An Uncommonly Simple Problem (superficial peroneal n. compression)
When choosing a topic for this column, I try to select something that will be meaningful to the largest group possible. Accordingly, most of the running injuries I’ve written about are the ones most commonly seen in the clinic and most familiar to runners. If you haven’t suffered from runner’s knee, sciatica, plantar fasciitis, etc., I’d say it’s a safe bet you’ve at least heard of them or know runners who have had to deal with them.
For a change of pace, then, I thought I would describe an injury not too often seen (I come across maybe one case per year) but interesting nonetheless, since it provides a good example of how a relatively simple problem can mimic and be mistaken for a far more serious one, which in turn precludes a relatively simple solution.
The individual suffering this injury will typically complain of a burning pain along the top of the foot, from the area of the ankle joint to the toes. Very often, he/she will also or alternately report a tingling sensation or numbness in the same area. Onset of these symptoms is gradual, no trauma having occurred, and the pain/tingling is generally worse with, but not exclusive to, running.
While pain can be caused by a multitude of problems and can involve injury to a wide variety of body parts (muscle, ligament, bone, etc.), tingling or numbness is almost always associated with nerves, as in one that is “pinched.” So it is not surprising when a health professional mistakenly attributes these symptoms to a problem in the low back, since this is the area most commonly associated with pinched nerves. In this case, however, the low back couldn’t be further from the true source of the problem.
The injury, in fact, is just about where it’s felt, at the junction between the lower leg and the foot. At this point, on the topmost part of the foot, the superficial peroneal nerve makes its way to the surface, having coursed down deep in the leg after branching off from the sciatic nerve in the thigh. From this point on, this nerve supplies most of the top of the foot with its sensory reception (touch, temperature, pain, etc.).
Assuming you now can identify where this nerve enters the foot, now visualize putting on your Reeboks and tying the laces. Where is the knot? Very often, right over the nerve, where, if it is too tight, causes a compressive injury resulting in burning pain and/or tingling down to the toes. The solution? Embarrassingly simple — loosen the laces or tie the knot more to the outside of the foot! Most people never think to do this because they aren’t aware that there is a nerve in this area so close to the surface, but now you are, so if you ever have these symptoms, try this first.
Wouldn’t it be nice if all running injuries could be solved so easily?