Most people do not experience serious complications. Still, it is helpful to understand what can happen, what warning signs to watch for, and how to participate in a safer recovery.
This article explains possible complications after knee replacement, including infection, blood clots, stiffness, nerve symptoms, and warning signs that should not be ignored.
Quick Answer
Serious complications after knee replacement are uncommon, but they can happen. Possible complications include infection, blood clots, stiffness, nerve or tissue irritation, wound problems, persistent swelling, implant loosening, or ongoing pain.
The goal is not to panic about every symptom. The goal is to know the difference between expected recovery symptoms and warning signs that deserve more caution.
Key Takeaways
- Most people recover from knee replacement without serious complications.
- Infection, blood clots, stiffness, wound issues, and nerve symptoms are possible risks.
- Some swelling, soreness, stiffness, and numbness around the incision can be part of normal recovery.
- Rapidly worsening symptoms, fever, drainage, calf swelling, chest pain, or shortness of breath should be taken seriously.
- Early movement, medication adherence, wound care, swelling management, and follow-up appointments all support a safer recovery.
How Common Are Complications After Knee Replacement?
Knee replacement is a common and generally successful procedure, but no surgery is risk-free.
AAOS notes that the complication rate after total knee replacement is low, and serious complications such as knee joint infection occur in fewer than 2% of patients. AAOS total knee replacement overview
AAHKS also notes that complications are relatively rare, but possible issues include infection, blood clots, stiffness or loss of motion, medical complications, and implant problems over time. AAHKS total knee replacement overview
The practical message is balanced: complications are not the norm, but knowing the warning signs helps you respond appropriately if something does not seem right.
Expected Symptoms vs. Warning Signs
Some symptoms are common after knee replacement and do not automatically mean something is wrong.
Common recovery symptoms may include:
- Swelling around the knee and lower leg.
- Soreness with movement or exercise.
- Stiffness, especially after sitting or sleeping.
- Bruising around the thigh, knee, or lower leg.
- Temporary numbness or sensitivity near the incision.
- Fatigue during the early recovery period.
These symptoms should generally become more manageable over time. The concern is when symptoms are rapidly worsening, unusual, severe, or associated with signs of infection, blood clot, or sudden loss of function.
Infection After Knee Replacement
Infection is uncommon, but it is one of the more serious complications after knee replacement.
AAHKS reports the average infection risk after knee replacement is around 1–2%. Infection can involve the incision or, more seriously, the deeper joint replacement. AAHKS infection and knee replacement overview
Warning signs of possible infection may include:
- Fever or chills.
- Worsening redness around the incision.
- Drainage from the incision.
- Increasing warmth around the knee.
- Rapidly worsening swelling or pain.
- A major change in how the knee feels or functions.
Some warmth and swelling can be normal after surgery, but worsening redness, drainage, fever, chills, or symptoms that are clearly getting worse should be taken seriously.
Blood Clots After Knee Replacement
The risk of blood clots increases after knee replacement surgery. This is one reason your surgical team may recommend early movement, compression devices, and blood-thinning medication.
Mayo Clinic notes that blood clot prevention after knee replacement may include moving early, using compression devices or stockings, and taking blood thinners when prescribed. Mayo Clinic knee replacement overview
Warning signs of a possible blood clot may include:
- New calf pain.
- New calf swelling.
- Redness or warmth in the calf.
- Unusual tenderness in the lower leg.
Warning signs of a possible pulmonary embolism may include:
- Shortness of breath.
- Chest pain.
- Coughing blood.
- Sudden dizziness, fainting, or feeling seriously unwell.
These symptoms should not be treated like normal soreness. Follow your surgeon’s post-op instructions or seek urgent medical care if you have symptoms concerning for a blood clot or pulmonary embolism.
Stiffness and Loss of Motion
Stiffness is common after knee replacement, especially early on. Swelling, pain, guarding, scar sensitivity, and limited movement can all make the knee feel tight.
Some stiffness is expected. The concern is when motion is not improving over time, the knee is becoming harder to bend or straighten, or stiffness is significantly limiting function.
Ways to support knee motion include:
- Frequent gentle knee bending and straightening.
- Managing swelling and workload.
- Taking short movement breaks instead of staying still too long.
- Working on quad activation.
- Progressing walking and exercise gradually.
- Following your surgeon’s and rehab plan’s instructions.
For persistent stiffness, some people may need additional treatment. AAOS notes that manipulation under anesthesia may be considered in some cases when scar tissue or stiffness significantly limits knee motion after surgery. AAOS total knee replacement overview
Nerve Symptoms After Knee Replacement
Numbness, tingling, sensitivity, or altered sensation near the incision can happen after knee replacement. Small skin nerves can be irritated or affected during the incision and healing process.
For many people, this improves gradually, but some numbness around the incision can persist.
Nerve-related symptoms may include:
- Numbness near the incision.
- Tingling or sensitivity around the scar.
- Burning or zapping sensations.
- Skin sensitivity with clothing or touch.
More significant nerve injury is uncommon, but new weakness, foot drop, severe nerve pain, or major changes in sensation should be discussed with your medical team.
Wound Healing Problems
The incision needs time to heal. Early wound care is important because the incision is the barrier protecting deeper tissues.
Be more cautious with:
- Drainage that continues or increases.
- Opening of the incision.
- Worsening redness around the incision.
- Increasing warmth, swelling, or pain around the wound.
- Fever or chills with wound changes.
Follow your surgeon’s instructions for dressing changes, showering, wound protection, and when to call if the incision does not look right.
Persistent Pain or Swelling
Pain and swelling are common after knee replacement, but they should generally trend in the right direction over time.
Sometimes swelling or soreness increases because the activity dose is too high. Other times, persistent or worsening symptoms may need a closer look.
Activity-related swelling may happen after:
- Increasing walking distance too quickly.
- Doing too much exercise volume.
- Adding stairs, errands, and strengthening all at once.
- Standing for long periods.
- Skipping recovery time between harder days.
If swelling is clearly worse later that day or the next morning, the first step may be adjusting the workload. But swelling that is rapidly worsening, paired with fever, severe pain, calf symptoms, or major functional change deserves more caution.
Implant Loosening, Wear, or Instability
Implant problems are usually more of a long-term concern, but they are still worth understanding.
Over time, possible reasons for revision surgery can include loosening, wear of the plastic spacer, instability, infection, fracture, or other mechanical problems.
Possible signs that deserve evaluation include:
- New pain that does not match your recent activity.
- A new feeling that the knee is loose or unstable.
- Repeated giving way.
- A major change in walking ability.
- New swelling or pain years after surgery.
These symptoms do not automatically mean the implant is failing, but they should not be ignored.
How to Reduce Your Risk
You cannot eliminate every risk, but you can support a safer recovery by following the plan and responding early to warning signs.
Helpful strategies include:
- Move early as instructed: Early walking and movement can support circulation and reduce complications.
- Take medications as prescribed: This may include pain medication, blood thinners, or other medications from your surgical team.
- Follow wound care instructions: Keep the incision protected and monitor for changes.
- Manage swelling: Use elevation, ice, compression, and activity modification when recommended.
- Progress activity gradually: Avoid sudden jumps in walking, stairs, strengthening, and errands.
- Attend follow-up visits: These appointments help monitor healing, motion, symptoms, and implant status.
- Communicate clearly: Report symptoms that are worsening, unusual, or concerning.
What Symptoms Should Not Be Ignored?
Warning Signs That Deserve More Caution
- Fever, chills, drainage, or worsening redness around the incision.
- Rapidly increasing swelling, warmth, or worsening pain.
- New calf pain or calf swelling.
- Chest pain, shortness of breath, coughing blood, or fainting.
- A sudden inability to bear weight after a fall or injury.
- The knee repeatedly buckles or gives way.
- A major change in walking ability.
- New or worsening pain that does not match your recent activity.
If you notice these symptoms, do not try to solve them by pushing harder through exercise. Follow your surgeon’s post-op instructions or contact your medical team.
Common Mistakes
- Assuming every symptom is normal because surgery was recent.
- Assuming every symptom is dangerous and stopping all movement.
- Ignoring incision drainage, fever, calf swelling, or shortness of breath.
- Doing too much walking or exercise when swelling is clearly escalating.
- Skipping blood clot prevention steps recommended by the surgical team.
- Stopping rehab completely after a flare-up instead of adjusting the dose.
Related Learning
If you are learning about knee replacement recovery and warning signs, these articles may help:
Want a Clearer Knee Replacement Recovery Plan?
The Knee Replacement Recovery Guide includes phase-based exercise plans, progress check-ins, focus tracks, and guidance for adjusting your plan as your knee recovers.
Instead of guessing what symptoms mean or how much to do, you can follow a clearer recovery path based on where you are in the process.
FAQ
What are the most common complications after knee replacement?
Possible complications include infection, blood clots, stiffness, wound problems, nerve symptoms, persistent pain or swelling, and implant issues over time. Serious complications are uncommon, but they should be taken seriously if they occur.
How do I know if my knee replacement is infected?
Possible signs include fever, chills, worsening redness, drainage from the incision, increasing warmth, rapidly worsening swelling, or worsening pain. Follow your surgeon’s instructions if these symptoms occur.
What are signs of a blood clot after knee replacement?
Possible signs include new calf pain, calf swelling, redness, warmth, or tenderness. Chest pain, shortness of breath, coughing blood, fainting, or sudden severe symptoms may suggest a more urgent problem.
Is numbness normal after knee replacement?
Some numbness or altered sensation near the incision can happen after knee replacement. However, new weakness, severe nerve pain, foot drop, or major sensation changes should be discussed with your medical team.
Can stiffness become a complication after knee replacement?
Some stiffness is common, but stiffness that is severe, worsening, or not improving over time may need additional attention. Swelling management, gentle motion, and consistent rehab are important.
When should I be worried after knee replacement?
Be more cautious with fever, chills, incision drainage, worsening redness, rapidly increasing swelling or pain, calf swelling, shortness of breath, chest pain, repeated buckling, or a sudden major change in walking ability.
