The repair of long-segment peripheral nerve defects is obviously a difficult clinical problem.For short-segment nerve defects (less than four times the diameter of the nerve),direct end-to-end neurorrhaphy can be applied by dissociating tissues surrounding the nerve or by adjacent joint flexion.However,for long-segment nerve defects that cannot be repaired by direct end-to-end neurorrhaphy,autologous nerve grafting is currently a preferred method of treatment.Simple nerve anastomosis may inhibit axon regeneration probably due to excessive tension.Moreover,direct nerve anastomosis can have certain error matching ratio and autologous nerve grafting also has some shortcomings such as lack of donors,increases trauma and needs multiple surgeries (Sabongi et al.,2015).Recently,the development of tissue-engineered nerve grafts and three-dimensional (3D) printing technology provides further possibilities for the treatment of peripheral nerve defects (Figure 1).