L6 Knee Flashcards
Knee Anatomy
-hinge joint
-largest in the body
-patella slides superior during extension and inferior in flexion
-screw home mechanisms is necessary for stability
Capsular pattern of knee
Flexion > Extension
Open packed = 25° flexion
Closed packed = full extension
Intra-articular problems of knee
ACL/PCL
meniscus
chrondral surface of tibiofemoral and patellofemoral
Extra-articular problems of knee
contractile
non-contractile = lcl, mcl, MPFL
Referred problems of knee
L3
peripheral nerve
systemic
Younger children
more likely to be developmental, epiphyseal, fractureT
Teen to middle aged
more. likely to be soft tissue
Older adults
more likely to be degenerative or fracutre
Peak incidence of knee trauma is at age
15 to 19
Prevalence of Knee pain
25% of population will have significant episode of knee pain
400,000 ACL reconstructions a year
790,000 TKA a year
patellar dislocations is the least common
Most common injured ligament in isolation
ACL
ACL MOI
valgus force with foot firmly planted
axial rotation torque
severe hyperextension of knee
ACL History
usually non-contact
landed awkwardly
felt pop
immediate effusion
PCL MOI
fallin flexed knee w/ankle in PF
dashboard contact
severe hyperextension of knee
PCL History
often posterior pain
immediate effusion
MCL MOI
valgus force with foot planted
severe hyperextension of knee
MCL History
contact or non-contact
medial pain and tenderness
LCL MOI
varus producing force with foot planted
severe hyperextension of knee
LCL History
contact or non-contact
lateral pain and tenderness
How common of injury of ligament?
ACL > MCL > medial meniscus > lateral meniscus > LCL > PCL
Patient history questions to ask
were they weight bearing when the injury occurred
was there twisting/pivoting occurring at the time of injury
were they immediately able to bear weight, feel stable
did the knee swell up rapidly
____ chain injuries tend to be less severe than ____ chain injuries
Open
Closed
For a patient with an acute knee injury, a knee radiograph is indicated if
Patient is 55 years old or greater
OR
isolated tenderness of patella
OR
tenderness of the head of fibula
OR
inability to flex knee to 90°
OR
Inability to bear weight both immediately and in the ED for 4 steps
Ottawa knee rules
useful in ruling out a fracture when negative but not good at ruling in a fracture
only valid for injuries < 7 days
limping counts as WB
cost effective
high sensitivity, low specificity
