The Knee Joint Flashcards
What are the 3 main types of knee problems?
- Acute injuries
- Acute swelling/pain
- Chronic knee pain/swelling
What sorts of injuries are acute knee injuries?
Fracture/tear/sprain.
-e.g. sport injury
What causes acute swelling/pain? (3)
- Acute gout
- Flare of arthritis (oseto-/rheumatoid)
- Septic joint
What causes chronic knee pain/swelling? (2)
- Osteoarthritis
- Bursitis
What type of joint is the knee joint?
Synovial hinge joint.
How many bones make up the knee joint?
3.
Which 3 bones make up the knee joint?
- Femur (distal)
- Tibia (proximal)
- Patella
Which bone articulates with the tibia but is not a direct part of the knee joint?
The fibula.
What are the 3 articulations at the knee joint?
- 2 femorotibial (medial & lateral)
- 1 femoropatellar
What are the 2 expansions at the distal end of the femur?
Medial and lateral femoral condyles.
What are the 2 slight expansions at the proximal end of the tibia?
Medial and lateral tibial condyles.
What are the flattened surfaces of the proximal tibia called (above the condyles)?
Medial and lateral tibial plateaus.
What movements are possible at the knee joint?
- Extension/flexion
- Lateral & medial rotation (leg)
What happens to knee flexion when the hip is extended?
Lose some knee flexion due to loss of tension of the hamstrings.
What must occur for rotation of the knee joint? (2)
- Flexion of the knee
- Collateral ligaments relaxed
What is locking of the knee?
As the knee approaches full extension, the femur undergoes a few degrees of MEDIAL rotation on the tibia.
Why does locking occur?
Produces a very stable position»_space; thigh muscles can relax.
What must occur before the knee can be flexed?
Unlocking.
Which muscle ‘unlocks’ the knee, and how?
Popliteus muscle.
-laterally rotates the femur
What is the area at the back of the knee called?
The popliteal fossa.
Which artery does the popliteal fossa contain?
Popliteal artery.
When is the knee joint most stable?
During extension.
-most congruence
Why is the knee joint most stable during extension?
More congruence.
-more contact between distal femur and proximal tibia
When do a lot of knee injuries tend to occur?
During knee flexion.
What deepens the tibial plateaus?
Menisci.
What are the menisci?
2 C-shaped rings of fibrocartilage (lat&med) that deepen the tibial plateau.
Where are the menisci thickest?
Externally.
What are the function of the menisci? (4)
- Increase joint congruency
- Distribute weight evenly
- Shock absorption
- Assist in ‘locking’
What do the external edges of the menisci attach to?
Fibrous capsule of the joint.
What is the medial menisci attached to?
Tibial collateral ligament.
What causes meniscal tears?
Sports injury.
Degenerative changes.
How do meniscal tears occur?
Displaced cartilage can become trapped during knee movements.
How are meniscal tears treated?
Repair/resection.
What are meniscal tears often associated with?
Osteoarthritis.
What are the main stabilisers of the knee? (2)
- Muscles (main)
- Ligament (extra-/intra-articular)
What are intra-articular ligaments?
Ligaments inside the joint capsule.
-Anterior and posterior cruciate ligaments
What are extra-axial ligaments?
Ligament outside the joint capsule.
-fibular and tibial collateral ligaments
Which ligament is firmly attached to the medial meniscus?
Tibial collateral ligament.
What are the main ligaments of the knee joint?
- Cruciate ligaments (post/ant)
- Collateral ligaments (tibial/fibular)
What do the cruciate ligaments do the centre of the knee joint?
Cross over each other.
-hold knee together
What are the attachments of the posterior cruciate ligament?
-Posterior intercondylar region (tibia)
» sup/ant
-Medial femoral condyle
What are the attachments of the anterior cruciate ligament?
-Anterior intercondylar region (tibia)
»sup/post
-Lateral femoral condyle
Which cruciate ligament is stronger?
Posterior cruciate ligament.
What is the function of the posterior cruciate ligament?
- Prevents posterior displacement of the tibia and hyperflexion.
- Main stabiliser of the flexed knee
What is the function of the anterior cruciate ligament?
Prevents anterior displacement of the tibia and hyperextension.
When can the posterior cruciate ligament be injured?
When landing on tibial tuberosity with knee flexed.
When can the anterior cruciate ligament be injured?
- When knee is hyperextended
- Force applied anteriorly
What are the 2 collateral ligaments?
- Fibular (lateral)
- Tibial (medial)
What are the features of the fibular collateral ligament? (2)
- Cord-like band
- Not attached to lateral meniscus
What is the function of the fibular collateral ligament?
Prevents adduction of leg at knee.
What are the feature of the tibial collateral ligament?
- Flat band
- Attached to medial meniscus
What is the function of the tibial collateral ligament?
Prevent abduction of the leg at the knee.
What are the functions of the collateral ligaments?
FIBULA - prevents adduction of the leg
TIBIAL - prevents abduction of the leg
BOTH - prevent rotation during knee extension (e.g. standing)
What is a combined knee injury also known as?
‘The unhappy triad’.
What causes a combined knee injury?
- Excessive lateral twisting of flexed knee
- Blow to lateral side of extended knee
Which 3 structures are torn with a combined knee injury?
- Tibial collateral ligament
- Medial meniscus
- Anterior cruciate liament
Which muscles are the main stabilisers of the knee joint?
- Quadriceps
- Hamstrings
- Sartorius
- Gracilis
- Iliotibial tract
How can building up the quadriceps with exercise/physio be beneficial to the knee joint?
Can compensate for ligament damage and avoid surgery.
What are bursae?
Fluid-filled sacs in/around the knee.
Which 2 bursae are most important at the knee joint?
- Prepatellar bursa (infront of patella)
- Suprapatellar bursa (above patella)
What is bursitis?
Inflammation/swelling of bursa.
-e.g. carpet fitters
What types of injury can occur at the knee joint?
- Bony
- Meniscal
- Ligamentous
- Dislocations
Which direction is a patellar dislocation normally?
Lateral.
-dependent on position of femur on tibia
Which femoral condyle is larger?
The lateral femoral condyle.
Which muscles contribute to a lateral patellar dislocation by pulling the patella superolaterally? (3)
- Rectus femoris
- Vastus intermedius
- Vastus lateralis
Which muscle pulls the patella medially?
Vastus medialis.
Who is a patellar dislocation more common in?
Females.
Why is a patellar dislocation more common in females?
Wider pelvis
|»_space; larger Q angle of femur on tibia.
What are the 2 main types of abnormal alignment at the knee joint?
- Genu varum (med)
- Genu valgum (lat)
What is genu varum?
Abnormal medial alignment.
- tibia adducted with respect to femur
- AKA bow leg
- decreased Q angle
What is genu valgum?
Abnormal lateral alignment.
- tibia abducted with respect to femur
- AKA knock knee
- increased Q angle
What is osteoarthritis?
Degeneration of joint cartilage and underlying bone»_space; pain and stiffness.
Give 2 possible causes of early-onset osteoarthritis.
- Obesity
- Knee injury
What are the main characteristics of osteoarthritis at the knee? (3)
- Osteophytes
- Decreased joint space (meniscus)
- Sclerosis (abnormal density»_space; white)
What is characteristic of a patella fracture?
Patella broken into 2 pieces.
What is a patella fracture often confused with?
Bipartite patella.
-patella composed of 2 bones as doesn’t fuse during childhood
What structures are involved in knee dislocations?
Displaced/torn:
- cruciate ligaments
- collateral ligaments
- muscles
What are possible complications of knee dislocations?
Blood supply and nerve damage.
-popliteal artery
What causes tibial plateau fractures?
Direct blow to front/side of knee when extended.
What do tibial plateau fractures affect?
Knee stability and motion.
What is a periprosthetic fracture?
Broken bone around a knee replacement.
-can cause serious complications
