Hereditary Symphalangism Associated with Carpal and Tarsal Fusions

Abstract

This presentation discusses symphalangism and describes the disease in 5 members from four generations of a family of 17. In all 5, there were carpal and tarsal fusions. Symphalangism is an hereditary anomaly manifested by partial or total absence of one or more interphalangeal joints, with fusion of the involved phalanges. The term was first used by Cushing (1), although the entity was described earlier and has been known by many names: congenital ankylosis, aplasia of the interphalangeal joints, phalangeal anarthrosis, and hereditary multiple ankylosing arthropathy. The cause of symphalangism is failure of differentiation of the interphalangeal joint, which normally occurs about the eighth week of fetal life (6). The defect has been traced through several generations and occurs in half the members of an involved family (2, 3). It is not sex-linked but follows a simple dominant mendelian type of transmission. Sites of predilection are the proximal interphalangeal joints in the fingers and the distal interphalangeal joints in the toes. The incidence of involvement decreases progressively from the fifth to the second digits. Involvement of the thumb and great toe has not been reported, probably because of the lack of a middle phalanx in these digits. Symphalangism can be recognized clinically at birth by the smooth appearance of the skin overlying the affected joints, as the normal skin folds produced by flexion are absent. Slight radial deviation of the involved fingers (clinodactyly) may be recognized. Inability to flex the involved joints in the fingers results in a weak grasp, although remarkable dexterity is retained in some patients whose unaffected joints compensate for those affected by symphalangism. In the patients to be described here, there have been persistent complaints of wrist and ankle pain. Ankle pain is usually prominent when the shoes lack stability as a result of the abnormal gait. One patient had no ankle pain when he purchased new shoes every two to three months. Case Reports Figure 1 illustrates the lineage of the involved family. In four generations, 7 of 17 members had symphalangism. Five of the involved members were available for roentgenological examination. All 5 showed involvement of both hands as well as carpal and tarsal fusions. Three members showed bilateral involvement of the toes. The 2 involved members of the family unavailable for examination were reported to have limitation of flexion of the fingers and wrist and ankle pain. The clinical and roentgenological findings of the 5 reported patients are presented in tabular form (Table I). Discussion The presence of symphalangism cannot be determined on roentgenograms at birth because the affected parts have not ossified. As ossification proceeds, the affected joint shows a faster rate of epiphyseal fusion than nonaffected joints. The epiphysis may fuse first to its own phalanx or to the more proximal phalanx.