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Archive for July, 2019

ICB Lower limb biomechanics

One issue that often surfaces when using orthotic products is, whether there is a need to heat mould and apply additions or grind and modify the orthotics?

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The question of heat moulding often arises and the answer is simply, it may not be necessary in every situation. However, heat moulding does assist in avoiding patient compliance issues.

Using additions to improve the treatment of the basic orthotic foot bed, is one, in which many practitioners are not that familiar with in the modification process.

Most additions are used to treat specific conditions by providing the support which has been lost, such as: metatarsal domes to support the transverse arch or a heel lift to support a short leg.

Many orthotic manufacturers promote their products as being one which can be taken from the display pack and placed in the shoe with no further alteration needed. This may be so for some patients, however, simple adjustments may provide the necessary comfort and treatment result the patient requires.

A key element to achieving a satisfactory treatment commences with checking that the ‘off the shelf’ orthotic contains at least a basic rearfoot varus angle to enable correct alignment for the patient.

Products available in pharmacies often only provide arch support without attending to rearfoot (calcaneal) control.

Practitioners should check the rearfoot position by simply viewing and where necessary measuring, using a biomechanical protractor.
Measuring, using a biomechanical protractor.

ICB heat mouldable orthotics exhibit a 50 rearfoot varus post to align the calcaneus with the average tibial varum angle, thus placing the foot into the patients ideal position.

ICB heat mouldable orthotics

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Reducing excess pronation can have substantial benefits, such as reducing internal tibial rotation.

ICB Orthotics Reducing Pronation

The product that a practitioner chooses to use, should be one which is easy to modify and alter, thus providing the necessary treatment requirements. For example, ability to incorporate an intrinsic dome into the orthotic device, thus providing the patient with a product with increased functionality or provide more comfort to the wearer.

Orthotic Heat Moulded

Use a heat gun to mould the dome into the plantar surface. (see other videos on Youtube)

Simple add on additions, such as, medial flanges can reduce medial rubbing of the foot on the shoe or provide increased support for patients such as CP suffers and excessive pronators can be quite useful.

ICB orthotic medial flange

For practitioners who want to modify the actual orthotic by grinding , there are many simple adjustments that can be made, such as a deflection for a plantarflexed 1st . (see below)

Orthotic modified by grinding

Pictured below is a 1st metatarsal deflection for a 2/3 or 3/4 length orthotic.
1st metatarsal deflection for a three quarter length orthotic

The ability to adjust and modify the product within the clinic can be a great asset. The product should have the ability to be modified by either application of heat (using a heat gun) and also be a material that can be ground and shaped using either bench grinders or hand grinders.

Modifying an Orthotic

(above) Deflection for dropped metatarsal heads using heat and a spoon to create a depression .

For those practitioners with higher hand skills the grinding option is fast and extremely effective.

One very useful modification is the use of a full length ICB orthotic product to fashion a Morton’s ramp in which toe separator is an incorporated feature.

The steps to creating this modification are as follows:

Step 1
Mark the distal position of the ramp, 5mm distal to the hallux.

Modifying Orthotics

Step 2

Mark out the Morton’s ramp ensuring that it sits between the hallux and the 2nd phalange.

Mortons Ramp

Step 3

Add the toe separator shape and cut to shape.

Toe Separator

Step 4

Use the heat gun and the grinder to position the toe separator and smooth down the edges.
ICB Heat Gun

ICB Heat Moulded Orthotic

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ICB Superior Biomechanics

When practitioners use orthotic therapy , there are a number of considerations that should be considered.

1) Assessing the patient and ‘getting it right’ !

2) Deciding if multiple orthotic devices will be needed to treat the patients condition.

3) Choosing the right orthotic style to fit in the patients shoe wear.

The assessment is crucial. Overlooking or failing to assess adequately, will certainly affect the efficacy of the prescribed device.

Issues such as unilateral excessive pronation or lateral ankle knee and hip pain can often indicate underlying biomechanical issues that should be pursued and addressed.

Often more than one type of device may be required to meet the needs of the patient and assist the practitioners suggested treatment. Treatment could involve a pair of orthotics for the cross trainer shoe and a further pair for high heeled shoe wear.

One consideration that has been driven by fashion is how to treat patients who wear shoes such as ballet flats!

Ballet Flat Shoes

Of course this style is not ideal and the patient needs to be made aware of that fact, however, patients continue to use the style and expect that they can receive a treatment result from orthotics.

The orthotic device will never be able to treat effectively when wearing this style . All a practitioner can do is to remind the patient of this and then prescribe an orthotic style that can , in some measure, provide the wearer with a degree of treatment and relief from the assessed condition.

ICB has a product that is very thin and able to be used in the ballet style as it does not feature a heel cup and therefore reduced heel slippage.

ICB High Heel Orthotic

This design was developed for High heel shoe wear and there-fore has a reduced rearfoot varus angle to allow fr the supination effect when worn in shoes with heels higher than 25mm.

ICB Rearfoot Addition

When prescribing for ballet flats it is advised that additional rearfoot varus control will be required to assist in reducing calcaneal pronation (eversion) .

Rearfoot ballet flats

ICB recommends that a 2 or 4 degree Rearfoot Varus addition be used to invert the rearfoot and compensate for the reduced intrinsic rearfoot in the High Heel orthotic model.

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ICB Lower limb biomechanics

The topic of Forefoot valgus is an interesting one due to the confusion that often arises as to whether it is an actual Forefoot Valgus or as is often the case a misdiagnosed Plantarflexed 1st and vice versa.

A forefoot Valgus deformity can be defined as ‘When the plantar plane of the forefoot remains everted relative to the plantar plane of the rearfoot when the sub talar joint is in the neutral (STJN) or patients ideal position.

Biomechanical protractor

Conjecture often arises as to whether the condition is solely genetic or acquired.

Forefoot Valgus has been described as a position in which a constant structural eversion of the forefoot exists and presents as the most common structural or positional deformity in the forefoot.

It is an everted position of the forefoot relative to the rearfoot at the level of the midtarsal joint. Inversion of the lateral column of the foot must occur to allow the forefoot to move to a pronated position during the midstance and then resupinate during the propulsive phases of gait.

forefoot valgus condition

There are generally two forms of forefoot valgus referred to in most texts:

1. Flexible forefoot valgus – This exists where there is sufficient flexibility in the midtarsal joint to allow the lateral column of the foot to reach the supportive surface during the stance phase of gait. The heel may function perpendicularly, but the amount of compensation that occurs leads to an unstable gait with late pronation through midstance into propulsion.

2. Rigid forefoot valgus – Where the range of motion in the midtarsal joint is not enough to allow the lateral column of the foot to touch the ground, rearfoot supination compensation is required to allow lateral strike and gait progression. This is a rarely seen condition clinically.

Generally the following issues are observed in Forefoot Valgus conditions or anomalies.

In the case of acquired it may be the result of surgery or as a compensation due to other issues which present and mechanically can present as rigid or functional.

Forefoot Valgus feet usually experience Excessive supination at the STJ accompanied by external rotation of the leg with resultant lateral instability of the knee, ankle and Sub Talar Joint. Forefoot Valgus feet will often present as a pes cavus structure exhibiting a loss of shock absorption mechanisms in lower limb with induced lower-back, hip, knee and shin pathologies.

The 1st MTPJ unlocks when supinated, with resultant forefoot hypermobility. A common com pensation is that a Plantarflexed  1st will present with the forefoot valgus to allow the 1st MTPJ to plantarflex to gain ground contact and thereby enabling gait positioning and toe off to take place.

Another common condition that may accompany the Forefoot valgus is a Tailor’s bunion and other conditions such as Plantar digital neuritis. Lateral Plantar fasciitis pain and Medial Sesamoiditis can occur together with Compensatory calcaneal (Sub Talar Joint ) pronation leading to Haglund’s deformity.

However when assessing often the forefoot valgus is misdiagnosed as a Plantarflexed 1st Metatarsal whereas both conditions can occur at times, in combination.

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plantar flexed metatarsal

A plantar flexed 1st occurs when the 1st Metatarsal joint sits plantarflexed to the lesser metatarsals, when the subtalar joint is in neutral. It can be either mobile of fixed (osseous).

Forefoot Valgus assessment

When assessing Forefoot Valgus commence by establishing the neutral or patients ideal position in supine Use the Anterior alignment to identify the neutral position.

Use the Left hand on the patients Left foot to ‘feel’ for Talo navicular congruity, whilst observing the Anterior Alignment position using ICB AAM technique.

Dorsiflex the 4th and 5th metatarsal Phalengeal joint to resistance whilst maintaining 10°of plantarflexion of the foot.

This is the most crucial part as, in assessment, one should not dorsiflex the foot past the point of resistance as this can ‘manufacture’ or create a forefoot valgus where none.exists

Observe the Anterior alignment ensuring that the 2nd metatarsal head is aligned with the Bisection point of the Talonavicular reference points and the Tibial crest on the lower 1/3 of the leg.

Compare rearfoot plane and forefoot plane and measure the amount of posting that needs to be applied to the orthotic using an ICB Biomechanical protractor. (see below) As a general rule, post only 1/2 the measured amount, or use the posting formula ouline in The Orthotic Solution book page 161 and 201.

To check for Plantarflexed 1st once you have dorsiflexed to resistance, take hold of the lesser metatarsals and maintain that position whilst

assessment for plantarflexed 1st

completing the assessment for plantarflexed 1st i.e. palpate the 1st MTPJ 5mm dorsiflexed to 5mm Plantarflexed whilst holding the lesser metatarsals in the Valgus position

See also: The Orthotic Solution book  Pages 34, 77, 160, 201

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ICB Lower limb biomechanics

A common complaint amongst patient’s who have been prescribed foot orthotics is ‘pain in the arch’.
This type of pain can be the result of 4 common issues:

1) Pain can be due calcification (similar to dupuytren’s contracture) or a fibroma in the body of the Plantar Fascia, or a Ganglion cyst may be present. Dupuytren’s contracture in the fascia of the foot is called Ledderhose disease, or plantar fascial fibromatosis, and is sometimes associated with plantar fasciitis.

Arch pain when wearing orthotics

A ganglion cyst is a tumor or swelling on top of a joint or the covering of a tendon (tissue that connects muscle to bone). Ganglion cysts are among the most common benign soft-tissue masses. Although they most often occur on the wrist, they also frequently develop on the foot usually on the top, but can also occur on the plantar surface. Ganglion cysts vary in size, may get smaller and larger and may even disappear completely, only to return at another time. The exact cause of ganglion cysts is un-known, they may arise from trauma whether a single event or repetitive microtrauma.

Foot Cyst

TREATMENT: If there is calcification in the fascia, use manual therapy to break it down. For a fibroma or Ganglion cyst, a deflection will need to be heated into the orthotic using a deflective device such as a spoon, to accommodate and relieve any pressure from this area.

 

Watch this video on youtube on how to use heat to make deflection on an ICB Orthotic. 

Using heat on ICB Orthotic.

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2) Plantar fasciitis pain can be experienced at the attachment to the calcaneus. It is also refered to as Plantar Fasciosis a degenerative syndrome of the plantar fascia resulting from repeated trauma at its origin on the calcaneus1.

TREATMENT: Control rearfoot pronation using orthotics with intrinsic rearfoot posting to realign the feet to the Subtalar Joint Neutral Position (STJN).

If additional inversion is required to control and achieve STJN, add extra rearfoot wedges (2° or 4°) to provide additional Calcaneal control2. 

ICB Rearfoot Varus Addition

Orthotic with Rearfoot Varus Addition

A medial arch infill can also be applied to the orthotic to provide increased arch support.

Medial Arch Infill on ICB Orthotic

3) The Plantar fascia may be tight, and during gait (at mid stance to toe-off), compressing into the medial longitudinal arch of the orthotic causing discomfort and pain. To test for a tight fascia use the ‘Windlass Test’ (pictured below).

Plantar fascia - Windlass Test

TREATMENT: Create a plantar fascial ‘relief’ or ‘groove’ in the arch of the orthotic using heat or by grinding the orthotic. Place the groove 1 cm from the medial edge through the arch contour. Watch video here.

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Create a plantar fascial 'relief' on ICB Orthotic

4) The patient may exhibit unilateral excessive pronation as a possible compensation or due to plantar injury.

excessive pronation

TREATMENT: Unilateral arch pain can be associated with a leg length differencedue to long leg compensatory excessive pronation. If a structural leg length discrepancy is identified, a heel lift will need to applied to the orthotic on the shorter leg.

ICB Orthotic Heel Lift

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References:

1. CORNWALL MW. MCPOIL TG. Plantar Fasciitis: Etiolo-gy and Treatment. J Orthop Sports Phys Therapy 1999;29:756-76.

2. FROWEN, P., O’DONNELL, M., LORIMER, D., BUR-ROW, G. (2010) Neales Disorders of the Foot 8th Edition, p127

3. MICHAUD, T.C. (1997) Foot Orthoses and Other Forms of Conservative Foot Care, Sydney: William & Wilkins, p.114

ICB Lower limb biomechanics

The issue of ‘Forefoot Varus’ is an interesting one as there are several misunderstandings in relation to this osseous condition. The first issue is the confusion in relation to Forefoot Varus and Forefoot Supinatus – the former being osseous in nature and the latter a soft tissue condition. The second issue is the proliferation of confusing terminology such as Forefoot Varus, Supinatus, flexible forefoot varus and forefoot invertus, to name a few.

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Therefore it can be said that a ‘forefoot varus is a cause of ‘overpronation’ and a forefoot supinatus is the result of ‘overpronation’.1

Merriman’s1 Assessment of the lower limb indicates that:

The Varus foot appears supinated with the lateral border of the foot rela-tively plantarflexed in comparison with the Medial border.

An inverted foot may be due to :

True forefoot varus. Boney abnor-mality, theoretically due to inadequate torsion of the head and neck of the talus during fetal development, but this is not well supported (Kidd 1997)

The presence of a true forefoot varus is said to lead to a very flat foot with no longitudinal arch (Grumbine 1987)

Forefoot supinatus is Acquired soft tissue deformation due to abnormal pronation of the rearfoot. The forefoot Is held in an inverted position be-cause of soft tissue contraction.

It can be difficult to differentiate be-tween a Forefoot Varus and a Fore-foot Supinatus.

The most common test is where a plantar grade pressure is applied to the dorsum of the 1st ray or metatarsal. The 1st Metatarsal shaft should plantarflex and is this does not occur then it is deemed to be fixed osseous condition, whereas if it is mobile or there is some ability to move in a plantarflex direction it a Forefoot Supinatus.

In summary ….a forefoot varus differs from forefoot supinatus in that a fore-foot varus is a congenital osseous deformity that induces subtalar joint pronation, whereas forefoot supinatus is acquired and develops because of subtalar joint pronation.2

Other conditions3 that are due to inverted forefoot are:

A) Dorsiflexed 1st Ray( metatar-sus Primus)
B) Plantarflexed 5th ray both fixed and mobile are possible.3

Assessment :
The Varus foot often looks banana shaped and the navicular has dropped and is excessively everted.

Forefoot Varus or Forefoot Supinatus?

The supinatus foot mimics the Varus foot in most respects, however, the banana shape is not as prevalent and it is able to be distinguished by the ‘Supinatus – Varus test’.

The supinatus foot

Orthotic Prescription:
Forefoot Varus
When devising the orthotic prescription, firstly the mobility of the rearfoot should be assessed.
If the Rearfoot is mobile, medium to firm orthotics can be prescribed to support and control the foot, with a forefoot varus addition posted to the medial forefoot.

ICB Orthotics addition

Alternatively, if the rearfoot is mobile and requires additional inversion (i.e more than the intrinsic posting in the orthotic device) an inversion ramp can be attached to the entire medial aspect of the orthotic.

ICB Inversion Rmp

ICB Orthotic Addition

Orthotic with Inversion Ramp.

When the patient has a fixed or arthritic rearfoot, then soft to mid density accommodative orthotics are more effective, with a forefoot varus wedge attached to the medial forefoot. This type of foot can, because of the mobile forefoot, experience conditions such as, Metatarsalgia, morton’s neuroma & mid tarsal periostitis.

Periostitis is an inflammation of the covering of the bones, if left untreated it can progress to a stress fractures.

The Forefoot Varus Addition on the orthotic fills the space under the 1st MTPJ providing the mechanism for toe off to occur by creating normal ground reaction forces to occur at toe off in gait.

ICB Orthotic FFT Varus Addition

ICB Full length Orthotic

Soft orthotic for fixed rearfoot

In both cases (i.e. mobile & fixed rearfoot with forefoot varus) extra support can be provided by applying medial flanges (soft or firm) to the dorsal arch area which can also assist in reducing friction on the medial aspect of the foot. Orthotic Prescription: Forefoot Supinatus.

ICB orthotic medial flange

Patient’s exhibiting a forefoot supinatus do not require any additional medial forefoot wedging or modification to the orthotic device .

The reason for this is that once the foot is inside the shoe wear the shoe ‘sock’ upper will assist in a plantarflex action to the dorsum of the foot and this will assist in stretching the contracted soft tissue.

Adding or Posting medial addition or wedge to a SUPINATUS condition will ultimately create a disruption and exostosis between the articulation of the medial cuneiform and base of the first metatarsal at the medial cuneiform joint (1st tarsometatarso joint). .4.

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References :

1. Merriman’s Assessment of the lower limb Ed 3 p259-261

2. Forefoot supinatus.Clin Podiatr Med Surg. 2014 Jul;31(3):405-13. doi: 10.1016/j.cpm.2014.03.009. Evans EL1, Catanzariti AR2.

3. Merriman’s Assessment of the lower limb Ed 3 p261

4. Neal’s Disorders of the foot 8th Ed Frowen, O’Donnell,Lorimer,Burrowp126

 

 

 

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