The fate of tendon grafts used to reconstruct the digital annular pulleys.

An experimental morphological study on the reconstruction of the digital annular pulleys has been carried out in dogs. The segment corresponding to zones 1 and 2 of the flexor apparatus of the 2nd and 5th digits of the left forepaw was chosen for the experiment. The whole flexor apparatus was resected and a single digital pulley (A 2) was reconstructed, using segments of the animals own deep flexor tendon. A length of silicone rubber tube was used as tendon spacer. The new pulleys showed marked degeneration of the collagen fibres and thinning which increased with time and may be the cause of decrease in strength. A layer of mesothelial cells with secretory properties developed at the interface between the tendon graft and the spacer.