Knee Dislocations and Fractures Flashcards
The knee is an articulation between which bones?
Distal femur and proximal tibia
The medial collateral ligament of the knee resists which type of stress?
Valgus
In which instance do distal femoral fractures usually occur?
- Osteoporotic bone
- Fall onto flexed knee
Which two categories can distal femoral fractures fall into?
- Intracapsular (intercondylar)
- Extracapsular (supracondylar)
Why will a distal femoral fracture usually adopt a flexed position?
Pull of gastrocnemius muscles
Why is it preferrable to treat a distal femoral fracture with a plate and screws versus a cast?
The fracture position is difficult to maintain in a cast
For which main reasons is a true knee dislocation considered a surgical emergency?
- High incidence of vascular injury
- Nerve injury
- Compartment sydrome
How can the vascular status of the knee be examined after dislocation?
- Doppler
- Duplex scan
- Angiogram
Virtually all patellar dislocations are _________
Virtually all patellar dislocations are lateral
In which type of patient is a patellar dislocation most common?
Adolescent females
In which two ways is a patellar dislocation most likely to reduce?
- Spontaneously when the knee is straightened
- During manipulation
Patellar dislocations are predisposed to by which main factors in adolescents, especially females?
- Generalised ligamentous laxity
- Valgus alignment of the knees
- Rotational malalignment (including femoral neck anteversion)
- Shallow trochlear groove
Where will patients have tenderness after a patellar dislocation?
Over medial retinaculum
(where medial patellofemoral ligament is torn)
For which reason is a patellar dislocation most likely to cause a haemarthrosis?
Impactation of medial patellar facet on outer aspect of lateral femoral condyle
Around __% of first time patellar dislocations will experinece a further dislocation and __% of those will have multiple recurrent dislocations
Around 10% of first time patellar dislocations will experinece a further dislocation and 50% of those will have multiple recurrent dislocations
How can further patellar dislocations be prevented?
Temporary splintage followed with physiotherapy
(physiotherapy is key to strengthen vastus medialis)
Many adolescent patients stabilise with time
Surgical stabilisation is rarely required
Tibial plateau fractures usually occur in which two scenarios?
- High energy in younger patients
- Low energy in elderly and osteoporotic
What are tibial plateau fractures?
Intra-articular fractures with either a split in the bone, depression of the articular surface or both
Classified via the Schatzker system
How can tibial plateau fractures be treated generally?
Reduction of articular surface, rigid fixation followed by early motion
Which type of injury may induce a lateral tibial plateau fracture, and which knee ligaments are most likely to be affected?
Valgus stress injury
MCL and possibly ACL
Injury to which nerve will induce foot drop, and which muscle is affected?
Common fibular (peroneal) nerve
Tibialis anterior
A medial tibial plateau fracture will be induced by which type of injury to the knee?
Varus stress
In tibial plateau fractures which are depressed, fractures must be raised back to normal and in order to do this, what is used to fill the void in the bone?
Bone grafting
Usually morsellised packed cancellous autograft from the iliac crest
What are the two major options for definitive management of high energy proximal tibial fractures?
- Open reduction and internal fixation
- External fixation (ring fixator and fine wires to hold fracture fragments under tension)
An external fixator is often required initially for initial stability and to allow swelling to reduce before definitive management
Failure to restore the articular surface at the proximal tibia after fracture usually results in what?
Total knee replacement
