capsule and medial meniscus) while LCL is discrete and not as broad.