Anatomy Of The Knee Flashcards
Why is locking mechanism important?
Reduces amount of energy needed when extended
What is the femoral angle?
Between anatomical axis and mechanical axis, the Q angle which is roughly 15 degrees
Genu varum?
Medial displacement of tibia, bow legged, decrease in Q angle
Common in children under 2, rickets
Genu valgum?
Lateral displacement of tibia, knock kneed, increase in Q angle
Common in children aged 2-4, rickets and arthritis
Extracapsular ligaments?
Medial collateral and lateral collateral
Interacapsular ligaments?
Anterior cruciate and posterior cruciate
Anterior and posterior cruciate ligaments attach to?
Intercondylar area of tibia
Lachman test?
Lay down supine and knee bent 20-30 flexion
Move tibia anteriorly and posteriorly while maintaining position of femur
Laxity during this manoeuvre indicates anterior cruciate ligament injury
Which is the principal stabiliser of the knee joint?
Posterior cruciate ligament
Unhappy triad?
Rupture of
Anterior cruciate ligament
Medial collateral ligament
Medial meniscus
Due to twisting on a flexed knee, blow to lateral side
Such as contact sport
Iliotibial tract is?
The deep fascia
Oblique fibres of vastus medialis?
Pull the patella inside, to prevent lateral tracking of patella
Extensor mechanism formed by?
Patella, patellar ligament
Quadriceps tendon
What is seasmoid?
Within tendons
What does quads tendon do?
Extension of knee
Hamstrings muscles?
Biceps femoris semimembraneous and semitendinous
Hamstring origin?
Close to ischial tuberosity
What helps with unlocking extended leg?
Popliteus
After adductor hiatus femoral artery will be called?
Popliteal artery
What kind of joint is the knee joint?
Synovial bicondylar hinge,
Extension flexion, some rotation when flexed
Which factors contribute to the locking mechanism?
- Shape of femur
- Rotation
- Centre of gravity
What does medial rotation of the femur on tibia in extension do?
Tightens ligaments of the knee
Where Is the centre of gravity?
In front of knee, hence maintains extension
Lateral collateral ligament is?
Strong round cord, prevents medial displacement of tibia
Therefore if you get tear then you get varus deformity, which is less common
Medial collateral ligament is?
Broad flat band, which prevents lateral displacement
Tear of it will cause valgus deformity
Medial collateral ligament attaches to?
Medial meniscus
Of the cruciate ligaments one is always?
Tense
Posterior cruciate ligament passes?
Upwards forwards and medially
Anterior cruciate ligament passes?
Upwards backwards and laterally
With a flexed knee medial rotation is?
10 deg because ligaments are tightened
With a flexed knee lateral rotation is …?
60 degrees because ligaments unwind
Which cruciate ligament is easily injured?
Anterior due to sports injuries, sudden twisting of knee
What are menisci?
Crescent shaped plates of fibrocartilage, deepen the articulating surface
Shock absorbers
Provide smooth viscous film for joint
Horns of menisci attach?
Intercondylar area of tibia
Why is the unhappy triad unhappy?
Poor blood supply to intracapsular structures, doesn’t repair easily
What does iliotibial tract do?
Reinforces joint capsule
And stabilises the extended knee
What protects quadriceps tendon from stresses during locomotion?
Patella
Why are lateral and medial patellar retinaculum?
Aponeurosis extensions of vastus lateralis and medialis, help stabilise patella
Fracture to the patella will result in?
Loss of active extension
What are the flexors of the leg?
Hamstrings and gastrocnemius
Hamstrings also medially and laterally rotate leg when its flexed
What is the purpose of bursae?
Protection and reduce friction
Where do bursae occur?
At tendon insertions
What is seen in carpet fitters and housemaids knee?
Prepatellar burisitis
What is seen in clergyman knee and in roofers?
Infrapatellars bursitis
Baker’s cyst?
Abnormal fluild filled sacs in popliteal fossa due to herniation of bursa
Seen in arthritic patients
How to treat bakers cyst?
Aspiration and cortisone injection
Other branches around knee are called?
Geniculate branches
