Distal Amputations
Patients with single-digit amputations distal to the flexor digitorum superficialis (FDS) insertion are good candidates for replantation. The average active range of motion in these patients was reported to be 82° by Urbaniak et al., whereas in patients with replantation performed proximal to the FDS insertion, the mean total range of motion was only 351. In a recent meta-analysis on distal phalangeal replantations, Sebastin and Chung reported an overall survival rate of 86%. No statistically significant difference was seen in the survival with regard to injuries in zone I or II. Vein repair was found to improve the survival in zone II. However, no difference was found for the more distal zone I injuries. The paucity of tissue in this type of injury may explain why vein repair is not crucial in zone I. The major complications observed were nail deformity (23%) and pulp atrophy (14%). Mean two-point discrimination was 7mm. Sensory recovery did not seem to be influenced by the number of nerves repaired. Even in cases in which the nerve was not repaired, good sensory function was observed (Figure 3). Unlike replantations at a more proximal level, there is no need for tendon surgery, as the distal interphalangeal joint is typically fused.
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Figure 3.
Amputation of the distal phalanx (left); 1 year after replantation (right).
Because of the small vessel diameters, replantation at this level is highly demanding and certainly not suited for an inexperienced microsurgeons. This is especially true for distal replantations in children.