Aims: Objective evaluation of contraction power of the neo-phallus reconstructed with a novel technique in female-to-male transsexuals. Patients and Methods: From December 2001 to September 2005, 22 patients with gender identity disorder underwent neo-phalloplasty with the re-innervated latissimus dorsi free flap. All the patients were subjected to an early rehabilitation protocol of the transferred muscle; the beginning time of neo-phallus voluntary contraction was recorded in 18 patients. 14 patients, who came for examinations, were objectively evaluated for the strength of transplanted muscle contraction in neo-phallus by electromyography and measurement of the maximum weight lifted. Results: 18 patients were able to voluntarily contract the neo-phallus after an average period of 4.11 months. In 14 of them, the average weight lifted was 1129 g. After electromyography, the mean number of positive peaks in the 100 ms period was 31.5; the mean amplitude from 10 highest positive peaks, measured peak-to-peak, was 0.99 mV. Discussion and Conclusion: The advantage of this technique is non-requirement of the prosthesis for sexual activity due to the development of strong voluntary contraction of the neo-phallus. Our findings document objectively the strength of voluntary contraction of the neophallus as a consequence of re-innervation of the transferred muscle. Furthermore, data represent useful tool for clinical assessment and comparison.

        Key words: phalloplasty, re-innervated latissimus dorsi flap, electromyography