Knee Flashcards
What mechanisms of injury can lead to PCL tears?
direct blow to anterior aspect of flexed knee- ex fall, femur fracture
MCL resists ____ and LCL resists ____
MCL resists valgus
LCL resists varus
What mechanism of injury can cause ACL damage?
bones of leg twist in opposite direction under full weight
The meniscus contains predominantly type ___ collagen
1
What is the key function of the meniscus
bearing weight
minimal contribution to stability, shock attenuation in the normal knee
What is the key function of the meniscus
bearing weight
minimal contribution to stability, shock attenuation in the normal knee
What is the Q angle?
angle between the shaft of the tibia and the patellar tendon, up to 15 degrees
patella is pulled laterally when the quadriceps contracts
Patellas tend to dislocate _______
laterally
What factors make patellar dislocation more likely
shallow femoral groove, increased Q angle, weak muscles, damaged patellofemoral ligament
Describe the classic load deformation curve of ligaments
ligaments have low stiffness at low loads, but high stiffness and resistance to deformity as load increases
How is the integrity of the ACL tested?
anterior drawer test
Lachmans test
ACL and PCL have a ________ location and heal poorly after injury
intra-articular
MCL and LCL are _____, and thus a blood clot forms when they tear and they heal well
extra-articular
When the patella dislocates, the _________ ligament is always torn
medial patellofemoral ligament
Describe the phases of ligament healing after injury
- inflammatory phase, including blood clot formation
- proliferative phase- increased fibroblasts, production of disorganized collagen matrix
- remodeling- decreased cellularity, organization of collagen
*** this pattern is classically seen in MCL which heals well, not seen in ACL which heals poorly
Describe radiographic findings in osteoarthritis of the knee
joint space narrowing, slcerosis, marginal osteophytes, subchondral cysts
What patterns of pain are common in knee osteoarthritis?
activity related pain, stiffness improves with activity, feels better early in the day and worse after heavy labor
can have joint effusions but not hot joints as in inflammatory arthritis
Describe the etiology of knee OA
genetics intra-articular fracture or bone bruise overloading obesity knee alignment- deformities that are self reinforcing
At the knee, varus causes loads to be concentrated ________, and valgus causes loads to be concentrated _______.
varus= medial valgus= lateral
self-reinforcing deformity
Describe the etiology of knee OA
genetics intra-articular fracture or bone bruise overloading obesity loss of meniscus knee alignment- deformities that are self reinforcing
At the knee, varus causes loads to be concentrated ________, and valgus causes loads to be concentrated _______.
varus= medial valgus= lateral
self-reinforcing deformity
_______ increases peak loads in the knee compartments by as much as 300%
meniscectomy
It seems that ACL tear predisposes to DJD only if there is concurrent ___________
meniscus tear
Describe treatment of knee osteoarthritis
- decrease loads: activity modification, weight loss, braces
- improve range of motion
- improve strength and balance
- surgical: joint replacement (arthroscopy for meniscus tear only is controversial)
