Knee Still Hurts 1-2 Years After Replacement? What’s Normal and What’s Not

Updated June 2026.

Some stiffness, occasional swelling, clicking with bending, and a numb patch beside the scar are common a year or two after knee replacement — and usually harmless. Pain that limits what you can do, wakes you at night, or is getting worse instead of better is a different matter: it deserves a structured workup, not another round of “give it time.”

If that second description sounds like you, hear two things clearly. First, you are not alone and you are not imagining it — persistent pain after knee replacement is far more common than most patients are told. Second, “common” does not mean “nothing can be done.” Below is what I look for when someone brings me a knee replacement that still hurts.

How Common Is Knee Pain a Year or Two After Replacement?

A systematic review of 17 patient cohorts found that roughly 10% to 34% of patients report an unfavourable long-term pain outcome after knee replacement — about 20% in the best-quality studies [1].

That number surprises almost everyone. Roughly one in five knee replacement patients — many with operations that were technically well done — still report meaningful pain months to years later. If that is you, you are not an outlier. The same review found persistent pain after hip replacement in about 7% to 23% of patients (9% or more in the best studies) [1]; knees simply hurt more often than hips after replacement.

The two most common mistakes here sit at opposite extremes. The first is dismissal: being told “some people just hurt, give it more time” year after year while a treatable cause — a smoldering infection, a loose implant — goes undiagnosed. The second is catastrophizing: assuming the surgery failed and must be redone, when most persistently painful knee replacements never need revision. Persistent pain is a symptom, not a diagnosis, and the job is to name its cause.

What Can Cause Knee Pain a Year or More After Replacement?

In one large single-center study of 781 revision knee replacements, the leading causes of failure were implant loosening (39.9%), infection (27.4%), and instability (7.5%) [2].

Those figures describe knees that came to revision; the list of reasons a replaced knee can hurt is broader, and most items never require another operation. The American Academy of Orthopaedic Surgeons lists loosening and wear, infection, instability, stiffness, and fracture around the implant as the principal causes of failure [3]; others mirror the everyday sources of knee pain in anyone. Here is the differential in plain language, in roughly the order I work through it — I have also written about the signs of a failed knee replacement if you want a symptom-focused checklist.

Low-grade infection — ruled out first, every time

A deep infection around an implant does not have to look like an infection. There may be no fever and a perfectly healed incision — just a knee that aches, swells, stiffens, or never quite felt right. In the revision series above, infection was the most common reason knees were revised within two years of the original operation [2]. No painful knee replacement should be revised, or written off, until infection has been excluded.

Implant loosening

The bond between implant and bone can fail, and when it does the knee protests under load: a deep ache with walking that eases with rest, and classically “start-up pain” with the first steps after sitting. Loosening was the single largest cause of revision in that series [2]. It is more typical in later years but can occur early — and is easy to miss on a single X-ray.

Instability

A knee replacement depends on balanced ligaments around it. When they are not, patients describe a knee they do not trust: giving way, soreness along the joint lines, and swelling after activity. The knee can look perfect on a film while behaving badly in real life — instability is a diagnosis made by examination, not imaging.

Kneecap (patellofemoral) problems

Pain concentrated at the front of the knee — worst on stairs, hills, and rising from a chair — points toward the kneecap and how it tracks on the implant. The kneecap may or may not have been resurfaced at the original operation, and either choice can cause trouble in a minority of patients.

Pain referred from the hip or spine

This one humbles every knee surgeon eventually. An arthritic hip can present almost entirely as knee pain, and a pinched nerve in the back can send pain down the thigh. If the knee examines well but rotating your hip reproduces your pain, the answer is not in the knee at all — which is why a thorough evaluation always includes the hip and the spine.

Nerve pain and CRPS

Small skin nerves are unavoidably cut during knee replacement, and a numb patch beside the scar is normal. Sometimes a cut nerve fires abnormally, producing burning, electric, or hypersensitive pain. Rarer still is complex regional pain syndrome (CRPS): pain out of proportion to any structural finding, often with skin color, temperature, or swelling changes. These are real diagnoses — and problems revision surgery cannot fix.

Soft-tissue causes

Tendons around a well-fixed implant can become irritated — among the most treatable causes on this list. Scar tissue is the other side of soft-tissue trouble: some knees form too much of it (arthrofibrosis), producing stiffness with pain — about 4.5% of revisions in the series above [2].

Unrealistic expectations — or a real problem?

I put this last deliberately: “expectations” should be a conclusion reached after a workup, not a label used to skip one. A replaced knee is not a 25-year-old knee. In surveys of joint replacement surgeons, more than 95% place no limitations on low-impact activities — level walking, stair climbing, level cycling, swimming, golf — while high-impact activities such as running are commonly discouraged [4]. A knee that aches after a five-mile run may be performing as designed; a knee that hurts during ordinary daily life deserves the full evaluation described below.

How the common causes compare:

What Does a Proper Workup of a Painful Knee Replacement Include?

Because infection was the most common cause of revision within two years of surgery in that 781-revision series [2], infection testing comes first in my workup — before any conversation about what else might be wrong.

A structured evaluation should include:

• A detailed history. Did the pain ever fully resolve, or has it been there since day one? Start-up pain, pain with every step, and pain at rest each point somewhere different.
• An exam beyond the knee. Stability testing, kneecap tracking, and gait — plus hip rotation and a spine check, because referred pain stays on the list until it is examined away.
• Blood tests. ESR and CRP are simple, inexpensive screens for deep infection.
• Aspiration when indicated. If labs are elevated or suspicion is real, fluid is drawn from the knee for cell counts and culture — before anyone proposes surgery.
• Serial X-rays, not a single film. Loosening often shows itself as change over time, so today’s film is compared against earlier ones, along with the operative note.
• Selective advanced imaging. CT can assess component rotation and subtle loosening; a bone scan occasionally helps.

Worked through in that order, this evaluation yields a working diagnosis for most painful knee replacements — and a genuinely negative result is informative too, steering treatment away from surgery.

Why Isn’t “Your X-ray Looks Fine” the End of the Story?

This is the sentence frustrated patients quote to me most often — and the X-ray probably does look fine. The problem is what a plain X-ray cannot show. Low-grade infection is invisible on it. Early loosening often only declares itself when films are compared over time. Instability is a dynamic problem no static picture can capture. Nerve pain and pain referred from the hip or spine will never appear on a knee film, because they are not in the knee.

One of the rules I practice by: treat the patient, not the X-ray. A normal film narrows the list of causes; it does not empty it. If your evaluation consisted of a single X-ray and reassurance — no inflammatory labs, no aspiration, no hip and spine exam — the workup is not wrong, it is incomplete. You are entitled to the rest of it.

When Should You Get a Second Opinion — and Is That Okay?

In a large Medicare study, knee replacement patients of surgeons performing more than 50 such procedures per year had a lower risk of serious perioperative complications (odds ratio 0.81) than patients of surgeons performing 12 or fewer [5].

I cite that study because experience measurably affects outcomes, and revision is more complex than primary surgery. If revision is on the table, it is reasonable to want the diagnosis confirmed and the operation planned by someone who does this work regularly.

A second opinion is clearly justified when pain has gone unexplained for six to twelve months, when you are told the knee “looks fine” while your life stays limited, or when revision is recommended without infection labs and an aspiration. Seeking one is routine, it is your right, and no good surgeon is offended by it. Sometimes the most valuable thing I can tell a second-opinion patient is that their current plan is sound.

Bring your operative note, implant record, X-rays from before and after surgery, and any lab results. Much of that groundwork can be reviewed remotely — our virtual second opinion service exists for exactly this situation — and I have written a step-by-step guide on getting a second opinion on a knee replacement.

What Can Actually Be Fixed — and What Is Better Treated Without Surgery?

The fixable column is real: deep infection (specialized, often staged, treatment), implant loosening, instability, and certain kneecap problems. When the diagnosis is clear, revision knee replacement has a good record of relieving the specific problem it targets; our failed knee replacement page covers that evaluation in more depth.

Revision is a bigger operation than the original, recovery is longer, and predictability tracks the quality of the diagnosis. Revising a knee for unexplained pain — negative workup, no identified cause — has a deservedly poor reputation, and I do not recommend it. An operation can fix a problem; it cannot fix the absence of one.

The non-surgical column is not a consolation prize. Nerve-related pain responds to medications, desensitization therapy, and pain-specialist care. CRPS does best with early, multidisciplinary treatment. Referred pain improves by treating the hip or spine actually generating it. Tendon and soft-tissue pain usually settles with focused physical therapy and, at times, a targeted injection. Whichever column your knee lands in, the destination is the same: a named cause and a plan that matches it.

Frequently Asked Questions About Knee Pain After Replacement

Related Resources

• Failed Knee Replacement – How we evaluate one
• Revision Knee Replacement – When redo surgery helps
• Signs of a Failed Knee Replacement – A symptom checklist
• Second Opinions on Knee Replacement – What to bring
• Virtual Second Opinion – Remote review of your records
• Knee Pain – Knee pain causes explained

Help for a Painful Knee Replacement in Long Beach, California

At Precision Joints, evaluating painful knee replacements — including knees replaced elsewhere — is a core part of the practice. Dr. Leo Zalikha is a Stanford fellowship-trained joint replacement surgeon specializing in hip and knee replacement, including complex revision surgery. Evaluations take place at our Long Beach office at 2760 Atlantic Ave; when surgery is the right answer, procedures are performed at MemorialCare Long Beach Medical Center, the Surgery Center of Long Beach, or DISC Sports & Spine Center in Marina del Rey.

References

1. Beswick AD, Wylde V, Gooberman-Hill R, Blom A, Dieppe P. What proportion of patients report long-term pain after total hip or knee replacement for osteoarthritis? A systematic review of prospective studies in unselected patients. BMJ Open. 2012;2(1):e000435. PMID: 22357571. PubMed
2. Sharkey PF, Lichstein PM, Shen C, Tokarski AT, Parvizi J. Why are total knee arthroplasties failing today—has anything changed after 10 years? J Arthroplasty. 2014;29(9):1774-1778. PMID: 25007726. PubMed
3. American Academy of Orthopaedic Surgeons (OrthoInfo). Revision Total Knee Replacement. orthoinfo.aaos.org. AAOS
4. Swanson EA, Schmalzried TP, Dorey FJ. Activity recommendations after total hip and knee arthroplasty: a survey of the American Association for Hip and Knee Surgeons. J Arthroplasty. 2009;24(6 Suppl):120-126. PMID: 19698910. PubMed
5. Katz JN, Barrett J, Mahomed NN, Baron JA, Wright RJ, Losina E. Association between hospital and surgeon procedure volume and the outcomes of total knee replacement. J Bone Joint Surg Am. 2004;86(9):1909-1916. PMID: 15342752. PubMed

Medical Disclaimer: This content is provided for general educational purposes and does not constitute medical advice. Treatment recommendations vary based on individual diagnosis, imaging findings, and health history. Please consult Dr. Zalikha or a qualified orthopedic physician for an evaluation specific to your condition.