The congenital undescended scapula syndrome: Sprengel and the cleithrum: a case series and hypothesis.

BACKGROUND: Sprengel deformity is a rare congenital shoulder girdle anomaly characterized by scapula malposition, periscapular muscle atrophy, and limited shoulder movement. Traditionally, it has been managed by omovertebral bar excision and muscle transplantation procedures guided by age and Cavendish grade. We present a unique observation in humans: a case series with Sprengel deformity possessing a cleithrum, an ancestral remnant of shoulder girdle development found in archaic bony fish.

METHODS: Nine patients presented with so-called Sprengel deformity to a tertiary referral shoulder clinic. All were assessed clinically and radiologically with scapular radiographs and computed tomography or magnetic resonance imaging scans. The clinical and radiologic features were classified according to Cavendish and Rigault systems, respectively, and the scapular ratio was assessed.

RESULTS: All patients were assigned grade 4 on the Cavendish scale. Six were grade 2 and 3 were grade 3 on the Rigault scale. The distinguishing pathoanatomic feature was partial endomuscular ossification of medial scapular suspension muscles, analogous to the cleithrum of bony fish. Five cases were treated operatively and 4 nonoperatively. Mean elevation and abduction significantly improved in surgical cases.

DISCUSSION AND CONCLUSION: This finding not only challenges classic management of these rare patients but offers insight into scapular embryology and development. The association of scapular developmental and urogenital anomalies suggests that screening of the renal tract and genetic investigation in those with undescended scapula syndrome be considered. We suggest, to emphasize the nature of incomplete scapular descent and associated congenital anomalies and to clarify imprecise common use of the term Sprengel deformity, that this condition be called the congenital undescended scapula syndrome.