Fig. 1From: Sonographically controlled minimally-invasive A1 pulley release using a new guide instrument – a case series of 106 procedures in 64 patients A-E Guide instrument and hook knife with sonographic view. A Guide instrument, as of November 2019; B guide instrument shown with inserted hook knife; C longitudinal and D axial sonographic view of guide instrument in the intrasheath position; E hook knife placed upright within channel just proximal to the A1 pulleyBack to article page