A Needle for POPS...?
Maybe your dad does need a needle, but that is not the POPS I’m talking about. I had an interesting case a few weeks on this deployment. Here’s the story…
37 y/o active duty Army male presents to “sick call” with pain just proximal to the base of his 5th metatarsal, pain with ambulation, and basically, he has been unable to run. On exam, his only complaint of pain with palpation was at and just proximal to the base of his 5th metatarsal. The rest of his exam was negative. Me being the high speed ortho PT that I am immediately assumed a possible stress reaction at the base of his 5th. Very common in the military. By the way, being a PT in the military is an entirely different experience than in the civilian world. You are the doctor. You order the imaging. You prescribe the meds. You refer if needed. It is a cool way to practice. So, I sent him for imaging. Plain film and CT are all I have access to here, so plain film it is. I was expecting some type of stress reaction or possibly even a fracture due to his amount of tenderness. Imaging was read as normal with an anatomic variant noted of an os peroneum. Radiopedia.org says an os peroneum is a small accessory bone located at lateral aspect of the cuboid within the substance of the peroneus longus tendon seen in up to 26% of feet. Well crap, everything looked ok, but you still hurt…here’s some drugs. So, I prescribed Naproxen 500mg 1 TAB PO BID PRN PAIN and gave him a ten-day supply. I also placed him on a no-run profile, gave him a HEP that included general ankle stuff since this could also have been peroneal tendinitis (the peroneus brevis inserts at the base of the 5th), and told him to follow up in four weeks. Military patients generally do what they are told, so he followed up in four weeks. He presented exactly the same. Same pain, same tenderness, same difficulty ambulating. Very localized pain. Now, I’m back in the 5th MT stress fracture boat so I order a repeat film and specifically describe to the radiologist his location of pain and to please evaluate for any type of pathology. God bless this radiologist for writing a very detailed impression that went on to educate me on something called Painful Os Peroneum Syndrome, or POPS. He mentioned the os peroneum in his first impression four weeks ago but reported it as a variant and I was apparently asleep the day in PT school or in my OCS studies that talked about how an os peroneum can cause trouble. Because I re-imaged, he mentioned that an os peroneum can cause pain. A quick google search educated me the rest of the way:
Painful os peroneum syndrome (POPS) results from a wide spectrum of conditions, including fractures, diastases, and other causes. POPS can result in tenosynovitis or discontinuity of the peroneus longus tendon with a clinical presentation of pain in the lateral aspect of the midfoot. (Chagas-Neto et al., 2016, p. 1)
Treatment includes NSAIDs, steroid injections, or surgical excision. Because we’re deployed and it isn’t worthy of a MEDEVAC, this fellow will have to suck it up until he gets home. I put him in CAM boot to calm it down, and of course when you are a hammer, the world is a nail…so I needled him. Needling included his peroneus longus/brevis and two places on his abductor digiti mini all with ES. Surprisingly, that provided some pain relief.
Here's a pic of an os peroneum.
Keep it in mind as a differential for patients with lateral foot pain at or near the base of the 5th! Stay safe, stay smart!
Chagas-Neto, F. A., Souza, B. N. C. D., & Nogueira-Barbosa, M. H. (2016). Painful os peroneum syndrome: Underdiagnosed condition in the lateral midfoot pain. Case Reports in Radiology, 2016, 1–4. https://doi.org/10.1155/2016/8739362