Knee pain can be caused by a variety of structures around the joint. Your diagnosis depends on the mechanism in which you injured your knee and also certain assessments that can help us understand the structure that is causing the pain.
The knee joint sits between the hip and the ankle. Although we call it a 'joint' due to its anatomy, in a simplistic sense it is really just the linkage point between the hip bone (femur) and the shin bone (tibia). Moving our lower limb puts tremendous stresses through the knee as it has to control a lot of movements that we do in our everyday life. Therefore, we have a strong system of 4 main ligaments alongside a shock absorbing cartilage in order to deal with the stress. This is then wrapped around by our thigh muscles from the front and back.
An injury is due to one of these structures being overburdened. Usually cartilage pain presents with a 'locking' sensation of the knee or a 'giving way' feeling when walking. Muscular or ligament associated pain usually has swelling, bruising or redness and occurs after a sudden unexpected movement. The aim of treatment of such injuries is to firstly identify what may be causing the symptoms. This may then require further investigations such as an MRI scan if there is a certain level of damage or hands-on therapy in combination with rehabilitative exercises to help you to return to your every day life comfortably.
Walking is an everyday unconscious activity, until you have experience of knee pain when everything unconscious becomes extremely conscious. Dealing with the injury early prevents it from becoming worse.