Stiff Joints: Stiff Knee

Stiff Joints: Stiff Knee

Normal Anatomy

The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap). The femur and tibia meet to form the knee joint which is a hinge with the knee cap(patella) in front of these two bones acting as a mobile shield to protect the joint. The patella slides up and down in a groove in the femur called the femoral groove as the knee is bent and straightened.

Ligaments hold the knee together and give it stability. The medial (inner) collateral ligament (MCL) and outer (lateral) collateral ligament (LCL) limit sideways motion of the knee. The posterior and anterior cruciate ligaments (PCL and ACL) limit forward and backward translational motion of the knee bones, keeping them stable and allowing the knee to function as a unit.

Two structures known as menisci sit between the femur and the tibia and act as cushions or shock absorbers for the knee. Menisci are one of two types of cartilage in the knee. The other type, articular cartilage, is a smooth and very slick material that covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. This articular cartilage allows the bones to move smoothly without pain. If this layer wears away, it is called arthritis and then the motion becomes painful.

Tendons connect muscles to the bones of the knee. The quadriceps muscles on the front of the thigh are connected to the top of the patella by the quadriceps tendon, which covers the patella and becomes the patellar tendon. The patellar tendon then attaches to the front of the tibia. The hamstring muscles in the back of the leg attach to the leg bone (tibia) at the back of the knee. The quadriceps muscles straighten the knee and the hamstring muscles bend the knee both of which are required for walking, running or simply standing.


Stiff knee, also referred to as arthrofibrosis, is a condition that is associated with moderate to severe pain with knee motion. The tissues in the knee causing arthrofibrosis are in the second layer of the knee, the knee joint capsule. These tissues are normally loose, but in arthrofibrosis, they become excessively tight and scarred. A stiff knee usually occurs after an injury to the knee or after surgery on the knee. In some cases, the knee was immobilized for a prolonged period of time after the injury or surgery, causing the knee joint capsule to stiffen.


The mainstay of treatment for a stiff knee is a cortisone injection to reduce the inflammation within the knee joint and physical therapy for stretching exercises. The therapy followed at ROC is very specific and focuses on an assisted, passive stretching program by the therapist. A patient cannot be left to themselves and expect improvement, because there can be a significant amount of pain experienced during knee capsular stretching. It is important that a therapist not focus on simple active-assisted exercises or strengthening exercises, since this does not address the problem and only delays improvement.

If therapy fails because the pain is intolerable, or the stiff knee has shown no improvement in spite of a good therapy protocol, a closed manipulation of the knee is recommended and if necessary, an arthroscopic release of the knee joint capsular tissue. Therapy is restarted immediately after a manipulation and/or an arthroscopic capsular release to maintain the gains in motion made during the manipulation and/or arthroscopic release. In some cases, the stiffness does not resolve with a closed manipulation and/or an arthroscopic release. In these cases, an open procedure is required to fully release the tight capsular tissue as well creating a new, more expanded capsule to begin therapy again.

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