3 The Knee

Question 1

At what point during knee extension does the patella increase biomechanical advantage of the quads?

Answer 1

increases biomechanical advantage of quads during last 30° of extension (redirects forces exerted by quads)

Question 2

In which direction does the patella track during extension?

Answer 2

tracks laterally (line of pull of the quads)

Question 3

What are the dynamic stabilizers of the knee?

Answer 3

• Pes anserinus (medial)
• Biceps femoris, semimembranosus (posterior)
• Gastrocs (posterior)
• Popliteus (posterior)
• Quads and extensor retinaculum (anterior)

Question 4

What are the degrees of rotation of the knee?

Answer 4

• flexion: 135°
• extension: 0°
• internal rotation: 30-40°
• external rotation: 20-30°

Question 5

Is the knee primarily a stable or mobile joint?

Answer 5

primarily a stable joint (poor articulation and some vulnerable static stabilizers – if varus/valgus/shear stresses, ligs and menisci can be damaged)

Question 6

What’s anteversion and retroversion?

Answer 6

• anteversion: rotated anteriorly (e.g. femoral neck rotated anteriorly at coxefemoral jt.)
• retroversion: rotated posteriorly

Question 7

What effect can femoral anteversion have on the patella?

Answer 7

can increase Q angle and thus lateral patellar tracking (increased Q angle can increase bowstring-effect tension on patella)

Question 8

How would a person compensate for femoral anteversion?

Answer 8

by rotating femur internally to correct placement of femoral head in acetabulum) (and vice versa for femoral retroversion)

Question 9

What’s the purpose of Craig’s test? How is it performed?

Answer 9

• tests for anteversion/retroversion of femur
• prone, knee flx to 90°, therapist holds ankle to rotate hip int/ext while palpating greater trochanter and feeling for most lateral alignment of greater tro; is lower leg int/ext or aligned in sag. plane at this point?

Question 10

What are the markers for the two lines used to determine Q angle?

Answer 10

1. ASIS to midpoint of patella
2. Tibial tuberosity to midpoint of patella

Question 11

What are the (3) factors that maintain a normal alignment of the patella?

Answer 11

• Balanced pull of vastus medialis (VMO) and lateralis
• Lateral condyle of femur projects more anteriorly
• Medial and lateral patellofemoral ligs

Question 12

What’s Chondromalacia Patella?

Answer 12

• softening or breakdown of articular cartilage
• secondary impairment to patellofemoral dysfunction
• also can occur from prolonged immobilization

Question 13

What’s the aka for Jumpers knee and what actions often cause it?

Answer 13

aka Quadriceps/Patellar tendonitis; often the result of repetitive jumping or squatting

Question 14

What types of activities are often linked to Popliteus tendonitis?

Answer 14

Often linked to downhill running, overuse in squatting. Popliteus checks anterior displacement of femur during knee flexion.

Question 15

What’s the aka for inflammation of the Deep Infrapatellar bursa?

Answer 15

aka carpet layer’s knee

Question 16

What’s the aka for inflammation of the Pes Anserine bursa?

Answer 16

swimmer’s/athlete’s knee

Question 17

What’s the aka for inflammation of the Bursa under the IT band?

Answer 17

IT band friction syndrome

Question 18

What’s the aka for inflammation of the Prepatellar bursa?

Answer 18

aka housemaids knee

Question 19

What’s the aka for inflammation of the Semimembranosus bursa?

Answer 19

aka Bakers Cyst (between MCL and semimembranosus tendon, lateral to med. head of gastrocs)

Question 20

What’s Osgood-Schlatter’s – traction epiphysis?

Answer 20

• excessive force placed on patellar tendon causes tractioning, microdamage to the bone and excessive growth of the tibial tuberosity
• common in adolescents
• self limiting
• more common in boys

MOI: repetitive irritation through patellar tendon or repetitive trauma; pain worse with jumping/repetitive activity

Question 21

What are common MOIs for meniscal injury?

Answer 21

• hyperextension
• sudden twist in a flexed position
• valgus force with rotation

Question 22

What are some S/S of meniscal injury?

Answer 22

• ‘pop’ , giving away
• pain along joint line
• quadriceps atrophy

Question 23

What are MOIs for ACL injury?

Answer 23

• hyperextension
• valgus force with/without rotation (severe injury)

Question 24

What structures are injured in the terrible/unhappy triad?

Answer 24

• ACL
• MCL
• Medial meniscus

Question 25

What’s a general MOI description causing PCL injury?

Answer 25

force on flexed knee pushing tibia posteriorly (e.g. dashboard injury during mva)

Question 26

Which collateral ligament and meniscus are attached?

Answer 26

MCL and medial meniscus

Question 27

What does a ‘pop’ indicate?

Answer 27

meniscal injury

Question 28

What does grinding or grating indicate?

Answer 28

patellofemoral syndrome; arthritis

Question 29

What does rapid swelling (e.g. intracapsular joint effusion) indicate?

Answer 29

joint capsule damage (e.g. with meniscal or cruciate ligament tear)

Question 30

What does edema over several hours (e.g. extracapsular interstitial edema) indicate?

Answer 30

extracapsular damage (e.g. inflammation to injured structures outside the joint – MCL)

Question 31

What does locking with stops/starts, changing direction indicate?

Answer 31

• loose body in joint
• scar tissue within joint capsule

Question 32

What does instability with stop/starts, changing direction indicate?

Answer 32

torn cruciate ligament

Question 33

The spinal nerve distribution to muscles crossing the knee originate from which spinal segments?

Answer 33

T12-S3

Question 34

Which nerves cross the knee?

Answer 34

• femoral
• obturator
• sciatic
• tibial
• common peroneal

Question 35

From which spinal segments do vascular sympathetic innervation (nerve supply of arterials supplying lower extremity) originate?

Answer 35

T10-S3