pamhong4-Congenital VERTICAL TALUS
Terms in this set (40)
What is congenital vertical talus (CVT)?
Rigid dorsal dislocation of the navicular ont he talar head & neck with a fixed equinus contracture of the hindfoot
Characteristic pattern of CVT
What must CVT be distinguished form?
OBLIQUE talus (milder condition)
What is the most likely pathophysio mechanism responsible for CVT?
1. result of arrested osseous foot development in the embryo at end of 2nd & beginning of 3rd intrauterine life
2. spinal cord lesion in early embryonic life results in muscular contractures -- eventually displacing osseous & hindfoot structures
3. CVT is associated with
-CNS conditions (arthrogryposis, neurofibromatosis, sacral agenesis, myelomeningocele,)
-chromosomal aberrations (Down's, Marfan, Patau, Freeman Sheldon, Edwards syndromes)
-acquired deformities (cerebral palsy, polio, spinal muscular dystrophy)
What are genetic evidence for CVT?
1. sarcomere gene mutation in skeletal muscles associated with distal arthrogryposis
2. trisomy 18 (edwards)
3. trisomy 14 (patau)
4. partial trisomy of 12q and 16p
5. HOXD10, CDMP-1, & GDF5 mutations
Epi of CVT
1. 1/10,000 live births with ~1/2 occuring as idiopathic deformity of one or more limbs
2. 50% associated with above etiologic factors
Natural History of CVT
1. rigid characteristics due to severe muscle imbalances, bony dislocation, & 2ndary soft tissue contractures
2. left untreated --> significant pain & disability with callus formations along medial plantar aspect where head of talus protrudes
Presentation of CVT in Children
1. 'peg-leg' gait --> limited FF push off, no heel contact, shortened cadence
2. CVT does not delay a child's ability to walk & may often not be apparent until child starts to ambulate
Risk factors for CVT
-same as etiologies
1. CVT from acquired deformity like cerebral palsy
-cerebral palsy: mother < 20 or >40 yo, low birth weight, premature birth, male gender, multiple gestation, & intrauterine viral infection
Describe how NAVICULAR is in CVT
-navicular displaces dorsolateral on the talar head & neck
-becomes more wedge-shaped & hypoplastic at is plantar aspect
Describe how TALAR HEAD is in CVT
-talar head becomes flattened dorsally & articular surface expands to accomodate the displaced navicular body dorsally
Describe what happens when the TN joint becomes dislocated
-dislocation of TN joint creates structural limitation
-talar head is trapped in a PF'ed & medial position thus there is decreased contact between the trochlea of the talar body & the tibial plafond
Describe the position of the calcaneus in CVT
-calcaneus is rotated posterolaterally & there is underdevelopment & sometimes absent of anterior & middle subtalar facet with hypoplasia of the sustentaculum tali
-thus NO SUPPORT TO TALAR HEAD & THE CUBOID can often times be laterally displaced
Describe the ligaments within the midtarsal & rearfoot region
-ligmanets within midtarsal & rearfoot become ATTENUATED OR CONTRACTED overtime depending on relationathip to the displaced osseious structures
Ligaments that become OVERSTRETCHED:
1. ligaments plantar to the talocalcaneoavicular joint
2. calcaneonavicular (SPRING) ligament
3. anterior fibers of teh deltoid ligament
4. medial fibers of the bifurcate ligament
Ligaments that become CONTRACTED:
1. Dorsal talonavicular
3. interosseous talocalcaneal
4. posterior capsules of the ankle & STJ
What happens to the superior and inferior extensor retinaculum?
1. sup & inf extensor retinaculum become one fibrous mass which shortens course of anterior compartment tendons & increases their mechanical advantage
What happens to the peroneal reticulum & what is the consequence?
1. Peroneal retinaculum attenultes, allowing peroneal tendons to sublux anteriorly on fibular & create a more DF pull rather than PF & evert
What happens to the posterior tibialis & what is the consequence?
1. Post tibialsis tendon is subluxed anteriorly & becomes attenuated as it passes inferior to the midfoot
What happens tot he triceps surae?
1. triceps surae become broad & shortened overtime with calcaneus in everted & valgus position in accordance to Davis' Law
Clinical Presentation of CVT
1. 'Persian Slipper foot' -->
-FF that is DF & ABducted
-RF in equniovalgus
-exaggerated convex medial longitudinal column
-elevated claw lateral toes
2. bony prominence at talar head usually with thick callus formation creating rockerbottom foot shape
3. deformity is RIGID especially after 2 yo
Is the deformity RIGID?
YES, esp after age 2
DDX of CVT?
1. Positional calcaneovalgus--> flexible deformity-foot DF'ed & everted, often tangential against leg
2. Posteromedial bowing of tibia --> forces foot to compensate in overpronation
3. congenital absence of fibular --> lack of structural buttress at ankle mortise -lead to ankle valgus that may mimic flatfoot deformity
4. congenital oblique talus --> contracture are suppler & more reducible, the TN joint is reduced upon PF of FF against RF
5. idiopathic flatfeet
Primary ossification of navicular:
age 2.5-5 years
Early RADIOGRAPHIC findings of CVT
1. vertical talus
2. AJ in equinus
3. ABducted FF (talar bulge, concave lat column)
4. increased Kite's angle
5. increased lateral talocalc angle
Late RADIOGRAPHIC findings of CVT
1. Kohler-like changes to navicular
2. anterior calcaneal beaking
3. altered CCJ surfaces
4. MT primus elevatus w/dorsal bunion (PL failure)
5. small talus
6. persisting TNJ dislocation
What angles will you check on AP VIEW?
1 TALOCALCANEAL (KITE'S) Angle
-NORMAL in child <5 yo: 20-40 degrees
-if increased angle--> indicate hindfoot VALGUS
2. TALO-1st MET
-NORMAL: -10 to +30 degrees
What angles will you check on LATERAL VIEW?
3. tibiotalar (can reach 90-180 with CVT)
4. talar-1st met angle
Lateral dynamic view
-actively DF'ing & PF'ing FF
max DF wil show fixed hindfoot equinus & max PF will show irreducible TNJ
How can MRI be used for CVT?
-aid in dx of CVT by allowing better viewing of cartilaginous anlage of bones esp navicular
Goal of CVT treatment?
1. restore anatomic relationship of naviular, talus, & calcaneus asap
2. reestablish WB capacity of 1st ray
Nonsurgical tx of CVT
1. Serial manipulation + casting to stretch anterior shin, ankle & STJ capsules, & musculotendinous soft tissues structures
*because of RIGIDITY of CVT, serial casting is not enough -- need to prepare foot for osseious & soft tissue surgical proceudre
2. manipulations= PF & inversion of FF while counterpressure applied to medial aspect of talar head -held for several minutes allowing TNJ to stretch --cast foot & change every 1-2 weeks
What ist he current STANDARD OF CARE FOR CVT?
1. INITIATING SERIAL MANIPULATION OF THE FOOT with casting in combo with EARLY SURGICAL INTERVENTION
What is the definitive age of surgery?
When are best results produced?
when surgery is performed prior to age 2
3 main themes for CVT Surgery
1. correction through staged multiple incision technique with extensive soft tissue release
2. single-staged posteromedial approach or single-stage dorsal approach
3. minimally invasive technque with casting
Describe the first theme: correction through staged multiple-incision technique
1. 1st stage = lengthening EDL, EHL, & TA tendons, release of vestigial TC ligament with TNJ & CCJ capsulaotomies through dorsal incision
2. 2nd stage = Achilles tendon lengthening with posterior ankle & STJ capsulotomies through posteromedial incision
BAD: high complication rates- stiffness, weakness, AVN of talar head, pseudoarthrosis, skin sloug, wound necrosis
Describe single-staged posteromedial appraoch
Seimon's technique uses single dorsal approach to release EHL, peroneous tertius & TNJ
reduction & pinning of the TNJ & percutaneous achilles tendon lengthening
GOOD: good correction of plantar grade, painless feet after ~41 months
Describe the minimally invasive sx + casting
Dobbs et al: approach involves percut pinning of TNJ after manual manipulation based on Ponsetti technique
percut Achilles tendon lengthening + casting
Surgical tx for recurrent deformity
1. salvage procedures
-ST arthrodesis (in older children)
-triple arthrodesis (considered in most adolscent pt)
-talectomy (for severe deformities usually in adulthood)