Role of Sonography in the Assessment of Clubfoot - An Overview

Introduction

Clubfoot or congenital talipes equinovarus (CTEV) is the most common congenital orthopedic disorder affecting infants. Clubfoot refers to a group of foot abnormalities that are usually present at birth (congenital) and cause the baby's foot to twist out of shape or position. The tissues that connect the muscles to the bone or the tendons are shorter than usual in clubfoot. It can be mild or severe, and it can happen in one or both feet. A child born with clubfoot is usually healthy and has no other health issues. It arises as part of a more serious condition, such as spina bifida, in a small percentage of births.

Ultrasonography can detect a clubfoot as early as 13 weeks of the fetus inside the womb. But it is most commonly diagnosed between the 18th and 24th weeks of pregnancy. Clubfoot affects the ankle and subtalar (hindfoot) joints. The causes of clubfoot are genetics, environmental factors, familial history (about 15 percent of cases), or decreased amniotic fluid when the baby is in the womb. In addition, children with club feet may have further complications such as arthritis and difficulty walking. About one infant in 1000 live birth cases has a clubfoot. This is more prevalent in males than females in a ratio of 2:1.

Clubfoot can be unilateral or bilateral, isolated, familial, or associated with other conditions such as:

• Aneuploidy is a genetic disorder having an abnormal number of chromosomes.

• Skeletal dysplasia is a group of genetic disorders affecting the bones and joints.

• Roberts syndrome is a rare genetic disorder that affects the limbs and face.

• Freeman-Sheldon syndrome is a genetic condition that affects the craniofacial muscles and joints.

• Marfan syndrome is a genetic disorder that affects the body's connective tissues.

• Ehlers-Danlos syndrome is a group of genetic disorders affecting the skin, bones, and blood vessels.

• Spina bifida is a congenital disorder that affects the spinal cord.

Understand that the baby's clubfoot is not a painful condition. Clubfoot can usually be corrected while the child is still a baby. Treatment should begin within a week or two of the baby's birth. Methods of correction range from manual foot manipulation over time to surgical foot repair.

What Are the Clinical Symptoms of Clubfoot?

Clubfoot clinically appears as:

• The foot is twisted downward and inward.

• Small calf.

• Small feet.

• The heel is small and high, and deep creases appear posteriorly (back) and medially (middle).

• Sole faces posteromedially (located at the back towards the middle).

• Severely turned foot looks upside down.

How Is the Ultrasonography Procedure Performed on the Clubfoot?

• During ultrasonography, a linear transducer having a frequency of about 5 to 15 MHz with 26 mm, 45 aperture, and a standoff pad is used. This procedure is performed by placing the infants over the mother's lap while breastfeeding.

• Then the radiologist holds the clubfoot in a neutral and correct position and holds the transducer with the other hand, and sometimes the parents are asked to stabilize the leg. The other normal foot of the babies with unilateral clubfoot is also assessed when the clubfoot is investigated. Each foot requires four standard projections before determining the treatment plan and during the treatment course. Each foot requires a clinical assessment before the treatment, and during each visit, either the Pirani score or Dimeglio score is calculated for clinical reference of the treatment completion.

• In ultrasonography, the ossification center appears as the area with increased echogenicity (bright white), and the cartilaginous component appears as a hypoechoic area.

What Are the Ultrasonographic Assessments in Clubfoot?

Clubfoot requires four standard projections such as medial, dorsal, lateral, and posterior. The medial, lateral, and dorsal view was explained by Aurell et al., and the posterior view was explained by Bhargava et al.

• Medial View:

  • The anteromedial view is obtained by aligning the transducer at the junction of the ankle and foot with the flexion of the foot plantar and is aligned along the distal tibia, talus and navicular.

  • The medial transverse view is obtained by placing the transducer transverse to the medial aspect of the foot.

• Dorsal View:

  • The anterior - medial view is used to detect the medial malleolus, talus ,navicular and medial cuneiform.The talonavicular relationship is obtained using the distance and angle.

  • The talonavicular relationship distance is measured by the distance between the medial malleolus epiphysis and the cartilaginous navicular. When this measurement is shorter, it indicates the medial displacement of the navicular in the clubfoot than in the normal foot.

  • Hamel and Becker introduced an angle to measure the talonavicular relationship. The medial subluxation of the navicular is determined by the positive angle rather than the negative in a normal foot. This measurement helps assess the preoperative estimation of the amount of the medial release required and determine the success rate of the conservative manipulation and the use of casts or braces.

• Lateral View:

  • The lateral transverse view is used to measure the calcaneocuboid relationship. It is measured by the calcaneocuboid angle (CC angle) and the calcaneocuboid distance (CC distance).

  • CC distance is the tangent drawn along the lateral border of the calcaneus and a perpendicular drawn from the tangent to the lateral border of the cuboid.

  • CC angle is calculated by the tangent to the lateral border of the calcaneus and cuboid.

• Posterior View:

  • The posterior sagittal view is obtained by aligning the transducer with the midline sagittal plane and is placed on the backside (posterior) of the upper part of the heel.

  • The posterior sagittal view is used to measure the Achilles tendon. This tendon is shortened in clubfoot and spastic deformities. In this view, the distal tibia, talus, and calcaneus are aligned perfectly. The distance between the distal ossified tibia and the superior ossified calcaneus can be measured in ultrasonography. This distance decreases with plantar flexion in the normal feet but remains the same in the clubfoot. This view is helpful for the talonavicular relationship in the dorsoplantar (DP) plane, which is abnormal after subtalar release.

Conclusion

Clubfoot affects the child both physically and psychologically. Hence the treatment should be given soon after birth. Most clubfoot cases are corrected by nonsurgical methods; however, half of the patients need orthopedic intervention. Ultrasonography is the readily available economic imaging tool that helps in the dynamic evaluation of the clubfoot. It is the first-line imaging technique of neonatal clubfoot, which does not cause any harm to the baby. In sonography, the tarsal bones can be easily visualized, which helps conservative management of the clubfoot.