Knee replacement is intended to reduce pain and improve movement. For most people, it does. But if your knee still hurts months later, you are not alone—and ongoing pain deserves a careful evaluation.
Research recognizes persistent pain after total knee replacement, also called total knee arthroplasty or TKA, as a real clinical problem. It does not mean you failed at recovery. It also does not automatically mean the implant has failed. The useful next question is: What is causing the pain?
How common is pain after knee replacement?
The answer depends on when patients are asked and how researchers define pain. A 2025 review estimated that about 22% of patients reported pain three months after total knee replacement. That figure fell to approximately 12% to 15% with longer follow-up, up to two years. These numbers include different levels of pain; they do not mean everyone in those groups has severe pain or needs another procedure.
The main point is that continued pain is common enough for clinicians to study—and specific enough to investigate when it is affecting your life.
When does pain become “persistent”?
Pain, swelling, and stiffness are expected during recovery. Improvement can be gradual, and a painful week does not by itself signal a lasting problem.
In research, chronic or persistent postsurgical pain generally refers to pain that lasts at least three months after surgery. That is a research definition, not a deadline you must wait for before calling your surgeon. New pain, worsening pain, or pain that is keeping you from progressing in rehabilitation may warrant a conversation sooner.
Your symptoms also matter more than a date on the calendar. Pain that is steadily improving is different from pain that never improved, returned after a good period, or is getting worse.
Why might a replaced knee still hurt?
There is no single cause of pain after knee replacement. An evaluation may consider:
- Problems involving the implant or how the knee moves, such as loosening, instability, or alignment issues.
- Infection, which needs to be assessed even when symptoms are less obvious than a fever or visible wound problem.
- Stiffness or surrounding soft tissue problems, which can affect movement and cause pain.
- Nerve related pain or changes in pain processing, which may contribute to pain even when a straightforward mechanical cause is not found.
- Pain coming from another area, including the hip or lower back, that is felt around the knee.
These are possibilities, not a way to diagnose yourself. More than one factor can be present, and treatments depend on what the evaluation finds. Published reviews describe both implant related and non-implant causes of pain after knee replacement.
What if the X-ray looks normal?
An X-ray can provide important information about the implant and surrounding bone. But one normal appearing image cannot answer every question about pain. Your surgeon may also consider your symptoms, examine the knee, review how your recovery has changed over time, and decide whether other tests are needed.
For example, evaluating a possible joint replacement infection may involve blood tests and, in some cases, testing fluid taken from the joint. That decision belongs to your treating clinician. A reassuring image is useful information; it is not a reason to dismiss pain that continues to limit you.
What should you tell your surgeon?
A clear account of your pain can help guide the evaluation. Before your appointment, note:
- When the pain began and whether it has improved, stayed the same, or worsened
- Where you feel it and what it feels like
- Whether it occurs at rest, with walking, on stairs, or at night
- Any swelling, warmth, stiffness, or feeling that the knee may give way
- What activities you can no longer do, or what has become harder
- Which treatments you have tried and whether they helped
You can ask: “What causes of persistent pain have we evaluated, and what would make you recommend another test or a referral?” The goal is a reasoned next step based on your symptoms—not an assumption that you simply need more patience.
When should you seek help promptly?
Contact your surgical team promptly if pain is newly worsening or you notice increasing redness, swelling, drainage, or other signs of possible infection. New calf pain or swelling also needs prompt medical advice. Chest pain or shortness of breath requires emergency care, as these can be warning signs of a blood clot in the lungs.
Persistent pain deserves an explanation
Many people recover well after knee replacement. Some continue to have pain, and the reasons vary. You do not need to know the cause before asking for help. A thorough evaluation is the starting point for deciding what, if anything, should happen next.
Still dealing with knee pain after surgery? Our 2-minute assessment can help you share your symptoms and find out whether a further evaluation may be appropriate. It cannot diagnose the cause of your pain or determine which treatment you need.
