Is surgery for a reasonable idea for an otherwise healthy 78 year-old man with a painful lower back caused by stenosis, arthritis & 3 bulging discs?

Yes: Healthy individuals usually have lower health risks. Spinal stenosis can cause some back pain but is usually noted for leg pain and weakness. The degenerative process which causes the stenosis is probably the cause for your back pain. Surgery is definitely an option at your age. There are different types of surgery which may be offered. See a neurosurgeon or ortho spine surgeon for options.

Last Resort: You need to try physical therapy, local modalities like a tens unit, oral pain meds like tylenol, (acetaminophen) or even mild opioids like low-dose vicodin or lortab. If none of these treatments work you might consider an epidural injection. If the epidural helps for more than a week or two you might consider repeating a couple of times per year. If that doesn't do it, i would try stronger opioids in low doses.

For leg pain: Stenosis causes leg pain surgery treats this well the backache from arthritis is not consistanly treated with fusion surgery try rf ablation for backache from arthritiv joints.

Not likely, but mayb: The expected outcome of surgery depends upon the nature of the patient's symptoms and their correlation with findings on ct, MRI or other studies. A 78 year old man will predictably have all of the cited abnormalities in the back. The question is whether they are the cause of symptoms and whether surgical correction is likely to be helpful.

Ok surgery but....: Surgery is not unreasonable. First option is to try to be conservative with other modalities of treatment.

Yes: If you have failed anti-inflammatory medications, physical therapy and epidural steroid injections, it may be an option.