Raspberries are known for being vigorous spreaders. Martha keeps hers under control with T-shaped raspberry trellises.
The trellises, strung with thick, 16-gauge wire, keep raspberry branches from bowing over and looking unkempt. They also make harvesting simple; the canes grow straight up, so you won't have to bend over to collect the fruit.
Attach any unruly branches to the wires of your trellis with twist ties.
Each spring, prune back the canes that produced fruit the season before, as only new canes will produce berries. Be sure to wear thick garden gloves while doing this, because the canes are prickly.