Pain on the anterior (outside) part of the lower leg may be compartment syndrome a swelling of muscles within a closed compartment, which creates pressure. To diagnose this condition, special techniques are used to measure the amount of pressure.
"With compartment syndrome, the blood supply can be compromised, and muscle injury and pain may occur," says podiatrist Stephen Pribut, D.P.M., of Washington, D.C. Sometimes surgical "decompression" is required.
So how do you distinguish compartment syndrome from shin splints?
"Symptoms of compartment syndrome include leg pain, unusual nerve sensations and, later, muscle weakness," Pribut says.
Pain in the lower leg could also be a stress fracture (an incomplete crack in the bone), which is a far more serious injury than shin splints. A bone scan is the definitive tool for diagnosing a stress fracture. However, there are clues you can look for that will signal whether or not you should get a bone scan.
Press your fingertips along your shin, and if you can find a definite spot of sharp pain, it's a sign of a stress fracture; the pain of shin splints is more generalized.
"Usually stress fractures feel better in the morning because you've rested the bone all night," says Letha Griffin, M.D., an Atlanta orthopedic surgeon who specializes in sports medicine. "Shin splints are worse in the morning because the soft tissue tightens overnight you get out of bed, and you can hardly walk."
"Shin splints will be most painful if you forcibly try to lift your foot up at the ankle," says Sheldon Laps, D.P.M., a podiatrist in the Washington, D.C., area. "If you flex your foot and it hurts, it's probably shin splints."
Also, a horizontal rather than vertical line of tenderness across the bone is typical of a stress fracture, Pribut says.