Ankle Fracture

It is malpractice IF the following two criteria are met:
1) At the time you saw a doctor, a reasonable doctor of that speciality (e.g. orthopedist) would or should have seen that some other or additional treatment was needed--i.e. that the need to do more than what was done should have been reasonably obvious to doctor in the position of the doctor(s) who examined or treated you.
2) If you'd had different treatment, you would have had a materially (significantly; i.e. not trivially) better outcome. This means that as a practical matter, malpractice is only malpractice if it causes harm. If the same thing would have occured no matter what, it is not malpractice.
Example: I practice karate. In my styles, we kick with the ball of the foot by pulling the toes back. My toes are relatively inflexible and I had trouble pulling them back enough, so they tended to get jammed. I saw my primary care physician with pain in/around my big toe; he thought it was just a sprain, had me rest, ice, etc. it, and then cleared me to go back to practice. Pain occured again, so I went to a podiatrist this time, who said that it was not a sprain but was obviously osteoarthritis brought on by years of impact. He felt my primary doctor should have been able to make that diagnosis.
My first doctor committed malpractice: he missed an obvous diagnosis and recommended ineffective treatment. However, all the damage had been done by then--I'd already had the arthritis in my toe. The treatment I received was irrelevant and did not affect the outcome. So therefore, while it was technically malpractice, there was no point in taking legal action: since the misdiagnosis did not cause me harm, I would not be entitled to compensation.
So in you case, the issue is, even if it is malpractice, did the failure to identify the problem or recommend a different treatment cause you harm? Or given the seriousness of your injury (avulsion fractures are very serious) was the damage already done and the treatment didn't matter--would you be in the same position even if the doctors you saw had spotted and told you about the problem you are still experiencing? If nothing significant would have changed with a different or earlier diagnosis, then you would not be entitled to compensation.
If you feel, based on the medical advice you have since received, that the problem should have been spotted earlier and different treatment(s) done, then you may well have a malpractice case and should consult with a malpractice attorney. (Many such lawyers provide a free initial consultation to evaluate a case; you can confirm this before making an appointment.) The lawyer can advise as to the strength of your case, what it might be worth, the cost to pursue it, and which doctors to bring it against.