Differntial diagnosis of Jumper's Knee vs. Patellar Tendinopathy, Posterolateral Corner (PLC) Instability, Iliotibial Band Friction Syndrome vs. L5 Radiculopathy, S1 Radiculpathy, Stress Fractures, Impaction Fractures and Post-Surgical Neuropathic Pain at the Infrapatellar Branch of the Saphenous Nerve.