Arthrofibrosis (from Greek: arthro- joint, fibrosis – scar tissue formation) has been described in most joints like knee, hip, ankle, foot joints, shoulder (frozen shoulder, adhesive capsulitis), elbow (stiff elbow), wrist, hand joints as well as spinal vertebrae. It can occur after injury or surgery or may arise without an obvious cause. There is excessive scar tissue formation within the joint and/or surrounding soft tissues leading to painful restriction of joint motion that persists despite physical therapy and rehabilitation. The scar tissue may be located inside the knee joint or may involve the soft tissue structures around the knee joint, or both locations. The pathology that causes arthrofibrosis also causes other forms of fibrosis. Injury and inflammation activates fibroblasts and other cell types, turning them into myofibroblasts which create scar tissue and more inflammation. Arthrofibrosis of the knee (frozen knee)
Arthrofibrosis of the knee, also known as "frozen knee", has been one of the more studied joints as a result of its frequency of occurrence. Arthrofibrosis can follow knee injury and knee surgeries like arthroscopic knee surgery or knee replacement. Scar tissue can cause structures of the knee to become contracted, restricting normal motion. Depending on the site of scarring, knee cap mobility and/or joint range of motion (i.e. flexion, extension, or both) may be affected. Symptoms experienced as a result of arthrofibrosis of the knee include stiffness, pain, limping, heat, swelling, crepitus, and/or weakness. Clinical diagnosis may also include the use of magnetic resonance imaging (or MRI) to visualize the knee compartments affected.
Biologics that reduce the signalling of the major inflammatory cytokines TNF-α (Simponi, Humira) and IL-1β (anakinra) are promising treatments. Consultation with a rheumatologist can help to determine appropriate medications. After knee replacement
Arthrofibrosis can occur after total knee replacement or partial knee replacement, when excessive scar tissue (collagen fibril) deposition occurs in and around the knee. This can be accompanied by shortening of the patellar tendon (patella baja/infera) which can also contribute to limited flexion. The rates of AF after TKA vary widely in the literature as there is no standard definition. One studys definition is a total range of motion (ROM) <90 degrees constitutes AF, another definition is flexion contracture >10 degrees, or inability to flex the knee >100 degrees. AF is a diagnosis of exclusion; before making a final diagnosis of arthrofibrosis, other causes of stiffness following knee replacement should be excluded (ex: infection, malposition of the implants, or mechanical block to motion). In the case of AF after total knee arthroplasty (TKA) management traditionally consisted of aggressive physical therapy, and in the case that failed, manipulation under anesthesia (MUA). As discussed above, aggressive exercise is now avoided. The rates of MUA after TKA vary widely. There are several reasons for this: there is no definite consensus to when a MUA is required (different surgeons follow different indications), there is no standardized definition of arthrofibrosis (see above), and MUA is not always a reliable treatment.