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 yesterday, 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? Should he continue to just do physical therapy, or should we find a specialist to see him ASAP?

Everything I’m reading says that the quicker a drop foot is addressed (in terms of finding out the reason — a compressed or damaged nerve — and getting that dealt with medically), the better the chance it has to be 100 percent repaired. Time seems to be of the essence. — H.S.

Answer: “Foot drop” is a simple name for a complex issue. It almost always involves damage to a nerve.

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 (but that doesn’t necessarily mean the surgeon did anything wrong). 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, though this is more common in hip surgeries (at least, that’s where I have seen it most often).