Knee osteoarthritis is a degenerative "wear and tear" disorder affecting mainly population over 50 years old. It can also present in younger people, especially after an injury or as a part of other diseases. While many therapeutic options exist for knee osteoarthritis, none of them has the potential to cure this condition. Cellular Matrix represents a combination of natural non-crosslinked hyaluronic acid (HA), thixotropic cell separation gel, and sodium citrate anticoagulant solution. A combination of Cellular Matrix with autologous platelet-rich plasma (A-PRP) is a novel therapeutic approach to the management of knee osteoarthritis. It is assumed that the active components HA and PRP have a synergistic effect contributing to a better therapeutic outcome in patients with knee osteoarthritis. Physiotherapy could provide an additional benefit. This is a retrospective pilot study assessing the potential benefit of Cellular Matrix and A-PRP combined with physiotherapy in the management of chronic knee osteoarthritis. Twenty-five patients were enrolled in the study and injected with three doses of Cellular Matrix combined with A-PRP with a time span of 2 weeks between each injection. All patients received standardized physiotherapy. The results showed that 68% of patients achieved more than 50% improvement in pain, stiffness, and function of the knee joints. There were no adverse reactions. This retrospective pilot study confirmed the positive effect of PRP and HA combination in the management of mild and moderate knee osteoarthritis. These preliminary results need to be verified in randomized control trials.