What Causes Pain After Knee Replacement Surgery
When you undergo knee replacement surgery, it should be the end of your pain, not the beginning of a new one. If you’re experiencing discomfort weeks or months post-operation, it’s understandable to worry. Around 10% to 34% of knee replacement patients experience chronic pain after the procedure, and many begin to wonder why there is so much pain after knee replacement, whether it’s normal or if something went wrong.
Fortunately, ongoing pain after knee replacement doesn’t always mean something serious or irreversible. It can often be identified and managed, usually without the need for a second operation. If you’re experiencing lingering discomfort after surgery, this blog will help you understand the possible reasons behind lingering discomfort, what you can do to prevent it, and your next steps to complete recovery.
Pain After Knee Replacement: Is It Normal?
It’s normal to experience discomfort in the first few weeks of recovery, especially after full knee replacement surgery. But if the pain doesn’t ease or seems to worsen over time, it may point to something more specific.
Pain following knee replacement may stem from issues related to the surgery itself, your body’s healing response, or complications affecting soft tissues or nerves.
Surgical and Implant-Related Causes of Ongoing Pain
Component Misalignment
If the artificial joint isn’t positioned correctly, it can cause uneven pressure in the knee. This might result in pain behind the knee, stiffness, instability while walking, or discomfort when bearing weight. Poor alignment can also wear down surrounding tissues.
Infection
Although rare, infections occur in about 1 out of 100 cases and can happen on the surface or deep within the joint. Signs include redness, swelling, and persistent pain. Deep infections (also known as periprosthetic joint infections) require prompt diagnosis and treatment to prevent further damage.
Aseptic Loosening
Sometimes, the bond between the bone and the implant weakens over time, causing it to detach due to wear or bone loss. This loosening can lead to pain with movement and may eventually require revision surgery.
Pain After Knee Replacement: Biological and Post-Surgical Factors
Arthrofibrosis
In some cases, excess scar tissue can form around the joint. This condition, known as arthrofibrosis, limits your range of motion and can make the knee feel tight, sore, or stuck. Physical therapy is often the first step in treatment.
Nerve Damage or Compression
Nerves, commonly the peroneal or tibial nerves, may become compressed or irritated during surgery or healing. Nerve injury can also result in neuropathic pain, which feels like a sharp, burning or a “pins and needles” sensation.
Blood Clots
Pain behind the knee accompanied by swelling, warmth, or tightness could indicate a deep vein thrombosis (DVT), a blood clot in a deep vein. If suspected, it requires urgent attention.
How Surrounding Soft Tissues Respond Post-Surgery
What causes pain behind the knee after total knee replacement often relates to local structures that were affected during surgery or are adjusting to the implant.
Popliteal Tendonitis: Inflammation of the tendon behind the knee can occur as your body adjusts to new joint mechanics.
Bursitis: The bursae (small fluid-filled sacs around the knee) can become inflamed, leading to sharp, throbbing pain when irritated by pressure or movement.
Cyst Formation: Occasionally, fluid can build up and form a cyst, pressing on nerves or surrounding tissues.
Why Total Knee Replacement Pain is Often Worse at Night
Total knee replacement pain at night is a common frustration for many patients. While your knee might feel manageable during the day, discomfort often becomes more noticeable once you're resting. Here’s why:
Fluid Accumulation: Lying down allows fluid to settle around the joint, increasing pressure and swelling.
Joint Stiffness: Inactivity during sleep can lead to tightened muscles, making the joints feel achy and stiff.
Sleep Position: Sleeping on your side, with one knee bent, or in an awkward position, can strain the healing tissues.
To ease these symptoms, adjust your sleeping position, use pillows for elevation, and stretch before bed to ease these symptoms. This discomfort may persist for a few weeks but will usually settle over time. If the pain persists, seek professional consultation.
What You Can Do to Feel Better
Treatment depends on the underlying cause, but the right approach can often reduce pain and improve mobility without the need for more surgery.
Effective solutions include:
Physical therapy to stretch tight tissues, improve joint flexibility, and build strength
Medication such as NSAIDs or gabapentin for neuropathic pain can help manage symptoms
Injections (e.g., corticosteroids or nerve blocks) for targeted relief
In cases of loose components, misalignment or failure, revision surgery may be needed
Preventive Tips
Strengthen your leg muscles before surgery
Ask your surgeon about robotic assistance for improved accuracy
Icing the knee frequently, especially after exercise, can improve pain and reduce swelling
Stay mobile early to reduce stiffness and prevent clots
If you’re unsure whether your current symptoms are expected or a sign of something more, learn about the signs and symptoms of needing a knee replacement or a revision to better understand your current pain or upcoming options.
When to Seek Medical Advice
Seek a review if you notice:
Persistent pain beyond 3 to 6 months after surgery
Sudden “giving way” or instability in the knee
Redness, fever, or swelling, which are potential signs of infection
Severe night pain that isn’t relieved by rest, elevation, or ice.
Take Charge of Your Knee Health
Pain after knee replacement shouldn’t be your new normal. Whether the issue is mechanical, biological, or nerve-related, identifying the cause early gives you more options and better outcomes. With the right treatment and therapy post-surgery, your knee replacement should ease your previous pain.
As one of Melbourne’s best orthopaedic surgeons, Dr David Sime can help. We can guide you through your options, shed light on how long a knee replacement lasts, and create a treatment plan that puts your mobility first.