Today on the Doc On The Run Podcast we’re talking about FHL tenosynovitis injections, corticosteroids versus PRP injection.
If you have pain of the bottom of the big toe joint, up along the arch, just above the plantar fascia, and you’ve been told that you have this thing called FHL tenosynovitis, or fancy word, long word, flexor hallucis longus tenosynovitis, that just means that you have inflammation of the tube that carries the tendon down to your big toe, so you can pull your big toe down.
That’s the FHL tendon. Flex, pull down, hallux, big toe, and longus because there’s a long one and a short one. And tenosynovitis is inflammation of the synovial tissue that lines the inside of that tube and makes the fluid that lubricates the tendon so it can slide through there and glide as you pull your big toe down when you push off when you run.
So what’s the difference between these two injections and why would you want one versus another? Well, it’s pretty simple. One of these injections is really trying to stimulate healing. The other one is trying to stimulate calming. That’s the simplest way to think about it. Corticosteroid injections or cortisone injection, you may have heard of this, it’s an injection with corticosteroids where we basically shut off the inflammatory response.
When would you want to do that? Well, if you have inflammation of the tendon sheath and it’s inflamed and every time you walk, every time you stand, every time you wiggle your big toe, you’re basically irritating that inflamed tissue that’s super swollen on the inside of that tube, you’re making it worse. So if you do a corticosteroid injection, the corticosteroids stop all the inflammation, they help shrink down that swollen tissue and it helps it calm down.
I have done that before, even on myself, where I’ve had inflammation of the tendon sheath. I had to inject it. It was all inflamed after a marathon. I injected corticosteroids into the sheath and it finally calmed it down. You don’t always have to do that, and there’s some circumstances where you would not want to do that.
When would you not want to do that? When would you want a PRP injection instead? Well, if you actually have a tear in the tendon or the tendon sheath, you do not want to inject corticosteroids because the tendon is a huge cable of collagen. Corticosteroids actually weaken collagen bonds, so if you have some little strands of collagen that are kind of starting to heal it and you inject corticosteroids, it can actually make that weaker and it can make the tendon worse. So you would not want to do that.
You would also not want to do it if you have a tear in the tendon sheath because there’s collagen in the sheath that actually makes it solid. And if there’s a tear in the sheath, it will stop any repair process and can even weaken the little collagen that’s repaired that, and that could get worse. So I would not do a corticosteroid injection in the sheath if you’re worried you actually have a tear in the tendon or the tendon sheath.
That’s where a PRP injection would come in. If you had a tear, a split in the tendon, a split or a tear, a rip or something like that in the tendon sheath around the tendon, then PRP would actually start to stimulate healing and potentially get that to repair a lot faster.
The only exception to that is if you have a once-in-a- lifetime race that is extremely important to you and you’re willing to take the risk of making it worse, then maybe your doctor would inject corticosteroids to try to calm it down enough just so you can get through the event with you understanding and accepting that there might be a real risk that it could get way worse during the race. If you’re willing to take that risk, it’s your foot, you can do whatever you want. Just got to be willing to pay the consequences.
Hopefully this helps you understand a little bit about the differences between these two conditions and if you like this episode, please like it, please subscribe and I’ll see you in the next training.
