Another update: I have complicated the protocol with ancillaries to the point that causality may become blurred. Nonetheless, I think that FGF-18 is and will remain the main actor, and it has the most supporting research.
After the previous series of three FGF-18 injections I injected—subcutaneously—some bioregulators—30 days of Cartalax @ 2 mg/day and 20 days of Vesugen @ 1 mg/day. The requisite six months passed and the promising early results were maintained. I had become aware of another peptide of interest, FOXO4-DRI. This peptide is intended to selectively kill senescent cells. This may be desirable in arthritis due to
senescence-associated secretory phenotype (SASP), because "SASP disrupts normal tissue function by producing chronic inflammation, induction of fibrosis and inhibition of stem cells."
Being the adventurous type, I decided to precede the next series of FGF-18 injections with a set of FOXO4-DRI injections. The protocol was based on animal research and consisted of a set of three intra-articular injections given every other day. Out of caution I started lower and worked up: the injections were 2 mg, 3 mg and 4 mg of FOXO4-DRI. At present all I can report about them is that nothing untoward occurred. I had some transient discomfort after the first injection, but that could have been due to forcing the injection into denser tissue rather than the sudden appearance of a bunch of dead senescent cells.
It's possible that IGF-1, or lack thereof, also plays a role in arthritis. However, intra-articular injections of IGF-1 have produced lackadaisical results. The short residence time and quick uptake by binding proteins are suggested as possible explanations. One possible workaround is to create slow-release formulations, e.g. gels. However, this gets more complicated for someone focused on DIY. I had become aware of a synthetic variant of IGF-1, IGF-1 LR3. I speculated that this might overcome some of the shortcomings of regular IGF-1 while maintaining the relative simplicity of straight water-based injections. AI indicates that synergy with FGF-18 is possible, though there are also some risks, and the correct doses are unknown. I decided to add some IGF-1 LR3 to the next set of FGF-18 injections.
Two weeks after injecting the FOXO4-DRI I proceeded with the set of three FGF-18 injections, and simultaneously started another course of the Cartalax and Vesugen bioregulators. The three FGF-18 injections included 30 µg, 40 µg and 40 µg of IGF-1 LR3, respectively
Thus the overall approach is to try several things that have promise and hope to get some synergy without doing harm. Subjectively nothing much has changed after just completing the final FGF-18 injection in this set. I am hoping for further improvements over the coming months. But even if things stay as they are it would be a remarkable result considering the original degradation of the joint to bone-against-bone; the residual soreness is well below the threshold needed to consider a joint replacement. Attempting to quantify peak pain on a 0-10 scale, it has dropped from 7-8+ down to about 4.