Patellofemoral Joint

Question 1

State the type of joint:

Patellofemoral joint

Answer 1

Synovial saddle joint

Question 2

Describe the location of the patella

Answer 2

Sesamoid bone embedded in the Quadriceps tendon above and patella tendon below; on the anterior aspect of the knee

Question 3

Describe the patellofemoral articular surfaces

Answer 3

Patella posterior surface - Oval in shape, covered in thick hyaline cartilage, divided into a large lateral facet, medial facet and small most medial Odd facet

V shaped patellar (trochlear groove) on anterior surface of distal femur

Question 4

Give the movements of the knee joint as a whole

Answer 4

Flexion, Extension plus Medial and lateral rotation of the flexed knee

Question 5

Give the direction of movement of the patella during specific knee movement

Answer 5

Knee Flexion - patella moves inferior in the patella groove of the femur
Knee Extension - patella moves superiorly in the patella groove of the femu

Question 6

Explain the Q angle and how it is measured

Answer 6

angle between the Quadriceps muscles (in particular Rectus femoris) and the Patellar tendon

Measured as angle between line from ASIS to centre patella and line from centre patella to tibial tuberosity

Represents angle of Quadriceps muscle force

Question 7

What are the normal ranges and abnormal ranges of Q angle

Answer 7

Normal men - 13 degrees
Normal woman - 18 degrees

Abnormal - <13 or >18 (may predispose patellar lateralisation - quadriceps pulling patella laterally)

Question 8

Factors of Patellofemoral joint stability

Answer 8

• Patella Position
		○ Alta - more proximal than normal
		○ Baja - more distal than normal 
	• Lateral femoral buttress wall - blocks lateral shift of patella
	• Ratio between vastus medialis obliquus (VMO) and vastus lateralis (VL) - medialising action of VMO
	• Balanced support of M/L retinaculum
		○ Fibrous tissue
		○ M retinaculum often ruptured
		○ L retinaculum tightness
	• Patella tendon