What is Arthrofibrosis?
Arthrofibrosis is a condition where excessive scar tissue formation and fibrous adhesions leads to a painful restriction in joint movement. It is classed as in inflammatory response and can affect all major joints. In the knee, arthrofibrosis is a complication of knee trauma, surgery, or prolonged effects of osteoarthritis. The scar tissue may form intra-articularly (inside the joint) or extra-articularly (outside the joint in the soft tissue spaces). The normal healing response gets altered and leads to disordered Type 1 collagen formation. Adhesions stretch across the joint maturing into fibrous tissue. This slowly contracts and the joint capsule thickens and slowly contracts.
What are the outcomes?
Arthrofibrosis results in pain and restricted knee motion. This in turn leads to muscle atrophy, adaptive muscle shortening and scarring in the tissues. This can significantly impair knee function and overall quality of life for the patient.
How common is it?
It is more commonly seen after ACL reconstruction. In the 1980’s incidences were high at around 35%, but due to advances in surgery and a better understanding of knee rehab, incidences today are as low as 10%. Knee arthrofibrosis also affects around 1% of patients after a total knee replacement.
What are the predisposing factors?
Although there is not one specific cause of arthrofibrosis, there may be factors that can put a patient at increased risk of developing the condition. These include:
- Injury- complex injuries i.e, fractures near the joint, multiple ligament injury, knee dislocations, associated meniscus tears, quadriceps or patellar tendon rupture.
- Having excessive swelling going into surgery and having surgery very soon after an initial injury
- Surgery- knee arthroplasty or high tibial osteotomy procedures. Or complications such as an ACL graft being too tight or poorly positioned
- Prolonged immobilization in a cast or brace.
- Post op complications such as infection, excessive inflammation or a hemarthrosis
- Rehabilitation- poor adherence, not getting the right advice, late mobilization
- Genetic pre-disposal for patients who form excessive scar tissue.
Early Signs & Symptoms
Pain, swelling, and stiffness are normal following a knee injury or surgery. However if these symptoms persist despite following instructions of both your physician and physical therapist, there may be concern for development of arthrofibrosis. Other potential symptoms include:
- Flexed knee gait
- Worsening pain despite following instructions from both your physician and physical therapist
- Restricted active and passive range of movement – The patient makes early gains in ROM, but then has no further improvement. Not achieving full knee flexion/extension 2-3 weeks post operatively. The patient may lack more than 5 degrees of extension
- Weak or atrophied quadriceps tendon- an inability to voluntarily perform a strong quadriceps contraction in the initial 1-2 weeks following knee trauma or surgery.
- Continued signs of inflammation such as a hot or swollen joint
- Worsening ROM – despite aggressive exercise
- Changes in patellar (kneecap) tension and mobility as a result of scarring of the soft tissues surrounding the patella and quadriceps tendon.
Your physician and physical therapist will work together to rule in knee arthrofibrosis by ruling out other mechanical or pathological knee disorders which may be blocking knee joint range. A MRI may be performed to help with a clinical diagnosis.
Prevention and Treatment
Although there is no way to prevent arthrofibrosis, there are steps that can be taken to reduce the overall risk that a patient may develop the condition. Some of these steps include:
- Correct surgical timing: A 1991 study by Donald Sherbourne et al in the American Journal of Sports Medicine did a study of 169 ACL reconstructions in young athletes. Those who had an early ACL reconstruction within 1 week showed a higher incidence of arthrofibrosis then those whose surgery was delayed for 3 weeks or more. This allowed time for any knee inflammation to subside pre-operatively and gave the knee a change to settle (Donald Shelbourne has also developed a knee arthrofibrosis 1-4grading system in increasing levels of severity)
- Controlling the inflammation; pre and post operatively
- Controlling the pain with analgesia to allow the patient to move pre/post operatively
- Corticosteroid injections
- Patellar (knee cap) mobilizations
- Early knee active range work pre and post-operatively.
For conditions of arthrofibrosis that are not resolving with conservative treatments, surgical treatment may be recommended. In the past manipulation under anaesthetic was used to regain knee range of motion. Currently, controlled surgical excision of the scar tissue tends to be utilized. The goal following surgical removal of scar tissue is to regain and maintain as much range of motion as possible to help restore function