Why would the skin on the hamstrings turn purple?

Caregiver husband asked...

My wife has been confined to bed and wheelchair for the past four months. She walks with a walker but very little due to her knees not functioning. I noticed the backs of her thighs have turned dark purple. Also, the skin on her calves have a purplish tone. What might be the cause of the discoloration? Poor circulation? What concerns are appropriate? She says the skin sensations are good, but I'm worried.

Expert Answer

Jennifer Serafin, N.P. is a registered nurse and geriatric nurse practitioner at the Jewish Homes for the Aged in San Francisco.

Since I cannot actually see what you are seeing, I am going to go through some scenarios of what could be the most likely causes of each of these issues.

1) "Purple" skin on the back of the thighs: Since she is now in a wheelchair, your wife is getting alot of pressure on the backs of her thighs and backside. She may need a pressure relieving cushion to sit on while she is in the wheelchair. If the skin looks purplish, like a rash, she may be sweating while she is sitting in her chair. An antifungal powder sprinkled on the backs of her thighs can help reduce wetness there. If the purplish skin looks more like bruises/bruising, that is more concerning, and I would let her health care provider know about it.

2) Purplish skin on the calves. Many older people develop poor circulation as they age. This will often times show up as skin changes on the lower extremeties. You do not mention if she has swelling of the legs or not. That would indicate more of a venous issue. Poor venous circulation usually also causes a dry, flaky rash known as venous stasis.

But, if her feet/legs are cool to touch, hairless (no hair growing on them), painful when walking, and purplish when they are hanging down, she may have an arterial circulation issue. Your best bet is to talk to her health care provider and have them assess her, as venous vs. arterial circulation have different treatments and risks. Good luck!