7: Subtalar Joint - Frush Flashcards
subtalar joint =
articulation b/w talus and calcaneus
the interosseous ligament limits …
inversion and eversion (more)
the cervical ligament limits …
inversion
STJ axis
42 degrees from the transverse plane
16 medial deviation from sagittal plane
motion STJ joint
inverion eversion and abduction adduction
little dorsiflexion plantarflexion
transver and frontal : sagittal
3:1
open kinetic chain supination
inversion, plantarflexion, adduction
open kinetic chain pronation
eversion, dorsiflexion, abduction
what does the STJ do during 1st and last half of OKC?
1st - pronates (allows for ground clearance)
Last - starts to supinate
just before heel strike
STJ in neutral
at heel strike
STJ supinated
what will you see during CKC?
inversion and eversion of calcaneus will be only thing externally visible
CKC supination
calcaneal inversion
talar dorsiflexion and abduction
tibial external rotation
CKC pronation
calcaneal eversion
talar plantarflexion and adduction
tibial internal rotation
CKC internal leg rotation =
talar adduction
CKC external leg rotation =
talar abduction
because CKC talus and leg are proximal to axis, will act in _______ motion of calcaneus
opposite
allows foot to become mobile adaptor and allows for shock absorption
STJ heel strike and starting to pronate
during CKC midstance, the STJ starts to …
supinate (to allow for heel off, foot becomes rigid lever)
how do you find STJ neutral?
palpate talar neck and move foot back and forth until it feels equal medially and laterally
STJ total ROM
30 degrees
20 calcaneal inversion/ supination, 10 eversion/ pronation
how do you calculate STJ neutral through ROM?
- prone pt
- bisect calcaneus and lower leg
- invert calcaneus to end ROM and measure angle
- evert calcaneus to end ROM and measure anlge
- add measurements together and divide by 3 (* if this number less than measured eversion = valgus, greater than eversion = varus)
- subtract this number from measured eversion
= calculated STJ neutral
describe the kirby method
- pt in STJ neutal nonweightbearing
- push onmedial foot and lateral foot until coming to point where foot does not move
- do at least 3 pts
- assumes the normal STJ axis passes through the posterior-lateral heel and through the first intermetatarsal space of platnar foot anteriorly
if STJ is laterally located (kirby method) …
foot supinates easily
if medially located, foot pronates more easily
position of STJ (calcaneus) when pt is fully compensated in midstance
releaxed calcaneal stance position
how do you measure the RCSP
- bisect calcaneus
- have pt stand and march in place
- measure calcaenal bisection in relation to weightbearing surface
normal RCSP
2 degrees varus to valgus
compensation rules for RCSP
varus= calcaneus will be vertical if fully compensated
valgus = neutral 2-10 degrees = foot will pronate/evert to maximum ROM
- if over 10 degrees = talar head hits fround and prevents further pronation
position of STJ when pt is placed in neutral position while standing
NCSP neutral calcaneal stance position
how do you measure NCSP
- bisect calcaneus
- march pt
- have pt slowly invert and evert until neutral talus is palpated
- measure calcaneal bisection in relation to weightbearing surface
normal tibial stance position
0-4 degrees varus
what is the tibial stance position?
bisection of lower leg (tibia) in relation to ground while in NCSP
adding the tibial stance position to STJ neutral =
neutral calcaneal stance position
if pitch of STJ is higher than normal, what type of increased motion will be seen?
abduction and adduction
a pt has 22 degrees inversion and 14 degrees eversion, what is their neutral position?
2 degrees everted (valgus)
during CKC pronation, the calcaneus …
everts
