Fosamax would not have been the right choice at the start and going on Evenity was a much better solution. Score one for your orthopedic surgeon! But now that you have completed Evenity, Fosamax could be the best choice, but it depends on the results you have so far. In my opinion, you have two paths to follow.

1. Transition to Fosamax for two years and get a DXA scan to see how you are doing. Combined with HRT, you could be in really good shape. If you are not in good shape, you could use Evenity again or you could transition to Prolia for a few years.

or

2. Transition to Prolia for a few years to get your hip T-scores in really good shape. Then you could transition to Fosamax or Reclast.

CTX is the shorthand name. Here is a link to the Mayo Clinic information https://www.mayocliniclabs.com/test-catalog/overview/83175#Overview

Not all doctors use bone markers, but all of the doctors I follow use at least one set of bone markers. There are blood and urine markers available. Since you're in a transition period between medications, measuring CTX (or other markers) is not ideal since it will swing from low to high. Your CTX is likely still being suppressed by Evenity but will swing above your natural untreated level in the next few weeks.

It's nice to have an untreated CTX value, especially if you are considering Prolia. If you can get it now, great, but at this point, I wouldn't worry about it.

As a side note, I bet your spine scores are better than your hip scores because you ride horses. The spine is being stressed more than you hips and femur.