To add to Smasher's list - diagnostic ultrasound can be another add-on to consider. You can do POCUS to confirm some concerns (e.g. tendon pathologies like itis and ruptures, DVT). It can aid local injections. It can also be used in place of or in conjunction with ABI/PVR non-invasive testing if your practice leans more vascular-friendly. Not 100% necessary to succeed, but handy to have and can be billable with the appropriate CPT code.
My ultra probe paid for itself within a year or so. It's a good tool to have. Not too expensive, insurance covered, not shady or too high charge when pts see their EOBs.
I very seldom do injects with it, but it gives you good viewing. I like it for Achilles, PF, peroneals, soft tissue masses, etc. A lot of pods use butterfly, I did Philips Lumify.
If you figure it's roughly a $5k buy for the pocus (and a bit for a basic tablet and stand to go with it), it is paid for in about 120 exams or 40 injects (or combo of such). That is only using it once every clinic day or two for a year... all profit after that. Perhaps replace tablet every few years?
Even for hospital or group employ pods, handheld ultra is a buy you should want the dept/facility to make for you. Good info and easy RVUs.... basically a "quick MRI" option for me (and often still order MRI anyways). It is basically standard equipment for ER, OBs, some cardio, etc these days to have a couple pocus for the dept - or even one for each doc, so it won't be a big deal to most hospitals to get one for podiatry office.
(I don't the handheld ultra for any vasc stuff or DVT, lol.... even if you wanted to, absolutely send for asap duplex dopp)
...I just have that pocus and OTC stuff. You can do fairly well with that, E&Ms and procedures, surgery, and basic DME (boots, ankle braces, NS, etc).
I could see shockwave if a larger group of DPMs or orthos that'll all send pts for it, but it's otherwise pretty hard to get the volume for recouping the cost of the truly high quality units (and doc or MA time of doing all the treatments).
Office DM shoes can be ok if you have the space anyways, but shoes start to take up a LOT of room and need MCR dme paperwork... and will draw audits.
The rest of things mentioned are grifter junk imo (swift, nail lasers, wound "grafts," prp or fancy injects, etc etc). They "solve" problems that don't exist and/or can't be solved with those things either. Shameful for all of us.
Oh, and don't forget the common podiatry supergroup scams of owning the toenail histo and ENFDs lab, over-test nearly everyone for ABI etc, own the vasc lab, own a "custom" dme shop (which strangely gives braces that look a lot like prefab!), maybe own PT place, etc.