A few years ago, my patellar tendon was getting sore from running, and I went to a sports medicine specialist.  At that first visit, he did an ultrasound scan over the length of my patellar tendons, and it was very discouraging to see these &quot;black&quot; sections in the mid-core of my tendons.  They were actually tissue that was a bit disrupted, but the way it scattered the sound, it appeared as &quot;black&quot;.  Kind of freaked me out that my tendon was &quot;dead&quot; in the middle. The actual diagnosis was patellar tendinopathy, previously referred to as patellar tendinitis, or &quot;jumper&#x27;s knee&quot;.<p>He gave me exercises to build up my tendons, mainly eccentric resistance exercise, but it was going to take a long time.  I wondered how I could monitor the progress of the healing.  The doctor visit and scan was at least $200&#x2F;visit, and the healing could take a year.  On AliBaba, I checked how much a low end machine would cost to use at home.<p>There were all sorts of machines available, and one manufacturer&#x27;s rep latched onto me.  I still get the occasional email checking if I&#x27;m ready to buy.  I think these machines may require some doctor&#x27;s approval, too, but I never went that far.<p>But they sure don&#x27;t cost anything like the prices in this article.  In 2013, for quantity 1, IIRC, I was quoted $1100&#x2F;each for this SUN-806F laptop plus sensor plus software unit:<p><a href="http:&#x2F;&#x2F;www.cnsunbright.com&#x2F;china&#x2F;english&#x2F;newshow.asp?Cid=108&amp;sid=149&amp;PID=135" rel="nofollow">http:&#x2F;&#x2F;www.cnsunbright.com&#x2F;china&#x2F;english&#x2F;newshow.asp?Cid=108...</a><p>Maybe I&#x27;m missing something critical in this price difference?  As the OP was explaining, you can almost build one yourself.