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is a serious condition that can afflict knee joints that have either been recently injured, operated upon, or both. The process begins when the traumatic stimulus of an injury and/or surgery leads the knee to form extensive, internal scar tissue. This is followed by shrinkage and tightening of the knee's joint capsule (surrounding envelope ligament). Sometimes even nearby tendons outside of the joint stiffen up. This internal and external tightening process may continue to the point where motion between the femur (thigh bone) and tibia (shin bone) is severely restricted. Afflicted patients may permanently lose the ability to fully straighten and/or bend their knee.

In general, the likelihood of developing arthrofibrosis increases with the severity of a knee joint injury, the extensiveness of related surgery, and the length of time that the knee is subsequently immobilized. However, not everyone who sustains a major knee injury or who undergoes major surgery will develop arthrofibrosis. Some people are more prone to developing this problem than others. Genetic factors apparently predispose some patients to develop arthrofibrosis by way of an inherited tendency to form hypertrophic (excessive) internal joint scar tissue in response to injury and/or surgery. Such individuals often heal surgical ligament repairs and grafts quite solidly, but go on to heal "excessively", forming an overabundance of unwanted fibrous scar in their knee. This essentially makes their knee too stable, to the point of being stiff and lacking proper joint motion. Such "heavy scar-formers" can literally fill up their entire knee joint cavity with thick, tough scar tissue. This obliterates all of the normal open spaces within the joint, adhering everything together and effectively "freezing" the joint (hence the traditional term "frozen joint").

Patients with "sensitive" knees or low pain thresholds are also more likely to develop this problem, as they find it more difficult than most to use and move their knee after injury or surgery. Lack of joint motion and use leads the knee to form more abundant and less compliant scar tissue than it otherwise would, and allows the relatively unused (and thus unstretched) surrounding knee capsule to contract down and tighten up, almost like "shrink-wrap" does. A stiff, arthrofibrotic knee is a very difficult problem for the orthopedic surgeon and physical therapist to handle. It usually requires a specially planned, intensive protocol of surgical treatment and post-operative management.

The traditional treatment approach for arthrofibrotic knees that did not loosen up with aggressive stretching and exercise in physical therapy has been to place the patient under anesthesia and then literally break up and tear the restrictive, internal scar tissue within the joint by forcing the knee to fully bend and straighten. The surgeon accomplishes this by way of strenuous, manual joint manipulation. The procedure therefore came to be known as a manipulation under anesthesia, or "M.U.A.", and is still in common use. In cases of severely frozen knees, extremely stressful manipulation forces may be required to break up the scar tissue and get the joint moving again. This poses a risk to a patient who has not been able to bear much weight on their leg for quite some time, because the femur and tibia may have lost a considerable amount of bone mineral (calcium phosphate), thus weakening them. This increases the chance of an inadvertent femoral or tibial fracture occurring at the time of the joint manipulation. My preference over the years has been to perform an arthroscopic, internal surgical scar resection to remove as much restrictive scar tissue as possible, prior to manipulating the knee. This approach not only leaves very little scar within the joint to re-organize and solidify once again, but it also reduces the manipulation force required to get the knee moving, thus reducing (but not eliminating) the chance of femoral or tibial fracture.


® 2007. The Knee and Shoulder Centers of New Jersey and Pennsylvania.