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Author Topic: ACL/PCL cyst: cause of posterior knee pain or red herring?  (Read 905 times)

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Offline jx1613

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ACL/PCL cyst: cause of posterior knee pain or red herring?
« on: October 29, 2013, 08:27:10 PM »
I am 34 with a background in competitive running.
My left knee has had patellar tendonitis on and off for 15 years, but I could usually run anyway by preferring soft surfaces etc.
That same knee developed a new injury six months ago, right in the middle of the back (along or slightly above the 'popliteal crease'). The injury set in slowly over the course of a few days, until it flared up badly after a run. I could not fully extend it due to great pain, and began RICE.
After 2 weeks, it was healing but not all that fast, so I went to dr and he said hamstring strain, which had been my suspicion too, and said just rest, come back in a month if it doesn't get better.
A month later I could extend my knee, but it hurt to support much weight. Still walked with limp. Pulling sensation in back of knee when extended. Tightness in calf and lower hamstring also. Condition has not really changed since that time.
After return to DR, he still said hamstring strain, go to PT. 8 weeks of PT, no improvement, off to sports med specialist who quickly re-diagnosed as popliteus strain, sent back to PT.
8 more weeks of different PT, no improvement. Still walk with limp, cant run or even do elliptical.
Back to specialist, popliteus theory pretty much dismissed now. MRI ordered. Small ganglion cyst found between ACL and PCL, 8mm diameter. Doctor says cyst is the problem, referred to surgeon, awaiting appt.

First PT thought calf, not hamstring. Second PT thought calf, not popliteus. So I still suspect that I did something to the medial head of my gastrocnemius tendon. Thing is, it just won't heal despite rest and PT. All healing occurred in that first six weeks. And the pain is back of knee, though belly of calf does feel tight at times. Fully extending knee hurts, and dorsiflexing (toes pointed upward) while knee extended exacerbates knee pain. So basically deeply stretching the calf activates pain in back of knee. But calf raises ie contracting the calf doesn't hurt it as long as the leg is not fully extended (anything with it fully extended hurts!)

Could the cyst still be the problem, despite the fact that stretching the calf hurts it? I'm particularly confused that dorsiflexing the ankle (or just shifting more weight onto my heel when standing) exacerbates the pain. Could lengthening the gastroc put more tension on the femur, thereby irritating the cyst area by some ripple effect? Or is this cyst stuff a red herring? I read about 1% of MRIs show this type of cyst, and they can be asymptomatic.