Hi, thanks for writing to HCM. As you have sustained a fall causing an injury to the knee joint, an Xray of the knee joint is mandatory to rule out any fracture of the involved bones. To know the integrity of the soft tissues within the knee joint (meniscus and cruciate ligaments), MRI scan is needed. So, a detailed clinical examination followed by appropriate investigations (as mentioned above) are necessary to establish the correct diagnosis of your condition. I suggest you to consult an orthopedic surgeon for further evaluation and management. Hope this information is helpful. Good day