Congenital upper limb deficiencies and associated malformations in Finland: a population-based study

To calculate the national incidence of upper limb deficiencies and associated infant mortality in children in Finland using the International Federation of Societies for Surgery of the Hand (IFSSH) classification. Radial ray deficiency, ulnar ray deficiency, central ray deficiency, transverse arrest, phocomelia, undergrowth, and constriction band syndrome with skeletal defects were evaluated.

We reviewed upper limb deficiencies among all 753,342 births in Finland during 1993 to 2005 reported to the Finnish Register of Congenital Malformations. Classification of these upper limb deficiencies was done according to a modified IFSSH system. We calculated incidence, gender and side distributions, frequency of associated anomalies, and infant mortality rates in different subtypes of the deficiencies. Familial occurrence of congenital upper limb defects was recorded.

A total of 419 cases (234 male, 185 female) of upper limb deficiencies were identified. The national incidence of upper limb deficiencies was 5.56 per 10,000 births and 5.25 per 10,000 live births. The most common upper limb abnormality was radial ray deficiency (138), followed by subgroups of undergrowth (91), upper limb defects due to constriction band syndrome (51), central ray deficiency (41), and ulnar ray deficiency (33). Perinatal mortality was 14%. Infant mortality among children with upper limb deficiencies was 137 per 1,000 live births, compared with an overall infant mortality of 3.7 per 1,000 live births in Finland. Additional birth defects were found in 60% of these children. Prevalence of upper limb defects in relatives of the census population was 2% (11 of 419).

The national incidence of upper limb deficiencies is 5.25 per 10,000 live births. Congenital upper limb deficiencies are associated with additional birth defects in two thirds of cases. These children, especially children with radial ray deficiency, have a high perinatal mortality rate. When divided into subgroups using IFSSH classification, differences emerge in both associated anomalies and mortality.