Hi @Steve sorry to hear about your predicament! Sesamoiditis is inflammation of sesamoid bones at their attachments. Sesamoids are unique in that they connect with muscles via tendons, unlike most other bones that connect with each other at joints. Sesamoiditis is more common at the knee (patella/knee cap which is technically a Sesamoid, but sometimes also called tendinitis) and the bottom of the foot, although the hand has sesamoids in the region called the "Volar plate".

There are several possible causes of pain in the region you describe, apart from bony disorders like Sesamoiditis, there can also be soft tissue disorders (e.g. affecting muscle tendons or their protective layer/"tendon sheath") in the area. Common examples for the latter include trigger finger and De Quervains tenosynovitis, although one would expect the shots to have at least provided some temporary relief. You can read more about them here: https://www.health.harvard.edu/diseases-and-conditions/tendon-trouble-in-the-hands-de-quervains-tenosynovitis-and-trigger-finger

Unfortunately, it would not be possible to distinguish between them without first finding out more about your lifestyle, circumstances surrounding the start of your symptoms, aggravating factors, as well as performing an examination in-person of the affected area. However, these are fairly standard assessments and I trust your provider would already have done them, and likely came to the conclusion of sesmoiditis based on these and has offered surgery due to the lack of response to the shots.

Perhaps if there is still uncertainty surrounding this, you may want to discuss with your physician the option of performing an imaging scan such as an MRI to evaluate further. Hope this helps!