That's been...4 months already. That's an awfully long time to go without seeing any improvement. I would be getting the opinion of a specialist if at all possible; given the amount of time that has passed, & the generally poor prognosis for a fracture of this bone, I would at least be asking my vet the question "would it be the kindest thing for her to put her down?"
I've heard of one elbow fracture, a long time ago but I don't have personal experience with this injury. Here is what the Equine Research Veterinary Encyclopedia has to say about the condition:
The olecranon (elbow) has a bone growth center in young horses, which is relatively easily separated from the shaft of the ulna. In older horses the trauma may result in damage ranging from small bone chips to serious fractures.
The horse nearly always demonstrates some sign of radial paralysis or 'dropped' elbow'. In this condition the horse cannot bring the leg forward to bear body weight. There is usually pain. Bone crepitation may be difficult to detect because of swelling. X-rays are needed to determine the extent of the fracture.
Bone chips are often removed successfully from the olecranon by surgery, and fractures with no separation of the bone sometimes heal properly with complete stall rest for six weeks. Other more serious fractures are seldom treated successfully. This is so primarily because of the tremendous pressure put on the olecranon by the triceps muscle. It usually displaces most surgical pins, wire or bone screws.
Permanent lameness usually results. If a separated olecranon does heal, it generally overrides the shaft of the ulna. The outcome of comminuted (crushed) fractures or compound fractures (which pierce soft tissue) is generally bone necrosis (death) and the formation of sequestra (dead bone fragments). The prognosis is generally poor.
That is word for word what the book says about fractured elbow; the only part I left out is the introduction, which explains that the most common cause of fractured elbow is a kick over the elbow by another horse.
I'm sorry that you're having to deal with this.
You know Katie, I was just thinking about you a couple days ago, wondering how you were making out with your riding mare. Is she still going well under saddle for you?
Holly