Zilretta is an anti-inflammatory steroid contained in microspheres, injected into joints for slow-release and continued efficacy over at least 3 months. This should be very useful for OA patients with a predominant synovitis phenotype.
An injectable trans-capsaicin lasting up to 6 months would be a boon for OA pain relief. Capsaicin "numbs" the pain-transmitting nerve fibres.
1 in 8 response lasting a mere 2 weeks certainly does not sound like an effective treatment for knee OA, but personal experience suggests otherwise.
Perhaps selecting patients with clinically overt synovitis would improve the response rate. For such patients, then, a longer-acting or slow-release steroid would prolong the duration of response.
Symptomatic pain relief may buy a better quality of life, but the degeneration and inflammation continues, possibly at an accelerated pace in a subset of patients (20%).
The evidence that Vitamin D replacement will improve knee OA symptoms and function remains elusive.
Clutching at straws (or fibre), if you ask me. When you're desperate, you'll try anything.