The condition often affects people aged 50 years and older, although it can also occur in younger people. According to the Arthritis Foundation, over 50 million people in the United States have arthritis.
Osteoarthritis (OA) is a chronic condition that causes the breakdown of cartilage between the joints. Cartilage serves as a cushion for joints and protects the surface of the bones. Without this cushion, bones can rub or grind together, causing pain, stiffness, and swelling.
If a patient continues to experience discomfort, swelling, or extensive joint damage, their doctor may suggest knee replacement or a knee injection.
Knee injection therapy
Doctors will typically recommend knee injection therapy before recommending surgery. There is a variety of different injections available. For some people, injections help to alleviate knee pain.
The following are knee injection therapy options:
Hyaluronic acid supplements, or viscosupplementation
Osteoarthritis can make everyday life and simple movement difficult.
These are also known as gel injections. During treatment, a substance called hyaluronic acid is injected directly into the knee joint to add to the quantities of this acid naturally present the body.
In functional joints, this fluid acts as a lubricant or shock absorber, helping the joints to work properly.
People with OA seem to experience a breakdown in hyaluronic acid. Hyaluronic acid injections can help to lessen joint pain as well as inflammation.
A small amount of joint fluid will be removed before the injection to make room for the hyaluronic fluid. Patients receive a single injection or weekly injections for 1 to 5 weeks depending on the product used. The supplement is available in solution or gel form.
Doctors may typically recommend knee injection therapy before recommending surgery. There is a range of different injections available. For some people, injections help to alleviate knee pain. However, according to the American College of Orthopedic Surgeons, this is not a recommended treatment because many people do not receive the desired benefit.
Side effects of knee injection therapy can include:
- skin irritation around the knee
- muscle pain
Patients should be aware of these possible side effects and report instances of these or any other problems to a doctor immediately. It may be necessary to discontinue the injection or try a different supplement.
Corticosteroid injections are among the most common knee injections. Doctors inject corticosteroids directly into the knee joint to help relieve knee pain and inflammation quickly.
They are a class of medications related to the steroid cortisone. They are routinely used to reduce inflammation. Corticosteroids mimic the effects of a substance called cortisol that is naturally produced by the adrenal glands.
In high doses, corticosteroids can reduce inflammation. They also effect the immune system. This can be helpful for controlling conditions in which the immune system mistakenly attacks its own tissues, such as rheumatoid arthritis.
The corticosteroid is absorbed into the bloodstream quickly and travels to the inflammation site. Injection therapy provides rapid relief to the inflamed area and is more powerful than traditional oral anti-inflammatory medications.
In addition to providing quick relief, the injection does not cause many of the side effects that oral corticosteroid medications do.
Doctors can administer the injection in their office. They may numb the knee area before injecting the corticosteroid drug directly into the joint. Some people feel almost immediate relief, while others feel the effects several days later.
Depending on the condition of the knee, the benefits can last from a few days to more than 6 months. Factors that play a role in how long the effects of the steroid injection will last such as the extent of inflammation and overall health. It is important to note that the effects of the shot are temporary.
Additional cortisone injections may be necessary.
Many people have no adverse effects after a steroid injection besides a little pain or tingling where the injection was made. However, corticosteroids can cause dangerous side effects for some people, especially when taken too often.
Side effects include:
- the death of nearby bone, known as osteonecrosis
- joint infection
- nerve damage
- thinning of the skin and soft tissue around the injection site
- a temporary flare of pain and inflammation in the joint
- the thinning of nearby bone, known as osteoporosis
- whitening or lightening of the skin around the injection site
- diabetic patients can experience elevated blood sugar
- allergic reaction
Exposure to high levels of cortisol over a prolonged period of time increases the risk of developing hypercortisolism or Cushing's syndrome.
These effects include:
- upper body obesity
- a round-shaped face
- increased bruising
- trouble healing
- weak bones
- excessive hair growth
- irregular menstrual periods in women
- fertility problems in men
This side effect is treated by gradually reducing the amount of cortisone used or adjusting dosage.
Platelet-rich plasma (PRP) injections
PRP injections are a possible future treatment for osteoarthritis.
PRP makes use of the healing and regrowth capabilities of platelets in the blood. These are dispatched by the immune system whenever wounds or injuries occur to clot the wound and trigger the healing process.
This injection involves taking blood from the patient and separating the plasma from the other blood cells. The concentration of platelets is then increased to between 5 and 10 times more than is naturally found in the blood. The platelets are then recombined with the blood and injected back into the patient.
Doctors can administer PRP injections straight into the affected tissue. At present, PRP is only used for knee injections on an experimental basis.
Stem cell injections
Stem cell injections are another potentially promising treatment for knee arthritis that could prevent the need for a knee replacement.
A stem cell is one that can be grown into a specific type of tissue or organ. In injection form, these are withdrawn from the bone marrow alongside cartilage tissue and injected back into the affected area.
It is not currently known whether stem cell injections will cure osteoarthritis or simply delay the need for a knee replacement.
Knee replacement therapy
Though corticosteroid and hyaluronic acid supplements can control pain and inflammation efficiently, they often provide only temporary relief. As OA progresses, mobility and quality of life may get worse, leaving a knee replacement as the only option.
A knee replacement is also referred to as knee arthroplasty or knee resurfacing, because only the surface of the bones is replaced. The surgeon will cut away damaged bone and cartilage from the shinbone and kneecap, and then replace it with an artificial joint.
During a total knee replacement, the damaged knee joint is removed and replaced with a prosthesis made out of metal, ceramic, or high-grade plastic, as well as polymer components.
Knee replacement surgery is a last resort for osteoarthitis.
There are four basic steps:
- Preparing the bone: The cartilage surfaces that are found at the end of the femur and tibia are removed along with a small amount of underlying bone.
- Positioning the metal implants: The removed cartilage and bone are then replaced with metal components to recreate the surface of the joint. The metal parts are either cemented or "fit" into the bone.
- Resurfacing the patella: The undersurface of the patella, or kneecap, may be cut and resurfaced with a plastic button.
- Inserting a spacer: The surgeon inserts a medical-grade plastic between the metal components to create a smooth gliding surface, making walking easier and smoother.
Before the procedure, patients will work alongside doctors to design their artificial knee. A range of factors is taken into account, such as age, weight, activity levels, and overall health.
Delaying your surgery
There are risks associated with delaying knee replacement surgery. The main risks are further deterioration of the joint, increased pain, and reduced mobility.
Other risk factors include:
- a risk of deformities developing inside and outside the joint
- a risk of muscles, ligaments, and other structures becoming weak and losing function
- increased pain or an inability to manage pain
- increased disability or lack of mobility
- difficulty with normal daily activities
The doctor will thoroughly explain the procedure and allow the patient to ask questions as needed. They will record a medical history, including any medications or supplements currently being taken, also taking allergies and previous health problems into account.
The doctor will give the individual general anesthesia before the surgery, making them completely unconscious. Patients often begin physical therapy to get the new joint moving during a short hospital stay. Rehabilitation continues after leaving the hospital. This can help regain strength and range of motion.
Knee replacement risks
Though knee replacement surgery often goes smoothly, any surgery comes with risks.
If surgery is postponed for too long, other risks may arise. Deformities may develop that complicate the knee replacement procedure. Surgery may take longer, and knee replacement options may be limited.
Learn more about the causes of severe knee pain here.