S4L2 - Disorders Of The Knee Flashcards
What are the standard x-ray series for the knee?
AP view, lateral view, patella axial (skyline) view
Who are prone to femoral shaft fractures and how do they occur?
Children and young adults as result of high velocity trauma.
Low velocity injury in elderly with osteoporotic bones.
Why is the proximal segment in a femoral shaft fracture often abducted and flexed?
Because the musculature acts as a deforming force. Abducted by gluteus medius and minimus and flexed by iliopsoas pulling on the lesser trochanter.
Why is the distal segment of the femur after a fracture adducted into varus deformity and extended?
The musculature acts as a deforming force. Adducted by the adductor muscles (gracilis, adductor Magnus). Extended due to the pull of gastrocneumius on the posterior femur.
What are signs of a femoral shaft fracture?
Tense swollen thigh, possible drowsiness from hypovolaemic shock.
What is a common complication of a femoral shaft fracture?
Hypovolaemic shock as blood loss in closed femoral shaft fractures is 1L-1.5L. Rarely have neuromuscular complications.
How are femoral shaft fractures treated?
Surgical fixation.
What complications can occur in a distal fracture of the femur?
Popliteal artery may become involved if there is significant displacement of the fracture.
How is a fracture of the distal femur treated?
Assessment of the nerurovasculature status of the limb before and after reduction of the fracture.
How do tibial plateau fractures usually occur?
High energy injuries. Axial loading with varus or valgus angulation of the knee.
What are tibial plateau fractures?
Fractures affecting the articulating surface of the tibia within the knee joint. Can be unicondylar or bicondylar.
What are complications of tibial plateau fractures?
Articular cartilage is always damaged. Most patients develop a degree of post-traumatic osteoarthritis in the affected joint. Also associated with meniscus tears and anterior cruciate ligament injuries.
How do patellar fractures occur?
Direct impact injury
Eccentric con ration of the quadriceps
20-50yrs
What can often be found on presentation of a patellar fracture?
Palpable defect in the patella
Haemarthrosis
Patient unable to perform a straight leg raise (extensor mechanism disrupted as fracture is distal to the insertion of the quadriceps tendon)
How are displaced patellar fractures treated?
Reduction
Surgical fixation
How are undisplaced patellar fractures treated?
Protected whilst healing by splints and crutches
Wha can often be mistaken for a patellar fracture?
Bipartite patella (failure of union of a secondary ossification centre within the main body of the patella)
What is patellar subluxation?
Partial displacement of the patella
What is the most common direction for the patella to dislocate?
Laterally
How is the patella usually dislocated?
Trauma, often a twisting injury with slight flexion. Usually with internal rotation of the femur on a planted foot
Direct blow to the knee.
What people commonly suffer from patella dislocation?
Athletic teenagers
What are predisposing factors to a patella dislocation?
Generalised ligamentous laxity
Weakness of the quadriceps muscles (especially the vastus medialis obliquus)
Shallow trochlear groove with a flat lateral lip
Long patellar ligament
Previous dislocations
How are patellar dislocations treated?
By extending the knee and then manually reducing the patella. Immobilise when healing. Physiotherapy to strengthen the vastus medialis obliquus after healing.
How do menisci life injuries typically occur?
Sudden twisting motion of a weight-bearing knee in a high degree of flexion.