Falls associated with lower-extremity-nerve blocks: a pilot investigation of mechanisms.

Objective: Documented falls after lower-extremity-nerve blocks are rare. We believe this paucity of documented falls is the result of underreporting and the lack of serious complications resulting from these falls. In addition, the mechanism(s) for falls after lower-extremity-nerve blocks has not been elucidated.

Case Reports: These reports highlight the mechanism of fall in a patient with a femoral-nerve block (FNB) and in a patient with a femoral-nerve and sciatic-nerve block (FNB/SNB). In addition, we report our findings when volunteers underwent FNB, sciatic-nerve block (SNB) and FNB/SNB and were studied in a gait-analysis laboratory.

Conclusions: Lower-extremity-nerve blocks result in decreased leg stiffness and lateral instability, which may lead to difficulty with pivoting maneuvers.