Knee joint & patholgies Flashcards
What is the knee joint ?
Synovial joint
Articulation between femur and tibia & the patella and tibia.
Articular surfaces covered in hyaline cartilage.
Involved in Flexion and extension. also a little of rotation.
Flexion - leg moving back e.g towards 90 degrees backwards - reducing angle.
Ligaments of the Knee joint ?
- Collateral ligaments - Medial ( Tibia )& Lateral (Fibular )
- reinforce the joint on both sides .
taut (tight ) when knee extended , promote medio - lateral stability in this position.
Medial CL - from medial epicondyle of femur to tibia. - just above insertion point o of gracilis , seratorius & semitendinous. ( SGT)
- Medial CL - has DEEP & SUPERFICAL layer - deep layer attach to medial meniscus - injury to ligament can cause injury to medial meniscus.
Lateral CL - from lateral epicondyle of femur to fibula head )
- Cruciate Ligament - 2 in the shape of cross.
0 Anterior & Posterior cruciate Ligament - PREVENT POSTERIOR & ANTERIOR DISPLACEMENT OF THE TIBIA ON THE FEMUR.
ACL - from medial surface of lateral femoral condyle (intercondylar fossa ( on femur ) ) to ———————— > anterior region of intercondylar region on of Tibial Plateau .
- stop sliding of tibia forward
PCL -
From lateral part of on medial femoral condyle ( in the intercondylar fossa ) ——————-> to posterior region of intercondylar region of tibial plateau.
0 stop sliding of tibia backwards
( for femur it is the opposite 0 stop it sliding forwards )
- Patella Ligament
- *
- continuous with quadricep tendon ( all 4 muscles join to form this ) - inserts onto Tibial tuberosity - anterior tibial surface - pad of fat ( Hoffa’s fat btw anterior surface
- together with quadriceps tendon control patella position during knee flexion & extension.
What is the Tibial spine ?
What is the Tibial plateau ?
Medial & Lateral tibial spine
Medial TS - where Anterior cruciate ligament attaches.
Ridge of bone at the top of the tibia.
Medial & Lateral - proximal ends of the tibia terminate in a broad flat region.
What are the three articulations of the knee joint ?
btw :
0 Lateral condyle & lateral tibial plateau
0 medial condyle & medial tibial plateau
0 Patella and Patella surface of the femur. - Patellofemoral joint btw the.
What are the menisci of the knee ?
2 of them :
0 Lateral & Medial
0 crescent shaped cartilage ( fibrocartilaginous ) located btw tibia and femur ( btw plateau of tibia and femoral condyles ) - sit within knee joint
FUNCTION
0 Provide stability to knee joint , shock absorption and distribute weight
more evenly through joint , distribution of synovial fluid.
STRUCTURE
All have posterior and anterior horns - anterior horns of bot menicus attached to each by transverse ligament
separated in 3 thirds ;
- peripheral 1/
3 - red - red
zone -
contains
blood
vessels -
geniculate
arteries ( thus
damage here
is repairable )
- middle 1/3 -
red - white
zone.
- inner 1/3 -
white - white
zone - no BV
-
non
repairable - Avascular ( both middle & inner 1/3 -damage + symptomatic - removal is best )
0 Lateral menisci
- More C
shaped
0 Medial menisci - more O shaped. - bigger than lateral one - covers more tibia surface.
have Anterior & posterior horns
What is the meaning of O Donoghue’s unhappy triad ?
0 Medial CL tear
0 Medial meniscus tear ( caused by medial cl TEAR )
0 Anterior Cruciate ligament tear.
Types of Meniscal tears ?
Acute - bucket handle tears
Degenerative - from old age & osteoarthritis
presentation
- knee locking.
Imaging of knee
MRI most commonly used
Ultrasound & CT can be used.
Lateral view taken when patient is lying down.
- shows effusions ( excess fluid in joint ) due to infection , gout , menicus or ligament injury.
Axial (skyline ) view - look for suspected fractures.
Type of fracture - supracondylar ?
fracture can be :
0 displaced - shifted significantly - fractured ends of bone no longer in alignment.
0 undisplaced - bone broken but shifted out of place
0 impacted - broken ends of bone jammed together because of force of injury
0 comminuted - fragmented into multiple different pieces.
What is knee dislocation
&
knee cap dislocation ?
Knee dislocation - Femur is detached from Tibia
Knee cap dislocation - Patella has become detached from its groove on distal femur.
( Patella usually dislocates laterally )
Consequences of dislocation in knee or knee cap ?
Haemarthrosis - bleeding ( haemorrhage )into the knee joint .
Osteochondral fractures - fractures of bone & overlying articular cartilage of lateral or medial femoral condyle.
What are the weaker and stronger ligamentous structures in the knee ?
Weaker - Anterior Cruciate L , Medial Collateral L
Stronger - Posterior Cruciate L , Lateral Collateral ligament
( PCL - Strongest ligament of knee - thicker than ACL)
(LCL - stronger than MCL as part of complex of structures on lateral aspect of knee which stabilise the lateral aspect. e.g deep fascia of thigh - biceps femoris tendon , facsia lata ) - LCL is also more mobile .
What are some of the ways the Collateral L can be damaged ?
Medial knee disolocations (tibia moves in medial direction - LCL & MCL can be damage.
Direct blow to Laterak aspect of knee damages MCL.
* forces the knee joint into Valgus ( Lateral Flexion – deformity involving oblique displacement of part of limb away from midline ( leg sticks out to the side in lateral direction - flexed ( bent).
SEVERE FORCE & INCREASED DEGREES OF LATERAL FLEXION CAN RESULT IN UNHAPPY TRIAD. (damage to medial menicus & ACL as well )
VERY SEVERE - damage to PCL , L femoral condyle , lateral tibial plataeu.
Collateral L can either be sprained or disrupted (torn ) - different degree of severity :
- can be superfical oedema - partial tear - Complete tear - avulsion of the attachment of MCL.
What does Avulsion mean ?
Detachment of bone fragment causing ligament to pull away.
Function of PCL & ACL ?
test to check function.
ACL keeps tibia from sliding in front of the femur - sliding foward
also prevents anteriolateral rotation - providing rotational stability.
Damage to ACL - causes anteriolateral rotational instablity
Pivot shift test - if there is ACL damage feel a clunk at 20 -30 degress flexion.
( iliotubial band acts as a flexor at - so tibia pulled posterior when flexed at this angle with ACL tear
( will feel a palpable clunk on outside of the knee - very specific to ACL tear ) - comparre with other knee - may hear clunk sound
- patient may decribe it as knee giving way.
Lachman’s test - At 20 -30 degrees the tibia can pulled fowards against the femur more than normal (anterior translation ) - lack of solid end point.
( with damage to ACL - Unhappy triad should be suspected )- check for damage to MCL , medial menicus.
