I wouldn't use a really strong stitch until you are sure you have taken it in the correct amount. If you take it in too much, especially at the top, it can cause problems. I had an elastic sock I used for plantar fascitis that was sliding down, so I sewed a zigzag on the outside of the sock to make it tighter. Took it in about an inch at the top (folded sock at seam and sewed half an inch in) and tapered it down. Sewing on the outside meant I didn't have to worry about cutting the sock or about having a hefty seam inside the sock to irritate my skin. However, taking it in an inch proved too much. It was comfortable, but it caused the varicose veins in my leg to pop out and inch after two continuous nights of wearing it. Thankfully, quitting the sock allowed my veins to go back to the way they were. Your type of sock is different but, if possible, I think you would be best off not cutting and simply using a plain stretch zigzag on the outside. Let your husband wear it that way for a day or two and then, if needed, you can take it in some more. Once you reach the right amount, that is when you might want to use a stronger stitch on the seam. Of course, sewing on the outside of the sock means your husband will need to wear long pants, but he probably is anyway.