After Surgery Knee Pain May Be a Sign of Nerve Damage

Baltimore Peripheral Nerve Surgeon Dr. Eric H. Williams Helps Patients With Nerve Pain After Knee Replacement or Knee Repair Surgery

You were hoping that knee replacement or repair surgery would relieve pain and improve function in your knee so you could get back to the activities you most enjoy. Instead, you’re struggling with chronic pain and wondering how to move forward.

Unfortunately, a significant number of patients—anywhere from 5% to 35%—experience chronic pain that may be caused by nerve damage after knee replacement or knee repair surgery. Baltimore peripheral nerve surgeon Dr. Eric H. Williams has helped many patients with knee-related nerve pain—and he may be able to do the same for you. 

Pain Six Months After a Knee Replacement or Knee Repair Is Not Normal

It is normal to experience some degree of discomfort, swelling, and difficulty moving your knee after surgery. However, your pain should decrease as your body heals. 

Knee pain that continues six months or more after surgery is not normal. Your first step should be to seek out a second opinion to ensure that your knee joint is healing correctly from an orthopedic and biomechanical perspective. If there are no identifiable issues with your knee replacement or knee repair, your pain could be neuropathic. This means that if your surgeon and a second opinion agree that there is nothing that can be fixed or improved upon with regards to the previous operation, or with the current “orthopedic state” of the knee (the bones are as good as they can be, the ligaments are all repaired correctly, there is no loosening or infection of any hardware placed in knee joint, and you are not allergic to the metal that is in the joint replacement), your pain may be due to damaged or entrapped nerves in or around the knee joint.  

How Knee Surgery Can Lead to Nerve Damage

Surgeons take precautions to minimize the likelihood of nerve injury during surgery, but no procedure is without risk. Nerve damage doesn’t necessarily mean the surgeon who performed your knee surgery was negligent or did anything wrong.  Surgery is inherently invasive, which is why patients must sign consent forms before an operation. 

Postsurgical neuropathic knee pain can be related to: 

• Incisions. The initial incision made during knee surgery can potentially damage nerves that run close to the surface of the skin or within the subcutaneous tissue. Nerves are small, and some incisions are big.  Sometimes we have to cut through these just to get the operation completed.  
• Retraction. During the procedure, surgical instruments and retractors are used to hold tissues and structures out of the way to provide access to the knee joint. Improper positioning or excessive traction on tissues can put pressure on nerves, leading to stretching or compression injuries.  More traction may have to be placed in larger legs.  There is always a battle between making smaller incisions and pulling harder to “get the job done.” Clearly, surgery can be done through larger incisions, but what patient volunteers for a larger scar? This is a challenge to balance at times.    
• Dissection. Tissues around the knee, including muscles, tendons, ligaments, and blood vessels, need to be dissected to access the joint. Nerves traveling through or adjacent to these structures can be inadvertently cut or damaged during dissection.  Sometimes they have to be divided on purpose to get past them.  Most will not have problems when these small nerves are cut, but some patients will.  It is impossible to know who will have these problems prior to the operation.  
• Implantation. Inserting and positioning the artificial components of the knee prosthesis can also pose a risk to nearby nerves. Instruments used to prepare the bone or place implants may injure nerves if not handled carefully. Even if they are placed as carefully as possible, sometimes nerve damage still occurs.
• Postoperative complications. Nerve damage can also occur as a result of postoperative complications such as hematoma, infection, or inflammation. 
• Neuroma formation. Nerve damage during knee replacement or knee repair surgery can lead to a neuroma, which is a non-cancerous growth or swelling of nerve tissue that forms when a nerve has been damaged.  While not every neuroma causes problems, some are incredibly painful and can lead to severe disability.   
• Patient anatomy. Variations in individual anatomy, such as abnormal nerve courses or branching patterns, can increase the risk of nerve injury during surgery.  Some patients just “did not read the book” that teaches us surgeons what “normal” anatomy is.  

Some of the specific nerves that can be damaged during knee replacement or knee repair surgery include:

• Infrapatellar branch of the saphenous nerve (ISN). This is the most common nerve injured during this operation. This nerve runs along the inside of the knee and can be damaged during surgery, leading to numbness or altered sensation along the inner aspect of the knee and lower leg. It might be nearly impossible to perform this operation without injuring it because nearly every incision to replace a knee joint will require cutting this nerve. You can tell if your infrapatellar branch has been cut if the outside half of the knee is numb to touch. If it is numb, the nerve has been cut. This is an expected outcome of the knee replacement surgery.  The complication comes if you are one of the 3% to 8% who have horrible pain from this that lasts over six months.  
• Medial retinacular nerve. The medial retinacular nerve is a branch of the saphenous nerve, and it innervates the medial (inner) aspect of the knee joint. This sensory feedback is essential for various aspects of knee function, including proprioception (awareness of the knee's position and movement), pain perception, and tactile sensation.
• Lateral retinacular nerve. While the medial retinacular nerve branches from the saphenous nerve supply sensation to the inner aspect of the knee, the lateral retinacular nerve serves the lateral (outer) aspect of the knee joint.  Damage to the lateral retinacular nerve during knee replacement surgery can result in sensory disturbances in the joint and can cause pain within the joint.
• Common peroneal nerve. This nerve wraps around the outside of the knee and can be vulnerable during surgery. Damage to the common peroneal nerve can result in weakness or paralysis of the muscles that lift the foot (foot drop) and altered sensation along the outer aspect of the lower leg and top of the foot.
• Anterior femoral cutaneous nerve. The anterior femoral cutaneous nerve (AFCN) is a sensory nerve that provides innervation to the skin on the front of the thigh and the top of the knee.    
• Medial cutaneous nerve. The medial cutaneous nerve (MCN) is a sensory nerve that provides innervation to the skin along the medial (inner) aspect of the thigh. Like the AFCN, it plays an important role in detecting sensory stimuli and can cause pain to the thigh above and medial to the knee.
• Tibial nerve. While less commonly affected, the tibial nerve can also be at risk during knee repair or replacement surgery. Damage to this nerve can lead to altered sensation or weakness in the muscles of the calf and sole of the foot.
• Sciatic nerve. Although rare, if the sciatic nerve, which is a major nerve of the lower limb, is affected during surgery, it can result in pain, weakness, or altered sensation in most of the lower limb.

Request a copy of “Chronic Nerve Pain Following Knee Surgery” to learn about the reasons why pain may continue following a surgical replacement or other procedure around the knee.  

Symptoms of Nerve Damage Following Knee Surgery

If it’s been six months or more since you’ve had a knee replacement or knee repair and you’re experiencing any of the following symptoms, nerve damage could be the culprit:

• Numbness or tingling. You may experience sensations of numbness, tingling, or "pins and needles" around your knee, lower leg, or foot.
• Altered sensation. Pay attention to any changes in sensation, like hypersensitivity or reduced sensitivity, in the areas around your knee affected by the surgery.
• Sharp burning or shooting pain. If you feel persistent or intermittent pain described as a sharp burning or shooting in the surgical area, it could be a sign of nerve damage.
• Weakness or muscle dysfunction. Notice any weakness, muscle wasting, or difficulty controlling movements in the muscles around your knee. For instance, if you have trouble lifting your foot, it might be due to nerve damage.
• Loss of reflexes. Keep an eye out for any changes in reflexes, such as the patellar reflex (knee jerk reflex), as this could indicate nerve involvement.
• Difficulty with balance or coordination. If you experience problems with balance, coordination, or a sense of where your body is in space, nerve issues could be to blame.
• Changes in gait. Watch for changes in your walking pattern, like limping or dragging your leg, especially if you notice weakness or altered sensation.

Dr. Williams will examine you and use a variety of tests, including nerve blocks, advanced imaging studies, MRN (magnetic resonance neurography), and EMG (electromyogram) to pinpoint the source of your persistent pain.

Surgical Treatment Options

The type of surgery recommended for your nerve pain will depend on what nerves are damaged as well as the extent of the damage. Options include:

• Nerve decompression. This procedure involves relieving pressure on pinched nerves to enhance their function. By alleviating the pressure on the nerve, the nerves can regain their normal functionality, potentially alleviating pain and discomfort.
• Nerve repair. In cases where critical nerves sustain severe damage, nerve repair may be recommended. This procedure involves techniques such as grafting to facilitate the regrowth of damaged nerves, aiming to restore their function and mitigate pain.
• Nerve resection. When conventional treatments fail to alleviate painful symptoms, nerve resection could offer a viable solution. This involves the surgical removal of less crucial nerves, such as those in the skin, which are responsible for transmitting painful sensations. By eliminating these nerves, the source of pain can be effectively addressed.
• Nerve denervation. Knee denervation relieves chronic pain by interrupting or disabling the sensory nerves responsible for transmitting pain signals from the knee joint to the brain. The procedure involves selectively disrupting the nerves that innervate the knee joint to inhibit their ability to transmit pain signals while preserving other sensory and motor functions in the knee.

Here are some examples of how we’ve helped people just like you find relief from chronic nerve pain after knee repair or knee replacement surgery:

• No need for a knee brace. Our patient was suffering from a foot drop following a knee replacement. After Dr. Williams decompressed the common peroneal nerve, she no longer needed to wear a brace and didn’t worry about tripping when using the stairs. 
• Able to bend her knee again. Our patient had four years of severe chronic knee after her knee replacement. One month out from a resection of the medial retinacular nerve, she can bend her knee without pain. 
• Walking 5 km a day. Before seeing Dr. Williams, our patient struggled with severe knee pain that made it difficult to walk, sit, or use the stairs. Now, four months out from a right knee denervation and six weeks out from a left knee denervation, he’s walking 5 km a day and seeing continued improvement.

You can learn more about the results Dr. Williams has been able to achieve with his patients on the testimonials section of our website.