Knee Pathologies Flashcards
Which three components make up the knee joint?
- The medial compartment of the tibiofemoral joint
- The lateral compartment of the tibiofemoral joint
- The patellofemoral joint
What is contained within the tibiofemoral joint and what is their function?
Fibrocartilaginous menisci
Act as shock absorbers and act to distribute load evenly
What are the four main ligaments of the knee?
- Anterior cruciate ligament
- Posterior cruciate ligament
- Medial collateral ligament
- Lateral collateral ligament
What is the role of the ACL?
Prevents abnormal internal rotation of the tibia
What is the role of the PCL?
Prevents hyperextension and anterior translation of the femur
What is the role of the MCL?
Resists valgus force
What is the role of the LCL?
Resists varus force and abnormal external rotation of the tibia
Early OA of the knee may be predisposed by which conditions?
- Previous meniscal tears
- Ligament injuries (esp. ACL deficiencies)
- Malalignment
Which treatment can help younger patients with isolated medial compartment OA?
Osteotomy of the proximal tibia
(high tibial osteotomy)
When would knee replacement be indicated?
Substantial pain and disability
Failure of conservative management
What is the treatment for younger patients who have isolated OA in either the medial or lateral compartment of the knee joint?
Unicompartmental knee replacement
(total knee replacement can be utilised if this fails)
Meniscal injuries to the knee classically occur with what?
Twisting force on a loaded knee
How does a patient with a meniscal injury present?
- Localised pain to the joint line (medial or lateral)
- Effusion the following day
- Catching or locking sensation may be present
- Feeling of knee giving way
- Pain on tibial rotation (Steinmann’s test)
Which type of meniscal injury (medial or lateral) is more common?
Medial meniscal injury
(it is more fixed and less mobile than its lateral counterpart)
What causes true knee locking?
A significantly torn meniscus flipping over and becoming stuck in the joint line
Knee locking is a clinical sign associated with which knee pathology?
Meniscal tear
How is knee “locking” with other knee pathologies such as OA different from that of a meniscal tear?
- There is only temporary difficulty in straightening the leg
- It can spontaneously resolve
- The patient may describe a specific manouvre they use to relieve the locking
This is known as pseudo-locking as it is not true locking
What causes ACL ruptures?
High rotational force e.g. turning the body laterally on a planted foot
What is usually felt during an ACL rupture which is characteristic?
A pop sound or feeling
How does an ACL rupture present?
- Haemarthrosis and swelling within an hour
- Deep knee pain
- Rotatory instability
- Excessive anterior translation of tibia on anterior drawer test
Valgus stress injuries usually tear what?
MCL
(high forces can also damage the ACL)
Which type of fracture can occur with valgus stress injuries?
Lateral tibial plateau fracture
How is the PCL most commonly ruptured?
- Direct blow to the anterior tibia whent he knee is flexed
- Hyperextension
A varus stress injury may rupture what?
LCL
(potentially also the PCL)
In younger patients, what usually causes a meniscal tear?
High impact sports
Acute meniscal tears are often related to which other injury?
Acute ACL rupture
Large longitudinal tears in the meniscus may lead to what?
Large bucket handle tears with subsequent knee locking due to the meniscal fragment flipping into the intercondylar notch
Degenerate meniscal tears can occur ______________ or with a seemingly ____________ injury
Spontaneously
Innocuous
Which type of meniscal tears tend to have complex patterns?
Degenerate
(horizontal, longitudinal and radial components are common)