A common ailment within the adult population is knee joint pain. People are aware of knee pain seen in athletes due to sports injuries or blunt force trauma. These injuries often require an operative intervention.
Another cause is osteoarthritis (OA), a common form of arthritis that is due to degenerative wear and tear. As the cartilage wears away, particularly in those over 65 years of age, the debilitation can be catastrophic.
Knee anatomy: many possible sources of trouble
The knee joint is where three bones meet, specifically the femur (thighbone), the tibia (shinbone), and the patella (kneecap). The ends of each of the bones are covered in a cushion, known as articular cartilage or meniscus. This joint is held together with ligaments, tendons and the musculature that surrounds the knee.
Commonly in sports-related knee injuries, one will hear of damage to any of the four ligaments that stabilize the knee:
- Medial collateral ligament (MCL)
- Lateral collateral ligament (LCL)
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
Injury to any of the ligaments is graded from one to three for severity of injury. Issues with the three bones, any of the cartilage-covered surfaces (meniscus), the tendons, or the ligaments may cause pain.
Between the tibia and femur bone are two crescent-shaped pads of cartilage that exist to reduce friction and disperse the weight of the body across the joint. They are known as the “lateral meniscus,” which is situated at the outside of the knee; and the “medial meniscus,” which is situated on the inside of the knee.
Two groups of muscles support the knee: hamstrings, which are muscles on the back of the thigh running from the hip to just below the knee and work to bend the knee; and quadriceps, which are four muscles on the front of the thigh that run from the hip to the knee and straighten the knee from a bent position.
Pain may also be due to inflammation, stress, or mechanical issues to any of the structures described above. Mechanical issues, such as loose bodies within the joint, Ilio-tibial band issues, or a dislocated knee cap (patella) may also be the culprit for knee dysfunction.
Lastly, arthritis or inflammation of the bony surfaces may be due to rheumatoid arthritis (RA), septic arthritis, or OA. A condition known as gout or pseudogout may also exist but isn’t as prevalent.
Treatments
Fortunately, the most common cause of knee pain, OA, can be relieved with self-management, pharmaceuticals, and non-pharmaceutical treatments. Scientific studies have looked at what interventions improve function and pain when OA is the cause of dysfunction.
Oral intake of acetaminophen (Tylenol) and non-steroidals (Motrin, Aleve) are recommended, with either class of the medications being the initial treatment. Tylenol has less side effects and may have the same benefit as NSAIDS for pain relief.
There is controversy over the use of glucosamine or chondroitin sulfate for the treatment of patients with OA.One should discuss their use with a medical professional prior to use.
Weight loss and aerobic exercise have been shown to be among the most effectiveways to improve long-term function in active patients who have inflammation in the knee due to primary knee osteoarthritis (OA). One can also strengthen muscles around the knee, further aiding function and pain relief.
Injections into the joint, known as intra-articular injections, can also be an option. Corticosteroids are commonly injected, but hyaluronic acid can also be effective. Many randomized controlled studies have demonstrated a longer-term effect in pain control with hyaluronic acid injections compared with corticosteroids. The injections seem to decrease inflammation and helps assist the joint in gliding.
Meditation, stress reduction, exercise, positive attitude, medications and weight reduction all can lead to improved function. Self-directed individual actions including aquatics, yoga, quadriceps muscle strengthening, range of motion exercises, and cycling can all be effective in decreasing knee pain due to OA.
Acupuncture, osteopathic manipulation, intra-articular injections, massage therapy, psychotherapy, and nutrition changes have also been shown to be useful. Knee replacement (knee arthroplasty) isn’t the only course of action when one has knee pain, but it may be considered if there is no improvement after six months of non-operative treatments.
Sean J. Ennevor M.D. graduated with a B.A.S. in biology and economics from Stanford University, and as a Dean’s Scholar from UCLA School of Medicine, where he received his MD. He completed his medical residency and fellowship in anesthesiology at Yale University, where he was chief resident and on staff. He practiced medicine in the Twin Cities for over 14 years and presently serves as an advisor and investor for medical technology companies throughout the country.