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#5 Surg > 67 and 68 - Flatfoot Surgery I and II > Flashcards

67 and 68 - Flatfoot Surgery I and II Flashcards

1
Q

Goals

A
  • Distinguish components of clinical and radiographic evaluation of pathologically pronated foot
  • Recognize the indications for various conservative and surgical treatments
  • Identify level of deformity
  • Differentiate the mechanics of corrective osteotomies before attempting to memorize historic names of procedures
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2
Q

Is Pronation Good or Bad?

A

Depends on if it is physiologic or pathologic pronation

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3
Q

Physiologic Pronation

A

o Necessary for shock absorption
o Movement is decelerated by muscle function
o Balanced by normal supination through GRF & muscle function based on axis position and orientation

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4
Q

Pathologic Pronation

A

o Joints, tendons, and ligaments are forced to function beyond their physiologic limits
o Net Result: Subluxation, dislocation, degeneration
o Flexible or Rigid
o Arch may be high, low or average
o Compensation for equinus or other deformities

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5
Q

Triplane movement – Pronation

A

Open Chain
o Eversion
o Abduction
o Dorsiflexion

Closed Chain
o Eversion
o Internal leg rotation
o Plantar flexion of the hind foot on the forefoot

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6
Q

Pronation

A
  • Starts at heel strike and should end at mid-stance
  • Major mechanism of shock absorption
  • Muscle activity required to slow pronation
  • Inefficient and degenerative if excessive
    o Joint subluxation and degeneration
    o Tendon degeneration
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7
Q

Pathologic pronation

A 
-	Arch height is not the primary determinant 
o	Arch may be high, low or average
-	Hallmarks of Pathologic Pronation
o	Progressive subluxation
o	Soft tissue degeneration
o	Postural symptoms of foot, ankle, calf, knee, back
o	Joint degeneration
-	May be primary 
o	Due to laxity or axis anatomy 
-	Or secondary to compensation for static deformity or kinematic abnormality
o	MTA
o	Equinus
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8
Q

Conditions associated with pathologic compensatory pronation

A 
Non structural
o	Heel pain & Plantar fasciitis
o	Shin splints
o	Medial Peri-Tendonitis
o	Knee pain (Patello-Femoral Syndrome)
o	Low back pain
o	Decreased endurance
Structural
o	HAV & Hammer toes
o	Mid foot subluxation
o	Tendinosis / PTTD
o	Degenerative arthritis
o	Stress fracture
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9
Q

Over pronation leads to:

A
  • Medial stretching
  • Lateral jamming
  • Excess muscle energy expenditure
  • Joint degeneration
  • Secondary deformities
  • Increases the demands on the leg muscles, knee, hip and back
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10
Q

Joints moving beyond their physiologic limits

A
  • Left image: normal foot position

- Right image: pronated foot position

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11
Q

Goal of surgery to correct flatfoot

A
  • Achieve rotational equilibrium
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12
Q

Indications for flatfoot correction

A
  • Restore proper biomechanics to the foot and the lower extremity
  • Improve stability and function
  • Halt progression
  • Treat painful symptoms
  • To alleviate or prevent structural and non-structural associated conditions
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13
Q

Flatfoot correction options

A

Posterior Muscle/Tendon Lengthening
o Reduces the pronatory force on the foot
o The foot pronates (dorsilexes at the midfoot) to compensate for the lack of ankle dorsiflexion

Calcaneal Osteotomy
o Realigns the subtalar and midtarsal axis
o Increases the supination force medial to the STJ axis
o Permanently reduces pronation and subluxation

Medial arch reconstruction required if secondary degeneration or tendon rupture has occurred

Correction of secondary deformities

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14
Q

Surgical correction principles

A

Primary correction
o Changes the axis alignment of the STJ / MTJ complex which results in improved stability and reduces secondary changes
o Removes compensatory forces

Secondary correction
o Repairs structures damaged by the pathologic pronation

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15
Q

Physical exam for flatfoot

A

Open Kinetic Exam
o Hypermobile STJ/MTJ with subluxation
o Normal muscle strength all groups
o Ankle ROM: DF -15 degrees, PF 50 degrees

Closed kinetic exam
o	RCSP  9 degrees everted
o	Medial TN subluxation
o	Patella internally rotated
o	Abducted forefoot
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16
Q

Questions regarding flatfoot correction

A
  • In which plane is this foot deformed? All 3 – it is a tri-plane deformity
  • How many procedures will be needed to realign the foot? ONE
  • Does each plane need to be addressed individually? NO
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17
Q

Rotational equilibrium

A
  • You can figure out the right procedure if you understand rotational equilibrium
  • Remove deforming forces (i.e. equinus)
  • Move GRF medial relative to effective STJ axis
    o Pick the most effective site
    o Structural alteration results in multi-plane correction
  • Treat secondarily degenerative joints and tendons
  • Give stability where there is instability
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18
Q

What are the procedure choices?

A
  • Remove the deforming forces

- Change the GRF

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19
Q

What is equinus?

A
  • Limitation of normal ankle dorsiflexion
    o Normal forward ambulation requires dorsiflexion at the ankle.
    o When adequate ankle motion is not available the foot is subjected to excessive bending forces. (pathologic pronation)
  • Most common limiting factor in equinus is tight Achilles tendon
  • However the block in motion can be at the ankle joint
    o More common in cavus foot
20
Q

Equinus level

A
  • Gastrocnemius
  • Gastrocnemius soleus
  • Pseudoequinus
  • Osseous equinus
  • A combination of the above
21
Q

Anatomy

A
  • Gastrocnemius and Plantaris are 3 joint muscles
    o Cross the knee, ankle and subtalar joints
  • Soleus is a 2 joint muscle
    o Crosses only the ankle and subtalar joints
  • Gastrocnemius aponeurosis lies on the anterior surface of the muscle
  • Soleus aponeurosis lies on the posterior surface of the muscle
  • Sural nerve and small saphenous vein are vulnerable
22
Q

Normal biomechanics

A
  • Maximum ankle dorsiflexion occurs at mid-stance just before heel lift (10 degrees is functional)
  • Dorsiflexion of the ankle joint is also important for clearance of the ground during swing phase
23
Q

Equinus biomechanics

A
  • More rapid entrance and exit into and out of mid-stance
  • Reduced step length
  • Slower walking velocity
  • Increased forefoot pressure
  • Pronation of foot to obtain required dorsiflexion
24
Q

Compensatory mechanisms – What if your ankle can’t dorsiflex?

A
  • Forward torso lean
  • Pelvic rotation
  • Hip Flexion
  • Knee hyperextension
  • External rotation of leg
  • Subtalar pronation
    o Unlocks midtarsal joint
    o Dorsiflexion of forefoot on rearfoot
25
Q

How do we test for equinus?

A
  • Must avoid pronation of the foot
    o Pronation will give a false indication of available DF by bending at the midfoot
  • Holding the foot Slightly SUPINATED is the most accurate way to measure
  • Knee Extended & Flexed
    o Testing gastroc and soleus
26
Q

Neutral to supinated is most accurate

A
  • Pronation of the foot increases the measured DF by more than 10 degrees
  • This DF does not represent ankle movement
27
Q

Achilles stretching

A
  • Universally recommended
  • Can you “stretch” a tendon?
  • Systematic Review
    o An average of 2.41 degrees of increased dorsiflexion was seen with extensive BID Achilles stretches
    o Is this amount of improvement clinically relevant? NO
28
Q

Gastroc recession technique options

A 
-	Position
o	Prone
o	Frog leg
o	Extended Knee Hemi-lithotomy
-	Incision Approach
o	Medial
o	Midline posterior
-	Level of cuts
-	Straight release vs. tongue and groove
29
Q

In a foot that is compensating for equinus, what happens if you correct the valgus heel without correcting the equinus?

A
  • The deformity will come back – the valgus heel will appear again or it will find a way to induce movement and pathology into a different joint
30
Q

Goal for flatfoot surgery

A

The goal is to achieve rotational equilibrium of all forces
o Ground reactive forces (GRF)
o Tendon and muscle forces

31
Q

Evans anterior calcaneal osteotomy indications

A 
-	Flexible Pes valgus 
o	Progressive
o	Painful
-	No DJD
-	Younger patients
32
Q

What does the Evans procedure accomplish?

A
  • KNOW THIS – UNIPLANE procedure induces TRIPLANE correction*
Static anatomic changes
o	Lengthens the lateral column
o	Relocates TN joint
o	Preloads the plantar fascia
o	Improves Peroneus longus function
 STJ axis changes
o	Lateral shift
o	Enlarges the supinatory lever arm of GRF - moves  FF medial and moves valgus heel more vertical
o	More effective MTJ locking
o	Medializes Achilles
o	Increases supination of TA

Rotational equilibrium

33
Q

Why does the calcaneus invert and dorsiflex?

A
  • Supination of the mid foot effectively moves the axis of the STJ lateral
  • Lateral shift of the STJ axis increases the supination moment across the STJ from GRF
  • GRF produces tri-plane movement of the STJ and MTJ (supination)
34
Q

Triplane correction

A
  • If we alter one planar component of the foot ground reactive force will then act on the foot to move the joints from the new orientation
  • Since the joints are tri plane, moving one segment results in correction of the other planar components by ground reactive force
  • The surgery changes the rotational equilibrium and therefore the GRF effect
35
Q

Triplane compensation

A

Triplane compensation

  • Remember the STJ & MTJ are tri-plane joints
  • Movement in one plane is accompanied by the other two planar motions
  • **Continuously variable axis, therefore… **
  • If the heel is everting to compensate for tibial varus, the talus also plantar flexes and adducts (STJ Pronation)
  • We see the first planar compensation, we must imagine the other movements and consider their effect on the patients complaint and on correction
36
Q

Why fixate the osteotomy

A
  • Loss of lateral column length (primary correction)
    o Graft collapse
    o Calcaneal collapse
  • Shift of the anterior fragment
    o Dorsal, plantar, medial, lateral
  • Stability
    o Early active ROM Improves rehabilitation
37
Q

STUDY: Does Locking Plate Prevent Length Loss and Displacement?

A
  • Dayton, Feilmeier, Prins, Smith JFAS 2013
  • N= 35
  • Without plate (12): Average loss - 2.45 mm (0-9mm) @ 6 mo, visible shift 5 = 23%
  • With Plate (23): Average loss - 1.0 mm (0-3mm) @ 6 mo, visible shift 1 = 8%
  • Main point: without fixation, we are losing a lot of our correction***
38
Q

Fixated technique

A
  • Longitudinal incision from the cuboid to the lateral malleolus just dorsal and parallel to the peroneal tendons.
  • Full thickness sub-periosteal flap raised with the peroneal tendons.
  • Osteotomy vertical 1.5-2 cm from cc, parallel to joint
  • Graft placed and fixated with locking plate
  • Trapezoid-shaped osteotomy
    o Linear advancement of the anterior calcaneus
  • Wedge-shaped osteotomy
    o Larger net medial shift of the midfoot
    o Cortical contact maintained medial-plantar
39
Q

Locking plate vs screw

A

Locking plate
o Load bearing bridge fixation provides the ideal mechanics for inter-positional bone graft
o Multi-planar stability

Screw
o Does not neutralize angular or compressive forces on the graft

40
Q

Allograft

A
  • Healing is based on new bone formation around the graft and biologic replacement of the graft
  • Incorporation???
  • Creeping substitution is replacement of the graft with host bone from the edges inward
  • This is a long process that takes many months to fully complete
41
Q

What does the Evans procedure accomplish?

A

Lengthens the lateral column
o Relocates TN joint
o Preloads the plantar fascia
o Improves Peroneus longus function

Moves the effective STJ axis lateral
o	Medializes Achilles
o	Increases supination of TA
o	Enlarges the supinatory lever arm GRF
o	More effective MTJ locking
o	Increased calcaneal inclination
o	Reduces valgus heel
42
Q

Posterior calcaneal displacement osteotomy

A
  • Sliding Calcaneal Osteotomy
  • Posterior Calcaneus is slid medially to increase the supinatory ground reactive force
    o STJ Axis moves lateral
  • Posterior calcaneus is slid laterally to decrease the supinatory forces across the STJ
    o STJ Axis moves medial
  • Rotational Equilibrium
43
Q

Cotton

A
  • Dorsal opening wedge Cuneiform osteotomy
  • Used to reduce elevated first ray (forefoot varus)
  • Adjunctive procedure to calcaneal osteotomy
  • Increase GRF medial to the STJ axis by PF first ray
44
Q

Triple arthrodesis

A
  • Salvage for chronic pain with DJD
  • ALWAYS correct the deformity
  • Mobilize and prepare all three joints before fixation
  • Congruous anatomic joint surfaces are preferable to planar or wedge fusion of surfaces
  • Reduction Sequence: Calcaneus, TN then CC
45
Q

SUMMARY

A 
Physiologic pronation
o	Normal motion 
o	Necessary for shock absorption
o	Arch may be high, low or average 
o	No soft tissue or joint morbidity
o	Responds well to orthotic / shoe therapy

Pathologic pronation
o Arch may be high, low or average
o Progressive subluxation
o Soft tissue degeneration
o Postural symptoms of foot, ankle, distal & proximal LE
o Joint degeneration
o Secondary to equinus, coalition or other
o Corrective treatment desirable before degenerative changes

#5 Surg (12 decks)

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