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Combating arthritis: The word on knee injections

Penn State

Characterized by painful inflammation and stiffness of the joints, arthritis is an affliction that ails many. As weight-bearing joints, the knees are particularly prone to the most common form of arthritis, osteoarthritis. In an effort to find relief, some may consider surgery and medication. For others, corticosteroid injections in the knee have become an effective means to combat their osteoarthritis.

To find out more about these knee injections and their effectiveness, “Take Care” spoke with Dr. Robert Shmerling, associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center.

Osteoarthritis, Shmerling explains, is highly associated with aging and the degeneration of cartilage lining the joints. This cartilage, along with naturally occurring hyaluronic acid, is what allows joints to move smoothly through their range of motion. Osteoarthritis can occur in any joint, but due to the stress we put on our knees throughout our lifetime, as well as the genetic inheritance factor, knee joints are frequently those affected.

Through an analysis of the patient’s history, their symptoms, a physical examination, and regular x-rays, doctors can confirm an arthritis diagnosis. Once the diagnosis has been verified, there are a few options to consider moving forward.

The first step, says Shmerling, is typically to offer pain relievers or mild anti-inflammatory medications like acetaminophen or ibuprofen. Osteoarthritis is less of an inflammatory issue than rheumatoid arthritis, for example, but the anti-inflammatory properties of medicines like Tylenol or Advil can still offer some relief.

Monitored exercise is also an option, as is physical therapy, and additionally, the application of heat or cold to the affected area can help as well, Shmerling says. And if none of those are effective? That is when injections are considered. They are not the first line of defense, explains Shmerling, and are typically reserved for those who haven’t found relief with the aforementioned options.

To combat the inflammation, the medication itself is a corticosteroid, which acts as a powerful anti-inflammatory when injected in the affected knee. Unlike other treatment options, says Shmerling, injections can provide fast relief, especially when the corticosteroid is combined with Novocain. The Novocain provides fast temporary relief, while the effects of the corticosteroid can be distinguished within 24 to 48 hours, he says.  

And post-injection, the duration of benefit is variable from patient to patient. Relief can last from weeks to months. In fact, Shmerling recalls, he has seen patients who didn’t need another injection for up to a year. However, in osteoarthritis of the knees, the duration of injections is typically in the order of weeks or months.

It’s important to remember that injections aren’t a cure, Shmerling notes, and are only meant to provide temporary relief. The rule of thumb for frequency is typically three to four per year. In fact, having too many injections is not wise due to the risk of infection in the injection site, as well as the possibility of damaging structures within the knee from exposure to the cortisone. This combination of risks means limiting injection frequency, although no one knows what the ideal interval is, Shmerling says.

Another injection option involves a synthetic hyaluronic acid. In osteoarthritis, the thickness of the naturally occurring hyaluronic acid in the joint becomes less lubricative, so through injection of a synthetic form, the joint gets some of that lubrication back, as well as some mild anti-inflammatory effects.

And if none of these methods work, the final option is surgery, Shmerling says. This decision is based on a host of factors, including the patient’s pain and quality of life, joint function, and x-ray analysis. There isn’t always a distinct moment when surgery becomes a must, he explains, so it often has to do with the effectiveness of previous treatment methods like injections, as well as how the individual is coping with their arthritis.

And like so many medical treatments, the responses to injections are varied. In fact, Shmerling adds, the overall effectiveness has been brought into question in numerous studies, with no clear conclusion on how long they can delay an inevitable surgery. But Shmerling says injections are worth a try for patients who are considering surgery but may not be an ideal candidate. While they aren’t a cure for arthritis, for those seeking relief, knee injections are a worthwhile option to consider to ease the effects of osteoarthritis.