3 The Knee Flashcards
At what point during knee extension does the patella increase biomechanical advantage of the quads?
increases biomechanical advantage of quads during last 30° of extension (redirects forces exerted by quads)
In which direction does the patella track during extension?
tracks laterally (line of pull of the quads)
What are the dynamic stabilizers of the knee?
- Pes anserinus (medial)
- Biceps femoris, semimembranosus (posterior)
- Gastrocs (posterior)
- Popliteus (posterior)
- Quads and extensor retinaculum (anterior)
What are the degrees of rotation of the knee?
- flexion: 135°
- extension: 0°
- internal rotation: 30-40°
- external rotation: 20-30°
Is the knee primarily a stable or mobile joint?
primarily a stable joint (poor articulation and some vulnerable static stabilizers – if varus/valgus/shear stresses, ligs and menisci can be damaged)
What’s anteversion and retroversion?
- anteversion: rotated anteriorly (e.g. femoral neck rotated anteriorly at coxefemoral jt.)
- retroversion: rotated posteriorly
What effect can femoral anteversion have on the patella?
can increase Q angle and thus lateral patellar tracking (increased Q angle can increase bowstring-effect tension on patella)
How would a person compensate for femoral anteversion?
by rotating femur internally to correct placement of femoral head in acetabulum) (and vice versa for femoral retroversion)
What’s the purpose of Craig’s test? How is it performed?
- 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?
What are the markers for the two lines used to determine Q angle?
- ASIS to midpoint of patella
- Tibial tuberosity to midpoint of patella
What are the (3) factors that maintain a normal alignment of the patella?
- Balanced pull of vastus medialis (VMO) and lateralis
- Lateral condyle of femur projects more anteriorly
- Medial and lateral patellofemoral ligs
What’s Chondromalacia Patella?
- softening or breakdown of articular cartilage
- secondary impairment to patellofemoral dysfunction
- also can occur from prolonged immobilization
What’s the aka for Jumpers knee and what actions often cause it?
aka Quadriceps/Patellar tendonitis; often the result of repetitive jumping or squatting
What types of activities are often linked to Popliteus tendonitis?
Often linked to downhill running, overuse in squatting. Popliteus checks anterior displacement of femur during knee flexion.
What’s the aka for inflammation of the Deep Infrapatellar bursa?
aka carpet layer’s knee
What’s the aka for inflammation of the Pes Anserine bursa?
swimmer’s/athlete’s knee
What’s the aka for inflammation of the Bursa under the IT band?
IT band friction syndrome
What’s the aka for inflammation of the Prepatellar bursa?
aka housemaids knee
What’s the aka for inflammation of the Semimembranosus bursa?
aka Bakers Cyst (between MCL and semimembranosus tendon, lateral to med. head of gastrocs)
What’s Osgood-Schlatter’s – traction epiphysis?
- 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
What are common MOIs for meniscal injury?
- hyperextension
- sudden twist in a flexed position
- valgus force with rotation
What are some S/S of meniscal injury?
- ‘pop’ , giving away
- pain along joint line
- quadriceps atrophy
What are MOIs for ACL injury?
- hyperextension
- valgus force with/without rotation (severe injury)
What structures are injured in the terrible/unhappy triad?
- ACL
- MCL
- Medial meniscus
What’s a general MOI description causing PCL injury?
force on flexed knee pushing tibia posteriorly (e.g. dashboard injury during mva)
Which collateral ligament and meniscus are attached?
MCL and medial meniscus
What does a ‘pop’ indicate?
meniscal injury
What does grinding or grating indicate?
patellofemoral syndrome; arthritis
What does rapid swelling (e.g. intracapsular joint effusion) indicate?
joint capsule damage (e.g. with meniscal or cruciate ligament tear)
What does edema over several hours (e.g. extracapsular interstitial edema) indicate?
extracapsular damage (e.g. inflammation to injured structures outside the joint – MCL)
What does locking with stops/starts, changing direction indicate?
- loose body in joint
- scar tissue within joint capsule
What does instability with stop/starts, changing direction indicate?
torn cruciate ligament
The spinal nerve distribution to muscles crossing the knee originate from which spinal segments?
T12-S3
Which nerves cross the knee?
- femoral
- obturator
- sciatic
- tibial
- common peroneal
From which spinal segments do vascular sympathetic innervation (nerve supply of arterials supplying lower extremity) originate?
T10-S3
