We report the case of a 43-year-old woman who underwent knee arthroscopy. Postoperatively, she developed a lesion of the common peroneal nerve, which was confirmed by neurophysiological studies. Exploration showed the nerve to be in continuity and externally undamaged. At review 17 months later, there was incomplete recovery. We believe this lesion was caused by a traction injury related to patient positioning, which has not been reported previously.