What Is a Bone Spur in the Knee?

Bone spurs in the knee are outgrowths of bone that develop in joints when there is increased pressure between bones from a lack of cartilage. Bone spurs are also called osteophytes.

Bone spurs (or “spurring bone”) in the knee can cause pain and limit joint mobility, which can cause trouble with doing everyday activities like walking, squatting, bending, and going up and down stairs. Bone spurs can also lead to muscle imbalances in the leg.

However, not everyone will have symptoms of bone spurs in the knee—some people don’t even know they have them. 

Bone spurs are common in people with osteoarthritis, (degenerative joint disease), which causes a breakdown of cartilage.

This article will go over why bone spurs in the knee happen and how they can be treated. 

How Do Bone Spurs Form?

If there isn’t enough cartilage around the knee joint, the bones of the knee get irritated and inflamed from increased pressure and friction within the joint during movement and weight-bearing of the leg as the bones rub against each other. 

Bone cells react to the increased pressure by producing more bone growth in an attempt to provide more protection to the joint, forming bone spurs that can change the appearance of the joint and limit mobility by restricting movement.

Anatomy of the Knee

The knee joint is where the thigh bone (femur) meets the shin bone (tibia). The midpoint is the kneecap (patella). 

The bones are surrounded by supportive cartilage, ligaments, tendons, and muscles. 

Bone spurs in the knee form in spots where cartilage has been worn down (like from osteoarthritis). Since there isn’t enough cartilage to protect the bones from damage, new bone forms to protect the worn-down areas. The growths of bone (osteophytes) are commonly called bone spurs.

Signs of Bone Spurs in the Knee

Bone spurs often do not cause symptoms (asymptomatic). You may not know you have one until you have X-rays taken of your knees.

Bone spurs can cause symptoms when they put pressure on nearby nerves, restrict movement, and rub against other bones or tissues.

Symptoms of a bone spur in the knee include:

• Knobby or bumpy areas
• Numbness and weakness
• Pain near the knee
• Reduced range of motion
• Stiffness
• Tendinitis

Causes of Bone Spurs in the Knee

The most common cause of loss of cartilage in the knee joint that leads to bone spurs is knee osteoarthritis, which affects more than 45% of Americans at some point in their lives.

Cartilage loss in the knee joint can also happen after an injury to the knee, including anterior cruciate ligament (ACL) ruptures, meniscus tears, and patellar (kneecap) dislocations. These injuries increase the risk of cartilage damage and knee osteoarthritis in the future. 

Anyone who overuses their joints—like athletes, military personnel, and people who work physically demanding jobs— are at an increased risk for osteoarthritis.

Diagnosis

Bone spurs can be diagnosed with X-rays, which can help your healthcare provider clearly see extra bone growths around the knee joints. 

Your provider will also do a physical exam of your knees to check your range of motion. They will ask you about your symptoms and medical history. Your provider may also want you to have CT scans or MRIs to look for any damaged ligaments and tendons in your knee.

Early diagnosis of knee osteoarthritis and any bone spurs that form from it is important for managing symptoms and preventing disease progression and further cartilage and joint damage.

Complications

If it is not treated, osteoarthritis can cause problems. As the disease progresses, it can get harder to stand and walk. 

If knee osteoarthritis is severe, a total knee replacement surgery can be done but it is usually a last resort. 

People with knee osteoarthritis and bone spurs often have pain when doing activities and movements that require bending and standing on the leg with the affected knee. 

Since they have so much discomfort, it’s common for people to avoid putting strain on the knee joint by compensating elsewhere in the body. 

When they do this, the supporting muscles of the hips and thighs can start to waste away (atrophy) and lose their strength, which limits balance and leg stability.

Similar to how bone spurs form, subchondral bone cells that are under the cartilage at the ends of the bones that make up the knee joint react to increased pressure from cartilage loss by producing more bone growth in an attempt to protect the joint. 

The damaged bone grows back thicker than it was before as the body tries to repair damage similar to thickened scar tissue that forms after an injury. 

The abnormal thickening of the bone is called subchondral bone sclerosis, and it increases the risk of more bone spurs.

Treatment

If a bone spur does not cause symptoms, no treatment is necessary. 

Bone spurs that cause pain, inflammation, swelling, stiffness, and decreased range of motion within a joint may need to be treated.  

If a bone spur breaks off from the bone within your knee, it becomes a loose body that can float in the joint space and limit your ability to move your knee comfortably.

Medication

There are a few medications that can help manage bone spur symptoms. 

Over-The-Counter Pain Relievers

Over-the-counter (OTC) pain-relieving medications such as acetaminophen (Tylenol) and ibuprofen (Advil) or anti-inflammatory medication like naproxen sodium (Aleve) can help reduce knee pain, swelling, and inflammation in the knee joint.

OTC creams and ointments—especially ones made with capsaicin (an extract derived from chili peppers)—can also be applied topically to the knee to relieve pain by decreasing the intensity of pain signals sent along nerve pathways. 

Topical pain medication is an alternative for people who cannot take pain medicine by mouth (for example, because they get gastrointestinal distress from them).

Prescription Medication 

If OTC medicine for pain does not help, your provider might be able to prescribe something stronger, such as an opioid painkiller.

Cortisone Shots

Cortisone is an anti-inflammatory medication that can be injected into the knee joint to reduce pain, swelling, and inflammation.

Cortisone injections are the most commonly used type of knee injections for treating knee pain from osteoarthritis.

The injections are done under local anesthesia. That means you will be awake to get the shot but your knee will be numbed. The medication usually starts to work in two to three days.

Cortisone can help relieve pain and reduce symptoms for six weeks to six months after the shot, but the injections are not effective for everyone. You will not be allowed to get more than two or three injections per year.

Physical Therapy

Physical therapy plays an important role in decreasing the symptoms of bone spurs and preventing the progression of cartilage loss in the knees. 

A physical therapist will look at your knee and hip alignment, muscle strength, range of motion, and movement patterns. They will use this information to come up with a treatment plan for you. 

Strengthening the muscles around the knees and hips helps to offload the knee joint and support your body weight so that less pressure is applied to the joint surfaces. This, in turn, can help make it less likely that bone spurs will form. 

Surgery

Knee arthroscopy is the most common type of surgical procedure to remove bone spurs and repair damaged cartilage in the knee joint.

During the procedure, a surgeon uses a tool about the width of a pencil with a camera and light attached (arthroscope), to look at the inside of your knee joint. 

The tool lets the surgeon can see the inside of the knee joint without making a large incision along the outside of the knee, which is done with open knee surgery.

Knee arthroscopy helps protect the knee joint from the risk of infection due to decreased exposure of the joint to the outside environment, and it often results in an improved cosmetic appearance of the knee by reducing the size of the surgical incisions and resulting scar formation. 

Since it only requires smaller incisions, knee arthroscopy also protects the surrounding knee structures, including skin, muscles, tendons, and ligaments, from being damaged.

If a person has severe osteoarthritis, knee arthroscopy is typically not helpful for long-term relief of pain.

Bone spurs can be surgically removed through other types of procedures as well, including microfracture surgery, autologous chondrocyte implantation, and osteochondral autograft transplantation.

A procedure called arthroscopic osteophyte excision is sometimes used to remove bone spurs through a small cut in the knee. However, it’s not clear how effective it is. 

Pain Management

Ongoing knee pain and disability from knee bone spurs caused by osteoarthritis and cartilage loss can be frustrating, but there are ways that you can help manage your pain. 

Maintaining healthy lifestyle habits to decrease inflammation and stress to the joints can make it easier to manage symptoms and prevent the worsening of bone and cartilage damage.

Here are some lifestyle changes to strive for:

• Get at least seven to eight hours of quality sleep every night
• Eat a balanced and nutritious diet
• Maintain a weight that supports your health
• Stay hydrated
• Find ways to manage stress
• Stay connected to others for social support
• Rest your knee joints to decrease pain and inflammation
• Limit high-impact and repetitive activities that stress the knee joint, such as running and jumping

Summary

Bone spurs in the knee are usually from osteoarthritis. The loss of cartilage in the knee joint that causes bone spurs to form can progress to irreversible damage to the knee joint bones. 

If you have severe knee pain, stiffness, and decreased range of motion and strength, talk to your provider. They can help you manage your symptoms and prevent more damage to your knee.