Knee Flashcards
What kind of joint is the knee?
Bicondylar type synovial joint
What does the knee joint allow for?
Mainly flexion and extension
Small degree of medial and lateral rotation
What is the knee joint formed by?
Articulations between the patella, femur and tibia
What does the shape of the knee joint mean?
It’s relatively weak, and so relies on muscle and ligaments to ensure stability
What does the knee joint consist of?
Two articulations, tibiofemoral and patellofemoral
What is involved in the tibiofemoral articulation?
The medial and lateral condyles of the femur articulating with tibia
What is involved in the patellofemoral articulation?
The anterior and distal part of the femur articulating with the patella
What is the weight-bearing joint of the knee?
The tibiofemoral joint
What does the patellofemoral joint allow?
The tendon of the quadriceps femoris (the main extensor of the knee) to be inserted directly over the knee, increasing the efficiency of the muscle
What are both joint surfaces of the knee lined with?
Hyaline cartilage
What are the joint surfaces of the knee enclosed within?
A single joint cavity
Where is the patella formed?
Within the tendon of the quadriceps femoris
What is the result of the presence of the patella?
It minimises wear and tear on the tendon
What are the medial and lateral menisci?
Fibrocartilage structures in the knee
What is the function of the medial and lateral menisci?
To deepen the articular surfaces of the tibia, thus increasing the stability of the joint
To act as shock absorbers
What shape are the menisci?
C shaped
Where are the menisci attached?
At both ends of the intercondylar area of the tibia
What is the medial meniscus attached to?
The tibial collateral ligament and joint capsule
What does any damage to the tibial collateral ligament result in?
Tearing of the medial meniscus
Why is the lateral meniscus fairly mobile?
Because its smaller and does not have any extra attachments
What is a bursa?
A synovial fluid filled sac
Where are bursa found?
Between moving structures in a joint
What is the aim of bursa?
To reduce wear and tear on moving structures
What bursa are found in the knee joint?
Suprapatella bursa
Prepatella bursa
Infrapatella bursa
Semimembranosus bursa
What is the suprapatella bursa?
An extension of the synovial cavity of the knee
Where is the prepatella bursa found?
Between the apex of the patella and the skin
What is the infrapatella bursa split into?
Deep and superficial
Where does the deep infrapatella bursa lie?
Between the tibia and patella ligament
Where does the superficial infrapatella bursa lie?
Between the patella ligament and the skin
Where is the semimembranosus bursa located?
Posteriorly in the knee joint, between the semimembranosus muscle and the medial head of the gastrocnemius
What are the major ligaments in the knee joint?
Patellar ligament
Collateral ligaments
Cruciate ligaments
What is the patellar ligament?
A continuation of the quadriceps femoris tendon distal to the patella
What does the patellar ligament attach to?
The tibial tuberosity
What are the collateral ligaments?
Two strap-like ligaments, the tibial (medial) collateral ligament and the fibular (lateral) collateral ligament
What do the collateral ligaments act to do?
Stabilise the hinge motion of the knee, preventing any medial or lateral movement
What shape is the tibial collateral ligament?
Wide and flat
Where is the tibial collateral ligament found?
On the medial side of the joint
Where does the tibial collateral ligament attach to proximally?
The medial epicondyle of the femur
Where does the tibial collateral ligament attach to distally?
The medial surface of the tibia
How does the fibular collateral ligament differ from the tibial?
It is thinner and rounder
Where does the fibular collateral ligament attach to proximally?
The lateral epicondyle of the femur
Where does the fibular collateral ligament attach distally?
To a depression on the lateral surface of the fibular head
What do the cruciate ligaments do?
Connect the femur and the tibia, and in doing so cross each other
What are the cruciate ligaments?
Anterior cruciate ligament
Posterior cruciate ligament
What course does the anterior cruciate ligament take?
Attaches at the anterior intercondylar region of the tibia and ascends posteriorly to attach to the femur, in the intercondylar fossa
What does the anterior cruciate ligament do?
Prevents anterior dislocation of the tibia onto the femur
What course does the posterior cruciate ligament take?
Attaches at the posterior intercondylar region of the tibia, and ascends anteriorly to attach to the femur in the intercondylar fossa
What does the posterior cruciate ligament do?
Prevents posterior dislocation of the tibia onto the femur
What are the main movements that the knee joint permits?
Extension
Flexion
Lateral rotation
Medial rotation
How is extension at the knee joint produced?
Quadriceps femoris
Where does the quadriceps femoris insert that allows it to produce extension at the knee?
The tibial tuberosity
What produces flexion at the knee?
Hamstrings, gracilis, sartorius and popliteus
What produces lateral rotation at the knee?
Biceps femoris
What produces medial rotation at the knee?
Semimembranosus, semitendinosus, gracilis, sartorius and popliteus
What is the most common pathology affecting the knee joint?
Injury to the collateral ligaments
What causes injury to the collateral ligaments?
A force being applied to the side of the knee when the foot is placed on the ground
How can damage to the collateral ligaments be assessed?
By asking the patient to medially rotate and laterally rotate the leg
What does pain on medial rotation of the leg indicate?
Damage to the medial collateral ligament
What does pain on lateral rotation of the leg indicate?
Damage to the lateral ligament
What is likely if the tibial collateral ligament is damaged?
That the medial meniscus is torn
What can be anterior cruciate ligament be torn by?
Hyperextension of the knee joint
Application of a large force to the back of the knee with the joint partly flexed
How can you test for a town anterior cruciate ligament?
You can perform an anterior drawer test, where you attempt to pull the tibia forward
What has happened if the you can pull the tibia forward?
The ligament has been torn
What is the most common mechanism of posterior cruciate ligament damage?
The ‘dashboard injury’- when the knee is flexed and a large force is applied to the shins, pushing the tibia posteriorly
How else can the posterior cruciate ligament be torn?
Hyperextension of the knee joint
Damage to the upper part of the tibial tuberosity
How is posterior cruciate ligament damage tested for?
The posterior draw test- hold the knee in flexed position, and push the shin posteriorly. If there is movement, the ligament has been torn
What can friction between the skin and patella cause?
The prepatella bursa to become inflamed, producing a swelling on the anterior side of the knee, known as housemaids knee
What can friction between the skin and tibia cause?
The infrapatella bursa to become inflamed, resulting in whats known as ‘clergyman’s knee’
What can damage to the medial collateral ligament cause?
Damage to the medial meniscus, due to its attachment
What can rupture the the medial collateral ligament?
A lateral force to the extended knee
What happens when the medial collateral ligament is ruptured?
The medial meniscus and the ACL are damaged, producing an ‘unhappy triad’
