A seatbelt pretensioning retractor assembly for use in a vehicle is provided. The seatbelt pretensioning retractor assembly includes a housing adapted for being mounted to a frame and having an interior cavity, a pretensioner tube having an arcuate and curved shape, a sprocket rotatably mounted to the housing and fixedly coupled to a spindle, a driving element as a pretensioner rod disposed within the tube and a guide plate having a guide portion and a rod guide. The pretensioner rod extends in a longitudinal direction from a proximal end portion to a distal end portion. In addition, the pretensioner rod forms a recessed portion or a recessed section to facilitate engaging with the sprocket during pretensioning.