I have a constant ache behind the knee. Could this be popliteal aneurysm?

It is possible. A constant ache behind the knee can be due to many things including a popliteal artery aneurysm. Pain behind the knee is most commonly due to orthopedic problems such as a baker's cyst. An ultrasound can easily diagnose a baker's cyst or a popliteal artery aneurysm.
Unlikely but Possibl. A popliteal aneurysm can cause pain but most often it is asymptomatic. It typically isn't found until a complication happens - mean arterial occlusion. Also someone in your age group is less likely. Other problems that may be more likely are bakers cyst, muscle injury, ligament damage or venous insufficiency. You should see your physician for further workup.

Related Questions

I have tingling sensation behind my left knee. Does this mean I have a popliteal aneurysm?

Unlikely. Popliteal artery aneurysms are not typically symptomatic (not painful) until they occlude. We don't worry about these rupturing. We worry mainly about these clotting and blocking circulation to the legs. Tingling would not be associated with a popliteal aneurysm. Read more...

Might a popliteal aneurysm cause the upper leg to feel like it is pushing into the lower leg with general tightness in the knee and on the sides?

Possibly. Popliteal aneurysms are a dangerous condition, as most do not cause symptoms until something catastrophic occurs; typically clots form in the aneurysm & embolize to the lower leg. This leads to emergent surgery & many times even with surgery the leg will be lost to amputation. The best way to diagnose is with ultrasound. Larger ones can be appreciated on leg exam. Sometimes tightness occurs. Read more...