Approximately 33% of Americans, aged 45 years or older, complain of knee pain. Knee pain and back pain are the most common musculoskeletal complaints which result in people visiting their physicians.
Injuries and medical conditions can cause knee pain. Preventative measures can reduce the risk of injury or disease.
Knees are joints which allow bending, straightening, twisting and rotating. As a result, they are vulnerable to more injuries than other joints in the body which are not as flexible.
The knee joint comprises four bones held together by ligaments. The top part of the joint comprises the thigh bone (femur). The lower part of the joint consists of two bones called the tibia and the fibula. The patella is the fourth bone which slides in a groove on the end of the femur.
Bands of tissue which connect bones to one another are called ligaments. The femur and tibia are held together by four ligaments. The collateral ligaments are along the inner (medial) and outer (lateral) sides of the knee. Two other ligaments are the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) which provide front and back and rotational stability to the knee.
Tendons are fibrous bands of tissue which connect muscles to bones. The quadriceps tendon connects the quadriceps muscle on the front of the thigh to the patella, and the patellar tendon connects the patella to the tibia. These two tendons allow straightening of the leg.
The meniscus is on the inside and outside of the knee and provides cushioning to the knee.
Fluid-filled sacs which surround the knee are called bursae. Bursae allow ligaments and tendons to slide across the knee joint smoothly.
The above-described structures normally work together smoothly. Injuries and disease can cause pain and decreased function.
Causes and Management of Knee Pain
Knee pain can arise from the knee itself or arise from conditions of the hip and lower back. Knee pain is immediate (acute) or chronic (greater than six months). Acute knee pain is usually the result of injury or infection. Chronic knee pain is usually the result of injury, inflammation or infection. An example of inflammation is arthritis.
Chronic Knee Pain
- Arthritis is defined as an inflammatory disorder of the knee joint. Causes include
- Osteoarthritis: This is the most common type of arthritis and occurs when the cartilage in your knee deteriorates with use and age. Severe cases will result in the menisci (cartilage) being completely worn away with resultant rubbing of the femur on the tibia. Swelling, stiffness, creaking or popping sounds and pain, especially with standing or walking, occurs. Pain control may be achieved with acetaminophen (Tylenol) and with anti-inflammatory medications (NSAIDS), both over the counter and by prescription – examples of nonsteroidal anti-inflammatory medications are Advil, Motrin, aspirin, Aleve, and Naprosyn. Discuss the side effects of NSAIDs and steroids with your doctor. NSAIDs should be avoided if you have ulcers, gastritis or kidney disease. Weight loss, physical therapy, Bionicare, injections of hyaluronic acid and regenerative pain management may also be beneficial. Regenerative pain management includes dextrose prolotherapy, platelet rich plasma prolotherapy and stem cell prolotherapy. Severe cases may require knee joint replacement.
- Rheumatoid Arthritis: This is the most debilitating of all the types of arthritis and can affect any joint in one’s body. Swelling, stiffness, decreased range of motion, deformities of the joints, pain, weakness and low-grade fever may occur. Periods of flare-ups often alternate with periods of remission. Treatment includes anti-inflammatory medications, pain medications, and immunosuppressants.
- Crystalline Arthritis (Gout and Pseudogout): Both forms of arthritis are caused by sharp crystals which form in the knees and other joints. Abnormalities in the absorption or metabolism of substances such as uric acid (gout) and calcium pyrophosphate (pseudogout) can cause these two forms of arthritis. Swelling, redness, and pain occur with gout. These episodes last for approximately five to ten days and then resolve over one to two weeks. They commonly recur. Swelling, severe pain and inflammation and enlarged joints, especially the knees, occur with pseudo-gout. Anti-inflammatory medications and medications which assist in the metabolism of the above-described chemicals are the treatments for these two forms of arthritis.
- Bursitis occurs when the bursae of the knee become inflamed because of trauma, crystalline deposits or infection. Acute or chronic injuries cause inflammation in the bursae resulting in the inability of tendons and ligaments to glide smoothly over the knee joint. Symptoms include pain, swelling, redness, warmth, and fever. Treatment includes elevation, compression, ice, rest, non-steroidal inflammatory medications (NSAIDS) and, occasionally, steroid injections.
- Infection (Septic Arthritis): Swelling, redness, and pain occur when the knee joint becomes infected. Fever commonly occurs. Antibiotic therapy is begun, and your doctor may perform aspiration of the knee joint (fluid removal). Besides decreasing pain, fluid removal allows your doctor to identify the organism causing the infection. In severe cases, surgical drainage is required.
- Patellofemoral Syndrome or Chondromalacia Patella: These conditions refer to pain which originates between the patella and the thigh bone (femur). This is more common in those with misaligned kneecaps, athletes and older adults with arthritis of the kneecap. A grinding and grating sensation is common with extension of the knee. Symptoms include tenderness and pain in the frontal aspect of the knee which worsens when climbing up or down stairs, getting up from a chair and sitting for lengthy periods. Treatment includes compression, ice, elevation, rest, NSAIDs and physical therapy. Occasionally, orthotic supports for foot abnormalities may decrease stress on the knee.
- Iliotibial Band Syndrome: When the ligament which extends from the outside of one’s pelvic bone to the outside of one’s tibia becomes tight, this can cause it to rub against the outer portion of the femur. This is common in long-distance runners. Pain may occur on the outside of the knee in the outer portion of the femur (lateral femoral epicondyle). Rest, compression, ice, elevation, NSAIDs and stretching the iliotibial band are treatments.
- Osgood-Schlatter Disease: This is common in athletic teens due to overuse. Pain is common with jumping and running. Tenderness just below the kneecap (tibial tubercle) is common as is swelling. Treatment includes compression, ice, rest, elevation and NSAID therapy. When the tibial tubercle ceases to grow at the end of adolescence, symptoms usually resolve.
- Jumper's Knee: This describes tendonitis (inflammation of the tendon) of the quadriceps tendon or patellar tendon. This is more common in jumping sports such as basketball and volleyball. Symptoms are worse when jumping and landing. Treatment involves ice, compression, elevation, rest and NSAIDs and physical therapy.
Acute Knee Pain
- Fractures (Broken Bones): Fractures are usually caused by traumatic events such as motor vehicle accidents or athletic activities. Swelling, tenderness, bruising and pain occur. It is not uncommon for a person to not be able to place weight on the knee. Fractures must be examined by a doctor immediately. Evaluation will include x-ray. Treatment included casting, splinting or surgery. There are usually no long-term complications. However, occasionally, arteries and nerves can be injured, and arthritis may develop because of the fracture.
- Sprained and Torn Collateral Ligaments: A partially ruptured ligament is a sprain, and a completely ruptured ligament is a tear. Medial collateral ligament (MCL) sprains and tears are more common than lateral collateral ligament (LCL) sprains and tears. Injuries during skiing and contact sports are common causes of sprains and tears of the MCL and LCL. After performing a history and physical examination, your doctor may order an x-ray, MRI or arthroscopy. Tears often, but not always, require surgery. Sprains can be treated with anti-inflammatories, elevation, ice, compression and physical therapy.
- Sprained and Torn Cruciate Ligaments: Anterior cruciate ligament (ACL) injuries are more common than posterior cruciate ligament (PCL) injuries because the PCL is stronger. Anterior cruciate ligament (ACL) injuries are common sports injuries caused by trauma, sudden twisting, and sudden stopping. Strong forces to the front of the knee can cause PCL injuries. A popping sound may be heard with an ACL tear. Pain, instability, and swelling commonly occur. Middle-aged and older patients who demand little from their knees may be treated with conservative treatment, including knee braces. Surgery is recommended for younger patients and athletes who require higher functionality.
- Tendon Rupture: Complete or partial rupture of the quadriceps and patellar tendons may occur. Complete ruptures result in an inability to extend the knee. Partial ruptures result in pain with extension of the knee. Partial ruptures may be treated with a splint, and complete ruptures usually require surgical repair.
- Injuries to the Meniscus: Overuse and trauma can cause injuries to the meniscus. An injury to the meniscus may cause a piece tearing off and floating in the knee joint. Symptoms include locking or clicking of the knee. Swelling usually occurs as well. If conservative therapy fails, then arthroscopic repair is indicated.
- Knee Dislocation: This is a rare injury which may cause the loss of the limb if not treated emergently. The reason for the severity of this injury is that not only are ligaments stretched, but arteries and nerves as well. The pain is generally severe, and a deformity of the knee is noted. Once the knee dislocation is put back in place, further evaluation is necessary to make sure no nerve or arterial injury has occurred. Nerve and arterial injuries require immediate surgery.
- Dislocated Knee Cap (Patella): This injury is more common in women and obese people. Your kneecap is likely to move excessively from side to side. Pain, swelling, difficulty straightening your knee and difficulty walking occurs. Your doctor will pop the patella back into place and order an x-ray to rule out a fracture. A knee splint will be in place for at least three weeks to allow the soft tissues around the patella to heal.
Steps to Decrease Knee Injury
- Avoid excess weight. This can decrease stress on the knee joints and slow down the onset of osteoarthritis.
- Avoid Overuse. Repetitive activity can lead to excessive loading stress on the knee joint. Repetitive activity leads to an inflammatory response which damages tissue.
- Maintain Muscle Strength and Flexibility: Discuss exercises, which can strengthen the muscles, tendons, and ligaments of your knee joint with your doctor and/or physical therapist. Stretching exercises should be discussed as well. Weak or tight muscles result in less support for one’s knees. Stretching and strengthening can also decrease and prevent knee pain.
- Be Aware of Mechanical Problems: Flat feet, misaligned knees, and having one leg shorter than the other are mechanical problems which can increase the risk of knee injury. Occasionally, orthotics may be helpful, and this should be discussed with your doctor.
- Avoid High-Risk Activities: Skiing, skateboarding, and intensive running are examples of activities which place greater stress on one’s knees.
- Knee Protection: Knee pads should be used when performing jobs which require one’s knees to be on the ground for long periods of time. Examples include housekeepers, carpet layers, and plumbers. High-risk sporting activities such as volleyball also necessitate the use of knee pads. Using a seatbelt will lessen the probability of one’s knees striking the dashboard during motor vehicle accidents.
- Prior Knee Injuries: Unfortunately, a prior knee injury increases the likelihood that the knee can be injured again. Aside from strengthening and stretching, consider exercises which lessen the stress on one’s knee joints – such as swimming.
- Self-Care: When an injury occurs, chemicals causing inflammation are produced in the knee, further injuring tissue. These techniques can decrease inflammation:
- Rest the knee: This can prevent further injury and allow the injured tissue to heal.
- Protect the knee: Wearing knee pads can prevent further injury in those persons resting on their knees a lot. Knee braces and crutches can provide joint support with weight bearing.
- Ice: Pain and inflammation are decreased with ice. This can be accomplished by applying ice to the injured knee three times a day for approximately fifteen minutes. Use a barrier between the ice and the skin to prevent burns.
- Elevate the knee: Elevating the knee above heart level can decrease swelling because of gravity.
- Compression: A compression bandage can decrease fluid build-up (edema). The compression bandage should be not too tight and should not interfere with circulation.
- Non-steroidal inflammatory drugs (NSAIDS): These medications can also decrease pain. Examples are Aleve, Naprosyn, Motrin, Advil, ibuprofen, etc. These drugs should be taken with food and should be avoided if you have kidney problems, stomach ulcers or gastritis.
Failure of Self-Care Techniques
If your symptoms have not resolved after trying the self-care techniques for seven days, schedule an appointment with your doctor. If you cannot stand or walk on your knee, have large wounds or have a fever with drainage, you should immediately go to the nearest emergency room to be evaluated by a doctor. Your doctor will obtain a history and perform a physical examination. He or she may ask
- “When did your symptoms begin?”
- “What is your pain scale from zero to ten?”
- “Do your symptoms come and go, or are they continuous?”
- “What improves your symptoms?”
- “What worsens your symptoms?”
- “Does your knee click, lock or pop?”
- “Does your knee feel unstable?”
- “Have you injured your knee in the past?”
- “Do you have pain in any other areas?”
During the physical examination, your doctor may check for pain, swelling, bruising, warmth and tenderness. He or she may check your range of motion, perform maneuvers to detect injuries to the tendons, ligaments, menisci, etc. Your doctor may order these tests:
- Magnetic resonance imaging (MRI): This can aid in the diagnosis, especially when movement of the knee is restricted by contracted muscles and/or swelling.
- X-ray: Osteoarthritis and fractures can be detected with an x-ray.
- Computerized tomography (CT) scan: Loose bodies and bone problems can be detected.
The following may be performed or recommended:
- Fluid removal: If crystalline arthritis (gout or pseudo-gout) or infection is suspected, the physician may remove fluid from your knees with a needle, for analysis.
- Blood tests: These blood tests can detect signs of infection or medical diseases such as rheumatoid arthritis, autoimmune diseases, and diabetes.
- Knee brace or arch supports: Knee braces may provide support to the knee joint, and arch supports can shift pressure away from the side of the knee most affected by osteoarthritis.
- Regenerative pain management: This includes dextrose prolotherapy, platelet rich plasma prolotherapy and stem cell prolotherapy.
- Corticosteroid injection: Injecting this drug into the knee joint can decrease inflammation, swelling, and pain. Although not common, complications include elevated blood sugar levels, water retention, and infection.
- Hyaluronic injection: Injecting this drug into the knee joint provides lubrication and can decrease pain.
- Topical drugs: These include Lidocaine patches and non-steroidal inflammatory drug patches or gels.
- Acupuncture: A study at the NIH demonstrated the therapeutic efficacy of acupuncture for knee osteoarthritis.
- Cold laser therapy.
- Glucosamine and chondroitin: These substances seem more effective for people with moderate to severe osteoarthritis.
- Arthroscopy: This involves placing a fiber-optic camera within the knee joint to detect loose bodies and to determine whether cartilage or menisci have been damaged. The fiber-optic camera (arthroscope) can remove loose bodies and shave down torn cartilage in the knee.
- Orthopedic consultation to consider partial or a total knee replacement: Candidates include those with severely arthritic knees, greater than 60 years of age, who suffer from moderate to severe knee pain and decreased mobility and functionality.
Jose Veliz MD is the medical director of Palomar Spine & Pain, in Escondido, CA (North San Diego County).