2. Knee joint - clinical conditions

Question 1

how would patella fragments displace after a fracture and why

Answer 1

• proximal fragment displaces superiorly due to quadriceps contraction
• distal fragment displaces inferiorly due to patellar ligament

Question 2

why is patellar dislocation more common in women

Answer 2

greater Q angle

Question 3

in which direction does patella usually dislocate

Answer 3

laterally

Question 4

which structures conterbalance tendency towards lateral patella dislocation

Answer 4

1- medial, more horizontal pull of powerful vastus medialis

2- more anterior projection of lateral femoral condyle and deeper slope for larger lateral patellar facet

Question 5

what is the most common knee joint pathology

Answer 5

collateral ligament injuries - caused by forces applied to side of knee when foot is fixed on ground and cannot move (knee often slightly flexed)

Question 6

what can cause ACL tears

Answer 6

1- hyper-extension of knee joint (as is taught during extension)
2- application of large force to back of knee when knee slightly flexed

Question 7

which test indicates an ACL tear

Answer 7

anterior drawer test: when hip and knee are flexed (P is supine), clinician can pull free tibia anteriorly

Question 8

what can cause PCL tears

Answer 8

1- large force applied to shin when knee is flexed (e.g. dashboard injury)
2- hyper-extension of knee joint
3- damage to upper part of tibial tuberosity

Question 9

which test indicates a PCL tear

Answer 9

posterior drawer test: when hip and knee are flexed (P is supine), clinician can push free tibia posteriorly

Question 10

what is a frequent consequence of tibial/medial collateral ligament tearing

Answer 10

tearing of medial meniscus (as are firmly attached)

Question 11

what are the 3 features of the ‘unhappy triad’

Answer 11

1- torn ACL
2- torn medial collateral ligament
3- torn medial meniscus

Question 12

what is knee locking and what are the 2 different types

Answer 12

knee stuck in 1 position, unable to flex or extend

1- true locking = mechanical block where something inside joint, e.g. meniscal tear or loose body, prevents mov.

2- pseudolocking = pain + muscle spasm

Question 13

what is housemaid’s knee

Answer 13

prepatellar bursitis, e.g. due to friction between skin and patella

Question 14

what is clergyman’s knee

Answer 14

superficial infrapatellar bursitis, e.g. due to friction between skin and tibial tuberosity