Descripton of Knee Arthrofibrosis

Arthrofibrosis of the knee is a condition whereby knee motion is limited due to scar tissue, contractures after injury or surgery, or due to the effects of osteoarthritis over time. There are 2 types of motion that we usually think of as being important to assess knee arthrofibrosis. First, a lack of an ability to straighten one’s knee out is a flexion contracture. Flexion contractures of more than 7 or 8 degrees compared to the opposite normal limb have been shown to limit patient’s function, lead to early arthritis and can cause secondary issues, such as pain or muscle weakness, with the same-sided hip or sacroiliac joint due to limping. This is because a joint with a flexion contracture effectively has a shorter limb. The other type of condition that we think about with knee arthrofibrosis is an inability to fully flex one’s knee. People need about 110-115 degrees of flexion to function with most activities of daily living. This includes being able to sit effectively in a car or bus, to be able to arise comfortably off a chair, and to be able to perform a full revolution on a stationary bike.

Symptoms of Knee Arthrofibrosis

  • Stiffness
  • Inability to straighten knee
  • Inability to flex knee
  • Difficulty in sitting in a car or in a chair

The workup for arthrofibrosis of the knee requires a full history and physical. It is important to determine the onset of the stiffness, associated injuries or conditions, and the previous treatments to address the issue. X-rays of that side are necessary to determine multiple things including evidence of extra bone healing, joint subluxation or abnormalities of position of the patellofemoral joint. One would also look for evidence of osteoarthritis to include joint space narrowing and bone spurs.

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(Please keep reading below for more information on this condition.)

Treatment for Knee Arthrofibrosis

The treatment for knee arthrofibrosis varies from observation, the use of bracing, physical therapy, and surgery. Observation alone is rarely performed, but may be recommended in some patients. Dynamic splinting for either extension or flexion deficits may also be indicated in some patients. This may be especially true in patients who have just had surgery or an injury and for whom these splints may be effective at improving motion due to the early timing after surgery or injury.

Surgical treatment for arthrofibrosis depends upon the specific pathology. In almost all circumstances, the surgery would be much less successful with a failure to follow specific rehabilitation principles. This can include the use of extension dynamic splints, a CPM machine and/or a very closely monitored physical therapy regimen.

Arthrofibrosis surgery can be very complex. It is important to have a very thorough assessment ahead of time to look at all the different causes of the joint stiffness. Complications can include intraoperative fractures from weak bones, ligament tears, especially from ligaments that may not have been surgical reconstructed in the ideal anatomic position, and recurrent stiffness. Since we do not know why patients form knee arthrofibrosis in all circumstances, there may be a genetic predisposition to it that we do not have the ability to recognize presently. Thus, even in the best of circumstances, some patients may develop a stiff knee again after surgery. However, when one follows the basic principles of releasing scar tissue, regaining motion, and then working with physical therapists after surgery, the chance of recurrent scarring is 10% or less.

In patients who have developed knee arthrofibrosis after an injury or surgery, one needs to make sure that the timing of surgery is correct such that one does not cause injury to a damaged ligament or healing fracture or a surgical repair or reconstruction. In most circumstances, we would wait a minimum of 3-4 months before proceeding with a surgery to treat knee arthrofibrosis.

Patients who have a flexion contracture after surgery usually need a cleaning out of scar tissue and need to be carefully assessed for a possible arthroscopic posterior capsular release. These patients are then monitored very closely postoperatively and most patients would use an extension dynamic splint to help maintain their knee extension for 6 weeks or longer after surgery. In patients who do not have full flexion, which is usually after a more severe knee injury or very large surgery, a cleaning out of scar tissue of the suprapatellar pouch and scar along the medial or lateral gutters of the knee is often required. Postoperatively, patients are almost uniformly allowed full motion and full weightbearing of their knee, with most patients requiring the use of a continuous passive motion machine to help decrease the chance of recurrence of scar tissue.

In patients with osteoarthritis, the removal of bone spurs, that can limit range of motion, is an effective treatment option for returning knee motion back to normal or near normal levels. However, these surgeries are often found to be unsuccessful if one does not follow specific rehabilitation guidelines.

Post-Operative Protocol for Knee Arthrofibrosis

In our practice, we have patients start physical therapy the first day after surgery with two 2-hour sessions daily for 1-2 weeks and then daily physical therapy until the knee quiets down over the course of the next few weeks. Most patients need to focus almost exclusively on maintenance of the knee motion gained in therapy for the first 6 weeks after their surgery. In our practice, we found this to be very successful in improving patient’s function and motion.

Arthrofibrosis of the Knee FAQ

Arthrofibrosis of the knee is a condition whereby scar tissue prevents normal knee motion. The decreased knee motion can either be with straightening the knee, bending the knee, or at the kneecap joint. Most cases of arthrofibrosis are due to a previous injury or surgery and having the body form significant scar tissue. This often leads to decreased function.

What is arthrofibrosis of the knee?

Arthrofibrosis of the knee technically means that there is  decreased motion of the knee due to scar tissue. This can be due to many causes, the most commonly being after an injury and after surgery.

What can be done for arthrofibrosis after a total knee replacement?

Total knee replacements need good motion to have the best function. In some circumstances, due to the significant trauma that is involved with cutting the ends of the bones off and cementing in metal and plastic components, significant scar tissue can form after surgery. The treatments for arthrofibrosis of a total knee replacement can include prolonged therapy, the use of stretching braces to try to improve straightening or bending of the knee, bringing the patient to surgery and bending their knee while they are asleep, or proceeding with an arthroscopic surgery to clean out scar tissue. All of these methods can be trialed, primarily depending upon how long after surgery the arthrofibrosis is treated. Arthrofibrosis that has been present for a while may not respond well to anything other than an arthroscopic cleanout of the scar tissue, but it is important to time any of these types of surgeries such that the knee does not become significantly inflamed again with a second procedure.

What type of arthroscopic releases are performed for arthrofibrosis of the knee?

The most important thing to document in terms of planning for knee arthroscopic releases is where the patient has decreased motion because of the arthrofibrosis.  If it  is mainly in the kneecap joint, releasing scar tissue in the retropatellar fat pad area and along the medial and lateral gutters of the knee can be effective at restoring patellofemoral mobility. If the patient lacks straightening of the knee, cleaning out scar tissue in the front of the knee, and performing an arthroscopic notchplasty to enlarge the size of the intercondylar notch, especially when there are bone spurs present, can be effective to restore extension.  In those cases where that is not sufficient, performing an arthroscopic posteromedial capsular release may also help the patient to restore extension. For those patients who cannot flex their knee, the source of the scar tissue is usually in the suprapatellar pouch, so a cleanout of the suprapatellar pouch would be indicated.  The general recommendation is to gently try to bend the knee in cases of arthrofibrosis prior to arthroscopic  surgery and determine where the stiffness is located, then perform an appropriate scar tissue release and work on manipulating the knee after the scar tissue has been released to try to minimize any risk of fracture or significant scar tissue reformation.

What is the recovery after arthrofibrosis knee surgery?

The recovery of function after arthroscopic treatment of arthrofibrosis depends on many factors. It can depend upon whether the patient’s kneecap is in the correct position or if it has become scarred down, if the surgery or trauma that caused the arthrofibrosis was recent or distant in time, and also if there were any other significant injuries at the time of the development of arthrofibrosis. This can include fractures or other pathology.

In general, if a knee is still looking quite irritated and warm from surgery, or an injury,  that causes arthrofibrosis, we would want to give the knee more time to quiet down before proceeding with another surgery. This is because there is a risk of having further scar tissue develop in a knee that is still irritated.  In addition, straightening the knee can sometimes be difficult after an arthroscopic procedure, so the use of extension braces may be useful to help maintain any gains in extension that are obtained in surgery. Similarly, working on knee flexion exercises is a balance between trying to make sure that one maintains the motion gained in surgery and also does not have any significant scar tissue reform, which can cause decreased motion over time. Decreases in kneecap motion due to scar tissue are often treated with therapy where kneecap motion is promoted both to the inside and outside of the kneecap joint as well as proximal and distal. It is important to recognize that other than bone, the body will heal with scar, and we want the scar that reforms in the knee after arthrofibrosis surgery to be loose scar rather than thick and adherent scar.

What is the way to prevent arthrofibrosis of the knee?

Prevention of arthrofibrosis in the knee is important. It can be best achieved by trying to minimize stiffness of a patient’s knee going into surgery when possible. There are times when a patient may have a stiff knee and surgery needs to be performed because of bucket-handle tears of the menisci, radial tears in the menisci which can be repaired, etc. However, if there is no immediate need for surgery, working on trying to improve someone’s motion when it is stiff may be beneficial to decrease the chance of the development of arthrofibrosis. Another important way to try to minimize the risk of arthrofibrosis is to start knee motion immediately after surgery. Patients who are immobilized for a period of time after surgery have a higher risk of developing stiffness, so trying to work on both kneecap and regular knee joint motion flexion and extension on the first postoperative day are important to try to minimize the risk of arthrofibrosis.

How often is arthrofibrosis of the knee found after ACL reconstruction?

Arthrofibrosis of the knee can occur after any ACL reconstruction surgery. Most commonly, these patients may have a stiff knee going into surgery or do not follow a postoperative rehabilitation program well. In these circumstances, making sure the patient engages in a regular therapy program, which includes motion of all the major portions of the joint, is essential.

What type of scar tissue forms in arthrofibrosis of the knee?

There can be varying amounts of scar tissue that can form with arthrofibrosis of the knee. This can be due to a very serious injury whereby the body tries to heal itself, or where there is a fragile portion of the surgery where early motion may not be able to be accomplished immediately after surgery and the body heals itself with loss of scar.  Some cases of arthrofibrosis form scar tissue bands that are just enough to prevent motion, while other patients probably have a genetic cause that causes thick and fibrotic scar tissue throughout the knee. For those patients who have relatively thinner scar tissue, that is well mature and does not appear angry and red, the arthroscopic releases for arthrofibrosis of the knee can be very effective. For those patients who have very thick sheets of scar tissue, getting full motion back may be difficult because the arthroscopic surgery itself may be perceived in the body as another injury and the body may try to have another round of scar tissue formation to try to heal itself after a reinjury.

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