Popliteal artery entrapment is a condition where the popliteal artery is compressed by surrounding muscles or tendons, leading to impaired blood flow to the lower leg. It is clinically significant because it can cause exertional leg pain, claudication, and, if untreated, may result in limb ischemia or thrombosis. This condition is often associated with young, physically active individuals and can mimic peripheral arterial disease.