What Causes Pain Behind Knee After Total Knee Replacement?

Experiencing knee replacement pain, especially behind the knee, after a total knee replacement can be unsettling. While it’s natural to expect some discomfort as you heal, persistent or sharp pain may leave you wondering if something more is going on. Consultant Orthopaedic Surgeon Mr Sujith Konan has created a guide to help you understand potential causes of pain behind the knee after knee replacement surgery, providing reassurance and information to help you take the next steps toward a full recovery.

Understanding Knee Replacement Surgery

Knee replacement surgery, also known as knee arthroplasty, is a medical procedure designed to replace a damaged or arthritic knee joint with an artificial implant. The primary goal of this surgery is to alleviate knee pain and improve the range of motion, enabling patients to return to their normal activities. There are two main types of knee replacement surgeries: total knee replacement and partial knee replacement.

In a total knee replacement, the entire knee joint is replaced with a prosthetic implant. This procedure is typically recommended for patients with severe arthritis or extensive joint damage. On the other hand, a partial knee replacement involves replacing only the damaged part of the knee joint, preserving as much of the natural joint as possible. This option is suitable for patients with localized damage.

Knee replacement surgery is a common and highly effective treatment for chronic knee pain. Many patients experience significant pain relief and improved mobility after the procedure, allowing them to enjoy a better quality of life.

Common Causes of Pain Behind the Knee

Pain behind the knee after total knee replacement surgery can arise from several factors. While most patients recover without significant issues, some may experience discomfort during the healing process. It’s important to recognise that pain can stem from a variety of sources, such as the:

• Post-surgical healing process
• Scar tissue formation
• Muscle imbalances

In addition to pain behind the knee, some patients may also experience anterior knee pain, which is discomfort located at the front of the knee.

Identifying the cause is the first step towards managing the pain effectively and ensuring a smooth recovery.

Less Common Causes of Pain

While infection, loosening, and alignment issues are well-known causes of pain after knee replacement surgery, there are several less common conditions that can also lead to discomfort. Understanding these can help in identifying and addressing persistent knee pain.

• Iliotibial Band Friction Syndrome (ITBFS): This condition occurs when the iliotibial band, a thick band of tissue running along the outside of the thigh, rubs against prominent structures like unresected osteophytes or misaligned implants. This friction can cause localized tenderness and a creaking sensation.
• Iliotibial Band Traction Syndrome (ITBTS): ITBTS happens when the iliotibial band is stretched due to forced guided motion from the implant. This stretching can lead to pain and discomfort along the outer side of the knee.
• Biceps Tendinitis: Inflammation of the biceps tendon can result in pain and tenderness along the course of the tendon. This condition can be particularly bothersome when bending or straightening the knee.
• Fabella Syndrome: The fabella is a small sesamoid bone located within the lateral head of the gastrocnemius muscle. When this bone becomes symptomatic, it can cause posterolateral knee pain, especially during activities that involve deep knee flexion.
• Popliteus Tendon Impingement: This condition occurs when the popliteus tendon, located at the back of the knee, becomes impinged against the tibial tray during deep flexion. This impingement can lead to pain and a snapping sensation along the posterolateral aspect of the knee.
• Synovial Tissue Impingement: When the synovial tissue, which lines the knee joint, becomes impinged, it can cause pain and inflammation. This condition often requires targeted treatment to alleviate the discomfort.

Post-Surgical Healing Process

After total knee replacement surgery, your body goes through a natural healing process, and postoperative pain behind the knee is common in the early stages of recovery as the surrounding tissues, muscles, and ligaments adjust to the new implant.

Swelling, stiffness, and discomfort can persist for weeks, sometimes even months, as the body heals. It’s important to follow the physiotherapy plan provided by your healthcare team to promote healing and strengthen the muscles around the joint. However, if the pain intensifies or doesn’t improve over time, it may indicate an underlying issue that requires further attention.

Scar Tissue Formation

Scar tissue, or adhesions, can form around the knee joint during the healing process, sometimes causing pain behind the knee. This is a normal part of recovery but, in some cases, excessive scar tissue can restrict movement and cause discomfort.

In some cases, scar tissue can lead to ongoing pain that requires targeted treatment to manage effectively.

Over time, stretching and physical therapy should help break down this tissue, restoring flexibility and reducing pain. However, if scar tissue builds up significantly, it may require more focused treatment to improve mobility and relieve discomfort.

Ligament Strain or Injury

The ligaments around your knee, particularly those at the back, are essential for stability and support. During surgery or recovery, these ligaments can become strained or irritated, leading to pain behind the knee.

In rare cases, the posterior cruciate ligament (PCL) may become strained, leading to severe pain, especially during movements that involve bending or straightening the knee. Careful attention to post-operative exercises and avoiding overexertion can help prevent ligament-related pain.

Nerve Sensitivity and Pain

Nerve pain is another possible cause of discomfort behind the knee after surgery. During a knee replacement, the nerves around the joint are sometimes stretched or damaged, leading to sensations such as tingling, sharp pain, or numbness.

This is often temporary, with nerves slowly healing over time. However, in some cases, nerve sensitivity can persist, requiring treatment such as nerve blocks or medications to manage the pain. In cases where nerve sensitivity and pain persist despite treatment, revision surgery may be considered to address the underlying issues.

Joint Inflammation

Inflammation in the knee joint is a common part of the healing process after knee replacements but can sometimes cause persistent pain. Inflammatory reactions to the surgery may result in swelling, redness, and discomfort, particularly behind the knee.

Anti-inflammatory medications, ice, and rest are typically recommended to manage these symptoms. If inflammation continues to cause problems, your surgeon may suggest further interventions.

Hardware Issues (Implant Problems)

While rare, issues with the knee implant can contribute to pain behind the knee. Sometimes, the implant may not fit perfectly, or components might loosen over time, leading to discomfort.

If you notice ongoing or worsening pain, particularly with movement, it’s important to consult your orthopaedic surgeon. Imaging tests, such as X-rays, can help determine whether the implant is functioning properly or if adjustments need to be made. If implant problems are detected, a revision knee replacement may be necessary to address the issues and alleviate pain.

Muscle Imbalances and Weakness

Following knee replacements, the muscles surrounding the knee often weaken due to inactivity and the surgical procedure itself. Muscle imbalances or weakness, particularly in the hamstrings and calf muscles, can place extra strain on the back of the knee, resulting in pain. A tailored physiotherapy programme focused on strengthening these muscles can help restore balance and alleviate discomfort.

Blood Clots (Deep Vein Thrombosis)

A more serious cause of pain behind the knee after surgery is the development of a blood clot, also known as deep vein thrombosis (DVT). This condition can cause swelling, redness, and sharp pain, particularly in the calf or behind the knee.

DVT requires immediate medical attention, as clots can travel to other parts of the body, including the lungs, causing potentially life-threatening complications. Preventative measures, such as medication and wearing compression stockings, are typically advised after surgery to reduce the risk of blood clots.

Diagnostic Process for Knee Pain

Diagnosing the cause of knee pain after knee replacement surgery involves a comprehensive approach that includes physical examination, imaging studies, and laboratory tests. This thorough diagnostic process helps healthcare providers pinpoint the exact cause of pain and develop an effective treatment plan.

• Physical Examination: During the physical examination, your healthcare provider will:
• Palpation: Feel the knee to identify areas of tenderness and crepitus (a crackling or grating sensation).
• Range of Motion: Assess your ability to move the knee through its full range of motion.
• Strength Testing: Evaluate the strength of the muscles around the knee.
• Neurological Examination: Check for any signs of nerve dysfunction.
• Imaging Studies: These tests provide detailed images of the knee joint and surrounding structures:
• X-rays: Used to assess the alignment and positioning of the implant.
• CT Scans: Provide detailed images of the bone and soft tissue around the implant.
• MRI Scans: Offer a clear view of the soft tissues and ligaments around the knee.
• Laboratory Tests: These tests help identify signs of infection or inflammation:
• Blood Tests: Check for markers of infection or inflammation in the blood.
• Joint Aspiration: Involves drawing fluid from the knee joint to test for infection or inflammation.

By combining these diagnostic tools, healthcare providers can accurately identify the cause of knee pain and recommend appropriate treatments to alleviate discomfort and improve function.

When to Seek Medical Advice

It’s important to monitor your knee replacement pain levels throughout the recovery process. While some discomfort is expected, severe or persistent pain, especially if accompanied by swelling, redness, or difficulty moving the knee, may indicate a problem that needs medical attention. If you experience symptoms such as intense pain, fever, or signs of infection around the knee, contact your healthcare provider promptly for further evaluation.

Conclusion

Total knee replacement is a highly effective procedure for alleviating chronic knee pain and restoring mobility. While most patients experience significant improvement, some may encounter complications such as infection, implant issues, or alignment concerns, leading to persistent discomfort. Understanding the potential causes of post-surgical pain, including scar tissue formation, ligament strain, or nerve sensitivity, is key to managing your recovery effectively.

At St John & St Elizabeth Hospital, we are dedicated to providing expert care before, during, and after your knee replacement surgery. If you’re experiencing ongoing pain or have concerns about your recovery, don’t hesitate to contact our orthopaedic team for advice and support. We’re here to help you every step of the way.

Total Knee Replacement FAQ’s

How long is pain normal after knee replacement?

It is common to experience pain for several weeks following knee replacement surgery. However, this should gradually decrease as the body heals. If pain persists beyond a few months, it is advisable to consult your surgeon.

Can exercises increase pain after knee surgery?

Some discomfort during physiotherapy and exercises is normal, especially in the early stages of recovery. However, these exercises are crucial to strengthening the muscles around the joint, improving flexibility, and ultimately reducing long-term pain.

What should I do if my pain doesn’t decrease after several months?

If pain continues for more than three to six months, it could indicate complications like implant issues or infection. In such cases, it’s important to see your surgeon for a thorough evaluation.

Are there any new treatments available to manage pain after knee replacement?

Yes, recent advancements include innovative methods such as infusing pain-relieving medication directly into the bone during surgery. These methods can help control pain more effectively in the immediate postoperative period.

What are the signs that knee pain may be due to an infection?

Signs of infection include excessive redness, swelling, warmth around the joint, fever, and worsening pain that doesn’t improve with rest or medication. If you experience these symptoms, you should contact your doctor immediately.

How effective is physical therapy in reducing pain after knee replacement?

Physical therapy is highly effective in reducing pain. Regular exercises tailored to your recovery can help restore flexibility, strength, and overall joint function, all of which contribute to long-term pain relief.

Is nerve pain common after knee replacement surgery?

Nerve pain can occur as a complication of knee replacement surgery, resulting in sensations like tingling or sharp pain. Treatment options may include medications, physical therapy, or nerve block procedures.

What is the risk of chronic pain after knee replacement surgery?

While most patients experience significant pain relief, a small percentage may develop chronic pain. Early intervention with a multidisciplinary pain management plan is key to addressing this issue.

Can obesity affect pain levels after knee replacement?

Yes, carrying excess weight can put additional strain on the knee joint, potentially leading to increased pain and slower recovery. Weight management through diet and exercise can help improve outcomes.

What should I avoid doing after knee replacement surgery to prevent pain?

Avoid high-impact activities, deep bending, and heavy lifting, especially in the early stages of recovery. Follow your physiotherapist’s guidance to gradually return to normal activities without straining your knee.

Seeking Help with St John & St Elizabeth Hospital

At St John & St Elizabeth Hospital, we are dedicated to providing personalised care to help you manage and prevent knee pain. Our experienced team of consultants and physiotherapists in our knee clinic work closely with you to develop tailored treatment plans, whether you’re dealing with chronic pain or seeking advice on knee surgery.

Located in the heart of St John’s Wood (NW8), our hospital combines state-of-the-art facilities with a caring approach to healthcare. Book an appointment with our specialists today.

• Telephone number: 020 7806 4060
• Email address: info@hje.org.uk