Last reviewed: September 29, 2026

Usually only for a short time. Lasting memory loss caused by anesthesia has not been shown.

Three different things get called memory problems after surgery.

The first is delirium: sudden confusion in the first days, sometimes with drowsiness or agitation. After hip and knee replacement, studies found it in anywhere from about 1 in 50 to about 1 in 7 older adults. It usually clears. It is often the quiet kind, drowsy or withdrawn rather than agitated, so it is easy to miss, and it can first appear after going home. It is much more likely in people who already have memory problems or dementia, and with older age, a past stroke, sleep apnea, several other illnesses, or sedative pills such as benzodiazepines. Poor sleep, before or after surgery, is also linked to more delirium. Confusion that gets worse toward evening, often called sundowning, is well described in people with dementia but has been little studied after joint replacement.

The second is slower thinking or memory in the weeks and months after surgery. In a large international study of people over 60 after major surgery, this was found in about 1 in 4 at one week and 1 in 10 at three months, far more often than in people who had no surgery. For most, it improves over months.

The third is dementia years later. Studies have not found that anesthesia causes it. In a large study of Danish twins, people who had had a hip or knee replacement scored no worse on thinking tests than people who had no surgery. Studies of later dementia found no clear difference between general and regional anesthesia. One study found that people who had delirium after surgery declined faster in the following years, but it is not known whether the delirium caused this or was a sign of brain changes already under way.

In trials, spinal and general anesthesia led to about the same rates of delirium and of memory problems at three months. The American Society of Anesthesiologists found no advantage to either for preventing delirium. Keeping anesthesia lighter with brain-wave monitoring gave mixed results, and the largest trial found no less delirium. Among medicines, the sedative dexmedetomidine has the strongest evidence for preventing delirium, though it can slow the heart and lower blood pressure. In hospital patients in general, programs that keep people oriented, mentally active and sleeping well lowered delirium from about 1 in 5 to about 1 in 10. They have not been tested separately in joint replacement.

In general:

  • Tell your surgeon and the anesthesia team about any memory problems, sleep apnea, or sleeping or anxiety pills you take.
  • Ask whether a family member can stay with you in the first days after surgery.
  • Sudden confusion or unusual drowsiness after surgery, in hospital or at home, needs to be reported to the care team right away.

Drafted with AI assistance from published sources, reviewed and edited by Babak Sheikh, MD.

Sources:

This is general information about what published research shows. It is not medical advice and it is not about your situation. Reading it does not create a doctor-patient relationship with me. I am a retired orthopedic surgeon and I do not see patients. Talk with your own doctor before changing anything about your care. If something feels suddenly or seriously wrong, get medical care promptly rather than waiting.

This page is provided as is. I make no guarantee that it is accurate, complete or current, and medical evidence changes. Use of it is at your own risk.

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