Patellar instability

Question 1

What way does dislocation always occur in patellar instability?

Answer 1

Laterally

Question 2

What ligament tears when patella dislocates?

Answer 2

Medial patellofemoral ligament tears

Question 3

Predisposing factors to patellar instability?

Answer 3

-Ligamentous laxity -Female -Shallow trochlear groove -genu valgum -Femoral neck anteversion -High riding patella (patella alta)

Question 4

Investigation for patellar instability?

Answer 4

X-ray

Question 5

What would be seen on patellar instability x-ray?

Answer 5

-Small opacification: osteochondral fracture: medial facet of patella strikes lateral femoral condyle -Lipohaemarthrosis can be seen

Question 6

Treatment of patellar instability?

Answer 6

-Physiotherapy to strengthen quadriceps -If recurrent dislocation is frequent: -Tibial tubercle transfer -Medial patellofemoral ligament (MPFL) reconstruction: tendon autograft