Knee injections into the joint

Knee injections are not all the same. In this study my colleagues and I compared the efficacy of three different injections commonly administered into the knee joint.

We compared an anti-inflammatory steroid (triamcinolone), a lubricant (hyaluronic acid) and platelet-rich-plasma (blood derivative).

These injections are commonly used both for osteoarthritis and for inflammatory arthritis like rheumatoid arthritis. They are administered for mild or moderate degree arthritis.

Around the world steroids are the most commonly used of the two agents, and are given to relieve pain. If symptoms continue then the doctor may try hyaluronic acid or platelet-rich plasma (PRP), and their use is recently on the increasing.

What is triamcinolone?

Triamcinolone is one of many steroids that can be injected in the joint. Depomedrol is the second commonly used steroid.

What is hyaluronic acid?

Hyaluronic Acid (HA) is a very long chain of disaccharides (sugars) and these are present in all connective tissues. As we age, levels of hyaluronic acid fall - some say by as much as 50 percent. That is why supplementing with hyaluronic acid can help promote healthy joints. It is a major component of both cartilage and the synovial fluid that bathes these joints, binding to water to create a thick, gelatinous substance that lubricates and protects the cartilage.

What is platelet-rich plasma?

Platelet-rich plasma is a blood-derived product comprised of blood plasma enriched with platelets. PRP contains different growth products and chemicals called cytokines that facilitate cell growth and healing.

The study results

Intra-articular injections are commonly used in moderate knee OA to relieve pain. We undertook this prospective, comparative, randomized study to evaluate the short and mid-term results of steroids (triamcinolone hexacetonide) and hyaluronic acid (HA) in knee osteoarthritis. 40 patients in steroid and 42 patients in HA group were studied and the outcome was evaluated with Knee Society Score (KSS) and Visual Analog Scale (VAS). On KSS function and VAS score, there was no difference in tow groups, till four weeks. On KSS pain there was no difference till 12 weeks (P > 0.05) after that score of steroid group deteriorated rapidly. At six months HA was significantly better than a steroid.The present study demonstrated that both the THA and HA are safe and effective in relieving OA pain temporarily and are effective palliative agents and are not curative therapy. Steroid given IA can give pain relief for about 12 weeks while HA provides significant pain relief until six months after the injection.

Summary

We undertook this study as part of a programme to test the efficacy of these three different commonly used injections, in terms of their ability to control pain and the sustainability of their effect.

We found all three of these injections to be effective in controlling knee pain, but the effect of steroids wanes earliest and that of PRP lasts longer, with HA in between.

The injections can be repeated after every few months. But repeated use of steroids is not advisable.

Reference

Intra-articular hyaluronic acid is superior to steroids in knee osteoarthritis: A comparative, randomized study. Vaishya R, Pandit R, Agarwal AK, Vijay V. Journal of Clinical Orthpaedics and Trauma. Available online 30 September 2016