Tell about knee jt:
- mechanical, stability, injury?
- Relatively weak mechanically due to incongurent articular surfaces
- stability dependent on surrounding
- > M and their tendon
- > Lig that connect tib and femur
- Common site for sports injuries, especially ligamentous injuries, due to their contribution to stability
What kind of joint?
What does the knee articulate with?
Synovial, modified hinge jt
Single jt capsule with two articulations
- Femorotibial jt
- Femoropatellar jt
What can you tell about the bone ends of the femorotibial jt?
Femoral Condyles:
- Convex
- Medial longer than lateral
- > this partially dictates biomechnics of knee jt
In full extention the flat part of femoral condyles articulates with tibia.
In flexion, the curved part of femoral condyles articulate with tibia.
=> distal part of femur not uniform.
TIBIAL condyles: Shallow, concave
-> MTC is LARGER than LTC
When larger femoral articular condyles are placed on shallow concavities of tibial condyles, INCONGURENCE is quite evident.
What can you tell about the femoropatellar jt?
Saddle jt.
Patella = Sesamoid bone (embedded in quadriceps fem tendon)
Patellar surface of femur + intercondylar groove.
Articular facets: LAT surface is more pronounced.
Where it the joint capsule?
Post attachment:
- Articular margins of femoral and tibial condyles. NB: popliteus emerges from capsule
Anterior attachment:
- Prox to articular margins of femoral condyles; to margins of patella, patellar tendon and tibial condyles.
What can you tell about the synovial membrane?
-> function, attachments..
bursa?
- Lines capsule and all internal surfaces of articular cavity NOT covered with articular cartilage.
- Forms LARGEST and most EXTENSIBL synovial cavity
- Post: Attaches to articular margins and follows contours of condyles and invaginates into the intercondylar notch and fossa
- Ant: Attaches to borders of patella & ant margins of femoral condyles.
- Inf: Covers infrapatellar fat pad
* Suprapatellar bursa => pocket of synovial mm between femur + QF (continuation of synovial membrane)
What kind of cartilage covers articular surfaces of femur, tibial and patella?
What is the mensiscus made of?
Articular hyaline cartilage.
Accessory fibrocartilage = Med + lat meniscus
What can you tell about meniscus?
- Interpose between femoral and tibial condyles.
- Is thicker at the edges.
- MM = C shape (omvendt side bare)
- LM = O shape. More mobile.
FUNCTION: (5)
- Maintain joint space
- Improve congurence of jt surface
- promotes stability
- decreases contact stress on articular surfaces
- shock absorbers when compressive force placed on it
- transmit load
What is ligaments made of?
Mention ligs at knee jt:
- Collagen fibres +++, and varying amounts of elastin
- Collagen/elastin ratio = ability to provide stability but allows some deformation (dependent on amount of elastin)
- PROVIDE STABILITY
PATELLAR LIG:
- Continuation of QF
- Runs from apex to patella to tibial tuberosity
- capsular ->ant
OBLIQUE POPLITEAL LIG:
- Capsular -> post
- Expansion of semimembranosus
ARCUATE POPLITEAL LIG:
- Capsular -> post
- Y shaped: 2 bands - head of FIBULA to lat epicondyle + intercondylar area of femur
M&L CORONARY LIGS:
- Capsular
- assoc with mensicii + adjacent capsule + articular edges of tibia
MEDIAL COLLATERAL LIG:
- Capsular
- Med epicondyle of femur to med condyle of tibia + med shaft of tibia-
- NB: deep fibres attach to meniscus (but only on med side!)
- ant fibres: Flat
- Post fibres: fan shapes
- prevent movements in FRONTAL plane (preveent tib in lat direction = valgus)
- position: knee in extension
LATERAL COLLATERAL LIG:
- non capsular!
- CORD like lig from lat epicondyle of femur to head of fibula
- popliteus emerges from capsule and runs deep to LCL
- limits excessive motion in FRONTAL plane -> resist tibia moving med direction (vaRUS)
- MCL & LCL: limits excessive extension, provide limited resistance to int and ext rotation when knee is partially flexed
CRUCIATE LIGAMENT:
- Non-capsular (intracapsular) Inside capsule, but outside synovial membrane
- With severe injury to collateral lig, crucate act as secondary restraints
- ACL: ant intercondylar area of tib to med aspect of lat femoral condyle
- Primary restaint to ant dispancement of tib. More common to damage
- PCL: Post & inf tibial plateau to lat surface of med. femoral condyle
- Primary restraint to post tibial displacement
TRANSVERSE LIG:
- non capsular
- joins ant edges of menisci
ANT & POST MENISCOFEMORAL LIGS:
- non capsular
- run ant and post to PCL
- present in 70% of population
- post horn of lat meniscus to med femoral condyle near insertion of PCL
- acts as 2nd.ary restraintt to post translation of tib
Mention all ligs of knee.
- Patellar lig
- oblique popliteal lig
- arcuate popliteal lig
- med & lat coronary lig
- Med & lat collateral lig
- Ant & post cruciate lig
- transverse lig
- Ant & post meniscofemoral lig
=> 8 stykk!
Where do you find bursa of the knee?
What is their function?
- Located between tissues that encounter high friction during movement
- Suprapatellar - between femur and QF
- Anserine - between tendons, tib, MCL (Husk pes anserinus! Tendons = say grace before tea)
RELATED TO PATELLA:
- Subcutaneous prepatellar
- subcutaneous infrapatellar
- deep infrapatellar
- superficial infrapatellar
Nerve supply to knee:
Joint supplied with articular branches via:
Femoral
obturator
tibial
common fibular
NERVES
Blood supply to knee
Via network of branches from:
femoral
popliteal
fibular
ant tibial
ARTERIES
Whats the compontents of flexion and ext (NWB OR WB)?
- Rolling
- Conjuct rotation
- sliding
What is the SCREW HOME?
In NWB position tib moves on femur. In last 30 degrees of et tibia EXT ROTATES!
Cannot be performed independetly
Brings jt into locked or closed packed position
adds STABILITY to knee in full ext.
FACTORS GUIDING SCREW HOME:
- Shape of med femoral condyle (tibia follows lat curved path during extension => ext rotation of TIB).
- Passive tension of ACL
- Lat pull of quads
In a WB position. Which way move FEMUR on tibia in flex and ext?
Into EXT: Femur med rotate
Into Flexion: femur lat rotate
What is the role of patella?
Mention the major guiding forces action on patella?
- Anatomic pulley (inc angle of pull of quads)
- Mechanis to reduce friction between quadriceps tendon and femoral condyles
These functions depent on ability of patella to slide on femoral condyles while remainin positioned between them
Forces:
- Overal QF force
- ITB
- Lat patellar retinacular fibres
- VMO
- Med patellar retinacular fibres
- patellar lig force
Opposing forces counteract each other so patella moves optimally during flexion & extension.
Movements at knee often happen in conjuction with other joints of lower limb
THE END. HURRA :-)
