In a previous work, via a second-order sphericalharmonic expansion, we built a generalized anchoring energy including two coupling constants. In the present paper, using this energy, we analyze the voltage-controlled-twist (VCT) effect [G.P Bryan-Brown et al., Nature (London), 392, 365 (1998)]. Our analytical results indicate explicitly the presence of the twist threshold and saturation field, and demonstrate the condition of the occurrence of the VCT effect.