The Efficacy of Intra-articular Triamcinolone Acetonide 5mg vs. 10 mg vs. 40 mg in Patients With Knee Osteoarthritis: a Non-inferiority Randomized Controlled Double-blind Study

Gonarthrosis is a very prevalent condition affecting especially people over the age of 60 years old. It is a major cause of pain and functional impairment in Canada. The prevalence and associated economic burden continue to increase.

Despite the prevalence of this condition, the management of symptomatic gonarthrosis remains a controversial subject. Multiple treatment alternatives are available, none of which has been proven to be superior to the others beyond any doubt. However, certain therapeutic modalities are better recognized and more frequently used, such as intra-articular corticosteroid injections. In 2022, an expert consensus review of the available literature concluded that the use of intra-articular corticosteroids is effective in the treatment of symptomatic gonarthrosis. This is also the conclusion of the most recent American College of Rheumatology (ACR) guideline, which "strongly recommends" the use of this type of injection in gonarthrosis .

Despite decades of use, there is insufficient evidence to recommend a specific type and dose of corticosteroid. The choice of cortisone type in the usual practice of physicians performing intra-articular knee infiltrations is therefore based on experience and the biochemical properties of the different cortisones. Those with larger particles due to esterification of the corticoid, such as triamcinolone acetonide (TA) and methylprednisolone acetate, are known to have a longer duration of action. They are therefore the two most frequently used in studies on the subject. The dose used is based on historical use and is not, to our knowledge, based on any fundamental evidence. This dose of TA injected into a joint is usually 40 mg. Some authors have shown us that it is not useful to inject higher doses than this into a knee because increasing the dose does not improve the outcome of the injection. However, there was no literature related to the minimally effective intra-articular TA dose in the knee, until recently. Indeed, Utamawatin et al. recently reported that 10mg of TA did not appear to be less effective than 40mg when injected into knees with primary osteoarthritis.

This minimally effective dose is important because side effects associated with cortisone use have been reported. The adverse effects of oral corticosteroids are better known and documented than intra-articular ones. By a mechanism that is only partially elucidated, intra-articular infiltrations can produce the same systemic effects as oral. Habib et al. reports that systemic side effects increase with the concentration and time of exposure to the substance. To our knowledge, the minimal dose of intra-articular corticosteroid to produce a systemic effect is not documented.

Systemic effects occur in multiple systems. They affect several metabolisms such as glucose, gastrointestinal, lipid, adipose tissue, bone, immune, cardiovascular, sex hormones and the hypothalamic-pituitary axis. The mood can also be affected.