Radiation Damage to sacrum/sacral insufficiency fractures

@pjebp I had a sacral insufficiency fracture following pelvic radiation for endometrial cancer. I didn't know I had the fracture as it showed up incidentally when I had a CT scan for one of my regular cancer follow-up appointments. I didn't have any symptoms. Since was in the osteopenia range I asked for a referral to endocrinology. It took 6 months to get the appointment. My DEXA scan showed I'd experienced more bone density loss since the radiation therapy which the radiation oncologist warned me could happen.

My endocrinologist said I was already doing everything possible on my own to maintain bone density but the sacral insufficiency fracture and my bone density loss from radiation meant that I should consider medication. So, that's what I did. Twelve months of Evenity injections, and a Reclast infusion with the weight training I did with my personal trainer resulted in a 10% gain in lumbar bone density and healed fracture. I also had a 4% gain in bone density in my hip.

At the time the sacral insufficiency fracture was found I was already working with a personal trainer. I'd been weightlifting and active for many years prior to the endometrial cancer and radiation therapy. My personal trainer made adjustments in my training. Had I not been already working with the personal trainer I would have asked for a referral to physical therapy. To me, a physical therapist is the best resource for this kind of thing.

I don't know what recommend for exercise because my situation was different than yours and I don't know what your pain levels are like. Have you worked with a physical therapist who can give you home exercises?

Hi, pjebp.
You might get a Pelvic MRI. Your primary shouldn't have any trouble ordering it. And take it to an endocrinologist. I think your best bet is with an osteoporosis medication Forteo or Tymlos because these two medications speed healing. I'd want the MRI to tell me if there were fractures and if there are fractures, are they stable.
If there is any chance of metastasis, it could be wise to repeat the PET/CT.
It sounds as though you may have had osteoporosis in the sacrum before radiation, though impact injuries can also cause sacral insufficiency.
I closing with this link because it outlines the diagnostic processes followed by others https://pmc.ncbi.nlm.nih.gov/articles/PMC8350190/
You probably want avoid any exercise where you are twisting or turning, sit-ups or crunches, toe touching, lifting any weight, or bicycling until you have the MRI results. I hope you aren't in pain.

@gently My endocrinologist said forteo is off the table for patients who have been through radiation. I was radiated near tailbone and in pelvic lymph nodes. She recommended prolia injections every 6 months. I am trying non pharmaceutical options first as I am still trying to overcome many longer term chemo and radiation side effects. I am 75 yo-not sure if that makes a difference in Endo recommendations.