The job of the popliteus muscle is to internally rotate the tibia. In addition, the popliteus muscle is the most important posterolateral stabilizer of the knee. Popliteal tendonitis causes tenderness at the insertion of the poplilteus tendon on the lateral femoral condyle near the femoral insertion of the lateral collateral ligament.
A over the counter orthotics/insoles with lateral posting tends to help hold the tibia in an internally rotated position and thereby decreases the stress on the popliteus. A lateral post also decreases the varus stresses on the knee which decreases tension on the posterolateral corner of the knee.
If you think you suffer from this condition please contact a medical specialist.