asked to perform a duckwalk. This requires the person to squat and walk in that position. In order to perform a duckwalk, the person has to be free of ligamentous tear, knee effusions, and meniscal tears. The person can also be asked to stand with both feet stuck together. This position is useful to observe for valgus or varus deformity of the knees which is suggestive of osteoarthritis. The circumference of each thigh can be measured to look for wasting of quadriceps muscles. Skin around the knee can also be observed for psoriasis, hematoma, rash, abrasions, lacerations, or cellulitis which could be important causes of the knee pathology. Palpation Palpation of the knee should begin from the unaffected side first. This will reassure the patient and is useful for comparison with the affected knee. The back of the hand can be used to assess the warmth of the knee. The knee is then flexed 90 degrees and the anterior structures are assessed. Inflammation of the patellar tendon is present if the patellar tendon is painful upon palpation. Radiographic imaging should be done if the examination findings fulfills the Ottawa rules: age 55 years and older, pain at the head of fibula, patellar pain, unable to flex the knee to 90 degrees, and inability to stand and walk at least four steps. If anterior cruciate ligament injury is suspected, radiographic imaging should also be ordered because it is frequently associated with lateral tibial plateau fracture. If there is a painful, reddish, and warm swelling in front of the patella, acute prepatellar bursitis should be considered which may require aspiration or drainage. Those presented with these features usually had history of frequent kneeling and direct trauma over the knee. Pain, swelling, and a defect of the insertion of the quadriceps tendon into the superior part of the patella is suggestive of quadriceps tendon rupture. A "pop" sound may be associated with this injury, followed by the loss of the ability to straighten the knee (knee extension). Pain at the medial joint line (medial to the inferior border of the patella) indicates medial compartment osteoarthritis, injury to the medial collateral ligament, or a medial meniscal tear. Pain at the midpoint between the anterior part of the medial joint line and tibial tuberosity is suggestive of Pes anserine bursitis (inflammation of anserine bursa. Lateral joint line tenderness is associated with lateral compartment osteoarthritis, lateral