10 year old artificial knee has burning sensation when bending
I have two artificial knees, one right at 10 years old (right knee), one about 9 3/4 years old (left knee). During the past week or two, I've begun having a burning sensation on the inside of my left knee occasionally when I bend it. It feels like I've come in contact with something hot. Changing the position of my knee pretty much completely eliminates the sensation. Until today, I've experienced it maybe 3-4 times total, usually maybe once a day. Today, I've experienced it at least a half dozen times, and it's getting more frequent and more extreme.
I have an appointment to see my orthopedic surgeon in 5 days to get basic x-rays and exam just to see if things are still doing well… but I've had this sensation at least 4 times since I called earlier today and scheduled the appointment. As things are right now, I'm not sure I should wait; I'm beginning to become concerned my joint may be failing… and – to be really transparent – I'm beginning to freak out. This was made worse 3 days ago when I walked a half mile at the YMCA, something I've done numerous times without any issues.
Any ideas what might be causing this? Do I have cause for concern, should I insist on being seen ASAP?