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Arthrofibrosis after knee replacement is a stiff, painful knee caused by too much scar tissue forming inside and around the new joint. It is one of the problems patients worry about most, and one I watch for closely in the first three months after surgery.
After more than twenty years and over 700 joint replacements a year, here is what I know. Most stiffness after knee replacement is normal healing. True arthrofibrosis is less common, and the earlier we catch it, the better it responds.
What Is Arthrofibrosis After Knee Replacement?
Arthrofibrosis after knee replacement means the body has laid down extra scar tissue that limits how far the knee can bend or straighten. The scar can form inside the joint, in its lining, and around the kneecap, leaving a knee that feels tight and stuck even when the implant is working well.
Every surgery heals with some scar; in arthrofibrosis, that repair process does not shut off on time. A 2023 review in JBJS Reviews describes it as new, excessive scar tissue that causes limited motion, pain, and trouble with daily tasks.
Is every stiff knee after surgery arthrofibrosis?
No. Almost every knee feels stiff in the first six to eight weeks, because swelling alone makes a knee tight.
The difference is direction. Normal stiffness improves week by week; with arthrofibrosis, motion stalls or slips backward despite steady therapy. That pattern, more than any single number, gets my attention.
How Common Is Arthrofibrosis?
Arthrofibrosis affects roughly 3 to 12 percent of knee replacement patients, depending on how it is defined. A widely cited review in The Journal of Arthroplasty put the range at 1 to 13 percent. The spread exists because surgeons do not all use the same cutoff for “too stiff.”
What matters to you is usable motion. Most people need about 90 degrees of bend to climb stairs comfortably and more than 100 degrees to rise easily from a low chair or put on socks. A knee that cannot fully straighten is just as troublesome, because it forces a bent-knee limp.
What Causes Scar Tissue After Knee Replacement?
Scar tissue after knee replacement builds up when healing cells stay switched on too long. Cells called myofibroblasts (repair cells that make collagen and can tighten like muscle) lay down a dense, stiff scar, driven by a chemical signal called TGF-beta (transforming growth factor beta).
No blood test predicts who will scar this way. What we do know is that several factors raise the odds.
Who is at higher risk?
- Limited motion before surgery. The stiffer a knee is going in, the more likely some stiffness lingers afterward.
- Prior knee surgery or fracture. Old scar gives new scar a head start.
- Younger age and male sex. Studies link both to higher rates.
- Other scarring conditions. Dupuytren’s contracture (thick, tight tissue in the palm), Ledderhose disease, Peyronie’s disease, and keloid scars share the same overactive healing response.
- Pain or swelling that limits motion. If the knee hurts too much to move, it doesn’t move, and scar sets in.
How your skin scars can offer a clue to how your knee may heal on the inside.Do keloid scars raise the risk of arthrofibrosis after knee replacement?
Yes, a 2026 study in The Journal of Arthroplasty suggests they do. Johns Hopkins researchers compared 1,205 knee replacement patients who had keloids (raised, overgrown skin scars) with 1,205 matched patients who did not. At one year, 4.7 percent of the keloid group needed a procedure for stiffness, versus 2.2 percent of the others.
Most of that extra risk showed up in the first 100 days, and revision rates were not meaningfully different at two years. If you form keloids, tell your surgeon. In my practice, that history means closer motion checks early, not a reason to avoid surgery.
What Are the Warning Signs of Arthrofibrosis?
The main warning sign is a knee that stops gaining motion, or starts losing it, despite regular exercise. These are the five signs I ask my patients to watch for:
- Motion that stalls. Your bend or straightening stops improving for two weeks or more.
- Pain that rises instead of fading. Normal pain eases week to week. Pain that builds, especially at the end of a stretch, is a flag.
- A bent-knee walk. You can’t get the knee fully straight, so you walk with it slightly bent.
- Swelling and warmth that linger. Some warmth is expected for months, but a hot, puffy knee paired with lost motion needs a look.
- A weak thigh muscle. You have trouble tightening your quadriceps or lifting your leg straight off the bed.
How Is Arthrofibrosis Diagnosed?
Arthrofibrosis is diagnosed by ruling out other causes of a stiff knee, not by a single test. I start with your history and measure how far the knee bends and straightens compared with earlier visits.
X-rays check the position and fit of the implant. Blood work, and sometimes a sample of joint fluid, rules out infection, which must be cleared before any treatment.
Measuring how far the knee bends, and comparing it visit to visit, is how a stalled knee gets caught early.How Is Arthrofibrosis After Knee Replacement Treated?
Treatment follows a ladder: start with the least invasive step and move up only if motion does not return. Physical therapy is the first and most common treatment. Revision surgery is the last resort, and most patients never reach it.
Physical therapy and home stretching
Supervised therapy is the first line of defense. The goal is steady, tolerable stretching, timed and paced to what the knee can handle that week, not forcing it through severe pain.
Calming the knee comes first. A swollen, inflamed knee fights every stretch, which is why I lean on ice, compression, and elevation in my quiet knee protocol before pushing harder. Some patients also benefit from a stretching brace or splint at home.
Manipulation under anesthesia (MUA)
If motion stalls despite good therapy, the next step is usually a manipulation under anesthesia. While you are asleep, I gently bend the knee to break up the scar tissue holding it back. There is no incision.
Timing matters: manipulation works best when done early, usually within the first 12 weeks after surgery. My knee replacement physical therapy guide shares the long-term results, and the American Academy of Orthopaedic Surgeons offers a clear overview of manipulation under anesthesia.
Scar tissue release surgery
For stiffness that lasts longer or does not respond to manipulation, I may recommend a procedure to cut away the scar. This is called lysis of adhesions. It can be done arthroscopically (through small incisions with a camera) or through an open incision.
These procedures can restore motion but carry more risk than a manipulation, including a higher chance of infection.
Revision knee replacement
Revision means replacing some or all of the implant. It makes the most sense when stiffness is tied to an implant that is too tight, out of position, or the wrong size. Earlier steps do not always prevent it; in one study of 726 patients, 6.9 percent of those who had a manipulation later needed a revision.
Can You Prevent Arthrofibrosis After Knee Replacement?
You can’t control every risk factor, but a few daily habits lower the odds of arthrofibrosis after knee replacement. Here’s what I tell my patients:
- Move the knee every day. Short, frequent walks keep new scar flexible.
- Win back straightening early. A knee that won’t straighten is harder to fix than one that won’t bend.
- Control swelling. Ice for 10 to 20 minutes at a time with a cloth barrier, and elevate the leg. My guide on how to ice after knee replacement covers the details.
- Take pain medicine as prescribed before therapy. You can’t stretch a knee that hurts too much to move.
- Keep every follow-up visit. I check motion at set points in the first six weeks so we catch a stalled knee early.
When Should You Call Your Surgeon About a Stiff Knee?
Call your surgeon’s office if your knee motion stops improving for two weeks, gets worse, or comes with rising pain. Don’t wait for your next visit; the first three months are when treatment works best.
Call the same day for fever, redness that spreads, drainage from the incision, or calf pain and swelling. Those can signal infection or a blood clot, which need prompt care. For a broader look at what makes a knee tight, read my article on the 7 causes of knee stiffness.
Where Can I Get Help for a Stiff Knee in Middle Tennessee?
If your knee replacement still feels stiff, you are not stuck with it. I evaluate stiffness after knee replacement for patients from Franklin, Nashville, Columbia, and across Middle Tennessee.
My office is at the Bone and Joint Institute of Tennessee, 3000 Edward Curd Lane, Franklin, TN 37067. Call (615) 791-2630 or schedule an appointment online. You can also learn more about total knee replacement in my practice.
Watch: Why Keloid Scars Matter Before Knee Replacement
In this short video, I explain what the new Johns Hopkins research on keloids and arthrofibrosis means for your knee replacement, and why you should tell your surgeon if you form raised scars.
Medical disclaimer: This article is for educational purposes only and does not replace professional medical advice. Talk with your orthopaedic surgeon about your symptoms; individual results vary.
References
- Ramos MS, Pasqualini I, Surace PA, Molloy RM, Deren ME, Piuzzi NS. Arthrofibrosis after total knee arthroplasty: a critical analysis review. JBJS Rev. 2023;11(12):e23.00140. doi:10.2106/JBJS.RVW.23.00140
- Cheuy VA, Foran JRH, Paxton RJ, Bade MJ, Zeni JA, Stevens-Lapsley JE. Arthrofibrosis associated with total knee arthroplasty. J Arthroplasty. 2017;32(8):2604-2611. doi:10.1016/j.arth.2017.02.005
- Garcia D, Thota P, Dogiparthi AV, et al. Keloidosis is associated with an increased risk for developing arthrofibrosis after total knee arthroplasty. J Arthroplasty. Published online 2026. doi:10.1016/j.arth.2026.07.059
- Wang CX, Flick TR, Patel AH, Sanchez F, Sherman WF. Patients with Dupuytren’s contracture, Ledderhose disease, and Peyronie’s disease are at higher risk of arthrofibrosis following total knee arthroplasty. Knee. 2021;29:190-200. doi:10.1016/j.knee.2021.02.009
- Akhtar M, Razick D, Seibel A, Asad S, Shekhar A, Shelton T. Outcomes of early versus delayed manipulation under anesthesia for stiffness following total knee arthroplasty: a systematic review and meta-analysis. J Arthroplasty. 2024;39:2872-2879. doi:10.1016/j.arth.2024.05.059
- Walsh JM, Sullivan TC, Varghese B, Incavo SJ, Brown TS, Park KJ. Manipulation under anesthesia after primary total knee arthroplasty. J Arthroplasty. 2025;40(9 Suppl 1):S535-S544. doi:10.1016/j.arth.2025.05.032
