Health

What are the types of congenital limb deficiency?

Some congenital limb deficiencies develop across the growing limb and are referred to as a transverse limb deficiency. For instance, the most common congenital limb abnormality outside of missing digits includes a deficiency across the forearm of the left  upper limb. This is also referred to as a transradial (across the radius) limb deficiency. Occasionally some congenital abnormalities are due to the complete absence or shortening of a leg or arm bone, but the rest of the limb beyond the absent or shortened bone developed normally. These types of abnormalities are referred to as longitudinal limb deficiencies. An example of this in the lower limb is Proximal Femoral Focal Deficiency (PFFD).

This occurs because the infant’s thigh bone or femur did not develop normally. Other types of longitudinal deficiency occur where a child may be missing one of the two bones in the lower leg or arm. If a child has a complete absence of an entire limb or limbs, the condition is referred to as amelia. These patients appear and are treated similarly to children who have an amputation at the shoulder or hip. Phocomelia is another type of limb deficiency in which the mid-portion of a limb is missing and the hands or feet are attached directly to the trunk. The terminology used for congenital limb deficiencies can be quite complicated.

What are the causes of congenital limb deficiency?

Parents should try to understand that when they have a child with a limb deficiency, there is often nothing that they did that resulted in this abnormality. In fact, according to the Association of Children’s Prosthetic and Orthotic Clinic (ACPOC), 60 percent of congenital limb deficiencies either have no known cause or are genetic in origin. Some congenital abnormalities may be due to poor blood supply, constricting amniotic bands. Only 4 percent are due to taking some type of drug or toxin (i.e., maternal drug exposure like thalidomide). Although many of these abnormalities cannot be prevented, some studies have suggested that taking a multivitamin with folic acid helps reduce the risk of congenital abnormalities, including limb deficiencies. Types of congenital limb deficiencies are shown in.

Do some congenital limb deficiencies have other medical problems associated with them?

There are some known congenital syndromes that also have other medical issues present in addition to the limb deficiencies. Some of these include the TAR Syndrome (low blood platelet counts), Holt-Oram Syndrome (heart defects), Fanconi Syndrome (anemia) and VACTERL Syndrome (spine, kidney and cardiac defects with throat, rectum and limb abnormalities). The care of these children necessitates treatment not only of the limb deficiency but also the associated medical problem. Some infants with congenital limb abnormalities may also have other musculoskeletal problems such as joint laxity or muscle weakness.

Will an infant with a congenital limb deficiency do the same things that other infants do?

Parents often ask whether their infant who has an upper-limb deficiency will be able to do most things that other infants do such as sit, crawl, stand and feed himself. The simple answer is “yes.” To assist with these developmental milestones, the initial upper-limb prosthesis normally should be fitted when the infant starts to sit, usually around 6 months of age. The reason for this is that infants use their upper limbs to support themselves when first learning how to sit. Additionally, the initial prosthesis can help the child in playing and holding objects with two hands such as a bottle or holding a spoon. The prosthesis can assist with feeding in the later part of the first year. Although some may not crawl, parents should be assured that, like infants without limb deficiencies, many infants with upper-limb deficiencies often proceed directly to standing and then walking. The initial prosthesis can be helpful in pulling the child from a sit-to-stand position, another developmental milestone occurring toward the end of the first year.

Goals for Infants who Use a Prosthesis

• Comfort wearing an initial prosthesis
• Child wears the prosthesis to aid in sitting
• Parents feel comfortable applying and removing the prosthesis
• Parents are able to recognize any problems with the child’s skin or prosthesis

Which congenital limb deficiency is more common, upper or lower, and how common is it that multiple limbs are involved?

When a child is born with a limb abnormality, the upper limb is two times more commonly affected than the lower limb; 40 percent of the children will have more than one limb involved.

Are there any surgical treatments that help lengthen a limb or help improve the function of a child with a limb deficiency?

Some children with congenital limb deficiencies may be candidates for an Ilizarov procedure. This orthopedic surgical procedure involves gradual lengthening of the limb over many months using implanted pins connected to a traction device. Choosing candidates for this procedure should be at the discretion of an orthopedic surgeon having vast experience, as this surgery can be met with various complications including neurovascular injury, infection or weakened bones. Candidates for this complicated procedure include children with amputations or limbs of unequal lengths or who have short residual limbs and need a longer residual limb in order to fit a prosthesis well. In this way, the child may experience an improvement in overall functioning.

Patients with Proximal Focal Femoral Deficiency or PFFD may be candidates for certain surgical procedures that improve the functioning of the residual limb. Recall that in this longitudinal-type congenital deficiency the child’s thigh bone or femur fails to develop to the normal length; however the child’s normal knee, ankle and foot developed normally. The family, surgeon and rehabilitation team may elect to fit a prosthesis without any surgical intervention or they may entertain the possibility of various procedures that may help shape the residual limb to better function with a prosthesis. For example, one surgical option would be a Syme’s amputation. This procedure is best used when the child’s femur is about 50 percent or greater than the normal side. This procedure involves removing the child’s foot just above the ankle, allowing the child to utilize his own knee joint with a below-knee prosthesis.

Occasionally the knee joint may be fused allowing the residual limb to be functionally lengthened. Then the child would be fitted with an above- knee prosthesis, requiring at some point a functioning knee joint. One disadvantage of this surgery is that the limb is made even shorter and may not be too cosmetically appealing. Another option is the Van Nes rotationplasty.

With this procedure, children with PFFD as well as those with tumors of the lower limb are converted into functional below-knee amputees. The surgeon removes a part of the limb and then rotates the foot and ankle 180 degrees, reattaching them onto the femur. This effectively creates a knee joint out of the ankle joint, serving as an excellent residual limb to fit a prosthesis.

One final but uncommon type of surgery associated with upper-limb amputees is the Krukenberg reconstructive technique. Children with long transradial amputations or congenital deficiencies are candidates for this procedure, which involves separating the forearm bones, forming them into a pincer-like mechanism. Although the limb now can function to hold on to objects, patients and their families often have difficulty with the poor cosmetic appearance of the residual limb. However, this surgery may be an option for a bilateral upper-limb amputee or a child who has visual difficulty, since tactile sensory feedback can be preserved. This procedure is not commonly performed in the United States but could be done in underdeveloped nations where prosthesis technology may not be available.