Shin Splints and Stress Fractures:
This is the time of year that I see several patients with complaints of leg pain aggravated by their running endeavors. Most often, the runner has begun the fall cross-country season and has ratcheted up the mileage substantially over a very brief period (several weeks). Usually the typical story goes like this: "I have pain in my shins during running, on the inside part, that gets worse with running, but sometimes I can run through it. I ice every time after my runs, but it seems to be getting worse. There is no pain with walking…my coach and trainer say it's probably just shin splints, but my mom (a runner) is worried about a stress fracture."
Every year, three to six runners come in with this story. First, I clarify the story. Where is the pain: medial (inside, toward the other leg), usually around the junction of the middle and distal thirds of the bone. When did it begin: came on gradually during the second week, "we were increasing mileage…worse third and forth weeks…more consistent during runs, lasting longer, even after". Training history: didn't do much running during the summer, doing other activities (camping, lacrosse camp, etc.)…"maybe running ten-fifteen miles per week…sudden increase with my fall training runs". Shoes: new shoes ("they discontinued my old line, but these felt comfortable"). Treatment: still running (with pain), but stretching, and taking ibuprofen, with icing after runs- "no relief".
The problem here is that although stress fractures of the tibia are far less common than shin splints, stress fractures mandate complete cessation of running. Sometimes shin splints do too, but the runner can often diminish mileage, modify footware, take anti-inflammatory medication, ice and stretch, and get through a bad case of shin splints. Stress fractures are a different story. It is virtually impossible to heal an established stress fracture without avoiding high impact activity.
So, the difference makes a difference. How can one distinguish the two? As we have seen, the history is not much help, although establishing the precise location of pain and tenderness may provide clues. Stress fractures usually cause more localized pain and tenderness, often transverse (a line parallel to the ground when standing), whereas shin splints often produce more longitudinal pain and tenderness, i.e.- up and down the leg, perpendicular to the ground when standing. Shin splints are more often bilateral, while bilateral stress fractures are rare. But (there is always a "but" in medicine) there are always exceptions to these generalizations.
Therefore, for persistent leg pain with the above story, get it checked out. X-rays are unreliable for early detection of stress fractures, as they are often normal, even when a fracture is truly present ("false negative study"). This is because the "crack" may be so small (even microscopic) that it cannot be seen on the x-ray picture. Most often, the first x-ray sign of a stress fracture seen on x-ray is the new bone of healing, "callus", a late finding. Therefore, more sensitive (but more expensive) tests may be necessary to distinguish the two, such as a bone scan or MRI.
The best "treatment" for these two problems is to avoid them in the first place: ramp up mileage slowly, stretch before and after running, wear appropriate shoes, avoid same side of road running, and cross train. For those student athletes that anticipate fall cross-country, or spring track, maintaining a good pre-season mileage base is wise, increasing gradually prior to the season. Alternate between two pairs of training shoes to allow time for the cushioning to recover. In my experience, shin splints seem to be more common in flat-footed runners (pronators), and supportive shoes with a good arch may prevent trouble.
Dan Wnorowski, M.D.