Brief Answer:
I have a few conditions that could be possible

Detailed Answer:
Hello ma'am and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. I am glad you have checked and ruled out blood pressure and blood sugar abnormalities. With the current symptoms at hand which are cold feeling at the knees and sweating.

I would like to say that being in the field of orthopaedics and traumatology I encounter many individuals coming into the hospital with these complaints, and in majority of these cases I find skeleto-muscular issue. But I would not like to concentrate on only that and would like to come up with a list of most likely causes, they are:

+Bone abnormalities: Arthritis, osteoarthritis of the knee, psoriatic arthritis, osteochondritis desiccans, etc.
+Obesity: Which also results in injury or damage to the knee joint and its ligaments due to the excess weight being XXXXXXX by the knee joint
+Ligament or meniscus injury: A few ligaments and the meniscus hold the knee together helping it to carry the weight of the body, run, walk and so on. When these ligaments are injured (more common in sports persons and obese individuals) it can result in a presentation similar to what your mother is experiencing
+Thyroid abnormalities
+Side effect of medications: Check with her treating doctor if the medications she is on can cause her current presentation
+Chronic conditions: Raynaud's phenomenon, rheumatic fever, sarcoidosis, etc.
and a few others.

I understand how the list of conditions here can be long, but a few investigations can help direct us towards any abnormalities, they are:

+MRI of the knee
+ESR, RA factor, ANA and CRP taken from a blood sample
+Thyroid profile
+Bone density scan

I hope you find my response both helpful and informative. Please feel free to write back to me for any further clarifications, I am always here to help.

Best wishes.

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