Short-Term Strength Deficit Following Zone 1 Replantations.

Background: Hand strength deficit following digital replantation is usually attributed to the mechanical deficiency of the replanted digit. Zone 1 replantation, however, should not be associated with any mechanical deficit, as the joint and tendon are intact. We evaluate short-term motor functions in patients who have undergone single-digit zone 1 replantation.

Methods: A single-institution retrospective review was performed for all patients who underwent zone 1 replantation. Hand and pinch strengths were evaluated using standard dynamometers. Each set of measurements was pooled according to follow-up periods (within 1 month, 1 to 2 months, 2 to 3 months, and after 3 months). The uninjured hand was used as reference for measurements.

Results: The review identified 53 patients who had undergone zone 1 replantation and presented for follow-up visits. Compared to the uninjured hand, dynamometer measurements revealed significantly less strength for the hand with replanted digit at one month. The relative mean grip, pulp, and key pinch strength were 31%, 46%, and 48% of the uninjured hand. These three strength measurements gradually increased, with relative strength measurements of 59%, 70%, and 78% for 4-month follow up.

Conclusions: Despite the lack of joint or tendon injury, strength of the injured hand was significantly lower than that of the uninjured hand during the 4 months following replantation. Improved rehabilitation strategies are needed to diminish the short-term negative impact that an isolated zone 1 replantation has on the overall hand strength.