Knee Pain Causes and Treatments

What leads to knee pain?

To understand what might be causing your knee pain, it’s helpful to get a better understanding of the anatomy of our knees.

The knee is one of the largest, most complex joints in the body. It is made up of four bones: the femur, the tibia, the fibula, and the patella. The muscles that support the knee are the quadriceps in the front of the knee and the hamstrings in the back.

These structures are connected through an intricate network of ligaments and cartilage. The anterior cruciate ligament (ACL) prevents the femur from moving backwards onto the tibia, and the posterior cruciate ligament (PCL) prevents the femur from sliding forwards. There are two collateral ligaments, medial and lateral, that also help to provide support.

The meniscus (lateral and medial) is tissue that sits between the femur and the tibia, providing ease of movement between the two bones. There is also articular cartilage that sits behind the patella. Finally, the knee is surrounded by bursae, fluid-filled sacs that help to cushion the knee joint.

What’s causing my knee pain?

While the function of the knee is a minor miracle, the complexity of the joint opens it up to many different causes of knee pain. The main movement of the knee is bending (flexion) and straightening (extension). The knee is also capable of twisting, but not too far, which is what accounts for many traumatic injuries to the ligaments of the knee.

The top knee pain causes include:

• Dislocated kneecap
• Bursitis
• Degeneration
• Patellofemoral pain syndrome
• IT band syndrome
• Gout
• Loose tissue or bone
• Tendinitis and tendinosis
• Torn meniscus
• Torn ACL
• Rheumatoid arthritis

Dislocated kneecap

A dislocated kneecap is usually an acute traumatic sports injury that occurs when your patella slides out of place. Like other dislocations, it is possible to pop the patella back into place, but other treatments may be necessary if this is not successful.

Knee bursitis

Knee bursitis occurs when the fluid-filled sacs in the knee (bursae) that cushion and protect tendons and ligaments become inflamed.

Degeneration

Osteoarthritis is the most common cause of degeneration in the knee joint. This is a wear-and-tear condition that occurs over time and with repeated use. Osteoarthritis is the most common form of arthritis and can occur in any joint in the body.

Patellofemoral pain syndrome

Pain that persists in the front of the knee may be due to patellofemoral pain syndrome. This injury is also related to overuse, but develops from improper kneecap alignment or excess weight. Knee pain due to patellofemoral pain syndrome typically affects athletes, teenagers, and manual laborers.

With this syndrome, knee pain develops from deterioration in cartilage underneath the kneecap. The cartilage may wear down, soften, or become rougher.

Symptoms include pain from sitting, jumping, squatting, or descending stairs. The sensation of the knee giving out and not supporting the body’s weight is also associated with patellofemoral pain syndrome.

IT (iliotibial) band syndrome

The iliotibial band (IT band) runs along the outer thigh and helps stabilize the knee and hip. With iliotibial band syndrome (ITBS), the fibers that make up the band overdevelop and rub against the knee or hipbone, creating friction and inflammation. This frictions results in knee pain.

This knee injury typically develops from overuse, and is common in runners, cyclists, and other athletes who heavily stress their knees or whose sports require repetitive flexing and extending of the leg.

Symptoms of ITBS include pain or swelling on the outside of the knee or hipbone. People with this injury will feel pain when bending their leg at a 45-degree angle.

Gout

Gout occurs when a uric acid build-up occurs in the blood, usually in and around the joints. Most common in the big toe, it can also occur in the knee.

Loose tissue or bone

During the normal course of activity, or in a knee that has a history of traumatic injury, small bits of tissue or bone can break off and lodge painfully in the joint.

Tendinitis and tendinosis

The patellar tendon connects your quadriceps muscle to your shinbone. If this tendon becomes injured or inflamed from overuse it can become quite painful and lead to tendinitis.

Tendinosis is a condition similar to tendonitis in that it’s characterized by pain and limited mobility. While tendinitis results from acute micro-tears in the tendon from overuse, tendinosis results when overuse continues unabated without giving the tendon time to heal.

Although similar, the two conditions affect the tendon in different ways. Tendinitis is an inflammatory condition while tendinosis results from weakened collagen, which is part of the makeup of a tendon.

Torn ACL

One of the more common sources of knee pain, especially from sports, is a torn ACL. A torn ACL occurs most frequently in sports with sudden changes in direction (i.e., soccer or tennis).

The ACL runs from the back end of the femur to the front of the tibia. By preventing the shinbone from moving forward beyond the knee, the ACL provides about 90% of the knee’s stability, according to the Department of Orthopaedic Surgery at the University of California, San Francisco (UCSF). That’s why the signature popping noise that typically accompanies an ACL tear is sometimes joined by a quick hyperextension of the leg.

About 200,000 people tear their ACLs each year, most of them while playing sports. The injury frequently develops during sudden stops, quick accelerations, twisting, or jumping. About half of the time, reconstructive surgery is needed for a full repair. Also about half the time, people with torn ACLs report simultaneous injuries to other structures in the knee, including the meniscus, articular cartilage, or medial collateral ligament.

Torn meniscus

Another common sports injury is a torn meniscus, although the injury can also occur in older people during awkward movements. The knee contains two menisci. These pieces of cartilage are located between the tibia and the femur and act as shock absorbers to cushion the impact between the bones during movement. The meniscus also helps to stabilize the knee.

Several different types of tears can develop leading to knee pain. Longitudinal tears develop along the backside of the horseshoe-shaped structure. A bucket handle tear is one located in the inside curve, while a flap tear affects just a small piece inside the curve. A transverse tear breaks the meniscus in two, while a torn horn affects an end of the meniscus.

Like a torn ACL, these injuries are also frequently indicated by a popping noise along with knee pain at the tear site. Any sudden twisting in the knee can result in a tear.

Surgery is not always necessary to heal a torn meniscus, particularly depending on the location, according to the American Academy of Orthopaedic Surgeons (AAOS). The outside of the meniscus is fed by a large amount of blood, and tears in this location can sometimes heal on their own. Other times, surgery is needed.

Rheumatoid arthritis

An autoimmune disease, rheumatoid arthritis is a chronic, inflammatory disorder that can cause incredible pain in the knees and other joints.

What knee pain treatments can help me?

The most important aspect of treating knee pain is getting a proper diagnosis for the cause of your pain. An MRI looks at the soft tissues of the knee, and an X-ray is used to examine the health of the bones. Both of these tools, in conjunction with a physical examination and medical history, can help uncover the root cause of your knee pain.

Once a diagnosis is reached, there are several knee pain treatment options that can help reduce your pain and inflammation and restore mobility in this hard-working joint.

Ice

Icing an inflamed knee during the acute phases of knee pain can go a long way towards pain relief.

Exercise

You may not feel like moving when your knee pain flares up, but regular exercise goes a long way to keeping your joints healthy.

Try knee pain exercises that build strength and stability in the muscles surrounding the joint, or switch to low-impact full-body exercise like swimming or walking.

Physical therapy

Physical therapy, on its own or in conjunction with other treatments, can help to strengthen the muscles surrounding the knee joint, improving its stability and function.

Bracing and a change of shoes

For modest knee pain, sometimes all you need is a little support from time to time. Knee braces can support the joint while the inflammation subsides.

Sometimes a change of shoes can help, too, especially if you routinely choose fashion over function in your footwear. These days, there are more stylish options for shoes that help knee pain.

Gait analysis

Gait analysis examines the manner in which you are using your knees during normal activity (in this case, walking or running). This can determine if your knee pain stems from improper use or imbalance in the way you carry yourself.

If this is the case, physical therapy and exercises to correct your gait can be very helpful.

Supplements

Supplements like Orthovisc and Synvisc provide lubrication to the knee joint for patients with degenerative conditions such as osteoarthritis.

This adds more lubrication to the knee joint to increase fluid movement.

TENS therapy

TENS, or transcutaneous electrical nerve stimulation, is a non-invasive treatment approach with few to no side effects.

Patches that deliver a mild electrical current are placed on the skin in the area of pain. A patient-controlled device triggers a mild current that disrupts pain signals to the brain. The pain is replaced instead by a mild tingling sensation underneath the patches.

Medications

A variety of medications, both over-the-counter and by prescription, can be helpful in treating acute flare-ups of knee pain.

Anti-inflammatory medications (e.g., ibuprofen, naproxen sodium, Celebrex) are the mainstay of treatment for people with knee pain, but other types of medication may be helpful as well. Neuropathic medications (gabapentin, Lyrica) are beneficial for patients with neuropathic pain (i.e., burning, numbness, or “pins and needles”), and opioid medications are beneficial for people with acute knee injuries.

It is important to note that opioids are not recommended in the treatment of long-term, chronic knee pain.

Injections

There are several knee pain injections that may help if you’re suffering from more severe knee pain. The most common injection is a corticosteroid injection directly into your knee joint. This type of injection reduces inflammation and pain. These need to be repeated and do not necessarily halt any progressive disease or damage, but they do restore mobility to and function of the knee.

Nerve blocks

There are also several nerve blocks that may be beneficial. Nerve blocks prevent painful signals in the knee from reaching the brain.

The most common type of nerve block for knee pain is called a saphenous nerve block, which can provide relief to patients with many types of knee pain, including people who have undergone total knee replacement.

Genicular nerve blocks are also good for people with severe osteoarthritis who cannot have knee surgery.

Spinal cord stimulation (SCS)

If your pain does not respond to more conservative treatments, neuromodulation through spinal cord stimulation may help.

Spinal cord stimulation involves placing small electrodes within the epidural space of the spine. The theory behind spinal cord stimulation is that stimulation of the large nerve fibers will inhibit the small nerve fibers, thus blocking the sensation of pain.

Peripheral nerve stimulation (PNS)

Peripheral nerve stimulation (PNS) is very similar to spinal cord stimulation, but the electrodes are placed along the peripheral nerves, typically close to the area of pain. Under a local anesthetic and minimal sedation, your doctor will first place the trial leads into the peripheral space.

For both PNS and SCS, a trial stimulator is typically worn for five to seven days and connected to a stimulating device. If the trial successfully relieves your pain, you can opt for a permanent SCS/PNS device if desired.

Orthopedic surgery

If all other treatments are unsuccessful, a surgical referral may be necessary. Unless the cause of knee pain is a traumatic event that caused the injury, surgery is usually the treatment of last resort.

Knee pain can range from a minor annoyance to a debilitating condition. If you are suffering from either, Arizona Pain can help.

We can help you create a knee pain action plan that is a mix of prevention, treatment of acute pain, and management of chronic pain. Get in touch today for more information.

References

• Kim, Philip (2004). Advanced Pain Management Techniques: An Overview of Neurostimulation. Retrieved February 16, 2010 from: http://www.medscape.com/viewarticle/473431
• Tennent, TD, Birch, NC, and MJ Holmes (et al)(1998). Knee Pain and the Infrapatellar Branch of the Saphenous Nerve. Journal of the Royal Society of Medicine 1998;91:573-575.
• The Center for Orthopaedics & Sports Medicine (2003). Knee Joint- Anatomy and Function. Retrieved February 16, 2010 from: http://www.arthroscopy.com/sp05001.htm
• The Mayo Clinic (2008). Knee Pain. Retrieved February 16, 2010 from: http://www.mayoclinic.com/health/knee-pain/DS00555