US Patent 11992668 Injection device

A needle assembly for an injection device is provided to facilitate delivery of a dermal filler. The assembly includes a cannula and a hub. The hub can be coupled to a syringe. The hub includes an inner bore that has a proximal retention section, a stepped section, and a cannula retention section. The stepped section, the proximal retention section, and the cannula retention section are configured to reduce the dead space within the inner bore for preventing detachment of the hub from the syringe during an injection procedure.