Insurance for knee braces

I want to know whether knee braces are covered in DME.
Will insurance company pay me if i purchase one from walmart store.I am a bit confused after reading this.
http://bestkneebrace.info/reviews/knee-brace-insurance-are-you-eligible-for-medicare-claim-on-knee-braces

[Amir Mostafaie]

Dear nisha712,

Generally speaking, knee braces could be covered under Durable Medical Equipment however there are 2 things you need to find out before you know for sure if and how YOUR plan covers this claim for you.

First of all the "equipment" has to be prescribed (in writing) by your physician and secondly you need to contact the customer service for your plan to find out if you are required to use a network provider; Walmart may not be an in-network provider.  

Sincerely,

Amir Mostafaie