Fig. 1

A hook knife was used to create a consistent lesion in lateral DDFT using a tenoscopic approach. Positions of instrument portals marked on intact forelimb by long arrows proximal (hook knife portal) and distal (tenoscope) to ergots (a). Relative position of lesion under sesamoid bone shown by short arrows in (a) and (b) at euthanasia. Dissected tendon sheath (comprised of DDFT and SDFT complex) reflected back to expose lesion within normal dorsal opening in SDFT (arrow in b). Scalpel blade positioned between tendons and sesamoid bones. Separated tendons shown with DDFT on left and SDFT on right (c). Prolapsed fibres from DDFT seen in tenoscope image during surgical generation of lesion, resembling naturally occurring tendon tears (d). Tissues divided into 10 segments with an additional segment taken proximal to the sesamoid bones. Identities are elaborated in the accompanying table. DDFT deep digital flexor tendon, SDFT superficial digital flexor tendon