Abstract
Summary Statement
Sprengel's deformity is a rare congenital anomaly, with scapula malposition. We present a unique subgroup of Sprengel's possessing a cleithrum, an ancestral remnant of shoulder-girdle development found in bony-fish. This challenges management providing valuable insight into scapular embryology and development.
Introduction
Sprengel's deformity is a rare congenital anomaly of the shoulder girdle characterised by scapula malposition, associated with atrophy of periscapular muscles causing disfigurement and limited shoulder movement. Traditionally, it has been managed by omovertebral bar excision and muscle transplantation procedures guided by age and Cavendish grading. We present a unique, previously undescribed observation in humans: a case series of patients with Sprengel's deformity possessing a cleithrum, an ancestral remnant of shoulder-girdle development found in archaic bony fish.
Methods
Nine patients presented with a so-called ‘Sprengel deformity’ to a tertiary referral shoulder clinic. All were assessed clinically and radiologically with scapular radiographs, and CT and/or MRI scans. The clinical (functional and cosmetic) and radiological features were classified according to Cavendish and Rigault systems, respectively and scapular ratio, assessed.
Results
All patients were classed grade 4 on the Cavendish scale. Six were grade 2 and three were grade 3 on the Rigault scale. Mean scapular ratio was 1.04. Associated renal, craniocervical and cervicothoracic anomalies were present. The distinguishing surgical patho-anatomical feature was partial endomuscular ossification of medial scapular suspension muscles, analogous with the cleithrum of bony fish. The bone commonly articulated with the spinal column through pseudarthroses.
Conclusions
This finding of the cleithrum not only challenges classic management of this rare patient group, as it cannot be managed by traditional muscle transplantation procedures, but offers insight into scapular embryology and development. The association of scapular developmental and urogenital anomalies suggests screening investigation of renal tracts in those with undescended scapula syndrome is relevant, and further genetic investigation might be pertinent to understand scapular development and pathology. We suggest, to emphasise the nature of the incomplete scapular descent and associated congenital anomalies, and clarify the imprecise common usage of the term ‘Sprengel’ this condition be called the ‘Congenital Undescended Scapula Syndrome’.
