Knee Replacements Save Lives?

Today’s Managing Health Care Costs Indicator is 50%

The New York Times “Well” Blog has the provocative title “Knee Replacement May Be A Lifesaver for Some.”   

Not really.

The article opens with a 64 year old who dropped 20 pounds in two months after her surgery – and continues with a 94 year old retiree who restarted windsurfing as soon as he finished post-operative rehab.

The study, financed by a medical device maker, is a classic example of selection bias.  It reviewed the Medicare claims records of 135,000 patients with a new diagnosis of knee osteoarthritis. Of them , about 40% had knee replacement.  Those who had knee replacement had 11% lower risk of heart failure within three years, and a 50% lower risk of death at seven years.

Of course!

Orthopedic surgeons just don’t do knee replacement surgery on the frailest of the elderly.  If they wanted to, the anesthesiologists would talk them out of it!

Knee replacement surgery can help get arthritis sufferers back to exercise. The surgery can dramatically improve the quality of life.  For the right patients, a knee replacement is a good idea. Delaying knee replacement surgery too long is a bad idea, since as patients age there are higher surgical risks and  less time to enjoy the new mobility.

But let’s not be misled into thinking that this surgery prevents heart failure or saves lives.   It is merely performed on those with good cardiac function who have longer life expectancies!