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Knee > anatomy biomech path > Flashcards

anatomy biomech path Flashcards

1
Q

What are the bursa of the knee?

A
  1. There are about 18 bursa of the knee
  2. prepatellar- on top of the patella
  3. infrapatellar- on top of and beneth the patellar tendon
  4. popliteal- ofter connect to synovial cavity
  5. head of the gastroc- often communicates with synovial cavity or the semimembranous bursa
  6. pes anserinus- beneath the pes muscles and MCL
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2
Q

How can you develop suprapatellar bursitis?

A

if the genu articularis does not clear the suprapatellar bursa from between the patella and femur during extension it can get pinched

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3
Q

How is the capsule attached to the tibia?

A

horse shoe shaped coming off the posterior edge of the tibia to run in and around the intracondylar eminance putting the ACL and PCL outside the capsule

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4
Q

How is the capsule attached to the femur?

A
  1. anteriorly- about 2 finger above the proximal articular surface
  2. medially and laterally it follows the edge of the articular surfaces
  3. it passes above the popliteus muscle laterally
  4. blends with the heads of the gastroc
  5. enters the intercondylar notch following the articular surface
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5
Q

How does the fluid in the knee move?

A
  1. flexion: quad compresses the supra patellar bursa pushing the synovial fluid posteriorly
  2. extension: posterior capsule is stretched pushing the fluid anteriorly
  3. Medial to lateral the fat pad can block movement since there is a central narrowing of the capsule
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6
Q

What are the attachments of the knee collateral?

A
  1. medial- medial femoral condyle running anterioinerfior to the tibia posterior to the pes anserinus. The deep layers attach into the capsule and medial meniscus
  2. lateral-run obliquely downward and backward from the lateral epicondyle of the femur to the head of the fibula
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7
Q

What is the function of the collaterals of the knee?

A

1.provide medial and lateral stability

2,assist cruciates with rotational stability

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8
Q

How much do the collaterals contribute to varus and valgus stability?

A
  1. 78% to varsus stability from MCL at 25% of knee opening

2. 75% of valgus stability from LCL at 25% of knee opening

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9
Q

What assist the LCL with lateral stability of the knee?

A
  1. TFL, during fleixon
  2. biceps femoris, during flexion
  3. popliteus, during flexion
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10
Q

How do the collaterals differ?

A
  1. the axis of motions runs through the medial collateral so the anterior part is taut in flexion and extension
  2. medial runs posterior to anterior while lateral runs anterior to posterior
  3. medial has superficial and deep fibers and is more flat
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11
Q

What are the attachments of the ACL

A

anterior medial tibial condyle to the posterior lateral femoral condyle

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12
Q

What is the function of the ACL?

A
  1. control forward gliding of the tibia on the femur

2. limit tibial IR as it wraps around the PCL during knee flexion

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13
Q

Will a varus or valgus load on the knee effect the ACL and how is it injuried ?

A
  1. Valgus load beyond 5 degree of flexion, but varus loads with tibial IR also load the knee.
  2. Current literature demonstrates that sagittal plane biomechanical factors, such as small knee flexion angle, posterior ground reaction force and quadriceps muscle force, are the major ACL loading mechanisms. posterior ground reaction force > quadriceps muscle force > anterior draw force at the knee.
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14
Q

What are the attachments of the PCL?

A

Posterior horn of the lateral meniscus to the the anterior medial femoral condyle passing medial to the the ACL

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15
Q

How does the length and shape of the cruciates compares to each other?

A
  1. PCL is 3/5th the length of the ACL, round at tibial attachment, widest in the frontal plane and is largest proximally
  2. ACL is larger at the tibial attachment, round in the mid section and wider in the sagital plane
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16
Q

How is the PCL tensioned?

A
  1. Anterior portion is tight during flexion especially beyond 30 degrees
  2. Posterior portion is tight in extension and resists hyper extensions
  3. posterior displacement of the tibial on the femur
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17
Q

What provides posterior stability of the knee?

A
  1. PCL prevents posterior displacement of the tibia on the femur
  2. posterior medial capsular structures
  3. posterior lateral capsular structures
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18
Q

Does the ACL or the PCL play a greater role in day to day stability of the knee?

A

PCL

  1. it is thicker
  2. it is shorter
  3. has a greater influence the development of the shape of the condyles due to its relatively greater characteristics of stability
  4. closed chain force loading on the knee is an anterior glide of femur on the tibia and in a extended knee position
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19
Q

How does the winding of the cruciate ligaments effect knee function?

A
  1. at about 15 degree of flexion the winding of the cruciates initiates the naterior glide of the femur on the tibia
  2. tibial internal rotation is always less than external rotation due to the winding of the cruciates
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20
Q

What roll do the cruciates play in femoral gliding during flexion and extension?

A
  1. during flexion the ACL tension at about 15 degrees causing anterior glide of the femur
  2. During extension the anterior roll of the femur is limited by the PCL which causes a posterior glide
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21
Q

What role to do the cruciates play in rotation of the knee?

A

1.winding of the cruciates during flexion helps limit tibial internal ration
2,during knee flexion the ACL is tensioned pulling the anterior medial tibia towards posterior lateral femur (i.e. tibial internal rotation)
3.during knee extension the PCL is tensioned pulling the posterior lateral tibial towards the anterior medial femur (i.e. tibial external rotation)

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22
Q

What are the meniscofemoral ligaments?

A
  1. ligaments following the path of the PCL from the posterior horn of the lateral meniscus to the the medial femoral condyle
  2. Humphry- anterior to PCL
  3. Wrisberg- posterior to PCL
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23
Q

How do mechanoreceptors play a role in knee function?

A

they assist in biasing muscle spindles, aid in muscle stiffness and facilitate muscle activation

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24
Q

How does the quad play a role in stability of the knee?

A
  1. sagital plane or vertical fibers prevent ipsalateral opening
  2. oblique fibers prevent contralateral opening
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25
Q

Where does the medial retinaculum attach?

A

1medial border of the patella

  1. VMO
  2. runs deep to pes anserinus to insert on MCL
26
Q

Where does the lateral retinaculum attach?

A
  1. creates a bridge between the lateral patella and the ITB
  2. patellofemoral fibers to the lateral femoral condyle
  3. patellotibial fibers to Gerdy’s tubercle
27
Q

Where does the ITB insert?

A
  1. lateral intermuscular septum
  2. lateral femoral condyle
  3. lateral capsule
  4. proximal tibia
  5. fibular head
  6. short head of the biceps femoris
28
Q

Describe the inversion behavior of the ITB

A
  1. at 30 degrees it switches between a flexor and an extensor
  2. it assist with terminal knee extension
  3. beyond 30 degrees it is a flexor
29
Q

Describe the insertion of the biceps femoris

A

the two heads for a common tendon that has three layers

  1. superficial- attaching to the lateral collateral ligament
  2. medial-
  3. deep- Gerdy’s tubercle, fibular head, posterior capsule
30
Q

What does the poplietieus attach to?

A
  1. posterior lateral femoral condule
  2. posterior horn of the lateral meniscus
  3. arcuate ligament
  4. fibular head
31
Q

What are the functions of the popliteus

A
  1. internal femoral rotation
  2. unlock the knee from terminal extension
  3. posterior lateral stability of the knee
32
Q

How doe the popliteus contribute to stability of the knee?

A
  1. In a closed chain with the tibia fixed it will exert a posterior pull on the femur
  2. reenforces the lateral compartment through its attachments to the lateral meniscus and capsule
33
Q

What are the average rotation ROMs of the the knee?

A
  1. internal rotation: 30 degrees in flexion

2. external rotation: 45 degree in flexion and 5 degree in extension

34
Q

What is the open and closed pack position of the knee

A
  1. open 25 degree fleixon

2. closed is full extension

35
Q

What are the different axis of motions of tibial rotation?

A
  1. screw home through the medial meniscus
  2. adjunct through the middle of the platuea
  3. normal medial to the knee
36
Q

How does the axis of motion shift from normal to the screw home?

A

the collagen slack is taken up in the medial compartment before the lateral compartment

37
Q

What is genu varus and valgus?

A

1varus- distal segment is turned in

2.valgus- distal segment is turned out

38
Q

What is genu recurvatum?

A

extension greater than 10 degrees

39
Q

What is regional interdependence?

A

the concept the remote unrelated anatomical regions can contribute to the patients complaints

40
Q

What is the concept of interregional dependency so important in the knee?

A
  1. it functions like a three hing door
  2. problem in the lower and upper hinge will have profound effects on the middle hinge
  3. where as dysfunction of the middle hinge will have limited effect on the others
41
Q

What is tensegirty?

A

stability is dependent on the balance of collagen tissues holding bone, muscles and organ in place

42
Q

What interregional factors are strong predictors of knee injury

A
  1. lateral trunk displacement
  2. history of low back pain
  3. decreased trunk rotation in the direction of the cutting motion
  4. decreased glut, hip ER and HS activation
43
Q

What is the extensor mechanism?

A

extensor mechanism includes quadriceps, quadriceps tendon, medial and lateralretinaculum, patellofemoral and patellotibial ligaments,patellar tendon and genu articularis

44
Q

What are the three categories of extensor mechanism deficiency?

A
  1. abnormalities of the patellofemoral configuration
  2. deficiency of the supporting muscles and guiding mechanism
  3. malalignment of the extremity
45
Q

What are petllofemoral configuration abnormalities?

A
  1. low lateral femoral sulcus

2. deficient patellar facet

46
Q

What deficiencies of the supporting muscles and guiding mechanisms of the extensor mechanism can occur?

A
  1. weakness of the medial extensor retinaculum
  2. VMO weakness or imbalance with VLO
  3. hypermobility of the patella
  4. genu recurvatum
  5. patella alta due to lose of lateral femoral condyle stability
  6. tight lateral retinaculum
47
Q

What malalignments of the extremity can create deficits in the extensor mechanism?

A
  1. genu valgum
  2. lateral displacement of the tibial tubercle
  3. femoral anterversion with femoral internal rotation
  4. genu recurvatum creates slack in the extensor mechanism
48
Q

Why won’t quad sets improve VMO function?

A
  1. in full extension the tibia is external rotated thus optimizing VLO function
  2. internally rotating the tibia with the knee working between 20-40 degrees
49
Q

What infections typically occur in the knee?

A
  1. acute and chronic oseomyelitis

2. syphilitic infections causing a thickening of the femoral shaft

50
Q

What tumors typically occur in the knee?

A
  1. giant cell- benign, typically effect lower end of femur in young adults
  2. osteosarcoma- malignant femur common, typically occurs in childhood or early adulthood and is a complication of paget’s disease
  3. Ewing’s tumor- malignant, mainly in children and the shaft of the bone
  4. multiple mylomas- typically effects upper shaft of the femur
  5. metastatic tumors- often effect upper shaft of femur
51
Q

What are the criteria for diagnosing RA?

A
  1. morning stiffness
  2. pain with motion
  3. symmetrical swelling of joints
  4. subcutaneous nodules
  5. typical changes on x-ray
  6. positive RA factor
52
Q

What are the stages of RA?

A
  1. stage 1: soft tissue involvement of the synovium only
  2. stage 2: pannus formation of the the synovitus and cartilage degeneration
  3. stage 3: loss of articular cartilage of subchondral bone
  4. stage 4: joint destruction and ligamentous instability
53
Q

What are some correlated motions for genu valgus?

A
  1. pes planus
  2. exessive subtalar pronation
  3. ER tibial torsion
  4. lateral patellar subluxation
  5. excessive hip adduction
  6. ipsilateral hip excessive hip IR
  7. lumbar spine contralateral rotation
54
Q

What are some compensatory motions for genu valgus?

A
  1. forefoot varus
  2. exessive subtalar supination
  3. toe in to decrease lateral pelvic sway (hip adduction) during gait
  4. ipsalateral pelvic ER
55
Q

What are some correlated motions for genu varus?

A
  1. tibial varum
  2. internal tibial torsion
  3. ipislateral hip ER
  4. excessive hip adduction
56
Q

What are some possible compensatory motions for genu varus?

A
  1. forefoot valgus
  2. excessive subtalar pronation
  3. ipsalateral pelvic internal rotation
57
Q

How can pathologies of synovial fluid flow develop?

A

entrapment of the fluid in the popliteal or gastroc resess can create a baker’s cyst

58
Q

How is the proximal tib/fib joint connected to the knee?

A

it shares ligamentous, muscular, and capsular attachments

59
Q

What planes of motions does the proximal tib/fib joint have?

A
  1. sagittal plane
  2. proximal-distal
  3. spin
60
Q

What joint has the most influence on the proximal tib/fib joint?

A
  1. subtalar dictates the position of the talocural

2. distal tib/fib joint follows the talocural

61
Q

What directly influences the motion of the proximal tib/fib joint?

A
  1. lateral collateral pulls the joint cranially during knee extension
  2. biceps femoris pulls it posteriorly during flexion
62
Q

How does the talocural joint cause the proximal tib/fib joint to move

A
  1. supination- distal
  2. plantar flexion- distal and IR
  3. dorsiflexion- proximal and ER
  4. pronation- proximal

Knee (4 decks)

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