Applying the “Twisted Plate Theory” of Foot Stability to ... · 30/03/2015 2 The Twisted Plate Theory of Foot Stability Key Point: Twisting the plate will raise the medial longitudinal

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Douglas H. Richie, Jr. D.P.M.Seal Beach, California

[email protected]

Associate Professor of Podiatric Medicine, Western University of Health Sciences

Adjunct Associate Professor of Clinical Biomechanics, California School of Podiatric Medicine, Oakland CA

Applying the “Twisted Plate Theory” of Foot Stability to Flatfoot Surgery

PAC-PFOLA SYMPOSIUM, APRIL 2015

Fig. 7. The truss is a triangular structure. Under the load (W) the struts are under

compression ( C ) and the tie-rod (AB) is under tension (T). Any joint, for example point

A, is in vectorial equilibrium as indicated in the insert diagram. C compresses the point

A and T tenses the same point.

Twisted Plate TheoryFOOT VIEWED FROM BEHIND

Rear Plate twisted clockwise (inversion)

Front Plate twisted counter clockwise

The Twisted Plate

Twisting of the lamina pedis, or skeleton of the human foot

involves Eversion or Pronation of the forefoot or… Inversion

or Supination of the rearfoot

Un-twisting of the lamina pedis involves Inversion or Supination

of the forefoot or…Eversion or Pronation of the rearfoot

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The Twisted Plate Theory of Foot Stability

Key Point: Twisting the plate will raise the medial

longitudinal arch, plantarflex the First Ray, decrease strain

on the medial central band of the plantar aponeurosis, and

decompress and improve ROM of the 1st MTP.

First described by:MACCONAILL, M. A. (1945). The postural mechanism of the human foot.

Proceedings of the Royal Irish Academy 50, 265-278.

Introduces the term “lamina pedis” to describe the footplate

Twisted Plate Model of the Human Foot

And then again by:MACCONAILL, M. A. & BASMAJIAN, J. V. (1969). Muscles and Movements. A Basis for

Kinesiology. Baltimore: Williams & Wilkins.

And Finally:SARRAFIAN S.K. (1987) Functional characteristics of the foot and plantar aponeurosis

under tibiotalar loading. Foot and Ankle Int. 8 (1): 4-18.

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The Twisted Plate

Twisting of the lamina pedis follows the lateral rotation

of the head and next of the talus, which occurs in-utero

This valgus, or eversion rotation of the neck of the talus

results in pronation positioning of the forefoot on the rearfoot…

Twisting the plate

McCarthy, 1994

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• Nine fresh frozen specimens

• Axial load in static stance 225-900N

• 6 degree wedges: Medial & Lateral, RF & FF

• Strain in plantar fascia measured with

reluctance transducer

Kogler GF, Veer FB, Solomonidis SE, Paul JP: The influence of

medial and lateral placement of orthotic wedges on loading of the

plantar aponeurosis. Journal Bone Joint Surgery 81-A:1403, 1999

In-Vitro Study




Wedge under lateral forefoot decreased

strain (p<0.05)

Wedge under medial forefoot increased

strain (p<0.05)

Rearfoot wedges had no significant effect




Plantar Fascia Strain

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Effects of Medial & Lateral Wedges under the Foot

15 Male running subjects, asymptomatic

4 conditions w/foot inserts w/4.5 mm posting: Full Lateral, Full Medial, Half Lateral, Half Medial

COP data collected with PEDAR system

Results: Only the Full Lateral Insert caused a significant change in shift of center of pressure: this shift was towards the LATERAL SIDE

Nigg BM, Stergiou P, Cole G et al: Effect of shoe inserts on kinematics, center of pressure, and leg joint moments during running. Med Sci Sports Exerc 35(2): 314-319, 2003.

Van Gheluwe B, Dananberg HJ: Changes in Plantar Foot Pressure with In-Shoe Varus or Valgus Wedging. JAPMA 94(1) 1-11 2004

“Indeed, as displayed for forefoot wedging and for rearfoot wedging of a typical individual, the COP shifts more medially with a varus wedge and more laterally with a valgus wedge. Internal wedges behave in the opposite manner from externally applied wedges.”

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In the weight bearing foot:

Increase ground reaction forces under

metatarsals 4 and 5

Twisting the plate

Increase ground reaction forces under

metatarsals 1 and 2

Untwisting the plate

In the weight bearing foot:

(During loading phase of gait):

Congruent motion is communicated to the subtalar joint and the talus is

effectively screwed home into the acetabulum pedis, about the comparatively

upright subtalar axis, and the leg bones reflect this movement by showing

medial rotation.

As the full weight is thus applied to the- foot the lamina pedis becomes flattened

or untwisted and this plays its part in causing the centre of gravity to veer back

towards the other side. The major part of this untwisting movement occurs at the

calcaneocuboid joint - effectively the calcaneus is exorotated. The lamina pedis is

now in a close-packed position with the plantar calcaneocuboid (short plantar)

ligament, plantar calcaneonavicular (spring) ligament and bifurcated ligament all

tensed.

Other descriptions of the “Twisted Plate”

LEWIS, 0. J. (1980a). The joints of the evolving foot. I. The ankle joint. Journal of

Anatomy. 130, 527-543.

The Twisted Plate The lamina pedis becomes twisted upon itself as we compare primates

and humans:

In primates, the lamina pedis is a flat plat resting on the ground. The

calcaneus is lateral to the talus, on the same flat plane as the metatarsals.

The subtalar joint is oriented vertical, separating the horizontal

arrangement of the talus and the calcaneus

In humans, the lamina pedis is “twisted” i.e the calcaneus has become

“twisted” to move under or beneath the talus. This change occurs in-utero.

The subtalar joint complex is now horizontal, separating the vertically

oriented talus and calcaneu

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The Twisted Plate

Un-twisting the lamina pedis allows the human foot to assume

the appearance of the adult acquired flatfoot: Lowering of the

medial longitudinal arch, eversion of the calcaneus, widening of

the Talo-Calcaneal angle, supinatus deformity of the forefoot.

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Orangutan

ChimpAssembled Bonobo

Assembled

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Removing FF SuppinatusSuppinatus Uncorrected

Twisted Plate Theory:

How Can We Raise the Arch?

Evert the Forefoot:

Increase Ground Reaction Forces under Lateral Metatarsals

Invert the Rearfoot:

Increase Ground Reaction Forces under Medial Calcaneus

► Is there any other evidence that increasing pressure

under the lateral forefoot will raise the medial arch

and/or decrease strain in the plantar aponeurosis?

Answer: Look at studies of lateral column lengthening

for flatfoot correction


Lateral Forefoot wedging

Lengthen Lateral Column


How do we increase GRF under lateral metatarsals?

Otis JC, Deland JT, Kenneally S et al: Medial arch strain after lateral column lengthening: An in vitro study. Foot Ankle Int 20: 797-802. 1999

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Lateral column lengthening: Correction of Flatfoot

Corrects forefoot abduction

DuMontier, TA; Falicov, A; Mosca, V; Sangeorzan, B: Calcaneal lengthening: investigation of

deformity correction in a cadaver flatfoot model. Foot Ankle Int. 26:166 – 170, 2005.

Myerson, MS, Corrigan, J; Thompson, F; Schon, LC: Tendon transfer combined with calcaneal

osteotomy for treatment of posterior tibial tendon insufficiency: a radiological investigation.

Foot Ankle Int. 16:712 – 718, 1995

Sangeorzan, BJ; Mosca, V; Hansen, ST: Effect of calcaneal lengthening on relationships among

the hindfoot, midfoot, and forefoot. Foot Ankle 14:136 – 141, 1993.

Restore medial longitudinal arch

Increased talonavicular coverage

JH – s/p 3yrs Left Gastroc,

Evans

JH – s/p 3 yrs Left Gastroc,

Evans

PRE POS

T

Lateral column lengthening: Negative Effects

Increased forefoot varus

Increased lateral forefoot pressure

Lateral column pain

Fifth metatarsal stress fx

Davitt, JS; MacWilliams, BA; Armstrong, PF: Plantar pressure and radiographic changes after distal calcaneal

lengthening in children and adolescents. J. Pediatr. Orthop. 21:70 – 75, 2001.

Tien, TR; Parks, BG; Guyton, GP: Plantar pressures in the forefoot after lateral column lengthening: a cadaver study

comparing the Evans osteotomy and calcaneocuboid fusion. Foot Ankle Int. 26:520 – 525, 2005.

Davitt, JS; Morgan, JM: Stress fracture of the fifth metatarsal after Evans’ calcaneal osteotomy: a report of two cases.

Foot Ankle Int. 19:710 – 712, 1998

Medializing Calcaneal Osteotomy

Also Increases Lateral Forefoot Pressure

Hadfield, MH; Snyder, JW; Liacouras, PC; et al.: Effects of medializing calcaneal osteotomy on Achilles

tendon lengthening and plantar foot pressures. Foot Ankle Int. 24:523 – 529, 2003.

Hadfield, M; Snyder, J; Liacouras, P; et al.: The effects of a medializing calcaneal osteotomy with and

without superior translation on Achilles tendon elongation and plantar foot pressures. Foot Ankle Int.

26:365 – 370, 2005.


How do we increase GRF under medial hindfoot?

Medial Rearfoot wedging

Medializing Calcaneal Osteotomy

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Medial Calcaneal Displacement

Myerson MS, Badekas A, Schon LC: Treatment of stage II posterior tibial tendon deficiency with flexor digitorum longus tendon transfer and calcaneal osteotomy. Foot & Ankle Int, 25: 445-450

• 129 Patients.

• Mean follow up, 5.2 years post op

• 118 Patients entirely satisfied, 7 patients partially satisfied, 4 patients dissatisfied.

• 125 Patients (97%) experienced pain relief.

• 121 Patients (94%) showed improvement of function.

Resnick RB, Jahss MH, Choveka J et al: Deltoid ligament forces after tibialis posterior tendon rupture: effects of triple arthrodesis and calcaneal displacement osteotomies. Foot Ankle Int 16: 14-20, 1995

• After medial displacement calcaneal osteotomy, strain decreased at the attachment point of the deltoid ligament

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“The medial displacement calcaneal osteotomy resulted in decreased length and, likely, less tension in the spring ligament.”

Otis JC, Deland JT, Kenneally S et al: Medial arch strain after medial displacement calcaneal osteotomy: An in vitro study. Foot Ankle Int 20:222-226, 1999

“From these results, we concluded that reconstruction LCL provides more

correction of the longitudinal arch at the midfoot and overall realignment of the

medial column of the foot than a reconstruction with MTO.”

“This result establishes that the final correction achieved in the LCL group was

significantly greater than the one achieved in the MTO group.”

“In summary, reconstructions performed with LCL produced a greater change

in the realignment of a flexible flatfoot, maintained more of their initial

correction over time, and were associated with a lower incidence of additional

surgery than reconstructions with a MTO of the calcaneus.”

MDCO vs Evans Osteotomy: Comparison of Correction

Patrick M. Bolt, M.D.; Samuel Coy, M.D.; Brian C. Toolan, M.D. A Comparison of

Lateral Column Lengthening and Medial Translational Osteotomy of the Calcaneus

for the Reconstruction of Adult Acquired Flatfoot. Foot & Ankle International/Vol.

28, No. 11/November 2007

Answer: It has to do with ligament strain and motion of the

foot at joints other than the subtalar joint


► Why would lateral forefoot wedging and lateral column

lengthening not cause pronation of the foot at the subtalar joint?

Mosca, V.S. Calcaneal lengthening for valgus deformity of the hindfoot. Results in children

who had severe, symptomatic flatfoot and skewfoot. J. Bone Joint Surg. 77A:500-512, 1995.

Lateral Column Lengthening: Facilitate the Windlass??

Mosca has suggested that the effects of lengthening

of the lateral column results in elevation of the

longitudinal arch and correction of the valgus

deformity due to the windlass effect of the plantar

fascia.

In fact, the opposite:

“The original hypothesis was that these manipulations would result in increased

tension on the plantar fascia with elevation of the medial longitudinal arch

secondary to an increase in the windlass mechanism. The results obtained reveal

that tightening of the plantar fascia does not occur with either medial calcaneal

displacement or lateral column lengthening. Medial translation resulted in an

average of 1.1 mm of loosening of the plantar fascia. Lateral column lengthening

through the calcaneocuboid joint resulted in even more loosening of the plantar

fascia (average, 1.9 mm). Lateral column lengthening was shown to produce

statistically significantly looser plantar fascia than medial displacement.

MDCO and Evans: No increased tension on the plantar fascia!

Horton GA, Myerson MS, Parks BG, Park YW. Effect of calcaneal osteotomy and lateral

column lengthening on the plantar fascia: a biomechanical investigation. Foot Ankle Int.

1998 Jun;19(6):370-3.

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Calcaneal Lengthening Osteotomy

The navicular center of rotation is within the head of the talus. The

shape of the talar head is therefore important to the degree of deformity

correction.

The effective center of rotation of the cuboid is within the calcaneus and

is compatible with rotation about the long plantar ligament.

The bony architecture and the plantar soft tissues, including the long

plantar ligament and possibly the plantar talonavicular capsule and the

lateral portion of the calcaneonavicular ligament, appear to contribute to

the mechanism of deformity correction.

Timothy A. DuMontier, Alexis Falicov, Vincent Mosca, Bruce Sangeorzan. Calcaneal

Lengthening: Investigation of Deformity Correction in a Cadaver Flatfoot Model. Foot & Ankle

International/Vol. 26, No. 2/February 2005.

It has been suggested that the long plantar ligament is

important in the success of the calcaneal neck osteotomy

for correction of flatfoot.

Long Plantar Ligament

Sangeorzan, B.J., Mosca, V., and Hansen, S.T. Effect of calcaneal lengthening on

relationships among the hindfoot, midfoot, and forefoot. Foot Ankle, 14:136-141, 1993.

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Lateral Plantar Ligament (LPL)

“Thus after an Evans procedure, the lateral one-third of the LPL is

under maximum strain, the spring ligament is extremely lax, and the

medial band of the plantar fascia is also lax.”

“In addition, when shortening bony procedures to the medial column

are performed in addition to the Evans procedure, the rippling effect

may be compounded: even more laxity in the PF and spring ligament

could be created.”

DiNucci, KR, Christensen, JC, Christensen, Kris A: Biomechanical Consequences of

Lateral Column Lengthening of the Calcaneus: Part I. Long Plantar Ligament Strain.

Journal of Foot Ankle Surg 43: 10-15 2004

DiNucci, KR, Christensen, JC, Christensen, Kris A: Biomechanical Consequences of Lateral Column Lengthening of the Calcaneus: Part I. Long Plantar Ligament Strain. Journal of Foot Ankle Surg 43: 10-15 2004

Before Evans Graft After Evans 8mm Wedge


Key Point: With the foot resting on the ground, inverting the hindfoot will

increase ground reaction forces (plantar pressure) against the 4th and 5th

metatarsal heads.

Applying a 6 degree lateral (valgus) wedge across the forefoot

will increase ground reaction forces (plantar pressure) against the 4th and

5th metatarsal heads.

A calcaneal lengthening osteotomy will increase ground

reaction forces (=plantar pressure) against the 4th and 5th metatarsal

heads.


Key Point: Increasing plantar pressure against the

4th and 5th metatarsal heads will:

- Increase tension in the long plantar ligament

- Close-pack or “lock” the Calcaneal-Cuboid Joint


Key Point: With the foot resting on the ground, everting the hindfoot will

increase ground reaction forces (plantar pressure) against the First

metatarsal head.

Applying a 6 degree medial (varus) wedge across the forefoot will increase

ground reaction forces (plantar pressure) against the First metatarsal head.

A Cotton osteotomy or plantar flexion osteotomy anywhere along the First

Ray will increase ground reaction forces (plantar pressure) against the First

metatarsal head.

Solution to Increased Lateral Forefoot Pressure:

Plantarflexion, opening wedge osteotomy

(Cotton) of the medial cuneiform

Hirose, CB; Johnson, JE: Plantarflexion opening wedge medial cuneiform osteotomy for correction of fixed

forefoot varus associated with flatfoot deformity. Foot Ankle Int. 25:568 – 574, 2004.

Johnson, JE: Plantarflexion opening wedge cuneiform-1 osteotomy for correction of fixed forefoot varus.

Tech. Foot Ankle Surg. 3:2 – 8, 2004.

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Aaron T. Scott, M.D.; Travis M. Hendry, M.D.; Joseph M. Iaquinto, M.S.; Plantar Pressure Analysis in

Cadaver Feet After Bony Procedures Commonly Used in the Treatment of Stage II Posterior Tibial

Tendon Insufficiency. Foot and Ankle Int. 28: 1143-1153, 2007.

Methods: Eight matched pairs of cadaver lower extremities were

axially loaded onto a TekScan HR Mat. (TekScan, Inc., South Boston,

MA) After intact testing, each specimen had a lateral column

lengthening (either a calcaneocuboid distraction arthrodesis [CCDA]

or Evans procedure), a medializing calcaneal osteotomy (MCO), and

a plantarflexion (Cotton) osteotomy of the medial cuneiform. The

measured plantar pressures were divided into three forefoot regions,

two midfoot regions, and two hindfoot regions. For each region,

average pressure, peak pressure, and contact area data were collected.

Aaron T. Scott, M.D.; Travis M. Hendry, M.D.; Joseph M. Iaquinto, M.S.;

Plantar Pressure Analysis in Cadaver Feet After Bony Procedures Commonly

Used in the Treatment of Stage II Posterior Tibial Tendon Insufficiency. Foot

and Ankle Int. 28: 1143-1153, 2007.

Conclusions: The present study demonstrated increased lateral forefoot

pressures after a combined lateral column lengthening and MCO and does not

support the idea that a Cotton osteotomy significantly reduces loading of the

lateral forefoot.

Clinical Relevance: The incidence of lateral forefoot pain and fifth metatarsal

stress fractures subsequent to either lateral column lengthening procedure

may not significantly decline after a Cotton osteotomy.

Cotton Osteotomy: Improved Alignment?

Radiographic and Pedobarographic Comparison of Femoral Head Allograft Versus

Block Plate with Dorsal Opening Wedge Medial Cuneiform Osteotomy: A

Biomechanical Study

Alan C. League, MD; Brent G. Parks, MSc; Lew C. Schon, MD Foot & Ankle

International/Vol. 29, No. 9/September 2008

“Radiographic change in this model was inconclusive.

The small radiographic differences noted in this study

fall within the 2- to 3-degree variation in angle

measurements taken by different examiners.”

STUDIES SHOW NO IMPROVEMENT OF

METATARSUS PRIMUS ELEVATUS OR HALLUX

EQUINUS MEASUREMENTS AFTER DISTAL FIRST

METATARSAL HEAD OSTEOTOMIES

Laakmann G, Green RM, Green DR: “The modified Waterman procedure: A

preliminary Retrospective Study” in Reconstructive Surgery of the Foot and

Leg: Update ’95, ed by CA Camasta, p 128, The Podiatry Institute, Tucker, BA,

1995.

Dickerson JB, Green R, Gren DR: Long-term follow-up of the Green-

Waterman osteotomy for hallux limitus. JAPMA 92: 543, 2002.

Roukis TS, Jacobs PM, Dawson DM, ET AL: A prospective comparison of

clinical, radiographic, and intraoperative features of hallux rigidus: short-term

follow-up and analysis. J Foot Ankle Surg 41: 158, 2002.

The Twisted Plate

When the rearfoot inverts, ground reaction force increases under mets 4 & 5:

Forefoot pronates, tension increases in long and short plantar ligaments,

medial arch raises, first ray passively plantarflexes: Twisting the Plate

When the rearfoot everts, ground reaction force increases under 1st Met:

First ray dorsiflexes, forefoot supinates : Un-twisting the plate

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Untwisting the Plate

Increasing GRF under the First

Metatarsal will not raise the arch of the foot

Untwisting the Plate: Theory

Medial column procedures intending to increase GRF under

the First Metatarsal will not change alignment of the arch

because the joints of the twisted plate will react with a

reciprocal lowering of the arch. Only when arthrodesis is

performed will the twisted plate mechanism be nullified.

Raising the Medial Longitudinal ArchRole of the Ligaments

Spring Ligament does not increase tension after calcaneal lengthening

Otis, JC; Deland, JT; Kenneally, S: Medial arch strain after lateral column lengthening: An in vitro

study. Foot Ankle Int. 20:12,797 –802, 1999.

Plantar Fascia reduces tension after calcaneal lengthening

Horton GA, Myerson MS, Parks BG, Park YW. Effect of calcaneal osteotomy and lateral column

lengthening on the plantar fascia: a biomechanical investigation.Foot Ankle Int. 1998 Jun;19(6):370-3.

Increased tension in the long plantar ligament is the key to

deformity correction with lateral column lengthening

Timothy A. DuMontier, Alexis Falicov, Vincent Mosca, Bruce Sangeorzan. Calcaneal Lengthening:

Investigation of Deformity Correction in a Cadaver Flatfoot Model. Foot & Ankle International/Vol.

26, No. 2/February 2005.

Conclusion: Interventions which INCREASE STRAIN on the Long Plantar ligament

will raise the arch of the human foot.

Answer: Yes. Numerous studies have verified.


Do Lateral Column Lengthening Procedures improve alignment by:

► Change forefoot alignment to increase supination moment at the STJ?

► Increase pressure (GRF) under the lateral metatarsals?

Answer: No. At least no evidence thus far

Essential Key Point!

Any measure which increases plantar pressure at the 1st metatarsal will

deliver dorsiflexion moment, resulting in dorsiflexion motion across the key

joints of the First Ray. As long as there is motion available in the N-C and

Med Cun-1st Met joints, any surgical procedure which increases pressure

against the plantar surface of the first metatarsal will cause an immediate

dorsiflexion of the first ray back to its original state of equilibrium.

In the lateral column, increased plantar pressure under 4th and 5th

metatarsals does not cause dorsiflexion motion of the Calc-Cuboid or

Cuboid-4th and 5th mets because these joints are inherently stable.


Key Point: Increasing pressure under the plantar surface of the 4th and

5th metatarsal heads will decrease pressure under the 1st metatarsal head

due to:

-Direct mechanical offloading (the more pressure you put

under one side of the foot, the less pressure on the other side)

-Tensioning of the long plantar ligament, which raises the

Calcaneal inclination angle, inverts the hindfoot, raises the medial

longitudinal arch

….in other words, this increased pressure

under mets 4 and 5 “Twists the Plate”!!


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- There is decreased tension in the medial slip of the central band

of the plantar aponeurosis.

- Improved dorsiflexion range of motion of the 1st MTP

- The medial longitudinal arch will elevate

Key Point: Decreasing plantar pressure under the 1st metatarsal

head will allow the First Ray to passively plantarflex.

When the First Ray plantarflexes:


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Applying the “Twisted Plate Theory” of Foot Stability to ... · 30/03/2015 2 The Twisted Plate Theory of Foot Stability Key Point: Twisting the plate will raise the medial longitudinal