Knee Flashcards
What in the knee has the thickest hyaline cartilage in the body?
retropatellar surface
Which joint contains the menisci?
tibiofemoral joint
What is the main role of the ACL?
prevents abnormal internal rotation of tibia
What is the PCL for?
prevents hyperextension and anterior translation of femur
How is the ACL assessed?
assessing anterior translation of tibia
How is PCL assessed?
assessing posterior translation of tibia
What does the MCL do?
resists valgus force
What does the LCL do?
resists varus force
What may predispose early OA of the knee?
previous meniscal tears
ligament injurines and malalignment
What side of OA does genu varum lead to?
medial OA
What side of OA does genu valgum lead to?
lateral OA
What should you consider in a patient with substantial knee pain and disability where conservative management is no longer effective?
knee replacement
Is there more of a chance of dislocation in knee or hip replacements?
hip
In which, knee or hip replacements is there a higher chance of unexplained pain?
knee
Which type of injuries classically occur with twisting force on loaded knee?
meniscal injuries
Describe presentation of meniscal injury.
localized pain
effusion develops by following day
catching sensation or locking - difficulty straightening knee
When do ACL ruptures tend to occur?
with higher rotational force, turning upper body laterally on planted foot
Normally during high impact sports
Describe what symptoms occur in an ACL injury.
pop is usually heard/felt
patient develops haemarthrosis and swelling within an hour
deep pain
What may patients complain of in ACL later?
rotatory instability
What happens to the tibia in ACL rupture?
excessive internal rotation
What may cause a valgus stress injury?
rugby tackle from side
What will a valgus stress injury usually tear?
MCL, but if higher force, may also damage ACL
A direct blow to the anterior tibia with the knee flexed eg in a motorcycle crash may rupture what?
PCL
What will a varus stress injury rupture?
LCL/PCL
What percentage of ACL ruptures also have a meniscal tear?
25%
What may clinical examination of a meniscal tear reveal?
effusion
joint line tenderness
pain on tibial rotation
A locked knee with a displaced bucket handle meniscal tear will have what degree block to full extension
15’
What type of meniscal tear is more common and why?
medial because medial meniscus is more fixed so force from pivoting movements is centred here
What may large longitudinal tears result in?
bucket handle tear
What happens in a bucket handle tear?
large meniscal fragment can flip out of its normal position and displace anteriorly and knee locks
Why does the knee lock in a bucket handle tear?
due to mechanical obstruction from trapped meniscal fragment
When do degenerate meniscal tears tend to occur?
as meniscus weakens with age
Why does the meniscus have limited healing potential?
only has arterial blood supply in outer third
What type of meniscal tears should be considered for meniscal repair?
fresh, longitudinal tears, involving outer 1/3 of meniscus in younger patient
What should be performed in patients with meniscal tear in whom pain or mechanical symptoms do not improve in around 3 months?
arthroscopic partial menisectomy
What is the principal complaint in an ACL injury?
rotatory instability, giving way on turning
What does clinical examination reveal in ACL?
knee swelling with excessive anterior translation of tiba on anterior drawer test and Lachman
Who are good candidates for ACL reconstruction and what does it involve?
those who want to go back to sports
involves tendon graft and intense rehabilitation
Do MCL tears tend to heal well?
Yes
How are acute MCL tears usually treated?
hinged knee brace
How can chronic MCL instability be treated?
MCL tightening or reconstruction with tendon graft
What is a complete knee dislocation?
rupture of all four of the knee ligaments
What may reperfusion in complete knee dislocation result in?
compartment syndrome, especially after prolonged ischaemia
When does an extensor mechanism rupture e.g. of patellar tendon or quadriceps tendon tend to occur?
with rapid contractile force eg after lifting heavy weight
What should the assessment of ANY acute knee injury include?
straight leg raise test to determine if extensor mechanism is intact
Which out of patellar tendon ruptures and quadriceps tendon ruptures occur in under 40s?
patellar tendon ruptures
Who may be likely to get an extensor mechanism rupture?
body builders
What antibiotics can cause tendonitis and risk tendon ruptures?
quinolones e.g. ciprofloxacin
Should steroid injections for tendonitis of the extensor mechanism of the knee be given?
no - high risk of tendon rupture
What may X rays reveal regarding the patella in extensor mechanism ruptures?
high patella in patella tendon rupture or low lying in quads rupture
What may determine the extent of the extensor mechanism injury in obese patient?
ultrasound
What does patellofemoral dysfunction describe?
disorders of patellofemoral articulation resulting in anterior knee pain
In whom is patellofemoral dysfunction more common?
females, particularly in teens
What do patients complain of in patellofemoral dysfunction?
anterior knee pain, worse going downhill, grinding/clicking sensation at front of knee
stiffness after prolonged sitting causing “pseudolocking” - stiffens in flexed position
When do you see true locking?
bucket handle tear
Which way does the patella almost always dislocate?
laterally
What is seen on X ray in patellar dislocation?
lipo haemarthrosis
Does risk of patellar instability increase or decrease with age?
decrease
