Injection treatments for Knee Osteoarthritis
●Hyaluronic acid Injection
●Platelet rich Plasma Injection
●Stem cell Injection
Osteoarthritis in the joint has the following components:
●Biomechanical changes- Alignment and Kinetic chain
●Secondary changes- Synovitis, Bone edema
●Peripheral and Central Sensitization
Intra-articular injections don’t address all the components of OA but are useful in combination with other treatments especially in the cases which are resistant to other standard treatments.
(Betamethasone, Methylprednisolone, Triamcinolone)
Corticosteroids are strong anti-inflammatory medications. They are useful on a short-term basis if there is synovitis associated with Osteoarthritis.
In a Cochrane review, 28 randomised controlled trials (RCTs) comparing all types of IA corticosteroids used for OA in the knees of humans to all other treatments found that the IA corticosteroids were more effective than placebo on pain reduction and global patient assessment at 1 week post-injection, with some evidence that this response continued for the first 2–3 weeks post-injection. There is almost no evidence to suggest that the effect on pain reduction was sustained for a longer term (at 4–24 weeks post-injection).
IA corticosteroids had a quicker onset of action than other products but had a shorter duration of benefit. The review supported the use of IA corticosteroids as a short-term option in the treatment of OA of the knee, especially for patients with obvious signs of inflammation and significant pain.
HYALURONIC ACID INJECTIONS
(Durolane, Synvisc, Euflexxa, Monovisc)
Hyaluronic acid (HA) is a component of Synovial fluid which is normally present in the knee. It is hypothesised that in Osteoarthritis there is loss of viscosity of the synovial fluid. The proposed benefits of Hyaluronic acid injections in Osteoarthritis are:
●Increased viscoelastic properties of the native Synovial fluids
●Protection against cartilage erosion
●Enhancement in the production of native hyaluronic acid in the synovial fluid,
●Direct or indirect analgesic effect
In a Cochrane review, 76 RCTs were reviewed comparing HA products to any other treatment for knee OA. There are different HA products with various class differences. There were statistically significant differences in the reduction of knee joint pain and improved joint function between HA products and placebo at 1–4 weeks, with a larger effect at 5–13 weeks post-injection. HA injections have long term benefits as compared to corticosteroids. The safety and efficacy profile of HA injection is high.
PLATELET RICH PLASMA INJECTIONS (PRP)
PRP is the fluid containing centrifuged and concentrated platelets extracted from the patient’s own blood. The treatment provides high concentration of autologous growth factors and bioactive molecules in physiologic proportions, with low costs and in a minimally invasive way. There is increasing evidence of benefits of PRP in osteoarthritis with their analgesic and anti-inflammatory role.
There is no convincing evidence for the role of PRP in regrowing of the cartilage loss in the joints. But it slows down the apoptosis (cell death) cascade of the cartilage. The chemo-attractant activity of PRP may contribute to the recruitment of other cells/factors that might migrate into the damaged tissues, thus triggering the healing response. Some studies do present some conflicting evidence for their efficacy. PRP might not change the clinical history with significant disease-modifying properties, but it still might offer a clinical benefit with symptoms and function improvement and possibly a slowdown of the degenerative processes. In terms of safety, no major adverse effects are reported with PRP injections.
STEM CELL INJECTIONS
Stem cells are the primitive cells which have a potential to differentiate into specialised cells as cartilage or bone. While animal studies suggest that MSCs may enhance recovery from certain injuries, findings from clinical trials in humans are yet to provide sound evidence of benefit. Although there is no evidence from research undertaken to date that Mesenchymal Stem Cells (MSC) caused serious complications, long-term safety can’t be assured. Australasian College of Sports and Exercise Medicine in their position statement on the role of MSC’s advise the use of stem cells only for research associated treatment and not for commercial use of the stem cells. Many trials are currently being done but are at very early stages of investigation.
1. Osteoarthritis management of the knee. Reprinted from Australian Family Physician. 2007; 36, (9): 217-218
2. Filardo G, Kon E, Roffi A et al. Platelet-rich plasma: why intra-articular? A systematic review of preclinical studies and clinical evidence on PRP for joint degeneration. Knee Surg Sports Traumatol Arthrosc. 2015;23(9):2459‐2474. doi: 10.1007/s00167-013-2743-1
3. Australian Rheumatology Association. (2014). Position Statement on Stem Cell Therapies. Accessed from https://rheumatology.org.au
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