The need for lateral release or "venting" of the A2 and A4 pulleys either to facilitate repair of the flexor tendon(s) or to allow free gliding of the repair(s) was examined in 126 consecutive zone 2 flexor tendon injuries within the tendon sheath and distal to the distal edge of the A2 pulley (zones 2A and 2B of Tang's classification) in which at least one flexor tendon had been completely divided. This study showed that 81 (64%) of these repairs required venting of one or the other pulley. It was necessary to vent the A4 pulley between 10 and 100% of its length in 71 (56%) of the fingers and to vent the distal edge of the A2 pulley by 4 to 10 mm in 10 (8%) of the fingers.