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Biomechanics > Lower Extremity > Flashcards

Lower Extremity Flashcards

1
Q

Hip Joint: Function

A

supports load of head, arm, and trunk (HAT); the hip is the “true core”; force transmission, locomotion

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2
Q

Pelvic Girdle: Structure

A

2 coxa or innominate bones; connected via symphysis pubis; pelvic girdle joints and symphysis joint;

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3
Q

Sacroiliac Joints

A

2 paired gliding synovial joints found posteriorly; only move about 2-5 mm; if the SI joint is “out”, its only barely slid; lower lumber pain could refer down to the SI joints; have the fluid and capsules of a joint

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4
Q

Innominate Bones

A

composed of 3 fused bones (fused, ilium, and ischium); contains the acetabulum, which is the articulating surface of the hip;

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5
Q

Acetabulum

A

normally directed laterally, anteriorly, and slightly inferiorly; contains a wedge shaped labrum that deepens the socket and increases the concavity of the acetabulum

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6
Q

Acetabular Anteverson

A

angle of anterior orientation of acetabulum is abnormal; normal range is 8 degrees for men and 14 degrees for women; increases in this angle associated with reduced joint stability and arthritis; decreased angulation associated with pathology;

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7
Q

Transverse Acetabular Ligament

A

considered to be a part of the labrum; however contains no chondrocytes

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8
Q

Acetabular Joint Capsule and Ligaments

A

joint capsule is strong and dense and contributes to joint stability; ligaments in the acetabulum reinforce the joint capsule (iliofemoral, pubofemoral, ischiofemoral, ligamentum teres)

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9
Q

Trabecular System in the Femur

A

Present in the neck of the femur; resists bending stress by weight of HAT on femoral head;

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10
Q

Zone of Weakness

A

area in the femoral neck where few trabecular fibers cross each other; likely to suffer fractures here when external demand is too great or when tissue can no longer resist stress/strain; decreasing crossing of trabecular fibers

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11
Q

Hip: Osteokinematics

A

flexion, extension (commonly limited), abduction, adduction, internal rotation (commonly limited), external rotation

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12
Q

Pelvis: Normal Position

A

12-15 degrees anterior pelvic tilt; if you have too much anterior tilt, you can encourage stretching the rectus femoris and strengthen the hamstrings and glutes

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13
Q

Pelvis: Open Chain Movement

A

hip flexion= posterior pelvic tilt; hip extension = anterior pelvic tilt;

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14
Q

Pelvis: Closed Chain Movement

A

hip flexion = anterior pelvic tilt; hip extension= posterior pelvic tilt; abduction/adduction = lateral pelvic tilt; right leg int/ left leg ext rotation = right pelvic rotation; left leg int/right leg ext rotation = left pelvic rotation

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15
Q

Pelvic Motions

A

4 primary muscle groups influencing pelvic position; spinal extensors (anterior tilt), spinal flexors (posterior tilt), hip flexors (anterior tilt), hip extensors (posterior tilt)

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16
Q

Hip Joint: Arthrokinematics

A

concave acetabulum and convex femoral head;

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17
Q

Hip Joint: Acetabulum on Femoral Head

A

concave; posterior pelvic tilt (extension) = posterior roll and glide; anterior pelvic tilt (flexion) = anterior roll and glide;

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18
Q

Hip Joint: Femoral head on Acetabulum

A

internal rotation = anterior roll and posterior glide; external rotation = posterior roll and anterior glide; abduction = superior roll and inferior glide; hip flexion = anterior roll and posterior glide

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19
Q

Hip Joint: Closed Packed Position

A

extension, abduction, and internal rotation (back kick)

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20
Q

Hip Joint: Open Packed Position

A

30 deg flexion, abduction, and 5 deg external rotation

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21
Q

Hip Joint: Combined Motion

A

lumbar spine and pelvis; “lumbopelvic motion”; similar to scapulohumeral rhythm; lumbar spine flexes first then pelvis rotates to allow for more flexion; a limitation in flexibility can occur in either of these areas; hip motion alone only goes about 90 degrees

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22
Q

Hip: Pathologies

A

Arthrosis, Fracture

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23
Q

Hip: Arthrosis

A

degeneration of joint surface (articular cartilage); primary occurs in 10-15% of those over age 55%; secondary is due to previous trauma or malpositioning; risk factors included increased age, ante/retroversion; increased height/weight ratio; asymmetry; decreased bone density

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24
Q

Hip Joint: Fracture

A

bending force across femoral neck –> increased force or weakening of bone= bony failure; average age of hip fracture 70; (cycle of fear of falling); trauma leads to sedentary leads to loss of balance and second trauma

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25
Q

Knee: Function

A

alters length of the lower extremity; stability during weight bearing; mobility for ambulation; largest joint in the body

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26
Q

Knee: Structure

A

ligaments (ACL, LCL, MCL, PCL) limit translation of the tibia; menisci (lateral and medial) reduces the incongruency of the joint (its a shallow joint);

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27
Q

Knee: Medial Meniscus

A

3x as thick as the lateral meniscus; accepts more load; increases joint stability, shock absorption, reduces friction, distributes force; well vascularized early in life; without menisci contact area is reduced by 50% and the load on the femoral and tibial condyles increases;

28
Q

Knee: Anatomical Axis

A

longitudinal axis; relationship between femoral and tibial axes gives slight valgus angle (knees slightly bent in)

29
Q

Knee: Q Angle

A

angle formed between the lines from the tibial tuberosity up to the ASIS and from midpoint of patella up; larger in females (17) than males (14)

30
Q

Knee: Dynamic Q Angle

A

Q Angle when in motion; an indicator of potential injury including ACL tears and patellofemoral pain; single leg squats can help test

31
Q

Knee: Genu Valgum

A

increase in knee angulation of 10 degrees or more (knees in)

32
Q

Knee: Genu Varum

A

decrease in knee angulation of 10 degrees or more (knees out)

33
Q

Knee: Joint Capsule

A

attached to the rim of the patella; encloses the condyles; strengthened by ligaments, muscle, and tendons (IT band); 30 degrees of knee flexion is the loose packed position

34
Q

Knee: Ligament Stress Tests

A 
MCL = stress test valgus by pushing ankle lateral
LCL= stress test varus by pushing ankle medial
PCL= stress test tibia backwards
ACL= test tibia forwards
35
Q

Knee: Osteokinematics

A

Flexion (135-145 degrees), Extension (-5 degrees), Int/Ext Rotation (only occurs in flexion)

36
Q

Knee: Arthrokinematics

A

tibia is concave; femur is convex; tibia moves on femur when in open chain; femur moves on tibia when in closed chain

37
Q

Knee: Tibia on femur (open chain)

A

flexion: posterior roll and glide
extension: anterior roll and glide

38
Q

Knee: Femur on tibia (closed chain)

A

flexion: posterior roll anterior glide
extension: anterior roll, posterior glide

39
Q

Knee: Rotation

A

can only occur with unlocking of the knee; why? locking during extension is due to arthrokinematic movement (screw home mechanism)

40
Q

Knee: screw home mechanism

A

how the knee locks during extension; medial condyle is longer than the lateral condyle, so when you extend the knee, you run out of room on the medial side; the lateral condyle spins, thus the foot is externally rotated in full locked extension; medial gliding and rolling continues and spinning occurs at the lateral condyles

41
Q

Knee: Motion Limitations

A

extension is limited by scar tissue, joint capsule, ACL/PCL/MCL/LCL, hamstring, gastroc, joint capsule tightness; flexion limited by soft tissue, rec fem length, joint capsule tenderness

42
Q

Knee: Patellofemoral Joint

A

patella is like a sesamoid bone; increases mechanical advantage for quads; femoral surface of the patella with patellar surface of the femur;

43
Q

Knee: Patello Femoral Joint Functions

A

increases mechanical advantage of quads; disperses compressive forces of quads onto femur; protects anterior knee;

44
Q

Knee: Patellofemoral Motions

A

medial and lateral tilt; superior and inferior glide; medial and lateral glide;

45
Q

Knee: Patellofemoral Structure

A

Patellar stability Dependent on: bony (depth of groove), passive (ligaments), and active (muscles)

46
Q

Ankle: Function

A

provides a stable base while conforming to uneven surfaces; shock absorption through foot flexibility; transmits rotational forces into forward progression; rigid lever for propulsion

47
Q

Ankle: Anatomy

A

talocrural joint; ligaments (MCL, ACL, LCL); subtalar joint tibiotalar joint, calcaneocuboid joint; superior and inferior tib/fib joints

48
Q

Ankle: Talocrural joint

A

hinge joint (1 degree of freedom); proximal tibia/fibula (mortus) with the distal talus

49
Q

Ankle: Superior and Inferior Tib/Fib Joints

A

works together with the ankle; proximal tib/fib joint is a plane synovial joint with a capsule reinforced with ligaments; distal tib/fib joint is a syndesmosis (no joint capsule or much movement)

50
Q

Ankle: Osteokinematics

A

Dorsiflexion (0-20), plantar flexion (0-55);

51
Q

Ankle: Arthrokinematics

A

Talus is convex, tibia/fibula is concave;

52
Q

Ankle: talus moving on tibia/fibula (open chain)

A

dorsiflexion=anterior roll, posterior glide; plantar flexion= posterior roll, anterior glide

53
Q

Ankle: tibia/fibula moving on talus (closed chain)

A

dorsiflexion = anterior roll and glide; plantar flexion = posterior roll and glide

54
Q

Ankle: movement exceptions

A

plantar and dorsiflexion don’t purely occur in the sagittal plane; has three components (eversion/inversion and a24/a44 are involved)

55
Q

Ankle: Dorsiflexion components

A

dorsiflexion, eversion, and abduction

56
Q

Ankle: Plantarflexion components

A

plantarflexion, inversion, adduction

57
Q

Ankle: Foot Anatomy

A

rearfoot = calcaneus, talus; midfoot= navicular, cuboid, cuneiforms; forefoot= metatarsals and phalanges

58
Q

Ankle: Subtalar Joint

A

talus on calcaneus; 3 separate articulations; single joint axis; contains the MCl, LCL and cervical ligaments

59
Q

Ankle: Subtalar Joint Function

A

dampens lower extremity rotations (when foot pronates, foot is adaptable and soft and can avoid shock); helps foot conform to uneven surfaces

60
Q

Ankle: Subtalar Joint Osteokinematics

A

pronation=loose pack position; allows foot to absorb shock during loading phase of gait; supination=closed pack position; creates rigid lever at beginning and end of gait

61
Q

Ankle: Transverse Tarsal Joints

A

motion in relation to subtalar motion; subtalar supination (axes of transverse tarsal joints cross to lock foot); subtalar pronation (axes align parallel to each other and foot unlocks); calcaneocuboid and talonavicular joints

62
Q

Ankle: Plantar Arches

A

longitudinal (calcaneus to metatarsal heads); transverse (across tarsals and proximal metatarsals); arches supported by ligaments and muscles; when you extend your toes, the fascia and spring ligament pulls the heel towards the toes

63
Q

Ankle: Plantar Fascia

A

pulls taut with 1st MTP extension; causes rearfoot supination or locking of the foot; windlass effect; arch raises or walks the foot when the toes are extended

64
Q

Ankle: Structural Pathologies

A

pes planus/cavus; rear foot varus and valgus; calcaneo-valgus and varus

65
Q

Ankle: Functional Pathologies

A

first ray hypomobility; hallux abductus valgus (bunions); ankle sprains cause ligament tears

66
Q

Ankle: Traumatic Pathologies

A

muscle strain, ligamentous strain, tendonopathy, plantar fasciitis

Biomechanics (7 decks)

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