Congenital limb differences require an understanding of the anatomic anomaly and all of the associated developmental, physical, and physiologic implications. In the management of pediatric limb anomalies, the child is a continuously changing patient in whom body size, limitations, and physical potential mimic the age-appropriate developmental advances expected in able-bodied children. The support and participation of the patient’s family, technologic advances, and the practitioner’s skill and experience all contribute to the prosthetic fitting outcome. The prosthetic prescription for a child is very different from that for an adult with a similar level of limb loss.

Lifelong and family-centered care are two additional distinctions in the treatment of a child with a limb deficiency. Unlike their adult counterparts, children often have no input in initial surgical planning or prosthetic prescription. All decisions are made by parents in consultation with the treatment team that often includes a physician, a prosthetist, a therapist, and a social worker. Prosthetic issues unique to children with limb differences encompass anticipated physiologic growth, healing potential, and tissue metabolism. In addition, the child who grows into adulthood with a congenital deficiency is often viewed as an adult amputee with minimal attention being paid to the underlying cause of the amputation, such as congenital malformation.

The incidence of congenital limb deficiency is approximately one out of 2,000 live births.¹ Children with upper limb deficiencies outnumber those with lower limb deficiencies by a ratio of 3:1, and they often have multiple limb anomalies and other comorbidities or syndromes² (Figure 1). A comprehensive examination of a child with a congenital limb difference should include facial, spinal, and pelvic evaluations so that other conditions can be quickly identified. If a syndrome is involved, the limb difference may not be the most pressing medical issue.

The prosthetic socket is the foundation of a well-designed and functional prosthesis and must be intimate, anatomically correct, and comfortable. The socket represents the interface between the patient’s body and technology. A poor socket fit will negate the advantages of good technology. Generally, a prosthesis for a child should be designed to last at least 12 months, although its useful duration is heavily dependent on the activity level and play habits of the child. A prosthesis that becomes unusable in less than 1 year may indicate that either the initial socket fit was too aggressive or it did not take into account both longitudinal and circumferential growth.³ From a global perspective, the ability to grow a prosthesis to coincide with the child’s physiologic growth is an important consideration for the prosthetist. Although manufacturers have provided an ever-increasing number of prosthetic components, the most desirable options are those in which parts are modular and can be added or exchanged to increase height or those made of materials that can be adjusted after fabrication.

Lower limb socket designs and components vary with the age, activity level, and functional requirements of the individual child. Most children with a lower limb deficiency will want to walk, run, and play in the same manner as their able-bodied peers. Knowledge gained over the past 10
years has demonstrated that protecting a young child (6 years or younger) from falling by incorporating a locking knee into a transfemoral-level prosthesis is not only unnecessary but may prove counterproductive. Studies have suggested that early knee placement in a prosthesis can reduce the adaptation of clearance options during the development of ambulation.^4,5,6

Although many component options are available for pediatric patients, the choice of whether to use a particular option must be based on sound clinical judgment. Manufacturers began producing pediatric component lines in the late 1980s and, over time, have substantially increased the variety of components available for most functional amputation levels. Lower limb milestones are used to help determine the best component match. While focus on gait is paramount, crawling, tall kneeling, and pulling to stand mark the onset of prosthetic intervention and the amputation level determines only a general prescription. The general consensus is that children progress to mature gait patterns between the ages of 2 to 4 years.⁷ The role of the prosthetist is to determine the necessary and optimal blend of socket and componentry to best compliment and support the milestone.

Stance control knees, which are frequently selected for adult amputees, are often unnecessary for the child with lower limb loss. For children, a step-over-step strategy for descending stairs is often impossible in a device with activated stance control. Step-over-step running is effortless if a child is exposed early to this activity, and it is hampered by a knee with prosthetic stance control. In the experience of this chapter’s author, most children request deactivation of the stance control feature in their knees so that their activity level is not reduced. Similarly, although a locking knee may be appropriate for geriatric patients, it is rarely appropriate in the pediatric cohort. If increased knee stability is required, simple alignment modifications can be made to articulating knees to increase stability.