Knee Arthrolysis: Your Comprehensive Guide to Arthrofibrosis Knee Treatment

knee arthrolysis

Do you have knee stiffness, possibly due to adhesions / arthrofibrosis, and have been told about knee arthrolysis or manipulation under anaesthesia (MUA)?

Or are you a physical therapist or a medical professional searching for information on outcomes, post-surgery recovery, and rehabilitation after these procedures?

As a physiotherapist, I frequently advise individuals on the suitability of knee arthrolysis in their cases.

In this article, I share my insights and experiences on this topic, drawing upon clinical study results involving individuals who have undergone either “forced” manipulation or a form of arthrolysis (arthrofibrosis cure).

At the end of the article, you will find all the sources I rely on, as well as a comment section where you can share your thoughts or ask questions. 😊

Happy reading!

Last update: October 2023
Disclaimer: Affiliate links. Complete disclosure in legal notices.

Written by Nelly Darbois, physical therapist and scientific writer

If you would like more information about this rehabilitation period, I have dedicated an eBook to this topic 🙂!

ebook fracture recovery

What is Knee Arthrolysis?

Knee arthrolysis is a set of procedures performed by an orthopedic surgeon, specialists in treating bones, muscles, joints, and ligaments.

The goal of knee arthrolysis is to improve the mobility and flexibility of the knee joint, primarily focusing on increasing flexion (bending) and occasionally extension (straightening).

Surgeons aim to eliminate fibrosis, adhesions or scar tissue that has formed within the joint, beneath the skin, through the process of arthrolysis.

Etymology note: The word “arthrolysis” is derived from ancient Greek, where “arthron” means “joint,” and “lysis” means “release.”

Thus, “arthrolysis” literally means “release of the joint.” It is an appropriate term to describe a surgical intervention aimed at freeing a stiff or fixed joint.

There are various techniques for knee arthrolysis employed by surgeons. The three main types of knee arthrolysis are:

  1. Knee manipulation under local or general anesthesia.
  2. Knee arthrolysis using arthroscopy.
  3. Open knee arthrolysis.

Knee Manipulation under General or Local Anesthesia (MUA)

Knee manipulation under general or local anesthesia is a less invasive procedure compared to arthrolysis, where the knee is entered into surgically.

Surgeons simply manipulate the knee manually, much like a physical therapist might do during a therapy session.

However, surgeons apply a bit more force, which is why it’s sometimes referred to as “forced mobilization or manipulation” of the knee.

To ensure that this increased force isn’t painful at the moment, patients are either under general anesthesia or receive regional or spinal anesthesia.

Sometimes, “forced” manipulations are also offered by physical therapists (at the hospital, in clinics, or rehabilitation centers) using Nitrous Oxide (a gas that relaxes you, delivered through a mask). However, this method allows for less range of motion.

Arthroscopic Knee Arthrolysis

Arthroscopic knee arthrolysis is slightly more invasive than forced manipulation but less invasive than open knee arthrolysis.

This surgical procedure involves:

  • Local or general anesthesia.
  • Surgeons using an arthroscope, a small optical instrument that is inserted into the knee joint through tiny skin incisions. This allows the surgeon to see the inside of the knee joint on screens.
  • The use of specialized instruments to remove adhesions and scar tissue that restrict joint mobility.

Open Knee Arthrolysis

Open knee arthrolysis is the most invasive procedure, requiring a larger incision in the skin to allow the surgeon direct access to the joint.

This procedure also requires anesthesia.

When is Knee Arthrolysis Proposed?

As a physical therapist, we often encounter individuals to whom surgeons recommend knee arthrolysis or knee mobilization under general anesthesia, primarily in the following situations:

  1. Stiffness following the placement of a total or unicompartmental knee replacement, occasionally after knee arthroscopy or arthrofibrosis after ACL surgery.
  2. Stiffness resulting from a broken tibia or femur fracture, particularly in the knee joint area, whether the fracture was surgically treated or not.
  3. Stiffness in the context of knee CRPS.

Arthrofibrosis after knee replacement (TKR or PKR)

One of the primary goals of rehabilitating a knee replacement (total or partial) is to regain flexion and extension in the knee joint.

Most individuals achieve good ranges of motion within 1 to 3 months: 0° in extension and 110 to 120° in flexion, which is generally sufficient for everyday life.

However, in some cases (4% to 16% of individuals), the knee struggles to flex or extend. Sometimes, a month after the surgery, the flexion may be as limited as 10, 20, or 30°, with it often being stuck around 60 to 80°.

In such instances, surgeons may recommend knee manipulation under anesthesia or knee arthrolysis.

Source: Rodriguez 2019

Arthrofibrosis after ACL surgery

Arthrofibrosis after ACL (Anterior Cruciate Ligament) surgery refers to a complication where excessive scar tissue, or fibrosis, forms within the knee joint following ACL reconstruction surgery.

It is considered an undesirable outcome of ACL surgery.

Knee Stiffness following a Fracture

Several fractures of the femur or tibia can result in knee stiffness. However, this remains the exception, as most individuals recover without experiencing knee stiffness.

Examples of such fractures include:

Knee Stiffness Due to Arthrofibrosis, Regardless of the Cause

When someone experiences significant knee stiffness following knee surgery, a prosthesis placement, a fracture, or any knee operation, it is often suspected to be caused by adhesions or fibrosis within the knee, also known as “arthrofibrosis” or “joint fibrosis.”

What are Knee Adhesions or Fibrosis?

The term “adhesion” or “fibrosis” refers to the tissues surrounding the knee, including muscles, ligaments, tendons, and fascia, sticking together, thereby limiting the mobility of the knee joint.

Anatomically, adhesions occur due to the formation of scar tissue, which can develop following an injury, surgery, or chronic inflammation. Scar tissue forms when the body’s cells produce collagen fibers to repair damaged tissues.

However, in some cases, these collagen fibers can develop haphazardly and create adhesions.

knee arthrolysis picture
Adhesion within the knee joint as seen through arthroscopy (top). At the bottom, you can see the equipment used by the surgical team to release the adhesion. Image: Abdul N, Dixon D, Walker A, Horabin J, Smith N, Weir DJ, Brewster NT, Deehan DJ, Mann DA, Borthwick LA. Fibrosis is a common outcome following total knee arthroplasty. Sci Rep. 2015 Nov 10;5:16469. doi: 10.1038/srep16469. PMID: 26553967; PMCID: PMC4639721.

How to Determine if You Have Knee Adhesions?

In fact, whenever there is knee stiffness following surgery or trauma, and it persists for several weeks, it is referred to as knee adhesion.

There is no definitive way to objectively observe or physically examine the presence of adhesions.

Ultrasounds, MRIs, or arthroscopies can be performed to attempt better visualization of these adhesions. However, it is challenging to precisely quantify them and determine their impact on knee stiffness.

Moreover, these diagnostic methods do not necessarily provide additional treatment options.

For these reasons, I do not encourage my patients to undergo imaging or arthroscopic examinations to investigate the presence of knee adhesions.

How to Avoid or Prevent Knee Adhesions?

Two main approaches are commonly recommended to prevent the development of knee adhesions:

  1. Maintain knee flexion and extension mobility, either by staying active in daily activities, performing exercises, or receiving passive knee mobilization from a physical therapist or a device (arthrometer).
  2. Massage the knee scar if one is present.

Personally, I do recommend maintaining knee movement, especially through active exercises. However, I do not believe that massaging the scar is beneficial in preventing adhesions.

The scar is superficial, and even though adhesions may sometimes form deeper, I think it is mechanically impossible to limit them simply by manually massaging the scar on the skin’s surface!

Some healthcare professionals may have a different perspective. Of course, each person is free to massage their scar if they believe that the benefit-to-risk ratio is relevant to their case.

Can Arthrolysis Treat Knee Arthrofibrosis?

In theory, it is reasonable to think that mobilization under anesthesia or arthrolysis through arthroscopy or open surgery can “break” or “release” these adhesions.

But what is the actual impact on regaining knee flexion or extension? I discuss this further in the article in the section “What Are the Results of Knee Arthrolysis?”

What Rehabilitation is Needed After Knee Arthrolysis?

To regain knee flexion (or extension) following knee arthrolysis or forced mobilization, it is essential to maintain the knee’s mobility during the post-operative period. Different protocols are proposed depending on the surgical or rehabilitation team:

  1. Some recommend using a continuous passive motion device / machine, a device that allows passive bending and extending of the knee. This is typically initiated immediately after surgery and may continue for several hours a day, or in the days following surgery, for 20 to 30 minutes daily. The arthrometer is generally supervised by a physical therapist, occasionally by nurses.
  2. Some prescribe physical therapy sessions. Physical therapists will instruct you on exercises to perform independently, provide guidance on daily activities, and may also manually mobilize your knee in various positions.
  3. Some may not prescribe formal physical therapy sessions but recommend exercises to maintain knee flexion or extension or encourage staying active in daily life (walking, climbing stairs, cycling, etc.).

In my 11 years of experience as a physical therapist (including 3 years as a student physical therapist), both in private practice and in hospital or rehabilitation center settings, I have not observed significantly better or worse recovery outcomes based on the specific protocol followed, whether in the short or long term.

For my patients who opt for knee arthroscopy, I present the information much like I do in this article. Then we discuss what seems most appropriate in their case, considering their expectations, motivation, and individual circumstances.

Generally, I recommend the following:

  1. Change positions regularly throughout the day (sit with the knee flexed, sit with the knee extended, lie down with the knee straight).
  2. Walk and stay active as much as possible.
  3. Perform daily 3×2-minute exercises for knee flexion and extension in one or more positions that we identify as most relevant to their case (e.g., sitting on a chair with a skateboard, standing with the foot on a step, lying on the stomach, lying on the back, etc.).
  4. If range of motion and pain allow, use a stationary bike with the seat initially set high and pedaling backward (which is easier and involves less knee flexion). Gradually increase the duration, starting with just 30 seconds to 1 minute.

What Are the Results of Knee Arthrolysis?

To answer the question regarding the results of knee arthrolysis, I prefer to rely primarily on data from clinical studies rather than my own experience.

To do this, I have searched for all studies on the subject published and referenced in the medical research database PubMed/Medline.

There are several dozen studies on knee arthrolysis and manipulation under anesthesia, involving a few dozen patients. However, these studies do not compare their progress to the progress of individuals in the same situation who did not undergo arthrolysis.

knee arthrofibrosis studies
The Preop motion column indicates the ranges of knee extension and flexion in these individuals before their knee arthrolysis. These were individuals who had developed knee stiffness following total knee prosthesis placement. All of them had between 85 and 90° of flexion and a flexum (a lack of flexion) ranging from 15 to 60°. Source: Hegazy 2011.

Here are the conclusions from the main and most recent synthesis of studies on the subject (Haffar, 2022).

This synthesis focused on studies in the context of knee stiffness following knee replacement surgery, as this is the most common reason for knee arthrolysis and mobilization under anesthesia.

It looked for studies related to:

  1. Knee manipulations under anesthesia (21 studies found).
  2. Knee arthrolysis under arthroscopy (7 studies found).
  3. Revision/revision of knee replacement (14 studies found).

Here are its main findings:

  • The median or mean knee flexion value after the operation was equal to or greater than 90°:
    • In 30% of the studies on knee manipulations under anesthesia.
    • In 71% of the studies on arthrolysis.
    • In 70% of the studies on knee prosthesis revision.
  • Scores from tests evaluating knee pain and function were better for people who had undergone manipulation or arthrolysis.
  • 43% of people who had a knee replacement revision needed additional care afterward, compared to 25% of those mobilized and 17% of those who had knee arthrolysis.

What can be concluded from this? Manipulation under anesthesia or knee arthrolysis are not “miracle cures” for knee stiffness. More than half of the individuals still had less than 90° of knee flexion afterward.

Another synthesis of studies mentions that it is more beneficial to perform these techniques for knee stiffness 3 to 6 months after the traumatic event (fracture, surgery, etc.), but not beyond that (Vaish 2021).

When asking the opinions of dozens of surgeons from different countries, 55% recommend doing it between 6 and 12 months after the traumatic event (Kumar 2021).

arthrolysis after knee replacement
56% of the 315 surgeons operated on in this study recommend mobilization under anesthesia for stiffness following total knee prosthesis placement 6 to 12 months after the prosthesis implantation. And 10% do not recommend mobilization under anesthesia. Source: Kumar 2021.

What are the Possible Complications and Risks of Knee Arthrolysis?

The main risk after mobilization under anesthesia or knee arthrolysis is that the operation may have been performed “in vain.” In some cases (rare), the situation can even worsen, leading to a diagnosis of knee CRPS. CRPS essentially means a “stiff and painful knee,” but it may not necessarily represent an additional problem.

Complications are more common after knee arthrolysis than after manipulation under anesthesia, although they still remain rare (0.5% of cases). When they do occur, they can include:

  1. Infection of the knee.
  2. Deterioration of the knee prosthesis or the materials within the knee.

CRPS of the knee can indeed occur following mobilization under anesthesia or arthrolysis. However, often, algodystrophy was already present, but the diagnosis had not been made previously.

Source: Hegazy 2011

how to reduce arthrofibrosis knee

How to Determine If Knee Arthrolysis Is Relevant in Your Case? My Opinion

It is always challenging to advise someone on the merits of undergoing manipulation or knee arthrolysis for a severely stiff knee because it is difficult:

  1. To predict in advance whether the procedure will be successful.
  2. To assess the benefit-risk balance on someone else’s behalf.

Generally, individuals who are suggested to undergo forced mobilization or arthrolysis have received opinions from various professionals, including physical therapists, rehabilitation doctors, general practitioners, and surgeons.

These opinions can sometimes be conflicting, as illustrated in this testimonial from another one of my articles:

“At present, my flexion is barely 100 degrees.

My surgeon wants to unlock my knee under general anesthesia; he thinks it’s adhesions preventing flexion.

My physical therapist believes it’s not a good idea, that edema will reform, and I just need to be patient.

My general practitioner tells me to trust my surgeon.

In total, I admit that I am a bit lost and don’t know what to decide. The surgeon I saw yesterday told me that if we don’t act now, I will never recover my flexion. What do you think? Thank you.”

A person with a stiff knee after a complex kneecap fracture. This situation is very representative of how things generally unfold, except that mobilization is usually suggested for more severe stiffness (30 to 80 degrees).

I recommend asking yourself these questions:

  1. Are you completely stuck with no progress (not even by 1 or 2 degrees) for more than 4-5 weeks, despite an active lifestyle and daily exercises?
  2. Is the limitation in range of motion (rather than pain or another issue) hindering you from doing important activities? Specifically, what activities are affected? Cycling? Climbing stairs? Putting on shoes?
  3. Have you tried increasing the frequency and intensity of knee manipulation exercises, even if it means taking more pain relievers to perform them?
  4. Are you aware that after the surgical procedure, you will still need to continue rehabilitation (or self-rehabilitation)?

I believe the answers to these questions should guide you in your decision. I hope you’ll become more confident in choosing the best option for you.

If you have comments or questions, please feel free to share them in the comments section, and I’ll respond 🙂.


If you feel the need to learn more about the recovery period, I wrote this guide in eBook format:

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Rodríguez-Merchán EC. The stiff total knee arthroplasty: causes, treatment modalities and resultsEFORT Open Rev. 2019;4(10):602–610. Published 2019 Oct 7. doi:10.1302/2058-5241.4.180105

Haffar A, Goh GS, Fillingham YA, Torchia MT, Lonner JH. Treatment of arthrofibrosis and stiffness after total knee arthroplasty: an updated review of the literature. Int Orthop. 2022 Jun;46(6):1253-1279. doi: 10.1007/s00264-022-05344-x. Epub 2022 Mar 18. PMID: 35301559.

Vaish A, Vaishya R, Bhasin VB. Etiopathology and Management of Stiff Knees: A Current Concept Review. Indian J Orthop. 2020 Oct 20;55(2):276-284. doi: 10.1007/s43465-020-00287-0. PMID: 33927806; PMCID: PMC8046887.

Hegazy AM, Elsoufy MA. Arthroscopic arthrolysis for arthrofibrosis of the knee after total knee replacement. HSS J. 2011 Jul;7(2):130-3. doi: 10.1007/s11420-011-9202-7. Epub 2011 May 19. PMID: 22754412; PMCID: PMC3145854.

photo de nelly darbois, kinésithérapeute et rédactrice web santé

Written by Nelly Darbois

I love writing articles based on my experience as a physiotherapist (since 2012), scientific writer, and extensive researcher in international scientific literature.

I live in the French Alps 🌞❄️, where I work as a scientific editor for my own website, which is where you are right now.

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