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#2 Surg > 20 and 21 - Rearfoot Varus and Valgus > Flashcards

20 and 21 - Rearfoot Varus and Valgus Flashcards

1
Q

Rearfoot varus

A
  • A positional abnormality which causes the calcaneus to be inverted to the ground when the subtalar joint (STJ) is in the neutral position (determined by measuring tibial influence and tibial position)
  • Inversion of rearfoot (calcaneus) relative to the ground when the STJ is in neutral
  • Positional deformity, corrected by changes in joint position
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2
Q

How common is rearfoot varus?

A
  • If the normal range is 0° to 7° of varus, then 7/8th’s of the population has a rearfoot varus deformity (because anything other than 0° is pathology)
  • Called a positional deformity because the type of RF varus is dependent upon the amount of soft tissue motion of the STJ in eversion to try and correct the deformity (compensation by soft tissue)
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3
Q

Three etiologies of rearfoot varus

A
  • Tibial varum
  • Subtalar varum
  • Calcaneal varum
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4
Q

Tibial varum is caused by

A

o Genu varum (bow-legged)
o Blount’s disease (premature closure of proximal tibial epiphysis, lateral growth continues causing the varus shape at knee)
o Failure of tibia to straighten from the infantile position

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5
Q

Subtalar varum is caused by

A

o Uneven epiphyseal growth
o Wedge shaped talus
o Retention of varus calcaneal torsion at birth

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6
Q

Calcaneal varum is caused by

A

o Improper development

o Malaligned calcaneal fracture

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7
Q

Which of the following can be an etiology of RF varus?
o Tibia varum
o Blount’s disease
o Genu varum
o Malaligned calcaneal fracture resulting in an everted position
o Failure of calcaneus to rotate from its birth position

A

1, 2, 3, 5

NOT 4 - calcaneus is inverted in rearfoot varum, not everted

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8
Q

3 classifications of rearfoot varus deformities

A
  • Uncompensated rearfoot varus
  • Partially compensated rearfoot varus
  • Compensated rearfoot varus
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9
Q

Rule for compensation for rearfoot varus

A

All RF varus deformities compensate by attempting to get the heel to vertical in Resting Calcaneal Stance Position (RCSP), but will NEVER exceed heel vertical
o RF varus is a deformity, abnormality, or pathology and the foot seeks to get its medial aspect on the ground

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10
Q

How to calculate whether rearfoot varus has compensated or not

A

Compensation would be present by reaching heel vertical instance
o Subtract the amount of STJ eversion from the amount of tibial varum
o STJ must be placed in neutral position while standing to calculate amount of tibial varum

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11
Q

Most common compensation

A

o Eversion of the STJ to get heel to vertical –> compensate for INVERSION w/ EVERSION

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12
Q

Other forms of compensation

A

Occasionally you may find a patient who plantarflexes the 1st ray to get the medial side of the foot to the ground (much more common with forefoot varus)

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13
Q

STJ eversion

A
  • The amount of STJ eversion is the amount of eversion you measure (with the patient NWB) from heel vertical after you bisect the lower leg and the heel
  • The amount of STJ eversion from neutral position is 1/3 of the total range of motion of the STJ
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14
Q

Calculate STJ neutral

  • 10° of eversion of the STJ
  • 26° of inversion of the STJ
A
  • STJ neutral equals 1/3 of the total range of motion from the maximally everted position
  • STJ neutral equals 2° of varus
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15
Q

Eversion from vertical vs eversion from neutral

  • 10° of eversion of the STJ
  • 26° of inversion of the STJ
A
  • In this case, you have 10° of eversion of the STJ from vertical, but 12° from STJ neutral position
  • You still will be able to evert the heel maximally in both cases to 10° past vertical
  • For RF varus, the tibial stance position will give you the amount of STJ eversion (?)
  • Remember: to calculate tibial stance position, we must place the STJ in neutral position while standing
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16
Q

Uncompensated rearfoot varus

A
  • Heel functions in an inverted position
  • The amount of tibial varum is greater than the amount of calcaneal eversion available through compensatory STJ pronation
  • In uncompensated RF varus, STJ eversion is 0° - NO compensation
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17
Q

Example of uncompensated rearfoot varus

  • 10 degrees of tibial varum
  • 20 degrees STJ inversion
  • 0 degrees of STJ eversion
A
  • As a result, the heel is at 10 degrees varus at relaxed calcaneal stance position (RCSP)
  • This is the maximally pronated position of this patient’s foot, even though it is varus
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18
Q

Signs and symptoms of uncompensated rearfoot varus

A

This will cause LATERAL strain on the foot and ankle. Can impact:

  • Skin
  • Muscle/fascia
  • Osseous
  • Genu valgum and ankle valgus
  • Gait
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19
Q

Skin problems in rearfoot varus

A

o Callus sub 1st, 4th, 5th metaheads
o Callus sub 5th metabase
o Corn 2nd toe

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20
Q

Muscle/fascia problems in rearfoot varus

A

o Peroneal tendonitis
o Plantar fasciitis
o Poor shock absorption

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21
Q

Osseous problems in rearfoot varus

A 
o	Heel spur
o	Hammertoe,  2nd
o	Lateral ankle instability
o	Plantarflexed 1st ray
o	Retrocalcaneal exostosis
o	Sesamoiditis
o	Tailor’s bunion
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22
Q

Genu valgum and ankle valgus in rearfoot varus

A

o Due to compensation for the varus

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23
Q

Gait in rearfoot varus

A

o Apropulsive – because there is not a lot of “toe-off”

24
Q

Partially compensated rearfoot varus

A
  • The degree of tibial varum is greater than the calcaneal eversion available with STJ pronation
  • Heel is inverted relative to the ground, but not as inverted as the degree of tibial varum
25
Q

Example of partially compensated reafoot varus

A
  • 10 degrees of tibial varum, 20 degrees of inversion of STJ, 5 degrees of eversion of STJ
  • As a result, the heel is at 5 degrees varus at relaxed calcaneal stance position
  • This is the maximally pronated position of this patient’s foot, even though it is in varus
  • Calculation: 10° of tibial varus - 5° of eversion of the STJ = 5° RF varus
26
Q

Signs and symptoms of a partially compensated rearfoot varus

A
  • Signs and symptoms same as uncompensated RF varus (lateral foot and ankle strain)
27
Q

Compensation trends in rearfoot varus

A
  • The degree of tibial varum is equal to the amount of STJ pronation available
  • Heel assumes a vertical position relative to the ground
  • Based on analysis of CPMS’ students in the last five 3rd year classes, an uncompensated or partially compensated RF varus deformity is seen less than 3% of the time
  • Therefore, it is extremely uncommon to find a heel that is unable to reach vertical position in weightbearing if there is no accompanying forefoot deformity
  • This can be expected by reviewing normal ranges of motion and tibial position
  • Normal tibial stance is 0 to 7° of varus
  • Normal total range of the STJ is 30°, of which 1/3 of the motion is eversion or 10°
  • Therefore, most people will have enough eversion to get to heel vertical (even with a maximum of 7° of tibial varum, you will usually have 10° of STJ eversion)
28
Q

Example of compensated rearfoot varus (1)

A

o 10 degrees of tibial varum
o 20 degrees of STJ inversion
o 10 degrees of STJ eversion

As a result, the heel is in a vertical position relative to the ground

29
Q

Example of compensated rearfoot varus (2)

A

A fully compensated RF varus deformity will only get to heel vertical, even if it has more available STJ eversion
o 10° tibial varum
o 20° STJ inversion
o 13° STJ eversion

The RCSP is 0°, even though there is still 3° of eversion still available

30
Q

Overall patient outcome in a compensated rearfoot varus

A
  • Least abnormal of the RF varus deformities, but can lead to forefoot hypermobility secondary to delayed resupination in gait
  • To keep the forefoot in total contact with the ground, the STJ needs to pronate up to the time of heel lift (38% of stance phase)
  • However, need to start resupination at about 25% of stance phase of gait
  • Thus, the foot never gets back to a supinated position in propulsion and remains a mobile adapter in propulsion
  • The forefoot is unstable in propulsion leading to shearing calluses
31
Q

“Root Theory”

A
  • When you make an orthosis for someone with a rearfoot varus, post the rearfoot the same number of degrees as the deformity to prevent any compensatory change
32
Q

Which of the following conditions is associated with a partially compensated RF varus deformity?
o Tibia varum of 7° and STJ eversion of 4°
o Tibia varum of 4° and STJ eversion of 7°
o Tibia varum of 7° and STJ eversion of 7°
o Tibia valgum of 4° and STJ eversion of 4°
o Tibia varum of 4° and STJ eversion of 5°

A

1

33
Q

Now we are moving on to rearfoot valgus…

A

Just an FYI

34
Q

Rearfoot valgus

A
  • A structural abnormality which causes the calcaneus to be everted to the ground when the subtalar joint (STJ) is in the neutral position.
  • Extremely rare deformity
  • Not to be confused with genu valgum, calcaneovalgus, or rigid flatfoot deformities (vertical talus, peroneal spastic flatfoot)
  • If you measure valgus, and not varus, for the tibial position, you have probably measured incorrectly (Normal tibial position is 0° to 7° varus)
35
Q

Cause of rearfoot valgus

A

Can be due to traumatic injury or congenital deformity
o May see it in acquired genu valgum, but it is not the tibia, itself, which is in valgus alignment (unlike the tibia being in a varus alignment with RF varus)

36
Q

Compensation of rearfoot valgus

A
  • Called structural because there is no soft tissue motion of the STJ to correct the deformity by inverting the heel towards vertical
  • There is no designation of compensated, partially compensated, or uncompensated because it is a deformity that does not correct itself
  • There is no rule of compensation for RF valgus… This is because the heel cannot invert in midstance once it everts past heel vertical and is in contact with the ground
  • It will invert at heel off
  • This deformity cannot be corrected by changing heel position
37
Q

Gait with rearfoot valgus deformity

A
  • Ground reaction force directed upward against heel is centered lateral to the center of mass of the calcaneus
  • Force exerted downward against the talus is located medial to the center of mass of calcaneus
  • End result is an eversion moment causing calcaneus to evert
38
Q

Resting calcaneal stance position in rearfoot valgus deformity

A

In all cases of rearfoot valgus the RCSP will also be in valgus

Exact degrees in valgus is often unknown, but can be predicted as follows:

  • Whenever the heel is able to evert past 3°, it may evert its complete amount of STJ eversion or until approximately 13° of eversion, whichever comes first
  • It cannot go past 13° of eversion, due to normal foot anatomy – at 13° of heel eversion, the navicular strikes the ground and prevents any further heel motion
39
Q

Example of rearfoot valgus deformity

A
  • Think of the heel as a cup with a curved bottom
  • It will not tip over if it does not exceed a valgus tilt of 3°
  • When it exceeds 3°, it MAY tip over until it strikes the ground
  • You cannot evert past vertical more than 13°, because that is the point where the navicular will rest on the ground
  • The navicular in this position will prevent any further eversion of the heel
40
Q

Calculate resting calcaneal stance position

- STJ neutral of 3° valgus and STJ eversion of 15°

A

o RCSP of 3° everted

41
Q

Calculate resting calcaneal stance position

- STJ neutral of 5° valgus and STJ eversion of 7 °

A

o RCSP of 5° everted to 7° everted

42
Q

Calculate resting calcaneal stance position

- STJ neutral of 5° of valgus and STJ eversion of 15°

A

o RCSP of 5° everted to 13° everted

43
Q

Orthosis for rearfoot valgus

A
  • When you make an orthosis for someone with rearfoot valgus (e.g., STJ arthritis with STJ fixed in a valgus position), the neutral position will be in valgus, so the orthosis must have a rearfoot post in valgus
  • Patient could not tolerate a heel in vertical on the orthosis
  • **Called casting in a “pronated position” **
    o With the heel everted – can’t put the patient in neutral
44
Q 
A patient has a STJ neutral position of 7° valgus.  The amount of STJ eversion is 10°.  The RCSP is:
o	7° valgus
o	17° valgus
o	0°
o	7 to 10° valgus
A

4

45
Q

Points to remember***

KNOW THIS

A
  • Rearfoot varus and valgus are deformities which can only be determined with the patient in WEIGHTBEARING***
  • Forefoot varus and valgus are deformities which can only be determined with the patient in NWB
46
Q

Rule of compensation when there is BOTH a forefoot and a rearfoot deformity

A

When there is a combination of RF and FF deformities, the rearfoot deformity will compensate BEFORE the forefoot deformity
o The foot always tries to get itself on the ground
o Considering how the foot will compensate
o The FIRST deformity that it corrects is ALWAYS the rearfoot varus, then depending upon how much motion is left over will determine the next positon
o Rearfoot varus is corrected by the STJ

47
Q

Clinical summary of tibial stance position

A

If you measure a tibial stance position in valgus, you have measured incorrectly
o Normal tibial position is 0° to 7° varus

48
Q

Clinical summary of compensation for rearfoot varus

A
  • A RF varus deformity causes a patient to walk in varus and the foot needs to compensate to keep the medial aspect of the foot on the ground
  • Almost all RF varus deformities are fully compensated
  • Almost all of your patients will be able to get to an RCSP of 0° (or vertical heel) because almost all will have 10° of eversion of the STJ
  • A fully compensated RF varus causes a minimum of pathological symptoms
49
Q

Clinical summary of orthosis for rearfoot varus

A

As a result of a rearfoot varus always being fully compensated, assuming that the only deformity is a fully compensated RF varus, make the orthosis so that the heel is vertical to the ground because it is the position of most comfort

50
Q

Clinical summary of orthosis for uncompensated or partially compensated rearfoot varus

A

If you have an uncompensated or compensated RF varus (which are rare), post (or tilt) the heel the same number of degrees as the RF varus
o Patient cannot get to heel vertical with these deformities
o If you try to force the heel to vertical, you will cause pain

51
Q

Clinical summary of rearfoot valgus

A
  • RF valgus is very rare-seen in cases of trauma or congenital malformations
  • If the RF valgus is greater than 3° of eversion (or valgus), the foot may go to its maximum everted position allowed by the number of degrees of eversion available at the STJ
    o However, it can never exceed 13° of eversion because the navicular strikes the ground and prevents any further eversion
52
Q

Clinical summary of orthosis for rearfoot valgus

A

When making an orthosis for someone with RF valgus, you will post (or tilt) the heel the same number of degrees of eversion as the RCSP

53
Q

Clinical summary of patient pathology

A
  • Patients will rarely exhibit one foot, ankle, or leg pathology
  • As a result, there will be more than just a RF varus deformity
  • But, the RF varus is always the first pathology that the foot will correct before it corrects for any others
54
Q

CLINICAL PEARL

A

o You will rarely measure tibial position, since almost everyone has a RF varus which is fully compensated

55
Q

5 biomechanical tests you will actually do on your patients

A 
o	1 = Forefoot varus or valgus 
o	2 - Equinus
o	3 - Genu varum or genu valgum
o	4 = Predominance of internal or external hip rotation
o	5 = Limb length inequality

THROW OUT REAR FOOT ASSESSMENT – we already know what it is going to do

#2 Surg (14 decks)

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