A force transmitting assembly of an adapter assembly includes a rotatable drive shaft, a strain sensor, and a drive member. The drive shaft includes a proximal portion, a distal portion, and a flange. The distal portion includes a threaded portion. The strain sensor is coupled to the drive shaft and disposed adjacent the flange such that longitudinal movement of the drive shaft imparts a force on the strain sensor via the flange. The distal drive member has a proximal end rotatably coupled to the threaded portion of the drive shaft and a distal end configured to be operatively coupled to a driven member of a surgical loading unit. Rotation of the drive shaft longitudinally moves the drive member relative to the drive shaft to actuate the surgical loading unit.