Hi thanks for asking question. Here you have suffered from trauma to knee joint.So lead to hematoma formation. Usually if hematoma small then it will be absorb automatically in few days. But depending on size of hematoma and degree of affection of movement decision have to be taken by doctor whether it has to be aspirated or not. Do your knee digital x ray for detection of patellar position, patteler fracture and fracture of femoral lateral condyle. Brace has to be wear for few days. Take enough rest for few days. Antiinflammatory drugs useful. Still for best detection of injury like injury to ligaments and mensci MRI will be the best one to do if swelling marked and movement at knee affected. Wish you good health. Dr.parth