Patients with problems in the knee commonly complain of pain, stiffness, giving way, swelling and mechanical symptoms of catching, clicking or locking. As well as knowing the exact mechanism, history, timing and immediate management of the injury, we need to know about where the pain is or was, what brings it on and what makes it worse and better.
Common Sense Questions to ask
For example, usually, but by no means always, an injury which allows an individual to complete the game is not going to be a serious one such as an ACL tear. On the other hand the absolutely typical history which we hear all the time of a complete rupture of the anterior cruciate ligament is of an audible “pop” caused by a non-contact twisting injury. The player falls to the ground and thinks he has broken his leg. The knee will swell within one to two hours because it is filling up with blood (as opposed to fluid leaking into the injured area, which occurs much more slowly) and everyone will be aware that something significant has happened to the knee. We will often see patients five or ten years after the injury whether or not the diagnosis has been made, but they will almost invariably remember the exact date and who they were playing against when they tore their cruciate. The fact that the diagnosis is commonly missed (only around 10% of patients coming to a specialist knee clinic with a torn ACL have the diagnosis made before they come!) is often because the physical signs on examination can be quite subtle.
The other helpful point in the history about the pain suffered is whether it comes on intermittently with specific movements or whether it is a dull background ache which is more or less there all the time. We often hear a history that a player can complete a game without too much trouble, perhaps just a little bit of an ache, but then that evening and more particularly over the next day he suffers for it and there is a vague deep ache inside the knee associated with some swelling. This will keep him off training for most of the week, but he is back to near normal to play the weekend after. This is an absolutely typical history of a problem with the articular surface of the joint, which can be quite a serious problem. This is by contrast with the intermittent sharp pain often associated with a click. This will come on unexpectedly and is associated with something loose inside the knee, in particular a tear of the cartilage.
Giving way or a feeling of looseness or instability in the knee is more typical of a ligament tear since the ligaments are the structures which hold the knee in place and make it run true. This is most commonly seen in injuries to the anterior cruciate ligament where the knee partially comes out of place during a twisting injury and the player will often fall to the floor. The classical history given in a chronic ACL tear is that the player is absolutely fine running and even sprinting in a straight line, there is no problem on stairs and no problems on a bike, but just occasionally when he is running quickly in a straight line and suddenly has to change direction, especially unexpectedly, the knee will go wrong on him and give way and he will fall to the floor. This needs to be distinguished from a functional instability which is commonly associated with problems in the kneecap (patellofemoral) joint where a sense of instability and giving way will occur typically going up or down stairs when more stress is put through the knee cap. This is a completely different problem which often responds to strengthening exercises as opposed to surgery. This is a particularly important distinction to clarify in patient assessment.
Patients will commonly complain of catching or locking. By “true” locking we mean that the knee is completely stuck in one position, usually in about 20 or 30 degrees of flexion. This will occur unexpectedly and the patient is able to bend the knee up from that position, but when he tries to straighten it out he will come to a mechanical block as though something is “caught in the works”. This is caused by something which is actually “caught in the works”, typically a piece of cartilage which has flipped round into the wrong position and needs to be jiggled back into place. This is a problem which is not going to go away without an operation to either remove or repair the torn cartilage. It may also be caused by a loose body or a piece of gristle or bone floating around in the joint and intermittently getting catching.
The common surgical problems we see in the knee are meniscal tear (cartilage tear), articular surface problems, ligament problems and problems with the kneecap. These are described on other pages.