Last December I was plagued with pulsing pain searing through my left shin. The throbbing, sometimes piercing, feeling became a constant in my daily life. I absentmindedly would run my hand over the aching spot during class, and automatically hold my weight on my right leg when standing around; my mom even caught me standing (unknowingly) entirely on one leg, with my left leg bent up so my foot wasn’t touching the ground. The pain wasn’t much of a mystery, I’m a runner, and I knew the diagnosis was inevitable for my symptoms: a medial tibial stress fracture. 6 months of cross-training, 1 week on crutches, 4 weeks of immobilization and exercise-restriction got me back to having the top half of my shin play nice with the bottom half of my shin. What a glorious reunion, like long-lost lovers meeting again for the first time, I only hope they never separate again.
Throughout this process I was often told by others who had similar injuries, that the pain would “never completely go away”. That I would always sort of feel that throbbing, broken feeling, even when my bone was completely healed, even years after the area had returned to normal. The funny thing is, I just accepted these comments as truths. And after feeling some of these familiar twinges of pain, I finally started to think about how a weird a phenomenon this is. What a terrible psychneuro major I am. How come, until now I hadn’t given much thought into this absurd observation?! Here’s my chance for redemption, some scientific musings….
This lingering feeling of pain made me think of phantom limbs. When a person has their limb amputated they often continue to feel pain in what is no longer a part of their body, and this perception of pain can persist indefinitely, it’s called phantom limb pain. There are some factors that determine how likely you are to have phantom limb pain, such as how intense and how long your actual pain was in the limb before amputation. However, these factors DO NOT play a role in whether or not your phantom limb pain persists for many years after amputation. That is more of a mystery.
So if we can experience pain in a limb that no longer exists, can we experience pain from an injury that no longer exists? I couldn’t find much (read: any) scientific papers on this. I read on a lot of message forums about stress fractures that residual pain can be from remodelling of the bone, but that lasts for 6-12months. So, what about after a year? The people who I have talked to had their stress fractures years ago, is it all in their head? Has the paranoia of re-injury caused us to create pain in a place that’s not in pain? How are we tricking our brain into thinking that there is pain in that spot? I don’t know that I have an answer for these questions, but I’m glad I started using my psychological noggin to think about this; sometimes I forget how nice it is to cross my psychological self with my runner self.
Troels S., Børge Krebs, Jørn Nielsen, Peter Rasmussen. (1985). Immediate and long-term phantom limb pain in amputees: Incidence, clinical characteristics and relationship to pre-amputation limb pain. Pain 21(3): 267-278.