15: 1st Ray, 1st MPJ - Feilmeier Flashcards
hallux bears weight for ______ of stance
60%
met 1 bears weight 80% of stance
first ray takes ____ of body weight in gait
35%
loss of hallux purchase reduces …
push off power and increases lateral loading
first ray is a ______ segment
stability
what is the first ray?
1st metatarsal and medial cuneiform
motion of first ray (Hicks)
dorsiflex -invert - adduct
plantarflex - evert - abduct
total ROM of first ray **
10 mm (1 cm) 5 mm dorsal 5 mm plantar
“hypermobile 1st ray”
- greater than 8 mm dorsal mobility
- total ROM over 15-20
- is it related to bunion?
*** orientation of first ray axis Hicks
proximal-medial-dorsal to distal-lateral-plantar direction
______ rotation has been shown to be consistent in HAV
valgus metatarsal rotation
*** positioning for measuring stability first ray
STJ neutral
midtarsal joint lock
1st Ray function in gait
- plantarflexion durign midstance and propulsion necessary for proper 1st MPJ function (allows dorsiflexion in toe off)
- requirements: supinated subtalar joint, stable midtarsal joint
in a mechanically stable foot, ______ stabilizes lesser tarsus and 1st met against ground allowing plantarflexion of 1st ray
- peroneus longus
- active plantarflexion by intrinsics
function of 1st MTPJ in gait
provide stability for propulsion
normal 1st MTPJ movement requires
- stability and plantarflexion of 1st ray
- normal sesamoid function (act as pulleys for muscles required for hallux stabilization during propulsion)
- normal function of 1st MTPJ muscle stabilizers
what type of joint is the 1st MTPJ?***
ginglymoarthrodial
- hinge/ginglymoid 1st 20 degrees
- gliding/sliding/arthroidal motion
when is there sliding motion at 1st MTPJ
- with plantarflexion of 1st ray with heel lift, STJ supination and normal seasmoid function
failure of 1st MTPJ to plantarflex causes impingement of met head on proximal phalanx of hallux –>
- causes joint erosion and inflamamtory reaction in cartialge and bone ends
- trauma stimulates the bone to grow, effect of osteogenic development is firstly to restrict and later to cause total seizure of joint
- loss of movement at first MTPJ may cause pain, which can lead to disruption of biomechaical function of foot and limb due to compensation and can compromise gait
*** average ROM of 1st MTPJ compared to bisection of 1st met
dorsiflexion 60-65
plantarflexion 5-10
average ROM of 1st MTPJ compared to plantar surface of foot
dorsiflexion 20
plantarflexion 45
what do you need at 1st MTPJ for gait?
- appropriate functional position, for stable push-off
- not ROM
what is hubscher maneuver?
- dorsiflexion of hallux in relaxed stance position
- engages windlass mechanism
- determines functional hallux limitus (WB prob, no prob NWB)
less ray plantarflexion is required for ..
MPJ dorsiflexion during propulsion
should you fuse 2,3,4, and 5 mets?
no - 5th should be separate b/c has independent ROM
info about the lesser MTPJs
- toe stabilization due extrinsic and instrinsic musculature
- dorsiflexion is by extensor digitorum longus through extensor sling
what is the kelikian push-up test?
- push up on met heads and watch what happens to digits at MPJ, PIPJ
- determines degree of fixed/structural deformity
what is the drawer/lachman test?
- checks for the stability of the joint
- stabilize the met head and attempt to dorsally translocate the proximal phalanx
- greater than 2 mm or 50% joint displacement is positive
