Atypical Clubfoot

Atypical clubfoot, also referred to as complex clubfoot in some studies, is a more recently recognized subtype of clubfoot. It differs from the more traditional form of clubfoot because it has distinctive anatomical and clinical features that require specifically adapted treatment methods. Although it can be treated using the Ponseti method, modifications to the approach and close attention to detail are required to achieve optimal outcomes.

Atypical clubfoot

What characterizes atypical clubfoot?

Atypical clubfoot has several specific features that distinguish it from classic clubfoot. These include:

1. Differences in appearance:

   • A short, rigid foot with limited flexibility.

   • A high arch and excessive plantar flexion through the midfoot.

   • Thick, short toes with skin creases behind the heel.

2. Limited response to standard treatment:

   • This type of clubfoot often responds poorly to the standard Ponseti method.

   • Manipulation and casting must be adapted to avoid complications such as increased stiffness or overcorrection.

3. Underlying structural differences:

   • Atypical clubfoot often involves more severe soft-tissue contractures.

   • The bones of the foot, particularly the talus and calcaneus, may be more markedly deformed than in typical clubfoot.

Treatment challenges

The Ponseti method, which is the gold standard for clubfoot treatment, must be modified for patients with atypical clubfoot. These modifications include:

• Precision in manipulation and casting: Manipulation should be performed more gradually, and casting must be adapted to account for the foot's stiffness and unique shape.

• More extensive soft-tissue management: Additional procedures, such as tenotomy, may be needed to release contractures and reduce the risk of recurrence.

• Close follow-up: Patients with atypical clubfoot have a higher risk of recurrence, requiring frequent review and adjustment of treatment.

Importance of early diagnosis

Early identification of atypical clubfoot is essential for initiating appropriate treatment and avoiding complications. Clinical assessment combined with careful observation of foot structure and function is important for distinguishing this subtype from classic clubfoot.

Atypical clubfoot is a challenging but treatable condition. With the correct approach and appropriate modification of the Ponseti method, many children can achieve a painless, functional foot that allows full participation in daily activities¹.

[1] Ponseti I.V., 2005, "Treatment of Congenital Clubfoot."

Recognition of Atypical Clubfoot

Atypical clubfoot differs clearly from idiopathic clubfoot in several distinctive ways. These include:

1. Short, cylindrical foot:

   • The foot is often broader and shorter than normal, which has led to the description "short, fat foot."

2. Changes in the first metatarsal and great toe:

   • The first metatarsal is often flexed, while the great toe is hyperextended.

3. Tightness of the foot:

   • The posterior aspect of the foot is very tight, resulting in marked equinus (plantar flexion).

   • The medial aspect of the foot is less tight, producing less varus deformity than is typically seen in idiopathic clubfoot.

4. Transverse plantar crease:

   • A deep transverse crease across the middle of the sole is common and results from flexion through the midfoot, a deformity referred to as "plantaris."

5. Curved tibia:

   • In some cases, the tibia may appear bowed, further contributing to the characteristic appearance of this subtype¹.

Comparison of Idiopathic and Atypical Clubfoot

• Tightness:

  • Idiopathic clubfoot is tight on the medial side, whereas atypical clubfoot is particularly tight posteriorly and plantarly.

• Great toe:

  • Hyperextension of the great toe and shortening of the forefoot are more prominent in atypical clubfoot.

• Midfoot flexion:

  • Atypical clubfoot often has a "plantaris" deformity with midfoot flexion, which is not typical of idiopathic clubfoot.

Causes of Atypical Clubfoot

The exact cause of atypical clubfoot is not fully understood, but research suggests two possible scenarios:

1. Congenital atypical clubfoot:

   • Some children are born with this subtype without an identifiable external cause.

2. Secondary development as a result of treatment:

   • Atypical clubfoot can develop as a consequence of incorrect casting. If a plaster-of-Paris cast slips downward between the second and fourth casts, this may result in:

     • Equinus and plantaris deformity: The foot is forced into excessive plantar flexion.

     • Midfoot flexion: The foot bends through the midfoot, which may lead to swelling and irritation.

Factors that may cause the cast to slip

1. Excessive padding:

   • Too much padding material can prevent the cast from holding the foot securely.

2. Insufficient molding:

   • If the cast is not adequately molded around the foot and heel, it may slip.

3. Insufficient knee flexion:

   • If the knee is not flexed sufficiently during casting, stability is reduced.

4. Below-knee casting:

   • Using a cast that does not extend above the knee can provide poor fixation and increase the risk of slipping¹.

Atypical clubfoot requires careful observation and individualized treatment to avoid worsening of the deformity and to achieve the best possible outcome.

Treatment of Atypical Clubfoot

Manipulation phase

1. Early recognition and assessment:

   • Identify atypical clubfoot as early as possible so treatment can be adjusted appropriately.

2. Management of swelling:

   • If the foot is severely swollen, provide a 1–3 week break from casting to allow the swelling to settle.

   • During this period, parents or caregivers can be encouraged to massage the foot following guidance from a healthcare professional.

3. Resumption of manipulation and casting:

   • Once swelling has decreased, resume manipulation and casting.

   • If cavus deformity (high arch) reappears during the casting break, correct this first.

4. Midfoot abduction and lengthening of plantar tissues:

   • Perform gentle midfoot abduction and stretch the plantar tissues.

   • Foot abduction is less important in atypical clubfoot than in idiopathic clubfoot.

   • Determine the amount of abduction by observing the plantar surface and palpating the bones of the foot. Excessive abduction may produce lateral or transverse creases. Ten to twenty degrees of abduction is usually sufficient.

   • Signs of adequate abduction:

     • The anterior process of the calcaneus can be palpated emerging beneath the lateral head of the talus.

Casting phase

1. Purpose of casting:

   • The cast should maintain the lengthening achieved during manipulation and support correction of the foot.

2. Cast characteristics:

   • Thin, snug padding:

     • Helps prevent cast slippage and ensures that the foot is well supported.

   • Good molding:

     • Ensure the cast is well molded around the foot and heel to provide stability.

   • Above-knee casting:

     • The cast should extend above the knee, with approximately 100 degrees of knee flexion to reduce the risk of slippage.

3. Correctly applied cast:

   • The toes should be well supported from underneath while remaining clearly visible.

   • The knee should be flexed sufficiently to improve stability and reduce the risk of the cast slipping off.

Treatment of atypical clubfoot requires precision, individual adaptation and careful observation to avoid complications and achieve a successful outcome. Early recognition of the foot's characteristics and tailored manipulation and casting techniques are essential for managing this specific subtype.

Tenotomy

In the treatment of atypical clubfoot, extensive foot abduction is not required because the talar head is often covered early in the treatment process. Tenotomy can be performed once the following goals have been achieved:

1. Coverage of the talar head:

   • When the talar head can no longer be palpated, the position of the foot is considered satisfactory.

2. Correction of the plantaris deformity:

   • Once the plantaris deformity has been adequately corrected.

3. Dorsiflexion after tenotomy:

   • Full dorsiflexion is not always achieved immediately after tenotomy.

   • A new cast may be helpful after one week to gradually improve dorsiflexion and optimize the result.

Bracing phase

After tenotomy and correction of the deformity, treatment continues with a foot-abduction brace. For atypical clubfoot, the brace should be adapted to specific needs:

1. Abduction angle:

   • Reduce foot abduction to 30–40 degrees to avoid overcorrection.

2. Dorsiflexion:

   • Gradually increase dorsiflexion over time according to the child's tolerance and treatment progress.

3. Monitoring for recurrence:

   • Monitor closely for signs of recurrence, including:

     • Reappearance of the plantar crease.

     • Return of the equinus deformity.

4. Activity and gait training:

   • Encourage the child to walk, as this helps improve the hindfoot.

   • However, be aware that the heel area may remain "empty" for several years, which can be normal.

5. Information for parents:

   • Parents should be informed that atypical clubfoot has a higher risk of recurrence and that careful follow-up is essential.

   • The importance of regular brace use and specialist follow-up should also be explained.

Expected Outcomes

With close follow-up, individualized treatment and good collaboration between healthcare professionals and parents, favorable outcomes can be achieved in children with atypical clubfoot.

Sources:

1. Africa Clubfoot Training Project. Chapter 12 Africa Clubfoot Training Basic & Advanced Clubfoot Treatment Provider Courses - Participant Manual. University of Oxford: Africa Clubfoot Training Project, 2017.