Success of knee replacements makes them worth the risk

including infection, nerve injury, instability and stiffness (the inability to properly flex the knee).

Only about 5 percent of people have stiffness, according to a 2006 paper, and these problems mostly improved with manipulation, although some needed a second operation.

Physical therapy after surgery is crucial for success (but, as your friend shows, not a guarantee of success).

My patients’ experiences have been largely favorable. I’ve seen some bad complications, but most people are very satisfied. Many say they wish they’d had the procedure done sooner.

Dear Dr. Roach: I have been on tramadol for 10 years and am worried that it is affecting or will affect my brain, as it works by changing the way the brain treats pain. I am 76 and take two or three a day for my arthritis.

A: Tramadol is an opioid pain medication, similar to codeine and others. It might slow breathing, especially in high doses. It works by blocking a pain receptor (the mu receptor) in the brain. The brain responds to this by inducing changes in the mu receptors, making them less sensitive, and in many cases reducing the effect of the dose over time, requiring higher doses for the same effect. This is one of the reasons that opioids aren’t good long-term medication for pain, especially for chronic conditions such as arthritis.

In addition to the fundamental change in the brain, long-term opiate use increases the risk of motor-vehicle crashes for drivers, can actually increase sensitivity to pain, are likely to cause constipation and put people at risk for accidental overdose.

I suspect that other medications might work better for you. I would at least consider an alternative. If you do switch, work with your doctor to slowly reduce the tramadol dosage; never suddenly discontinue it.