KNEE DISORDERS Flashcards
What are femoral shaft fractures
In healthy children and young adults usually due to high velocity trauma e.g. falls from height or road traffic collisions.
In elderly with osteoporotic bone they can occur from low velocity injury e.g. falling from standing position
what should be considered in injury in young children
consider child abuse (non accidental injury)
Describe appearance of proximal fragment in femoral shaft fractures
proximal fragment is often abducted (due to pull of glut med and min on the greater trochanter)
also flexed due to the action of iliopsoas on the lesser trochanter.
Describe appearance of distal fragment in femoral shaft fractures
Distal segment is adducted into a varus deformity due to action of adductor muscles.
Extended due to the pull of gastronemius on the posterior femur
What are the signs of a femoral shaft fracture
-The patient will have a tense swollen thigh
-Blood loss in closed femoral fracture (1-1.5l) and the patient may develop hypovolaemic shock.
Are there neurovascular complications in femoral shaft fractures
- complications due to involvement of neighbouring neurovascular structures within the fracture site are rare.
How are femoral shaft fractures treated
treated with surgical fixation
How do distal femoral fractures occur in younger patients?
-usual mechanism is a high energy sporting injury and there is often significant displacement of fracture fragments.
How do distal femoral fractures occur in the elderly?
Usually seen in association with osteoprotic bone, mechanism is falling from standing.
Describe impact on the popliteal artery in distal femoral fractures
Popliteal artery may become involved if there is significant displacement of the fracture.
careful assessment of the neurovascular status of the limb before and after reduction of the fracture is needed
How do tibial plateau fractures occur?
Tend to be high energy injuries, mechanism is axial loading with varus or valgus angulation (an abnormal medial/laterak flexion load) of the knee.
What do tibial plateau fractures affect?
affect the articulating surface of the tibia within the knee joint.
Describe the types of tibial plateau fractures?
-They can be unicondylar (affecting one condyle) or bicondylar (affecting both tibial condyles)
-Fractures affecting the lateral tibial condyle are the most common
After effects of tibial plateau fractures
-Articular cartilage is always damaged
-Most patients will develop a degree of post traumatic OA in the affected joint
-Can be associated with meniscal tears and ACL injuries.
Describe Patellar fractures
-Accounts for 1% of all skeletal injuries
-Either caused by a direct injury e.g. knee against dashboard.
-Or caused by eccentric contraction of quadriceps
-Most occur in patients aged 20-50 years
Describe appearance of patellar fracture
-Often a palpable defect in the patella and a haemarthrosis (blood in the joint)
What may the patient be unable to perform in a patellar fracture
If the extensor mechanism is disrupted (complete split of patella to quadriceps tendon insertion)
-Patient will be unable to perform a straight leg raise.
Treatment of patellar fracure
Displaced patellar fractures require reduction and surgical fixation
Undisplaced patellar fractures can be protected whilst healing takes place via splinting + crutches
(do not usually require surgical fixation)
What is a patellla dislocation
Refers to the patella being completeley displcaed out of normal alignment
Partial displacement is known as subluxation
Causes of patella dislocation
-Trauma, often a twisting injury in slight flexion or a direct blow to the knee
-Usual mechanism is internal roatation of the femur on a planted foot whilst flexing the knee
Most common affected by patella dislocation
-Athletic teenagers
(MOI: sudden change of direction during sports)
What factors can predispose a patella dislocation (5)
-Generalised ligamentous laxity
-Weakness of the Quadriceps. especially the VMO.
-Shallow trochlear groove with a flat lateral lip
-Long patellar ligament
-Previous dislocations
Treatment of patella dislocations
-Treatment involves extending the knee then manually reducing the patella.
-Immobilisation is used whilst healing takes place + physiotherapy to strengthen the VMO.
Describe meniscal injuries
-Meniscal injuries (meniscal tears) occur due to sudden twisting motion of a weight-bearing knee in high degree of flexion.
