Post-back-surgery foot drop possibly nerve-related

DEAR DR. ROACH: My husband had surgery two weeks ago to fuse his three lowest vertebrae due to degenerative disc disease. He had no issues with his legs or feet prior to surgery.

Since the surgery, his back pain is gone, but his legs are extremely weak — he can walk only with a walker and his left foot has drop foot. My main concern for him is the drop foot issue because I recognize that the leg strength is something that’s just going to have to heal, whereas the drop foot could be from nerve compression or nerve damage.

At his two-week post-op appointment with the surgeon, the surgeon basically said, “Well, it’ll get better or it won’t,” and wrote him a script for orthotics for his shoes. Of course, he’s doing physical therapy, as well.

Does his drop foot have a good chance of improving just from the physical therapy? Everything I’m reading says that the quicker a drop foot is addressed, the better the chance it has to be 100 per cent repaired. Time seems to be of the essence. — H.S.

ANSWER: “Foot drop” is a simple name for a complex issue

The nerves to the muscles that hold up the foot come off the spinal column at L4/L5, travel down the sciatic nerve and then branch off as the peroneal nerve. Foot drop can result from damage at any of these places. Clearly, your husband’s is related to the surgery. I think it’s most likely an issue at the nerve root on its way out of the spinal column.

One way to confirm would be with an EMG and nerve conduction velocity studies. Damage can occur during surgery to the sciatic and peroneal nerves.

You are right about getting treatment quickly. If foot drop is due to ongoing compression of a nerve, such as by a herniated disk, then relieving the compression sooner enhances the chances of complete recovery.

I am glad you saw the surgeon, as I would be extremely concerned. It sounds as though his surgeon is convinced there is not an ongoing anatomical problem. Assuming this, my reading indicates that foot drop after back surgery is not so uncommon, and usually it does resolve on its own. Physical therapy and an anklefoot orthotic are indicated.

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