Disorders Of The Knee Flashcards
(45 cards)
What is the standard X-ray series for he knee
AP, lateral and patella axial (skyline)
In a femoral shaft fracture, how does the musculature act as a deforming force
Proximal fragment abducted due to pull of gluteal medius and minimus on the greater trochanter
Flexed due to the action of iliopsoas on the lesser trochanter
The distal fragment is addicted due to adductor Magnus and gracilus and extended due to gastrocnemius
What is the volume of blood loss in a closed femoral fracture
1000-1500ml
In a distal femoral fracture, which artery may be involved
Popliteal
Where do tibial plateau fractures occur
Articulating surface of the tibia within the knee joint.
Lateral condole most common
What is the usual mechanism of a tibial plateau fracture
Varus or valves anglation of the knee with loading
What are some common causes of a patellar fracture
Direct impact - knee against dashboard
Eccentric contraction of the quadriceps
Where does the most important blood supply to the patella come from
The inferior pole
If the fracture completely splits the patella distal to the insertion of the quadriceps, what with the patient to be able to do
?
Perform a straight leg raise
What is a bipartite patella
The patella is in two parts as there is a failure of union of a secondary ossification centre with the main body of the patella
What is the most common direction for a patella to dislocate
Laterally
What are the 5 factors that can pre-dispose to a patellar dislocation
1) generalised ligamentous laxity
2) weakness of the quadricepts esp VMO
3) shallow trochlear (patellofemoral) groove with a flat lateral lip
4) long patellar ligament
5) previous dislocation
How do meniscal injuries occur
Sudden twisting motion of a weight bearing knee in a high degree of flexion
In a meniscal injury, why is swelling a delayed symptom
Swelling due to a reactive effusion or not at all, as menisci are largely avascular
How does a patient with a meniscal injury present at examination
Joint line tenderness
Restricted motion due to pain or swelling
A mechanical block to motion or locking
What ligaments normally prevent excessive posterior motion of the tibia on the femur
Medial and lateral collateral ligaments
Posterior cruciate
What is varus angulation of the knee
Medial angulation of the distal segment
What is valgus angulation of the knee
Lateral angulation of the distal segment
L=Lateral
In acute valgus (lateral) strain, which ligament is at risk
Medial collateral ligament
The medial collateral ligament is more commonly injured but it is the LCL that causes more knee instability, why?
Medial tibial plateau forms a deeper and more stable socket for the femoral condyle
In a collateral ligament injury, when does the patient experience swelling
Immediately after the injury
What is the unhappy triad AKA blown knee
Injury to the anterior cruciate ligament
Medial collateral ligament
Medial meniscus
Why is the anterior cruciate ligament more commonly injured than the posterior
It is weaker
How does a patient with an ACL injury present
Popping sensation
Immediate swelling
Instability of the knee, the tibia slides anteriorly under the femur
