Arthrofibrosis after Knee Replacement

Introduction

Arthrofibrosis involves formation of excessive scar tissue in a joint. It can affect any joint.

Arthrofibrosis of the knee can occur after soft tissue injuries or fractures in and around the knee, arthroscopic knee surgeries like anterior cruciate ligament reconstruction or meniscal surgery, open knee surgeries and knee replacement. The incidence of arthrofibrosis after knee replacement is 1.2% to 17%. This section gives information about arthrofibrosis following knee replacement.

Causes and Development of Arthrofibrosis after Knee Replacement

The exact cause of arthrofibrosis following knee replacement remains unknown. Many factors like genetic predisposition, immune response and allergic reaction have been proposed as potential risk factors but none has been proven.

The molecular steps and mediators involved in the development of arthrofibrosis are unclear. There is chronic inflammation in the soft tissues in and around the knee. This leads to the formation of excessive amount of scar tissue, sometimes even cartilage or bone, in the soft tissues.

Symptoms and Signs of Arthrofibrosis after Knee Replacement

The characteristic symptoms of arthrofibrosis of the knee following knee replacement are stiffness and chronic pain in the knee. The patient may not be able to bring the knee fully straight (flexion contracture) or there is decreased ability to bend the knee fully (decreased range of flexion). Many patients have both. The stiffness varies in severity. The knee is swollen, red, warm and painful to touch (tenderness). The soft tissues around the knee feel firm. Patients may have quadriceps weakness. Patients may also have leg length discrepancy and altered gait. Arthrofibrosis affects the patient’s professional and personal life.

Diagnosis

Diagnosis is mainly based on the characteristic symptoms and signs. After knee replacement, the range of motion of the knee progressively improves and the pain progressively decreases over two to three weeks. Arthrofibrosis is suspected if the motion does not progressively improve, remains stable or decreases after knee replacement. Arthrofibrosis is also suspected if the pain does not progressively decrease, persists without any change or increases after knee replacement.

Plain radiographs may show bone formation in soft tissue.

Treatment of Arthrofibrosis after Knee Replacement

The following are the five treatment options currently available for arthrofibrosis following total knee replacement.

1. Physical Therapy (PT) Appropriately directed physical therapy is usually considered within 6 weeks after the knee replacement. Additionally, mechanical devices like flexionator / extensionator or CPM (continuous passive motion) can be used.
2. Manipulation under Anesthesia (MUA If physical therapy fails, MUA is considered. MUA is usually considered between 6 and 12 weeks after the knee replacement. MUA breaks the immature scar tissue and improves motion. In addition, splints or braces can be used. Patients may also need serial manipulation and casting.
3. Arthroscopic Lysis of Adhesions If physical therapy and MUA fail, arthroscopic lysis of adhesions is considered. This is preferably done between 3 and 6 months after the knee replacement. This procedure involves removal of scar tissue present inside the knee joint using arthroscopic instruments. This procedure is not useful for removal of scar tissue that is present outside the knee joint.
4. Open Lysis of Adhesions If physical therapy, MUA and arthroscopic lysis of adhesions fail, open lysis of adhesions is considered. This procedure is usually considered between 6 months and 1 year after the knee replacement. This procedure involves removal of scar tissue by means of an open surgery. This procedure is useful for removal of scar tissue that is present both inside as well as outside the knee joint. Open lysis of adhesions is less often performed these days and arthroscopic lysis of adhesions is preferred over open lysis of adhesions by many physicians.
5. Revision Knee Replacement Revision knee replacement is considered when all other treatment approaches fail. It is usually performed one year after knee replacement. In this procedure, the existing prosthetic components are removed and replaced with new prosthetic components to improve flexion contracture and range of flexion.