Lecture 20: Knee joint Flashcards
What are the two articulations of the knee joint that are both included in the articular cavity
Between the condyles of femur and the tibial plateaus of tibia
and between the Femur and the patella
What is the movements permitted at the knee joint
Mainly flexion and extension (140’) with limited rotation (5-10’). There is also a locking mechanism which reduces the muscle energy required to keep the knee fully extended when standing/walking
What are the 5 ligaments of knee joint
Patellar ligament, Medial and Lateral collateral ligaments and Anterior and Posterior Cruciate ligaments.
What is the attachment and function of Patellar ligament
Attaches from the inferior margin of the patella to the tibial tuberosity. It acts as a continuation of the quadriceps mechanism (making the patella act as sesamoid bone which stops it from getting broken on between the tibiofemural joint)
What is a sesamoid bone
rounded bones within tendons
Where do the Medial and Lateral collateral ligaments attach and what are their functions
Medial attaches from the medial femoral epicondyle to the medial tibia (behind pes anserinus). It prevents varus from happening (tibia sliding medially)
Lateral attaches from lateral femoral epicondyle to the fibula head. It prevents valgus from happening (femur sliding laterally)
What is Valgus and Varus
Valgus is the alignment of joints where the apex of the joint is pointed outward.
Varus is the alignment of joints where the apex of the joint is pointed inward. (eg knockkneed)
Where do the Anterior and Posterior Cruciate ligaments attach and what are their functions
Anterior CL runs from the anterior tibial spine to the lateral condyle of the femur. It stops the tibia from sliding forward.
Posterior CL runs from the posterior tibial spine to the medial condyle of the femur. It stops the tibia from sliding backward
Overall stabilise the AP plane of the knee in the intercondylar region
What is the relationship of the MCL and LCL, ACL and PCL with the joint capsule
MCL and LCL are extracapsular. MCL does blend with the underlying joint capsule but LCL is completely discrete whereas ACL and PCL are intracapsular but outside of the articular cavity (therefore not in the synovial membrane).
What are the two menisci main structure and function
Lateral and Medial menisci are fibrocartilagnous pads which improve articulation between the tibia and the two condyles of the femur as the SA of contact changes through full range of motion as well as shock absorb.
Which menisci is more commonly injured and why
Medial because its bigger and attached to joint capsule and MCL making it less mobile.
Lateral is not attached to the joint capsule so its more mobile
What are the 3 bursae of the knee joint, location and function
The Prepatella: anterior to patella and Infrapatellar bursae: superficial and deep to the patella ligament do not communicate with the knee joint and allow skin to slide over the patella and its ligament.
The Suprapatella bursa is an extension superiorly of the joint capsule of knee joint between Quads tendon and distal femur. It is where fluid buildup from the knee is aspirated from.
Where does the vascular supply to the knee come from and why is this useful
It comes from the branches of the femoral, lateral femoral circumflex and popliteal vessels (superiorly) anastomosing with branches of the anterior tibial land circumflex peroneal arteries (inferiorly).
Anastomoses allow alternate blood supply to leg if the popliteal artery is blocked (over time)
What is the clinical relevance of the Terrible/unhappy triad
This is a common injury pattern resulting from a lateral (valgus) force to the knee. This is damage to medial collateral ligament, anterior cruciate ligament and lateral OR medial meniscus (tear)
What are the myotomes for flexion of knee
L5 and S1
