Voluntary winging of the scapula: Proposed diagnostic criteria.

We report a series of 10 patients with unilateral, dynamic, winged scapula (WS), without cause, that was diagnosed as voluntary winging of the scapula (VWS). We compared clinical, electrodiagnostic, and other examination data for 10 patients with VWS and 146 with dynamic WS-related neuromuscular disorders, to establish a detailed pattern of the VWS subtype. In VWS, electrodiagnostic and other examinations did not reveal any neuromuscular or orthopedic cause. Winging was dynamic, obvious, neither medial nor lateral, and mainly involved the inferior angle of the scapula, in young patients. VWS never appeared during floor push-ups. Patients could produce WS at will with the index and healthy shoulder, between 25° and 65° of anterior elevation, or with shoulder internal rotation. VWS is a benign disorder that can be distinguished from neuromuscular WS by normal electrodiagnostic results for muscles and nerves of both shoulders and two specific clinical tests.