3: Soft tissue injuries of the knee Flashcards
Name six important soft tissue structures of the knee which must be considered when talking about knee injuries.
Medial and lateral menisci
Medial and lateral collateral ligaments
Anterior and posterior cruciate ligaments
What are the prominences of the femur and tibia which articulate with the menisci?
Medial and lateral condyles
What is the area between the tibial condyles called?
Intercondylar region
The menisci only have a ___ blood supply, so central tears tend not to heal.
peripheral
Compare the mobility of the medial and lateral menisci.
Medial meniscus is fixed
Lateral meniscus is mobile
Which menisci is under more stress - medial or lateral?
Medial meniscus
What sort of stresses do the
a) MCL
b) LCL
c) ACL
d) PCL ligaments resist?
a) Valgus stress
b) Varus stress
c) Internal rotation and tibial anteversion
d) Hyperextension of knee
What sorts of instability result from tears of the
a) MCL
b) ACL
c) PCL?
a) MCL tear - valgus instability
b) ACL tear - rotatory instability
c) PCL tear - recurrent hyperextension, difficulty descending stairs
What sort of meniscal tear produces locking of the knee?
Bucket handle meniscal tear
50% of patients with an ACL rupture will also have a ___ tear.
meniscal
Are medial or lateral meniscal tears more common?
Medial tears x10 more common than lateral ones
What is the name for a surgical removal of all or part of a torn meniscus?
Menisectomy
If a locked knee isn’t resolved, what may the patient develop?
FFD
(fixed flexion deformity)
stiffening of the joint and muscles, inability to flex properly
Is there any evidence to show that operating on degenerative meniscal tears bears any benefit?
No, compared to placebo there’s no difference
What are the grades of ligament injury and what do they describe?
Grade I - sprain - some fibres torn, but overall structure is fine
Grade II - partial tear - some fascicles torn
Grade III - total tear
How is the MCL usually torn?
What is the outcome of treatment (bracing, early motion, physio)?
Extreme valgus stress e.g slide tackle in sport
Outcome usually good, tear resolves itself
How is the ACL ruptured?
Extreme internal rotation
usually during sport
Can the ACL be repaired?
No, only reconstructed
By which three means can the ACL be reconstructed?
Autograft - from same patient - Achilles tendon, hamstrings
Allograft - from someone else / a cadaver - Achilles tendon
Synthetic graft (not common)
Can people compensate for ruptured ACLs without surgery?
Yep
some do fine, some have to give up sport
ACL runs from ___ to ___.
(medial , lateral)
lateral to medial
The PCL runs from ___ to ___.
medial to lateral
What is the only purpose of ACL reconstruction?
Regain rotatory stability
no impact on pain or OA risk
What is a common consequence of ligament injury in the knee?
More rapid onset of OA
How is the LCL ruptured?
Hyperextension and varus stress
Does the LCL resolve in a way similar to the MCL?
No, doesn’t heal
may need urgent repair or reconstruction
How may the PCL be ruptured?
Direct blow to the anterior tibia or hyperextension
e.g dashboard or motorbike collision
Where may pain be felt following a PCL rupture?
Popliteal area
In which situations would patients with a PCL rupture feel unsteady?
DESCENDING stairs (extension of knee)
Any situation requiring knee extension
Which tests can be used to assess the condition of the ACL and PCL?
ACL - Lachman test
PCL - posterior drawer test
What are some consequences of a severe knee dislocation?
Multi-ligament tear/rupture
Neurovascular compromise
A rapid turn or direct blow to the ___ can cause it to dislocate.
patella
Does the patella usually dislocate medially or laterally?
Laterally
A significant proportion of patellar dislocation patients will have (one / recurrent) dislocations.
recurrent dislocations
Which group of structures, responsible for extension of the leg, can be ruptured by a blow to the flexed knee?
Extensor mechanism
Give a possible mechanism of injury for the following:
a) ACL rupture
b) PCL rupture
c) MCL tear
d) LCL tear
e) Meniscal tear
ACL rupture - internal rotation (a twisting injury)
PCL rupture - dashboard / hyperextension injury
MCL tear - valgus stress
LCL tear - varus stress
Meniscal tear - twisting injury, rising from a squat
A pop indicates what sort of injury?
Ligament tear, likely ACL
A crack indicates what sort of injury?
Fracture
What is a haemarthrosis?
What accompanies it?
Blood and synovial fluid
Hideous pain
In which sort of knee injuries would you see a haemarthrosis?
ACL rupture or fracture
In which sort of knee injury would you see a generalised effusion?
Meniscal tears, cartilaginous injuries
A Sunday league footballer has suffered a twisting injury on the pitch. He recalls a loud pop, swelling around his knee and horrendous, generalised knee pain. The pain settled after a few days. He now notes that his knee gives way if he rotates on it too quickly.
What knee injury has he suffered?
ACL rupture
A weightlifter was squatting when she noticed sudden sharp medial knee pain and associated swelling. The pain returns periodically. She has noticed that her knee “catches” and occasionally locks up when she extends it.
What injury does this describe?
Meniscal tear
