Effect of AI on tendons

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I’m wondering if anyone else has experienced tendon effects of AIs?

I had a lumpectomy then mastectomy for triple pos BC around a year ago. Due to a pre-existing condition I couldn’t have chemo or herceptin and started Letrozole in March 22. After around 5 months, as well as more standard side effects, one of my ankles gave way and the tendon popped. This happened again a few weeks later and other tendons were weakened eg the other ankle, wrist, hip. I ended up having to use a wheelchair as I was unable to tackle even the slightest of inclines and stairs were horrendous. After two consultations, we decided to stop the Letrozole, leaving me without any protection. We did discuss trying Anastrazole if / when my body gets stronger.

I’m finding it a very very slow process. I’m still nowhere near back to full ankle strength and have had many setbacks after trying to push on with physio. I’ve not met anyone else in this situation in terms of tendons and soft tissue, so am wondering if there’s anyone else out there who’s been like this. If so, how long did it take for soft tissue to get back to ‘normal’?

I daren’t think about the lack of protection, as it was the right decision for me. It’s too scary if I do dwell.

  • Hi  

    Sorry to hear of your tendon issues. I can fully empathise as I have been diagnosed with bilateral archilles tendonitis in my ankles and it has been attributed to the AI I am on ( originally generic anastrozole now Arimidex) I am also having issues in both elbows and my knees but not to the extent of my ankles at their worst

    Priot to my diagnosis I had very "stretchy" ligaments and a degree of double jointedness so did have some issues, particularly with my knees and hips due to misalignment. My knees have occasionally dislocated for decades ! Ironically the stiffening up I have on the AI has helped that a little but my knees remain a problem

    I had a drug holiday for 6 weeks prior to switching to Arimidex and things did improve and also doing the physio exercises has helped my ankles that were at one point, very debilitating and stopping me doing my weekly dance class. Most days now they are OK but are stiffer ifirst thing the day after a dance class or a swim, but it wears off. 

    I did find an obscure research paper from Japan I think about this and it was accepted as a side effect of the estrogen depletion AIs cause

    I hope you are able to manage things and that they improve. Tendon injury recovery is a long process unfortunately. I can completely understand why you have stopped the AI as it was my ankles that drove me to contact the patient led follow up and have the drug holiday. 

    Best wishes 

  • I have just done a post exactly with this issue. I’m on tamoxifen for about 20 months and now have toxic tendonopathy. We believe caused from the tablets. I’m having a scan on my Achilles Thursday but wondered if anyone found another AI that wasn’t so bad on the tendons.