Loss of, or damage to the flexor tendons dictates flexor tendon reconstruction procedures. Our study includes 17 digits where two-stage profundus reconstruction was performed. Both flexor tendons(FDS & FDP)were excised due to excessive scarring. Because of the absence of FDS, 65% digits demonstrated swan neck tendency. Biomechanical analysis, using videography & fluroscopy of these digits in stage II active mobilization phase, revealed that the tendency towards swan neck deformity was due to an excessive flexor force at the distal interphalangeal joint. This in turn caused greater translational forces and uninhibited extensor (EDC & Lumbrical) force acting at the proximal interphalangeal joint contributing to PIP joint hyperextension. A similar phenomenon was also observed and reported in the normal digit where superficialis is harvested for transfers. Whereas, in the reconstruction of intrinsic negative hand using superficialis transfers,the tendency for swan neck was absent. From these findings, the intrinsics, especially the lumbricals played a major role in causing a biomechanical imbalance in 1 tendon - 3joint digit.