the knee joint Flashcards
what is crucial for the functioning of the knee?
the thigh muscles - front, medial and posterior
they can also flex and extend the hip
how can joint pain present?
acute pain, chronic pain or atraumatic pain
what is atraumatic or traumatic injury?
inflammatory conditions
where will acute injury present?
to A&E
fractures, tear or sprain of the soft tissues, from sports, falls or in elderly
where will chronic injuries present?
to the GP
such as OA or bursitis
where will atraumatic present?
to A&E
septic joint, flare up of OA/RA or acute gout
what can be the result of joint injury?
poor sleep, poor quality of life and poor mobility
how common are injuries to the knee?
common however dislocation of the whole knee joint is rare and catastrophic
what types of injury can there be?
soft tissue - meniscal tear (acute or chronic/degenerative) or ligament tear/rupture (acute) and bony - fractures of patella, distal femur or tibia
what is the knee joint?
it is a synovial hinge joint with 3 bones (distal femur, patella and proximal tibia) and 3 articulations (2 femorotibial and 1 femoropatellar)
what are the condyles?
on the femur they are bulky projections medially and laterally and on the tibia they are flattened plated which are medial and lateral tibial plateaus
what is the bony projections between the tibial condyles?
intercondylar eminence or tubercle
what is the projection on the tibia?
tibial tuberosity for muscular attachment
is the joint congruent?
no the tibial plateaus are poor fit for the femoral condyles and therefore the knee is more stable in extension when the joint is more congruent
what increases the stability of the knee joint?
two wedge shaped fibrocartilagenous plates - deepen the joint
what are the menisci?
they are half moon shaped fibrocartilage discs that sit on top of the tibial plateaus to deepen the joint - they are thicker at external margins where they attach to the fibrous capsule of the joint
what is the function of the mensici?
shock absorption, distribute weight evenly, increase joint congruency and assist in locking mechanism
where is infrapatellar fat found?
in between the transverse ligament (runs between two menisci) and the patellar tendon
what type of mensical tears are there?
there are six vertical horizontal parrot beak peripheral bucket handle flap
how are tears treated?
resection or repair
how can tears occur?
injury or degenerative
what are complications of displacing cartilage?
it can trap during knee movements and therefore cause pain or locking
what is the risk of damaging menisci?
predisposition to OA
what increases the stability of the knee joint?
surrounding muscles - thigh muscles cross the knee joint and form a sheath
ligaments inside the knee capsule - intraarticular - ACL/PCL
extraarticular ligaments outside the knee capsule - lateral and medial collateral ligaments
what is the course of the ACL/PCL?
anterior cruciate ligament - travel from origin in the anterior intercondylar region of the tibia supero-posteriorly to insert into the lateral condyle of the femur
posterior cruciate ligament - travel from origin in the posterior intercondylar region of the tibia into the medial condyle of the femur
criss-cross
what are the functions of the ACL/PCL?
stabilisation of the knee joint - the posterior will stop the tibia displacing on femur posteriorly and anterior wilt restrict the tibia from displacing on femur anteriorly
prevent the tibia and femur from separting laterally
PCL is the main stabiliser of the flexed knee when weight bearing
what is hyperflexion and hyperextension?
hyperflexion is restricted by the PCL - when the tibia moves posteriorly on the femur and vice versa
how can hyperflexion and extension occur?
hyperflexion through a fall on the tibial tuberosity when the knee is bent
hyperextension is thorugh an anterior force or through excessive extension
what are the differences between the two collateral ligaments?
these are the extracondylar ligaments
medial - tibial - flat band that is attached to the meniscus that prevents abduction of leg at knee
lateral - fibular - cord like structure that is not attached to the meniscus and prevents adduction of leg at knee
what is the relationship between extra and intracondylar ligament tears?
if once of the extra tears then the intra can also tear
what is the unhappy triad?
occurs mainly through excessive twisting/rotation - it is through blow to the lateral side of the extended knee or excessive lateral twisting of a bent knee. It is when the tibial collateral ligament tears and therefore the medial meniscus tears with it as they are attached. The ACL then also tears
what are the complications of tearing ligaments in knee?
it will be unstable forever
can the PCL tear?
yes but not commonly
what are hamstrings for?
flexion (bend)
what are quads for?
extension (straightening)
what is the function of the front, medial and posterior thigh muscles?
flexion and extension of the knee and the hip
what are the main stabilising muscles of the knee?
gracilis, sartorius, iliotibial tract, hamstrings and quadriceps
how can you avoid surgery for knee ligament damage?
building up quads through physio or exercise can compensate
what is locking the knee?
it is the very stable position where the knee is fully extended and the femur has undergone a few degrees of medial rotation on the tibia meaning that the thigh muscles can relax
what is unlocking?
the femur is laterally rotated by popliteus muscle
what tendons can you see from posterior view of knee?
semimembraneous vertically and the oblique popliteal laterally
what is patellar dislocation and how frequent is it?
it is common and is when the patellar slips out of normal position. It is more common in females due to the alignment of the femur in relation to the tibia
what are bursae?
they are fluid filled sacs that are found between points of friction - around the patella there is the suprapatellar, deep and superficial infrapatellar and prepatellar bursae
what is bursitis?
inflammation or autraumatic swelling
how can OA come about from the tibia and femur?
there is abnormalities of alignment of the femur relative to the tibia - the tibia will be abducted or adducted with relation to the femur
what are signs of advanced OA?
reduced joint space, osteophytes and sclerosis
where are the adductor longus, brevis and magnus found?
medially
what is a characteristic of gracilis?
it is weak
where do adductors insert and originate?
the originate and the inferior pubic ramus and insert on the femur
which is the longest adductor M, L or B?
Magnus is longest
where are ad. longus and brevis in relation to each other?
longus is more superficial
what are the boundaries of the femoral triangle?
the inguinal ligament, the medial border of sartorius and the superior border of adductor longus
what aer the contents of the femoral triangle?
the femoral artery vein and nerve and the ilipsoas and pectineus in the floor
where does the external iliac vein originate from?
the femoral veins
what is the course of the obturator nerve and where does it supply?
it comes from L2-L4 spinal levels, goes through the pelvis and obturator foramen to the medial thigh to innervate the adductors
what are the characteristics of gracilis?
it comes of the medial pelvis and inserts onto tibia therefore is long, thin and medial
what do the hamstrings act on?
the hip to extend and the knee to flex - cannot do both maximally simultaneously
what are the hamstring muscles and where do they insert?
biceps femoris inserts laterally, and semimembranosus and semitendinosus insert medially
