This paper presents a novel skeleton design for avatar animation. This design includes new bones, whose purpose is to meet the requirements of sign language (SL) synthesis. SL synthesis presents particular challenges regarding the processing of phonetic descriptions of signs to create animations. Although traditional animation techniques have solved the synthesis of signs, the proposed skeleton design allows for the simplification of the phonetic processing, the inverse kinematics calculations, and the collision avoidance processes. The proposed design has been tested to demonstrate that the generated animations have the same quality as the ones produced with state-of-the-art techniques. Importantly, the proposed structure reduces the time required for generating an animation by 52% compared to existing solutions and requires less storage resources.