Diagnosis of Knee Injuries

The initial evaluation by the physician or health care provider will begin with a medical history. Whether the evaluation is occurring immediately after the injury or weeks later, the physician will ask about the mechanism of injury to help isolate what structures in the knee might be damaged. Is the injury due to a direct blow that might suggest a fracture or contusion or bruise? Was it a twisting injury that causes a cartilage or meniscus tear? Was there an injury associated with a planted foot to place stress and potentially tear a ligament?

Further questions will address other symptoms. Was swelling present, and if so, did it occur right away or was it delayed by hours? Did the injury prevent weight-bearing or walking? Does going up or down steps cause pain? Is there associated hip or ankle pain?

Physical examination of the knee begins with inspection, in which the physician will look at the bones and make certain they are where they belong. With fractures of the kneecap or patellar tendon injuries, the kneecap can slide high out of position. Also, patellar dislocations, where the kneecap slides to the outside or lateral part of the knee, are easily evident on inspection. Looking at how the knee is held is also important. If the knee is held slightly flexed, it can be a clue that there is fluid in the joint space, since joint space is maximal at 15 degrees of flexion.

Palpation (feeling) is the next part of the exam, and knowing the anatomy, the physician can feel where any pain might exist and correlate that to the underlying structures like ligaments or muscle-insertion points. Palpation over the joint line, the space between the bones in the front part of the knee, can show fluid or tenderness associated with meniscus injury. This is also the part of the exam where the ligaments are stressed to make certain that they are intact. Sometimes, the physician will also stress the uninjured knee to see how loose or tight the normal ligaments are as a comparison. Finally, the blood supply and nerve supply to the leg and foot will be assessed.

Sometimes x-rays of the knee are required to make certain there are no broken bones, but often with stress or overuse injuries where no direct blow has occurred, plain x-rays are not needed and imaging of the knee may wait until a later date, where an MRI might be considered.