Autologous-conditioned serum: evidence for use in the knee

Since the first description of autologous-conditioned serum (ACS) almost two decades ago, there has been a presumption of beneficial proteins found within this product. Thought to be a key protein in ACS, interleukin 1 receptor antagonist (IL-1Ra) has received the majority of the attention; although the extent of biological proteins is not known and likely because of the autologous nature of the product, vary from individual to individual. Following the positive anecdotal evidence, preclinical data demonstrated both symptom and disease-modifying effects. These results were followed by two randomized placebo-controlled clinical trials, both showing significant improvement compared with placebo or hyaluronan acid in one study for quality of life, pain, and patient assessed efficacy when ACS was administered in the human knee. Much is still unknown regarding the key active proteins found in ACS as well as definitive dosing, frequency, and administration time postinjury, which hopefully will be the focus of future studies.