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 a collection 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. The knee is surrounded by bursae, fluid filled sacs which help to cushion the knee joint.

Types of Knee Pain

The main movement of the knee is bending and straightening. Because the knee is, also, capable of twisting, many traumatic injuries to the ligaments can occur. Some symptoms of this type of injury include a “popping” sound, immediate inability to bear weight on the affected limb, or the sense of the knee “giving way.” These types of injuries, sometimes, require surgical repair. Twisting can cause injury to the tendons or the meniscus as well. Both of types of injuries can cause pain, swelling, and difficulty straightening the leg.

Another main cause of knee pain is degeneration. This is called “osteoarthritis”, and it is the “wear and tear” of the cartilage of the knee, which degenerates as we age. When the condition becomes severe, there is no more (or very little) cartilage left between the knee bones, and this can cause significant pain. Chondromalacia patella is also a type of degeneration, and it means that there is damage to the cartilage beneath the kneecap.

Treatment

Establishing a correct diagnosis for knee pain is the first, and most important, aspect of treating knee pain. An MRI is usually used to make this determination. Also, there are several injections that may help knee pain. One of the most common is a corticosteroid, which is injected directly into the knee joint. This type of injection reduces inflammation and pain. Viscosupplementation (Orthovisc, Synvisc) provides lubrication to the knee joint for persons with degenerative conditions such as osteoarthritis. There are several nerve blocks that may be beneficial as well.

The most common type of nerve block for knee pain is called a saphenous nerve block. A saphenous block provides relief for many types of knee pain, including the pain that sometimes accompanies total knee replacement. Other treatments for knee pain are – chiropractic therapy, gait analysis, bracing, and TENS unit application. Physical therapy can, also, help to strengthen the muscles surrounding the knee joint, improving its stability. Icing the knee can help decrease pain and swelling, as well, and anti-inflammatory medications (ibuprofen, naproxen sodium, Celebrex) are helpful mainstays of treatment for people with knee pain. However, other types of medication may be helpful as well.

Neuropathic medications (gabapentin, Lyrica) are beneficial for persons that have neuropathic pain (burning, numbness, ‘pins and needles’), and opioid medications (hydrocodone, oxycodone) are beneficial for people with acute knee injuries. If a person is experiencing an acute-type injury of the knee, an orthopedic surgery referral is may be immediately made by a primary physician.

If the patient does not respond to more conservative treatments, neuromodulation through spinal cord stimulation may be a consideration. Spinal cord stimulation involves placing a small electrode within the epidural space of the spine. The stimulation of the large nerve fibers will inhibit the small nerve fibers, blocking the sensation of pain. Peripheral nerve stimulation (PNS) is very similar, but the electrodes are placed along the peripheral nerves instead, typically close to the area of pain. Both are completed under a local anesthetic and minimal sedation. The trial stimulator is typically worn for 5-7 days and connected to a stimulating device. If the trial successfully relieves your pain, it may be beneficial to undergo a permanent SCS/PNS.

Knee pain can be quite disabling. Arkansas Pain provides a comprehensive and multidisciplinary approach to your pain. If you suffer from chronic knee pain, please call us to schedule an appointment today!

References:

• Knee Pain– PainDoctor.com

• Kim, Philip (2004). Advanced Pain Management Techniques: An Overview of Neurostimulation. Retrieved February 16, 2010 from: 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: The Mayo Clinic (2008).

• Knee Pain. Retrieved February 16, 2010 from: