Uncommon Upper-Limb Deficiencies

Longitudinal Deficiencies of the Forearm

Radial deficiencies are approximately three times as common than ulnar deficiencies, occurring in 1 in 30,000 and 1 in 100,000 live births, respectively (85).

Ulnar deficiencies are associated more with mus­culoskeletal conditions than systemic conditions, and isolated genetic predispositions have been dis­covered (89). Cornelia de Lange syndrome, ulnar­mammary syndrome, and ulnar fibula dysplasia are examples of syndromes that involve ulnar deficiencies. With ulnar-side involvement, the thumb and another digit are usually present.

Central ray syndrome, a form of ectrodactyly, had been described previously as having genetic predispo­sition. This is commonly referred to as “lobster claw,” as the central component of the hand and/or feet are absent. This can present as a mild condition, with the more ulnar and radial digits still present, or it can pre­sent as two longer and thicker digits. Functional abil­ities with this condition will vary, depending upon the degree at which the syndrome affects the deformity.

Figure 13.6 Child with Robert’s syndrome. Note flexion contractures of all limbs.

Longitudinal Deficiencies of the Humerus

When a longitudinal deficiency of the humerus is present, it is often associated with deficiencies in the radius and ulna and with phocomelic digits. The length of the arm is compromised, which leads to the inability to work in a larger envelope of space when attempting to perform bimanual tasks. For this rea­son, prosthetic fitting is more likely a consideration instead of longitudinal deficiencies of the forearm. The shoulder complex is quite often compromised as well. Therefore, if the child were to be fit with a prosthesis, he or she would most likely receive some externally powered components. Frequently, the phocomelic dig­its will be used to provide input to these components.