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67 Cards in this Set
- Front
- Back
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What is the calcaneo-cuboid locking mechanism?
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The CC locking mechanism is an evolutionary development that enables bipedal locomotion.
In midstance, the superior border of the pronating cuboid locks with the dorsal border of the overhanging calcaneus. This "locks" the RF against the FF and enables the foot to act as a rigid lever for propulsion. This action is essential for transfer of forces from proximal to distal foot. |
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Define ankle equinus
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Ankle Equinus describes ankle dorsiflexion limited to <10 degrees, when the joint is at 90 degrees and with the STJ in neutral and the MTJ fully pronated abour both axes.
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Define rearfoot varus
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Rearfoot varus describes a structural, frontal plane deformity in which the rearfoot is inverted relative to the bisection of the leg, when the STJ is in neutral and the MTJ fully pronated about both axes.
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Define rearfoot valgus
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Rearfoot valgus is a structural frontal plane deformity in which the rearfoot is everted relative to the bisection of the posterior leg, when the STJ is in neutral and the MTJ fully pronated about both axes.
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What are the axes of the subtalar joint?
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16 degrees from sagittal plane and 42 degrees from transverse plane.
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What ankle joint ROM is considered necessary for adequate function in gait?
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10 degrees.
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Name 4 main etiologies for ankle equinus
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Ankle equinus main etiologies:
1) congenitally short gastrocsoleus 2) neuromuscular disorders 3) a unilateral compensation for limb length discrepancy 4) osseous ankle equinus 5) accommodative shortening 6) "pseudo equinus" |
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What plane of movement is affected by ankle equinus?
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Ankle equinus affects the sagittal plane motion.
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What is the main purpose of DF during gait?
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Ankle DF allows forward progression of the trunk over the weightbearing limb.
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Name the two types of ankle equinus
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1) soft tissue equinus (can be reduced, spongey end-feel)
2) osseous ankle equinus (cannot be reduced, hard end-feel) |
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What is "pseudo equinus"?
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Pseudo equinus or "apparent equinus" is actually plantarflexion of the forefoot. The foot functions as an ankle equinus, however.
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Describe compensation for ankle equinus.
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Compensatory dorsiflexion is required.
The STJ pronates and thus provides additional dorsiflexion. The foot may be excessively pronated. |
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Where does compensatory DF come from in ankle equinus?
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Compensatory dorsiflexion in ankle equinus comes from either the STJ (pronating) or the MTJ (pronating).
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Define Fully Compensated ankle equinus.
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Fully compensated ankle equinus occurs if the foot achieves 10 degrees dorsiflexion, and the lower leg inclines 10 degrees from frontal plane as it passes over the plantigrade foot in midstance.
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What secondary pathology might you see in a foot with fully compensated ankle equinus?
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Secondary pathologies include: HAV, plantar fasciitis, digital neuritis, and hypermobility-related pathology.
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What is uncompensated ankle equinus?
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In uncompensated ankle equinus, the combined STJ & MTJ cannot offer any compensatory dorsiflexion.
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Which part of the foot would be WB in an uncompensated ankle equinus?
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The forefoot would WB as the calcaneus cannot make ground contact.
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What lesions would you expect to see in uncompensated ankle equinus?
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Lesions in uncompensated ankle equinus are dramatic, including:
- callus on met heads - callus under PMP1&5 - and lesions from clawing of the toes. |
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What is partially compensated ankle equinus?
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In partially compensated ankle equinus, the combined additional DF offered by the STJ and MTJ is still not enough to enable normal limb movement in midstance.
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What lesions are associated with partially compensated ankle equinus?
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The lesions would depend on the degree of compensation achieved by the STJ and MTJ.
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What general compensations are seen for reduced ankle DF?
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Reduced ankle DF results in:
1)Early heel lift 2)Swayback knees (genu recurvatum) 3)Excessive knee flexion 4)Abductory Twist |
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True or false?
MTPJ pathology is common in ankle equinus? |
True - compensatory pronation and early forefoot loading makes the foot unstable, which leads to degenerative changes to the 1st MTPJ.
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Describe what sort of gait changes you would see in ankle equinus?
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Gait would be:
- bouncy - apropulsive - with early heel lift - and shorter steps |
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What lesser toe deformities might you see with ankle equinus?
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Clawed toes
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In what way is the foot's shock absorption capacity affected by ankle equinus?
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Yes. Lack of DF in gait decreases the shock absorption capacity of the foot.
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Which part of the foot may collapse through the additional forces caused by ankle equinus?
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The midfoot may collapse, causing a rocker-bottom foot.
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True or false?
Even mild rearfoot varus can cause foot/leg pathology. |
True - especially if an individual does a lot of physical activity.
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Why do rearfoot varus abnormalities occur?
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Rearfoot varus results from
1)congenital varus of leg/foot 2)severe trauma (inc epiphyseal) |
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Name two types of congenital LEG varus
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Congenital leg varus:
1) talar varum 2) genu varum |
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Name two types of congenital FOOT varus
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Congenital FOOT varus:
1) subtalar varum 2) calcaneal varum |
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Name two compensatory mechanisms that may be seen in rearfoot varus
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1) plantarflexion of the first ray
2) Abductory twist |
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What is an Abductory Twist?
What does it achieve? |
Abductory Twist = on heel lift the forefoot abducts and the heel moves medially.
It enables loading of the medial forefoot. |
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What compensation occurs in fully compensated rearfoot varus?
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Fully compensated RF varus:
1) excessive, rapid STJ pronation 2) plantarflexed first ray 3) abductory twist |
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What signs and symptoms are associated with fully compensated rearfoot varus?
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Fully compensated RF varus:
- callus on lateral heel - fatigued re-supinator muscles - hypermobile first ray - reduced 1st MTPJ ROM - callus on PMP2-4 - Haglund's deformity |
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What compensation occurs in uncompensated rearfoot varus?
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Although there is no STJ motion available, the foot may still:
1) plantarflex the first ray 2) Abductory Twist |
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What signs and symptoms are associated with an uncompensated rearfoot varus?
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Uncompensated rearfoot varus:
1. callus PMP5 2. callus on lateral foot 3. Tailor's Bunion 5th met 4. Pressure lesions under 1st met 5. tendency to lateral ankle sprains 6. lack of shock absorption in gait (leading to knee, hip, back problems) |
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What compensation occurs in partially compensated rearfoot varus?
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Partially compensated RF varus:
1) some STJ pronation 2) may be LMTJ pronation 3) Plantarflexed first ray 4) Abductory Twist |
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What signs and symptoms are associated with a partially compensated rearfoot varus?
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Partially compensated RFvarus:
1) pressure lesions PMP4-5 2) Soft corns ID 4/5 3) lateral heel callus 4) lateral ankle sprains 5) Haglund's deformity |
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A partially compensated RFvarus causes lesions in relation to what two main areas?
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Partially compensated RFvarus causes lesions associated with:
1) plantarflexed first ray 2) increased lateral WB |
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What effects on the plantarflexed first ray, will a partially compensated RFvarus have?
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Effects on PF first ray:
1) sesamoiditis 2) callus on 1st Met 3) callus on plantar hallux 4) osteophytosis of the 1st met/cuneiform joint |
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Why might a patient suffer from shin splints if they have a rearfoot varus?
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If the RFvarus is compensated, the STJ will necessarily be excessively pronating. Muscles resisting pronation must work harder and over a greater distance than normal and this is thought to lead to shin splints.
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Why would a patient get callus on PMP2-4 if they have compensated RFvarus?
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When a hypermobile first ray contacts the ground it will DF the hallux out of the way and met heads 2-4 will take the force instead, leading to callus formation.
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Why does compensated RFvalgus cause reduced 1st MTPJ motion?
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Excessive pronation restricts 1st Met plantarflexion, thus 1st MTPJ dorsiflexion is restricted.
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Why does RFvarus put patients at risk of lateral ankle sprain?
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1) the rearfoot is more inverted than usual when it contacts the ground
2) in midstance the MTJ is fully pronated and cannot offer any compensatory pronation 2) in uncompensated and partially compensated RFvarus the foot is WB mostly on the lateral side |
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Define rearfoot valgus
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Rearfoot valgus described a structural frontal plane deformity in which the sagittal plane bisection of the calcaneus is inverted relative to the ground when the STJ is in neutral and the MTJ is fully pronated about both axes.
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Is rearfoot valgus a primary or secondary deformity? and why?
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Rearfoot valgus is primarily a secondary deformity which is a compensatory mechanism for primary abnormality elsewhere.
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Name two common etiologies of rearfoot valgus
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Rearfoot valgus can becaused by:
1) Traumatic (TPTD, Pott's fracture) 2) Congenital (tarsal coalition, absent fibula) |
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Describe the pathomechanics of rearfoot valgus
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Rearfoot valgus is a destructive cycle.
- calc is everted - GRF exterts pronatory force - bodyweight falls medial to STJ axis, creating a pronatory force at STJ - tibia internally rotates, causing more eversion - muscles cannot stabilise the medial border fast enough |
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How would a rearfoot valgus present in clinic?
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Rearfoot valgus presentation:
1) severe valgus foot type 2) absent MLA 3) no shock absorption 4) OA changes in joints 5) unstable first ray |
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What are the axes of motion of the STJ?
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16 degrees from sagittal
42 degrees from transverse |
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What type of joint is the STJ?
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plane joint
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What is pronation?
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Pronation=
eversion (calc) dorsiflexion abduction |
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What is supination?
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Supination=
inversion (calc) plantarflexion adduction |
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How many facets has the STJ commonly?
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Usually 3 articular surfaces, but may be one of four common arrangements
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What is STJN?
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the neutral position of the STJ is that position of the joint in which the foot is neither pronated nor supinated
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Is there more inversion than eversion possible from the neutral position?
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There is more inversion than eversion possible from STJN
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What are the main functions of the STJ?
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- torque conversion
- allows the leg to rotate in response to closed chain foot positions |
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What is planal dominance?
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The plane that the STJ axis is nearest to will dominate the STJ motion in that foot.
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A high STJ axis would result in?
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High STJ axis = more transverse movement than
frontal plane |
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A low STJ axis would result in?
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Low STJ axis = more frontal plane movement than transverse plane
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What muscles are "anti-pronatory" during gait?
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TibPost (eccentrically)
TibAnt Long flexors soleus & gastroc |
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What is the function of the CC locking mechanism?
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- prevents excessive midtarsal pronation
- enables bipedal ambulation |
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How does the CC locking mechanism work?
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- Cuboid rotates on the calcaneus
- pronating cuboid pivots about the calcaneal process until its dorsal border contacts the overhanging calcaneus |
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What impact does the STJ have on the MTJ?
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STJ pronation renders the two axes of the CC and TN joints parallel thus enabling greater MTJ motion.
STJ supination makes axes more divergent and decreases their available motion. |
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Pronation is necessary to...
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Absorb shock during initial contact
Absorb tibial rotation during stance Adapt to uneven terrain |
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Supination of the foot is necessary to...
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Create a rigid lever to enable normal propulsion during gait
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What are the phases of gait?
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Heelstrike
Contact Forefoot Loading Midstance Heel lift Propulsion Toe Off |
