Incorrect shape of the casts

The cast plays an important role in the Ponseti method. When it is applied, a doctor corrects a foot/feet of a child. However, it is not “any” cast applied “somehow”, but a specific cast, put in a specific manner, by specific persons.

When we talk about applying plaster casts in the Ponseti method, we need to realize that it is not “any” cast, which can be put “somehow” by “someone”, who has some free time in a medical unit or in a ward. It is not applied by an “accidental” person. When we think this way, there are either no results or they are grotesque and end in a failure. We get caricatures instead of feet.  Is it what we are looking for? Then the high-sounding phrase “Primum non nocere”  loses its meaning.

We would like to draw your attention to incorrect casts today, which we often observe as casts applied “according to the Ponseti method” by specialists. However, the truth is that none of them is correct and compliant with the treatment method. Before we move on to the main topic of our article, just to remind you:

PROGRESS

Each cast brings change to foot presentation. It means that each subsequent cast places a foot in a different position, bringing it closer to its natural and “healthy” shape. It can be observed easily, while looking e.g. at the picture below, which shows the positions for each applied subsequent cast. Where this is not the case – treatment is wrong.

Each time new cast “positions” a foot externally – external foot rotation should change by about 10-15°. The last cast (before the percutaneous tenotomy of the Achilles tendon) should be placed in the external rotation of about 70° (atypical and complex feet have other norms).

WHO?

Casts are only applied by a qualified paediatric orthopaedist, who knows the Ponseti method well and his assistant (a plastering technician trained in correct plastering in this method). No one else should do it! A parent is also active at this stage, who holds a child in such a way to stop the child from moving and above all, diverting his or her attention from what is going on, soothing the child and giving him or her sense of security.

MATERIAL

Above all, cast applied in the Ponseti method is standard, white cast (mineral, non-synthetic, not fiberglass and modern light perforated plaster, etc.) on the basis of calcium sulphate, namely cast, which you could have seen in your life. However, there is a little “catch” here. This is quick-setting cast, the so-called plaster of Paris, namely the type of cast used in modelling or moulding. Why isn’t the traditional plaster the best material?

• the traditional cast can be modelled and shaped very well and THIS IS ESSENTIAL – therefore CORRECT SHAPE OF THE CASTS
• it is cheap
• it has been common and known for many years

Correct shape of the casts

As cast modelling in the Ponseti method is essential and it must be precise, traditional plaster is suitable for this purpose, as it offers a lot of forming possibilities. This material is very ductile. The so-called quick-setting plaster bandages are used during plastering. A plaster bandage is nothing else, but the cast placed on gauze (bandage) and wound on a reel (roll).

THE METHOD OF DETAILES

The Ponseti method is actually “the detail method”, as thanks to them we can talk about progress in treatment of a congenital clubfoot. The proverb “the devil is in the details” suits here and it can be applied widely. There can be numerous complications in treatment, no progress and postponement of child’s fitness, if these “details” are not known and the Ponseti method is treated “with neglect” or not know at all and confused with other methods or … modified.

The so-called modelled plaster is used in this method, which comes from the technique of prof. Lorenzo Böhler – a traumatologist from Vienna. The Böhler method was based on possibly autonomous putting of the broken bones or joints together and immobilizing them in the plaster cast placed in such a way, which enabled early immobilization of a patient and then his or her quick recovery without any procedures, rehabilitation or long convalescence. It required precise plaster modelling in strategic places. This technique was assimilated by Dr Ignacy Ponseti in his clubfoot treatment method.

THE SHAPE OF THE PLASTER CAST DOES MATTER

We wrote a short article some time ago that THE SHAPE OF THE PLASTER CAST DOES MATTER and it is of great importance! Check this article. You will undoubtedly see some significant differences in relation to examples, which we will provide here. We want to show you incorrect casts today, which are put by physicians, plastering technicians, physiotherapists or third parties.

---

The photos come from various centers around the world.
We do not know the authors of many of the images included.

CASTS SPLINTS

The cast splint (lonugette) is a semi-cast in other words, most commonly in a gutter form (it has a shape of a letter U in the cross-section), which is applied to partial and temporary limitation of limb movements, its stiffening during its swelling, open fracture, when it is not possible to put a full cast due to the reasons, which have been mentioned before.

Why isn’t the cast splint a good idea for children with clubfeet? As it corrects nothing. It is useless. It has no “power” to maintain redressment, which has been made earlier. However, it should be noted here that the cast is modelled in a specific way, in specific places: the ankle areas, the talus head, the heel, the toes, the knee, and the thigh. The author of this method writes about it:

SHORT CASTS

We use the term short cast when the cast covers the foot and ankle, and sometimes the lower leg (the calf), ending below the knee.

Why is a short cast not recommended for children with clubfoot?
According to the functional anatomy and biomechanics of the foot, it is impossible to abduct the foot — specifically, to rotate the calcaneus under the talus — using a short cast alone, unless the mechanism is stabilised by bending the knee and holding it in that position.

Because the calcaneus is locked beneath the talus, it can only be released when the foot is abducted in supination. When the knee is not immobilised in a cast at 90° (or 110–120° for atypical and/or complex clubfoot), the entire subtalar complex rotates inward, following the tibia, which turns internally (internal tibial torsion). That’s why LONG-LEG CAST should be applied.

A “TUBE” ON THE LEG

The cast should follow the natural shape of the leg and foot. When using traditional plaster (plaster of Paris) applied in the correct amounts and proportions, achieving the proper contours is not complicated — but it does require extensive knowledge of the deformity, excellent casting technique with high precision, and… manual skill.

Very often we see casts that we jokingly call “tubes” or “pipes”. They look as if someone placed a straight cylinder over the child’s leg and simply bent it at the knee. They do not resemble the shape of a leg, calf, or foot. It is impossible to know what is really happening underneath a tube-like cast. In most cases, it is also too loose and slips off the leg. In such a tube-like cast, a number of additional deformities can develop — including COMPLEX CLUBFOOT.

Atypical and complex clubfoot

THE CAST, WHICH SLIDES OFF, SHOULD BE REMOVED IMMEDIATELY! THE SAME CASE APPLIES TO TOO TIGHT CAST, WHICH SHOULD BE REMOVED IMMEDIATELY! JUST TO AVOID FURTHER COMPLICATIONS.

HORNS?

We also see casts that resemble buffalo horns: misshapen, poorly molded, bulky, and bent. After removing such a cast, one can expect not only a complex clubfoot, but also a deformed tibia bent in various directions (forward or sideways).

Such a deformed, bent tibia makes it much more difficult for the next physician to perform proper foot correction — and that physician must, of course, be experienced in managing these “non-typical” cases. In this type of cast, we also often observe excessive equinus of the calcaneus, sometimes so severe that the heel bone touches the lateral malleolus and becomes trapped behind it. This leads to numerous complications and represents an extreme challenge when attempting to correct the deformity.

THIN? THICK? BULKY AND MASSIVE!

The cast cannot be too thin — in that case it loses its shape, cracks, moves, and any correction achieved is essentially lost. It also cannot be too thick, because its weight creates additional problems. Applying a cast to the leg of a small child requires great sensitivity, experience, and continuous assessment, so as not to cause harm with excessive weight or inadequate support.

A well-molded heel, combined with a flexed knee, helps keep the cast securely in place. It also helps lower and stabilize a high-riding calcaneus. Since each cast changes the foot’s position, gradually bringing it closer to that of a normal, healthy foot, the calcaneus should—before the tenotomy—be positioned neutrally or in slight valgus, and in 0° dorsiflexion or −5° plantarflexion

Let’s take a closer look at the individual parts of the casts so we can clearly observe these differences.

THIGH

The cast must reach from toes to the groin, not end halfway up the thigh or just above the knee. A cast that is too short does not hold the knee securely in flexion and allows for excessive movement. It also significantly increases the risk of the cast slipping, which is dangerous and requires immediate removal. A slipping cast can lead to the development of a COMPLEX clubfoot deformity.

KNEE

The cast used in the Ponseti method is a long-leg cast, meaning it extends from the toes to the groin, with the knee flexed at 90° (and 110–120° for atypical and/or complex clubfoot) as mentioned above. If the knee is not positioned at 90° (or 110–120° in atypical/complex cases), the risk of achieving only a partial correction of the foot is high. This means that not all components of the deformity will be fully corrected — and eventually they will “come back with a vengeance” as an early RELAPSE. As a result, the foot will not become fully functional.

Relapse of clubfoot

FOOT SHAPE

Although it may seem difficult to achieve, the foot inside the cast should essentially retain the shape of a real foot, with a clearly defined heel. When looking at the sole of the cast (which should be straight and flat), the foot should be narrower at the heel and wider at the toes.
In the foot portion of the cast, there must not be too much space around the ankle joint (this risks losing the correction!), but excessive space around the toes is also not recommended.
At the same time, a cast that is too tight around the toes is also inappropriate. More on this later in the article.

HEEL

During the manipulation (redression) performed before applying the cast, the physician must not touch the heel, so as not to block it. The heel must be able to move freely beneath the talus, because the goal of treatment is to free the talus and restore normal anatomical relationships within the foot.

However, when the cast is applied, the heel must have an anatomically correct shape. It cannot be flattened, compressed, pushed upward, or misshapen. Proper molding of the heel is essential because the heel is what “holds” the cast on the leg and prevents it from slipping off.

TOES

All toes should be visible in the cast: positioned side by side, aligned evenly (in one line and plane), not curled, not crushed, not overlapping, and not twisted. It is also important that there is a plaster platform beneath the toes. Why is this platform important?
Because it helps stretch the plantar flexors of the foot — the soft tissues that are particularly problematic in clubfoot. Without this support, the child may subconsciously try to grip the edge of the cast with the toes, which prevents the necessary stretching.
The toes should also be exposed from above so the child can make a slight upward movement of the big toe. This also protects the toenail plate from mechanical damage (pressure) and prevents moisture buildup.

The toes should also be exposed from above so the child can make a slight upward movement of the big toe. This also protects the toenail plate from mechanical damage (pressure) and prevents moisture buildup.

Summarizing: connection: the cast platform under the toes + toes moderately uncovered on the top = toe movement upwards, which activate tibial muscles and cause tissue stretching in a foot sole.

The toes must also not disappear inside the cast. This is a sign that the cast is slipping.
It is true that the toes may move slightly backward within a day or two after the cast is applied — this happens because the internal padding compresses.
However, toes that are truly disappearing inside the cast are a red flag in Ponseti treatment.

The position of the toes in the cast makes it easy to assess the alignment of the entire foot. Pronation of the forefoot is unacceptable!
It leads to a worsening of the cavus deformity, which should in fact be corrected at the very beginning — with the first cast.

BALOON WITH WATER

Cast should not be too tight. A child’s leg is like a balloon with water: when this balloon is closed in a tight tube, it gets pressure and is painful, the toes swell, a child cries and once the cast is removed, the skin is oversensitive, bedsores appear, there is much swelling and if another cast is placed, it will be a simple way to create COMPLEX CLUBFOOT.

IMMEDIATELY!!!

THE CAST, WHICH SLIDES OFF, SHOULD BE REMOVED IMMEDIATELY! THE SAME CASE APPLIES TO TOO TIGHT CAST, WHICH SHOULD BE REMOVED IMMEDIATELY! JUST TO AVOID FURTHER COMPLICATIONS.

FOREFOOT OVERCORRECTION

Inadequate manipulation (correction on calc-cub joint), an unsuccessful percutaneous Achilles tenotomy, or excessive abduction of the forefoot while the hindfoot remains stable (meaning there is essentially no abduction occurring in the subtalar joint) leads to a caricature-like deformity. The most characteristic feature you will notice is a deep crease on the lateral border of the foot. This is known as overcorrection at the midfoot. It results from excessive mobility in that region.

In such cases, the forefoot inside the cast rotates outward, while the hindfoot remains relatively normal. After removing the cast, the foot has a very typical appearance.
This is a treatment error.

JOYFUL CREATIVITY

When a doctor does not know a defect, which is inborn clubfoot, he or she does not know correct treatment, namely the Ponseti method and makes caricatured creations. It is obvious that in the majority of cases, which are referred to our foundation, the most frequent explanation of such situation that there is no progress in the cast form, is:

This is foot’s fault, as the foot is difficult, heavy, and resistant. It is not possible.

Unfortunately, each such statement concerns us, if the person, who says so, has adequate know-how and experience in treating this defect by using the Ponseti method. The counter-argument that captures us each time, when we hear such statements as above, we say:

The example of such “author’s method” are the so-called frill casts, when a physician or a technician is not able to put a correct cast.

DETAILS…

We have decided “to provide” some knowledge about casts:

• when a doctor plasters a foot (a leg) endlessly, then you have to change a doctor. Each additional cast over 8 pieces causes deformities and maintains the ones, which are present, as well as leads to joint stiffness;
• use of 2 casts, when a foot has been defined as the 3rd or 4th degree of deformity (Dimeglio scale) is also pointless and causes complications, as there are no corrections, no partial correction, and overcorrection;
• when a calf placed in the cast is unnaturally bent outside and it looks like a boomerang in the cast and between the casts – it means that the tibial bone and the fibula have been bent. They are often retracted. Iatrogenic deformity occurs, which is difficult to treat and gives different prognosis.

IS THERE SUCH A THING AS THE “PERFECT” CAST?

It’s hard to define exactly what that would be. But what does exist is a very good, proper cast — one that fully meets all the principles of the Ponseti method and is well-molded, precise, and appropriate for the individual child. Refined and carefully crafted.

Correct shape of the casts

TWO WAYS

The objective of placing plaster casts is to correct deformities. The aim is to bring the foot back to normal look and functioning. Unfortunately, a foot can be correct by using the cast, but it can also be “damaged” even more, when you use the plaster. Everything is a matter of know-how, experience, intuition, and talent.