Test 3 Flashcards
0
Q
What is the difference between the hip and the shoulder joint
A
Hip has a really round head deep in the fossa It is more stabile, less mobile
1
Q
The hip joint
A
Coxofemoral joint
Between acetabulum of pelvis, and head of femur
Ball and socket 3df- flex/ext, add/abd, IR/ER
Primarily functions in weight bearing
2
Q
Proximal articulating surface of the hip
A
- formed by ilium, ischium, and pubis
- all 3 bones contribute to acetabulum
- horseshoe shaped area with cartilage and is the surface that articulates with the femur
- weight bearing on the top of the acetabulum
4
Q
Acetabulum
A
- positioned laterally
- inferior and anterior tilt
- acetabular depth can be measured by center edge angle
- decreased angle (dysplasia) causes instability and changes the loading surface bc moves head outside of joint
- increased angle causes decreased ROM and impingement because the head is further in the joint
5
Q
Acetabular labrum
A
- Ring of wedge shaped fibrocartilage
- deepens the socket
- strong
- seal to maintain negative pressure in the joint
- enhances joint stability
- nerve endings within provides proprioceptive feedback
- Can also be a source of pain: anywhere there are nerve endings, there can be pain
6
Q
Distal articular surface
A
- head covered by hyaline cartilage: no friction but have to get liquid in and out of the joint
- fovea is not covered with cartilage
- ligamentum teres is attached at the fovea
7
Q
Angulation of the femur
A
- angle of inclination
- normal 110-144 degrees
- with normal angle the greater trochanter lies at the level of the center of the femoral head
8
Q
Coxa Valga
A
- moving distal arm out laterally
- increased angle
- decrease bending force of the neck; shaft and head more stacked on eachother
- decrease m.a of hip abd
- require increase in muscular force= increase joint compression; if weight of body and what’s causing torque is excessive, get osteoarthritis
- decreased joint surface contact= less room to distribute force= decreased stability
9
Q
Coxa Vara
A
- decreased angle
- increased bending force of the neck
- may increase m.a of hip abd but not as much as valga
- increase stability
- femoral head deeper in acetabulum–> GOOD
10
Q
Femoral torsion
A
- affects knee and foot
- normal 10-20 degrees
- anteversion
- retroversion
- put condyles down on the table and see the position of the femoral head and neck
11
Q
femoral anteversion
A
>15-20 degrees
increased IR decreased ER
bc already sitting in eversion
decreased joint stability
decreased m.a for abd
* head and neck look to be standing up
12
Q
femoral retroversion
A
<15-20 degrees
increased ER decreased IR
same total ROM, just starts at different points
* head and neck rotated back to same level of condyles
13
Q
Effect of femoral anteversion on the knee
A
Medial femoral torsion
knock kneed
knee is medially rotated and the hip is normal
not getting good bony contact if already starting in ER
14
Q
Hip joint articular congruence
A
- increased articular contact in flexion, abduction, slight ER (NWB)
- feel better in slight flexion: put pillow under hip
- less congruent in WB
15
Q
Hip joint capsule
A
- contributes to joint stability
- thickened anterosuperiorly: when we stand, we tighten anteriorly
- femoral neck is intracapsular
- blood flow to femoral head and neck
16
Q
Hip joint ligaments
A
ligament teres
capsular ligaments
17
Q
Ligament teres
A
- intra-articular but extrasynovial attaches to the fovea
- blood supply to femoral head
- also stabilizes the hip
- can cause symptoms if impinged
18
Q
Capsular ligaments of the hip
A
Iliofemoral ligament
pubofemoral ligament
ischiofemoral ligament
ALL tight in extension - if weak hip extensors: lean back so center of upper body is behind the hip joint. minimal muscle activity
19
Q
Closed packed position of the hip
A
- extension, slight ABD, IR
- the ligaments are tight, pulling the head into the acetabulum
- Not the position of optimal articular contact (congruence)
20
Q
When is the hip joint vulnerable to posterior dislocation
A
flexion and ADD
- like in a car accident, and the feet are on the dashboard, will slam back into knee
21
Q
when is capsuloligamentous tension of the hip joint the least?
A
moderate flexion slight ABD midrotation
- position assumed if there is swelling
22
Q
Structural adaptations to the hip in weight bearing
A
stress determines structure
- loading makes the bone thicker and stronger, but it also makes part of the bone weaker, results in fracture
- distraction laterally and compression medially makes the femur stronger
23
Q
Hip flexion
A
90 degrees with knee straight (passive insufficiency of the hamstrings)
120 degrees with the knee bent
24
Q
Hip extension
A
10-30 degrees
bent knee may limit ROM due to passive insufficiency of the quads
May look like a lot more extension because moving more than the hip
25
Abduction of the hip
45-50 degrees
may be limited by the gracilis
26
Adduction of the hip
20-30 degrees
may be limited by TFL or ITB
27
IR/ER of the hip
42-50 degrees
test in supine or sitting
28
Motion of the pelvis on the femur
in standing, the femur is fixed and the pelvis moves
29
Lateral pelvic tilt- unilateral stance
- standing on left hip: that is the AoR
- Right hip hike: right hip ADD, left hip ABD, lumbar SB to the right
- Right hip drop: right hip ABD, left hip ADD, lumbar SB to the left
30
Right hip drop
right hip ABD
left hip ADD
lumbar SB to the left
angle gets smaller
31
Right hip hike
right hip ADD
left hip ABD
lumbar SB to the right
=left hip drop
32
Lateral pelvic tilt in bilateral stance
pelvic shift to the right
left hip drop
can not have hip hike in bilateral stance
opposing and/add muscles cause shift back to left hip
33
forward and backward pelvic rotation
- movement of the pelvic ring in the transverse plane
- AoR is weight bearing hip (unilateral stance)
- If bilateral stance, have to be specific such as forward rotation on the left with backward rotation on the right
\*need IR and ER of the hip to walk
34
When pelvis moves on fixed femur, what happens?
- head and trunk will follow the motion (open kinetic chain)
- the head will remain upright (functional closed kinetic chain): want to keep head and eyes balanced
- these 2 choices produce different responses in proximal and distal joints
- to be able to reach the floor combine hip, pelvis, and trunk motion
- what happens in lower body causes changes in upper body to maintain fixed gaze
35
femur, pelvis, and lumbar spine in hip abduction
- when you lie down, L hip ABD
- if you get to end range, will tilt pelvis to get more ROM (hike)
- counteract pelvic hike with L. lumbar flexion
36
hip flexors
9 muscles cross the anterior
hip primary flexor- iliopsoas
other important muscles: rectus femoris, TFL, sartorius
37
hip adductors
pectineus
adductor brevis
adductor longus
adductor magnus
gracilis
38
hip extensors
gluteus maximus
hamstring
- assisted by posterior fibers of gluteus medius, posterior adductor magnus, and piriformis
39
hip abductors
gluteus medius
gluteus minimus
40
hip external rotators
obturator internus and externus
inferior and superior gamellus
quadratus femoris
piriformis
41
Hip internal rotators
no muscle with primary IR function
- most consistent IR are the anterior portion of gluteus medius, gluteus minimus, and TFL
42
hip joint in standing
- hip joint, capsule and ligaments support 2/3 of the body weight (HAT), 1/3 on each side (legs)
- in bilateral stance, the hip joint is neutral or slight ext
- in this position the capsule and ligaments are under tension
- line of gravity falls behind hip joint axis
- keeps in slight ext
- the capsule and ligaments can counteract extension torque by gravity
- no muscle activity needed to maintain posture
43
Bilateral stance in the frontal plane
- HAT weight load sacrum
- transmit force to pelvis, to femurs
- the forces are in balance
- hip joint compression caused by weight only if no muscle force is needed.
- because rotation of body weight counteracts and torques are balanced
- if balance things, do not need muscles
- if stand on 1 leg, HAT cause rotation
44
Unilateral stance
- right hip supports HAT and left leg weight
- right hip joint compression now= weight of HAT (2/3) and weight of leg (1/6)
- weight also causing a torque at the hip into R. hip add
- abductors counteract ADD force
- the muscle force also causes compression at the joint
- get compression from weight and muscle
- also get rotary force
45
Compensatory lateral lean of the trunk
- decrease m.a of the weight from 10cm to 2.5cm
- decrease the joint compression force by approx. half
- increased stress on the lumbar spine
- R. lumbar flexion to keep head up
- to minimize torque, lean to that side: will decrease m.a of HAT. hip ABD don't counteract as much
46
Pathological gaits
- on same side as lean
- if trunk lean due to gluteus medius weakness= gluteus medius gait (for compenated Trendelenburg)
- If trunk lean due to hip pain= antalgic gait (to decrease compression and decrease pain)
47
Trendelenburg sign
- pelvic drop with weak hip abductors
- the lateral trunk lean with weak hip abductors also called compensated Trendelenburg
- stand on L. pick up R., R. hip drops weak abductors on side standing on compensated= lean over
48
Use of cane ipsilaterally
- pushing down on cane should reduce the superimposed body weight by the same amount that is taken up by the hand
- suggested that approx. 15% if the body weight can be supported by the hand on the cane
- if no lateral trunk lean, then more joint compressing force with ipsilateral cane compared to trunk lean: still use abductors to hold self up
49
Use of cane contralaterally
- reducing the weight by placing force through hand (15%)
- the cane can also assist the right hip ABD
- can eliminate the need for hip ABD force
- only joint compression by body weight (minus what is loaded through the hand)
- don't need lateral trunk lean
- decreases compression by abductors
50
Femoroacetabular impingement (FAI)
CAM impingement
Pincer impingement
51
CAM impingement
- deformity of femoral neck: thicker
- Responses to stress: pinch, impingement
- sits really far in
- in end ranges, jams parts of bone together and get tissue damage
52
Pincer impingement
abnormal acetabulum
deeper acetabular fossa
disc sticks further out
53
Labral pathology
- associated with FAI
- 95% of patients with labral tears had clinical signs of FAI
- labrum can be source of pain
- can be overuse injury
- traumatic tear can occur with pivoting, forceful rotation, or with dislocation
- labrum stabilizes the hip
- capsule strain labrum with ER and ABD
- loss of intra-articualr pressure decreases stability
54
Arthrosis
- FAI and labral tears suggested as etiological factor for developing osteoarthritis
- OA is the most common painful condition of the hip: occurs in 7-25% of individuals
- related to anatomical abnormalities
- factors associated with hip OA: increased with age and weight/height ratio
- running not associated with hip OA changes
55
Hip fracture
- bending force at hip (neck)
- either excessive force or weaker bone
- break at the zone of weakness
- age of occurrence \>70 y/o and more in women
- often moderate trauma so associated with bone weakness (decreased bone density)
- high health care cost
- mortality within 1 year after hip fracture is 21-24%
56
Ankle and foot complex
proximal distal tibiofibular joint
talocrural joint
talocalcaneal (subtalar) joint
talonavicular and calcaneocuboid joints
5 tarsometatarsal joints MTP joints
9 IP joints
- the foot can withstand large WB stresses while accommodating to a variety of surfaces and activities
- a lot of sensory input from foot, good for where you are in space and putting foot to ground
57
Definitions of motion of the foot and ankle
- axes of motion of the foot and ankle
- in reality the axis are oblique and cut across all 3 planes
- DF/PF, ADD/ABD, INV/EV
- a lot of the motions occur together
58
Pronation of ankle and foot is combination of what
DF EV ABD
59
Supination of ankle and foot is a combination of what
PF INV ADD
60
Calcaneovalgus
\>180 degrees Pronation
61
Calcaneovarus
\<180 degrees Supination
62
Talocrural joint
- tibia, fibula, talus
- three facets: distal tibia, tibial malleoli, fibular malleoli
- lateral malleoli more distal
- the ankle mortise is adjustable
63
Proximal tibiofibular joint
Plane synovial joint
Small movement
64
Distal tibiofibular joint
A syndesmosis
Fibrous joint and anterior ligament
65
Proximal and distal tibiofibular joint
All ligaments between tibia and fibula support both joints Only about 10% of WB forces are transmitted in fibula
66
Distal articular surface: talus
The body of the talus has 3 articulating surfaces/ facets The body of the talus is wider anteriorly
67
Ankle joint capsule and ligaments
- capsule fairly thin and weak anterior and posteriorly to allow for DF/PF
- stability of the ankle depends on ligaments
68
Deltoid ligament of ankle
Prevents eversion and pronation
Medial
Very strong
69
Anterior talofibular ligament (ATF)
- lateral
- weakest
- most common in ankle sprains, usually goes first
- stressed with PF, medial rotation, and INV
70
Most common type of ankle sprains
Plantarflexion and inversion
71
Calcaneofibular ligament
Stressed with DF and INV
Not as much bothered by PF
72
2 ligaments in ankle most commonly injured
Anterior talofibular
Calcaneofibular
73
Posterior talofibular ligament
Rarely torn in isolation
Won't be affected until full dislocation and other ligaments are gone
74
Superior and inferior fibular ligaments
Lateral
Works when foot goes to side
Held in place by retinaculum
75
Tibial torsion
When one part of the tibia is turned
20-40 degrees ER of tibia
- because of slight IR of femur, usually some lateral torsion
- depends on how you are trying to get your foot forward, in pigeon toes: lateral tibial torsion
76
Axis of the ankle joint
Axis angled 14 degrees
- plantarflexion: foot moving medially
- dorsiflexion: foot moving laterally
77
Dorsiflexion normal ROM
20 degrees
Varies
78
Plantarflexion normal ROM
50 degrees
Varies
79
How much DF needed for walking
10 degrees
80
What happens with talus in DF
Wider talus gets wedged in the ankle mortis
81
Loose packed position for ankle
PF
82
What are ankle DF and PF primarily limited by
Soft tissue restrictions
83
Subtalar joint- talocalcaneal
-3 separate facets -
cause a triplanar movement
- in WB the subtalar joint dampen proximal rotational forces while keeping the foot on the ground
- 2 capsule: anterior and medial facet share capsule with the talonavicular joint
- posterior facet: 75% of the force
84
Sinus tarsi
Between talus and calcaneus
A lot of swelling, scarring, stiffness, and pain occur here
85
Subtalar joint function
- in WB dampens the proximal rotational forces while keeping the foot on the ground
- motion of the talus on calcaneus is a complex twisting or screw like motion
- triplanar motion of the talus around a single oblique axis
- supination and pronation
86
If calcaneus is everted
Must pronate talus
Adduction of talus
PF of talus
IR tibia
Tibia and fibula move with talus
87
Non weight bearing SUPINATION of subtalar joint
Calcaneus motions of ADD, inv, PF
88
Non weight bearing PRONATION of subtalar joint
Calcaneal motions of ABD, EV, DF
89
Weight bearing of subtalar joint
Calcaneus locked but can move INV,EV Limited to perform DF/PF, ADD/ABD
90
Weight bearing supination of subtalar joint
Calcaneus inv or vagus
Talar ABD (lateral rotation) and DF
tibiofibular lateral rotation
91
Weight bearing pronation of subtalar joint
- calcaneal EV or valgus
- talar ADD (medial rotation) and PF
- tibiofibular medial rotation
92
Medial rotation of leg in WB causes what at subtalar joint
Pronation
93
Lateral rotation of leg in weight bearing causes what at subtalar joint
Supination
94
Measurement of subtalar inversion/eversion
- find subtalar neutral
- eversion= 5-10degrees
- inversion= 20-30 degrees
- measurement difficult
- normal WB more in EV= calcaneal valgus
95
Why is calcaneal valgus good
Because it puts foot in pronation
Helps to absorb shock
96
Transverse tarsal joint
- also called the midtarsal or Chopart joint
- formed by the talonavicular and calcaneocuboid joints
- s shaped joint line
- motion occurs together with subtalar joint
97
Talonavicular joint
- the capsule of the talonavicular joint also includes the anterior and medial facets of the subtalar joint
- inferior aspect of capsule is formed by spring ligament, laterally is the bifurcate ligament, and medially the deltoid ligament
- concave socket supports convex head of talus
- talonavicular joint and subtalar joint are functionally linked in weight bearing
- in NWB the joints can move separately
98
What 3 ankle joints are linked in weight bearing
Subtalar and talonavicular
Subtalar and calcaneocuboid
99
Calcaneonavicular ligament
Spring ligament
B/t calcaneus and navicular
If torn, talus can drop down in pronation and you lose the arch
100
Calcaneocuboid joint
- complex joint, combination of convex and concave surfaces
- more restriction then the talonavicular joint
- linked to subtalar joint in WB
- more motion on medial side where arch flattens out
101
Transverse tarsal joint function
- linked to subtalar joint mechanically so that any weight bearing subtalar motion causes the talonavicular and calcaneocuboid joint to move simultaneously
- supination of subtalar joint (locked position) then the transverse tarsal joint is also moved into supination (locked position)
- stiff foot -
pronation of subtalar joint (loose packed) the transverse tarsal joint is also mobile and loose packed
- the foot can absorb forces and adjust to surfaces
102
Supination and push off phase
More supination with push off
Also stiffer so you get more activation from gastrocnemius bc locked in
103
Pronation and landing
Pronation as you go over foot
External rotation of tibia
Supination of foot and push off
104
Pronation effects on mechanical properties of foot
Increases foot flexibility
Allows shock absorption
Allows accommodation to uneven surfaces
105
Supination effects on mechanical properties of foot
Increases foot stability
Makes foot rigid for propulsion (push off)
106
Closed kinematic chain of ankle and foot
- proximal tibia and talus move on a stable distal calcaneus
- pronation causes IR tibia, facilitates knee flexion
- supination causes ER of tibia, facilitates knee extension IR tibia= adduction/ PF of talus
107
Pes cavus foot
Supination
Curled toes
High arches
108
Pes planus
Flat foot
Pronated
Over pronates ER impaired in tibia, compensate at knee by IR femur, at hip IR
May see a lot of calluses on medial side of big toe
109
Where does most tarsometatarsal motion occur
At first and fifth ray
Each axis is oblique
110
Supination twist at tarsometatarsal joint
- pronation at hind foot
- transverse tarsal joint supinated
- if further pronation the first and second ray will be pushed into DF by the ground
- the fifth and fourth ray will PF to maintain contact with the ground
111
Metatarsophalangeal joints
Condyloid synovial 2 degrees of freedom
- DF/PF, ABD/ADD
Convex metatarsal head, concave base of phalanx
Sesamoid bones in 1st MTP joint, protects FHL and anatomical pulley for FHB
112
MTP joint function
- allows WB foot to rotate over the toes through MTP extension= metatarsal break
- oblique axis (related to decreased length of metatarsals)
- walking= 36-65 degrees of ext
- hallux rigidus= limited extension of 1st MTP
113
Plantar arches
Medial longitudinal arch
Lateral longitudinal arch
Talus the "keystone" of the arch
Evolve with the progression of WB
114
Function of arches
- needed for mobility and stability of the foot
- flexible to dampen impact of WB forces
- dampen superimposed rotational motion
- adapt to changes in surfaces
- distribute weight through foot
- help convert the flexible foot to a rigid lever
115
Plantar aponeurosis
Plantar fascia
Attach proximal phalanx of each toe
- if on other side, would have no effect if extended
- faster way to transfer forces
- Tension of 96% of weight during gait
- Transmits forces from Achilles' tendon to forefoot
116
Elevation of plantar arch with toe extension
Toe extension assist with supination
Windlass mechanism elevates arch
117
Muscles of the ankle and foot
Muscle activity critical for dynamic stability
All muscles act over 2 joints
118
Posterior compartment of ankle and foot muscles
- all posterior to talocrural joint= plantarflexors
- gastrocnemius
- soleus
- Achilles' tendon large moment arm
- triceps surae helps with supination
- tibialis posterior- relatively large ma for supination
- flexor digitorum longus
- flexor hallucis longus
119
lateral compartment of ankle and foot
peroneus longus- causes pronation
peroneus brevis
120
anterior compartment of ankle and foot
tibialis anterior: DF and supination
Extensor hallucis longus
extensor digitorum longus
peroneus tertius
121
intrinsic muscles of ankle and foot
- stabilize the toes
- dynamic supporters of the arches
- important to activate/ exercise intrinsic muscle when foot injured
- lumbricals and interossei help to flex MTP and extend IP joints of foot
122
1st layer of plantar foot muscles
abductor hallucis
flexor digitorum brevis
abductor digiti minimi
123
2nd layer of plantar foot muscles
quadratus plantae
lumbricals
tendons of flexor digitorum longus
tendon of flexor hallucis longus
124
3rd layer of plantar foot muscles
flexor hallucis brevis
adductor hallucis
flexor digiti minimi brevis
125
4th layer of plantar foot muscles
dorsal interossei
plantar interossei
tendon of tibialis posterior
tendon of fibularis longus
126
knee complex
- one of most injured joints in the human body
- needs both mobility and stability
- 2 distinct articulations within one joint capsule
- tibiofemoral
- patellofemoral
127
Femur
- convex, tibia is concave
- medial condyle larger, greater radius of curvature, and projects further distally than the lateral condyle
- Lateral condyle shifted anteriorly in relation to the medial condyle
- Condyles slightly convex to allow motion but less stability. To increase stability, menisci are there to make tibia more concave
128
If you put the femur on a table how is it angled?
- out to side
- good because of angle of femoral head, keeps hips straight and creates a flat joint
129
Tibia
- flat tibia condyles, slight concavity
- Menisci are in the joint to improve congruency
- medial tibial plateau is longer in the AP direction
- Lateral tibial cartilage is thicker
- b/c more load on lateral tibial condyle because it is a smaller surface
- Tibial plateau slopes 7-20 degrees because menisci curves up and keeps femur from sliding off
- Condyle are separated by intercondylar eminence
130
anatomical longitudinal axis of tibiofemoral joint
- femur: inferiorly and medially
- tbia vertical
- tibiofemoral angle medially is then up to 185 degrees
131
if tibiofemoral angle is \>185 degrees
genu valgus (knock knees)
132
if tibiofemoral angle is \<175 degrees
genu varum (bow leg)
133
Mechanical axis and weight bearing line of tibiofemoral joint
- line from center of femoral head to talus
- in normal knee, this line is in center of knee joint
- bilateral stance, equal distribution of weight between medial and lateral condyle which is good for sharing the load. SA smaller, but compression is higher
- Unilateral stance: the weight bearing line shifts medially and increases load on medial side
- compression medially
- distraction laterally
134
knee malalignment changes what
forces at the knee joint and is associated with knee OA
135
Menisci
- fibrocartilaginous discs- semicircular shapes
- medial side has more attaches than lateral
- lateral menisci covers more of the smaller lateral condyle
- improves the joint congruency
- distribute the weight bearing forces
- provides more area to distribute weight
- reduces friction
- shock absorbing
- menisci assumes 50-70% of the load
- when injured, want to try and repair it
136
Compressive forces on knee with walking
1-2x body weight
137
compressive forces on the knee with running
3-4x body weight
138
menisci attachment
- anterior horns connect to each other, the tibia, and patella
- strong attachment makes sure they stay in place during compression
- increase contact area
- removal of menisci increases load on the condyles
- periphery is vascularized and has nerve endings so can heal
- central portion needs synovial fluid for nutrition
- damage in the center, no pain, can't heal, must remove
139
medial meniscus attachments
MCL
ACL
PCL
semimembranosus
STABLE
140
Lateral meniscus attachments
ACL
PCL
femur
popliteus
141
knee joint capsule
- large and lax, lots of motion, little stability
- reinforced medially, laterally, and posteriorly by ligaments
- mechanoreceptors in capsule important for stability
- I.e in a new building already know how much to lift foot for stairs
- closed pack position is extension for tibiofemoral joint
- synovial layer is complex
- has a lot of folds that become patellar plica
142
Patellar plica
synovial folds not absorbed during the development medially may cause patellofemoral pain
143
Fibrous knee joint capsule
- provides passive support for the joint
- capsular thickenings= ligaments
- extensor retinaculum: anterior portion of joint capsule
144
MCL
- superficial and deep portions
- deep portion continuous with joint capsule and attached to medial meniscus
- resist valgus forces and lateral tibial rotation
- secondary role as a restraint to anterior translation of tibia
- tight in full extension
- most important as medial stabilizer with knee flexion
- test in 20-30 degrees flexion
- bigger because needs to be stronger because of muscle attachments and angle of inclination
- More valgus= medial meniscus injury
145
LCL
- between lateral femoral condyle and fibular head
- joined by the biceps femoris muscle
- not a thickening of the capsule
- resist varus stress
- tight at extension
- resist varus stress at knee flexion (account for greater degree of there resistance)
- secondary role to limit excessive lateral rotation of the tibia
- thinner and not as strong as MCL
146
ACL
- high injury rate
- two separate bundles: anteromedial bundle, posterolateral bundle
- the different bundles are tight in various positions of knee flexion
- prevent anterior translation of tibia
- max anterior translation occurs at 30 degrees of flexion due to neither bundle being very tight
- secondary roles to provide rotatory stability and resistance to valgus and varus stresses
- muscles a round the knee joint can either increase or decrease the load of the ACL Contractions of muscle can either increase or decrease the force on the ACL
147
Anterior shear and ACL
quadriceps puts strain on ACL
Gastrocnemius is right behind joint and may push tibia forward
Soleus will pull back if you can't plantarflex the foot
148
Posterior shear on the ACL
Hamstring limits anterior shear when weight bearing the soleus
149
PCL
- sometimes mistaken for ACL injury
- also 2 bundles
- primary restraint to posterior displacement of tibia
- resists about 90% of the posterior shear forces. prevents from dropping down
- better at resisting flexion
- max posterior displacement of tibia occurs at 75-90 degrees
- resists varus and valgus forces and medial tibial rotation - gastrocnemius can cause posterior shear at \>40 degrees and quadriceps can decrease shear at 20-60 degrees
- if contract, not allowed to go back
- a muscle that crosses 2 joints can vary in what it does
150
ITB
- attach at the anterolateral tibia: gerdy's tubercle
- mostly a passive structure
- taut regardless of hip and knee joint position
- minimal resistance to varus stress of joint
- can resist anterior displacement of tibia (in flexion)
- adipose tissue between ITB and femoral condyle
- compressed 0-30 degrees
- if running on angle, more strain on leg on downhill side of ITB
151
Bursae of knee
Suprapatellar
Subpopliteal
Gastrocnemius
Connected If slightly bent, all swelling moves to front
Flexion, pushed posteriorly
Extension pushed anteriorly
152
Tibiofemoral flexion/ extension
- femur rolls posterior and glides anterior during flexion
- glide is important so femur does not roll off the tibial condyles
- 0-25 degrees primarily roll then roll and glide together
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Meniscal motion- distortion
- menisci must remain under the femur in the right place
- during flexion the menisci distort posteriorly
- failure can cause meniscus tear/injury
- at old age, a deep squat could damage menisci
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Flexion/ extension ROM of tibiofemoral
- PROM flexion 130-140 degrees
- WB flexion 160 degrees
- gait 60-70 degrees of flexion
- PROM extension 5 degrees (hyperextension)
- genu recurvatum: excessive knee hyperextension
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Ski boot example
Ski boot attached in dorsiflexion
Too get knee straight, you walk on heels
- if you do not have enough dorsiflexion, you cannot get heel down and you get hyperextension of knee to straighten
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Medial and lateral rotation of the knee
Medial condyle the pivot point
Lateral condyle moves through greater motion
Most rotation in 90 degrees flexion 35 degrees of total rotation with lateral rotation greater than 20 degrees
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Valgus (ABD)/ varus (ADD) of knee
Frontal plane motion
Only 8 degrees in full ext
13 degrees at 20 degrees of knee flexion
Excessive frontal plane motion indicative of ligamentous insufficiency
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Coupled motion of knee
Varus and valgus
- medial femoral condyle more distal causing slight valgus angle in extension ( like the elbow)
- with flexion, the tibia moves medially= flexion is coupled with varus motion
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Locking mechanism of the knee
- lateral rotation of the tibia accompanies the last part of knee extension
- automatic terminal rotation or screw home mechanism
- during NWB extension the lateral part of the joint completes the motion before ( lateral articular surface is smaller) the medial part
- cause closed pack position in extension
- have to unlock the knee when flexing
- popliteus helps unlock
- to lock, laterally rotate tibia, medial rotate tibia
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7 muscles cross posterior knee to flex
1) semimembranosus
2) semitendinosus
3) biceps femoris ( long and short head)
4) sartorius
5) gracilis
6) popliteus
7) gastrocnemius (greatest knee flex torque in ext)
8) plantaris Position of muscle determines if it can cause rotation and valgus and varus forces
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In WB what muscles help in knee extension
Gluteus Maximus
Soleus
Use them when you have knee problems If quads are weak, these muscles can help you get hip straight
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4 extensors of knee
Rectus femoris (2joint muscle)
Vastus lateralis
Vastus medialis
- helps to control lateral displacement of patella, really affected by knee joint swelling Vastus intermedius
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Patellar influence on quadriceps muscle function
- patella increases moment arm, especially in early flexion
- max knee extension torque at 45-60 degrees because increase moment arm and optimal length tension relationship of muscle.
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Quadriceps lag
When weak, quadriceps can contract but need help with last bit of ROM Could be b/c patella missing or weak quads
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Anterior translation caused by quadriceps
The effect on the ACL WB vs. NWB Good compression, no translation When knee extended, more anterior glide of ACL
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Quads and standing
With standing, quads work less Last part of extension do in standing because quads work less and more of a compressive force
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ACL injury and tibial shear
- ACL tears cause knee joint instability
- giving away episodes
- cause increased damage to the joint
- surgery try to replace the ACL
- copers and non copers
- discussion on what are appropriate exercises
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What muscle is the patella embedded in?
Quadriceps Different parts of the patella touching different parts of the femur
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Patella
- in extension, least amount of joint congruency in patella femoral joint
- the vertical position of patella depends on patellar tendon length
- if sits high= patella alta (increased risk for patella instability)
- lateral lip of femur control lateral stability
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Patellofemoral articulation
- contact between patella and femur changes during flexion
- during flexion, patella slides down the femur
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Patellar motions
- flex/ext - Lat/medial tilt
- lat/med shift
- med/ lat rotation
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Lateral/ medial patellar tilt
- rotation along longitudinal axis
- with lateral tilt, the lateral edge approximates the lateral femoral condyle
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Lateral and medial patellar shift
Gliding motion
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Medial and lateral rotation of patella
- needed to keep patella seated within femoral condyles
- inferior pole with point to tibial tubercle
- patella will shift depending on position
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How does the patella shift during early flexion
Medially
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Patellofemoral joint stresses
- stresses depend on joint surface contact area and joint forces - patella cartilage very thick
- least in extension
- during walking, approximately 25-50% of body weight at 20 degrees knee flexion
- running is 5-6x body weight
- nutrient to patella cartilage with movement, pump fluid in.
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A valgus angle between the femur and tibia will cause the quadriceps to exert what kind of force
A lateral force on the patella
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Medial patellofemoral ligament resists what kind of force
Lateral force
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Hypermobility of patellofemoral joint
Greater risk for subluxations and dislocations
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Hypomobility of patellofemoral joint
Greater patellofemoral stress
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The more knock kneed you are....
The more chance of pushing patella out laterally
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Stability of patellofemoral joint provided by
Joint surfaces
Ligaments
Extensor retinaculum
Muscles
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Patellofemoral joint stability depends on
Knee angle
Muscle strength/ weakness
Malalignments
The shape of joint surfaces
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Q angle
A clinical measure Angle between ASIS and midpoint of patella And tibial tuberosity and mid patella
Normal is 10-15 degrees
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With femoral anteversion what happens to the Q angle
Increases it
186
WB vs NWB exercises with patellofemoral pain
- Exercises most effective when pain free
- Can use WB vs NWB in different knee flexion angles to manipulate joint forces
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