@loplady
Firstly, to quantify my reply. The below is based on my experience and research of about 30years. Links to research at the bottom of the reply. Sharing with your doctor and discussing this is always best.

Ok, take a deep breath and let's talk Research 101, how it works and what it means to us in this particular case of strontium ranelate vs strontium citrate.

The distinction exists between pharmacology (the strontium drug's effect) and toxicology (the side effects). Scientists view these two substances as different, as "cousins" that share a muscle (strontium) but wear different armor (ranelate vs citrate). They are studied in different and overlapping ways.

Bioequivalence also plays a role. Think of a generic vs a brand name drug; the two are considered bioequivalent or acting the same but may have different side effects because of their different carriers.

When research is conducted on any form of strontium the studied effect of bone health is the same and easily transferred to all strontium.

The difference occurs in the additives and the carrier (ranelate/citrate etc) and how it might affect the active ingredient (strontium). Indeed, some differences are found in absorption from the citrate to the ranelate.

Here is a tortured metaphor for strontium vs citrate vs ranelate:
Think of a "Driver vs. The Car" analogy:

The Driver (Strontium): This is the active ingredient that actually strengthens the bone. Whether it arrives to your body in a "Citrate car" or a "Ranelate car," the passenger (Strontium) is exactly the same once it gets out and goes to work in your body.

The Car (The Carrier): This is the "additive" used to deliver the strontium.

Citrate is like a basic, safe sedan (a natural fruit acid).
Ranelate is like a car with a known mechanical flaw (a synthetic molecule) that research may have linked to rare but serious risks like blood clots. (different population studies disagree)

The Bottom Line: Scientists view the "bone-building" strontium as identical in both products because the driver of strontium is the same, but the "safety risk" is different because one delivery vehicle has "baggage" that the other doesn't. Ranelate is totally different from citrate.

Below bottom line: Tortured metaphor time for Research....To further understand how research works... think of the research process as a 3 story building.

The first floor: the foundation is composed of preclinical and lab studies to study the active ingredient, in this case Strontium. The Finding: Research in this layer shows that the strontium ion itself is what stimulates bone-building cells (osteoblasts) and slows down bone-clearing cells (osteoclasts). At this level, strontium is strontium, regardless of whether it's attached to citrate or ranelate.

The second floor: Clinical trials where the whole item, the pill is studied with the active ingredient (strontium) and the carrier. The Finding: Trials confirm that both versions successfully deliver strontium into the human bloodstream. However, this is often where the first "safety signals" for the carrier (the additive) appear, such as minor digestive issues or skin sensitivity.

The third floor: Population and Post Market Studies: This is the most critical layer for side effects. Scientists look at what happens when thousands of diverse people take the substance for years. The Finding: This "real-world" data is what revealed that Strontium Ranelate might be associated with an increased risk of blood clots and heart issues in some populations. Because Strontium Citrate uses a natural carrier (citric acid) already found in the human body, population data or longitudinal studies on customers hasn't shown those same synthetic-related risks (but no gold level population studies similar to the million dollar ranelate studies have been conducted) .

Now if there are further concerns research will be reconducted as it was with strontium ranelate population studies . This is done to rule out mistakes; in the strontium ranelate population study the mistake seems to be that people with existing heart problems were part of the population study and the population study found, viola, heart problems. Additional and better conducted studies have found no connection between strontium ranelate and the cardio concerns found in that first study.

This actually happens frequently with research and with population studies. Research has to be redone and better population studies must be conducted. When that does happen research and population studies are repeated and honed to be more precise and therefore accurate.

Compilation of strontium research and posts:
https://www.inspire.com/groups/bone-health-and-osteoporosis/discussion/dd823b-strontium-a-compilation-of-research-and-information/

@loplady
Here is a post which I recently did on MK4 and Mk7. on Inspire:
https://www.inspire.com/m/Kathleen1314/journal/7c2651-mk4-and-mk7-research-and-studies-affecting-bone-health-vitamin-k/
Beginning paragraphs of the post:
"Vit K is a frequent topic on Inspire.

MK4 is actually used as a prescription in Japan as a treatment for Osteoporosis. Mk4 has a solid body of research supporting its fracture prevention. The problem is that it seems that Mk4 does not stay in the system very long while Mk7 has a longer life in our bodies, but Mk7 does not have the body of evidence which Mk4 has in terms of bone health.

Said another way: While MK4 has more extensive clinical trials specifically for fracture reduction, proponents of MK7 argue it is more effective at lower nutritional doses and provides more consistent activation of bone-building proteins. Some providers suggest using both Mk4 and Mk7 together to provide a well rounded attack."