A prospective study of postoperative mobilization of flexor tendon repairs in zone 5 was conducted over a 2-year period between 1994 and 1996 using a controlled active motion (active extension-active flexion) regimen of mobilization. Fifty-two patients, who had a total of 151 flexor digitorum superficialis (FDS) and 103 flexor digitorum profundus (FDP) divisions, were available for review at a mean follow-up of 10 months. Of the 161 fingers with division of one or both flexor tendons, 66% exhibited independent FDS function and 90% achieved good or excellent results of digital range of motion. No rupture of an FDP tendon repair occurred during the study period. The data allowed us to define a new method of classifying the results of treatment of these injuries in terms of the injured wrists as a whole and not simply as a series of isolated observations for each individual finger with divided flexor tendons. The results of recovery of independent FDS action and range of finger movement achieved for injuries in which the flexors of all four fingers had been divided indicate a statistically significant interdependence of injuries of finger flexors of adjacent fingers at the wrist. Multivariate analysis showed the presence of a "spaghetti wrist" injury to have a significant adverse effect on the recovery of the independent FDS action but not on the recovery of the digital range of motion.