“I played a lot of tennis over the weekend, and I woke up Monday morning and my knee was killing me. I limped around for a week or so, and then I felt a lot better.” When I hear this kind of complaint from a patient who otherwise checks out to be completely normal, I immediately consider the possibility that he may have had a stress fracture. A stress fracture is a microscopic crack in the bone’s surface. Although it is not a serious injury, it can be a very painful one.
Stress fractures can occur when bones are overworked. If you sliced a piece of bone and looked at it under a high-powered microscope, you would see that bone is a hotbed of activity. Bone cells are constantly engaged in a process called remodeling: new bone is being laid down by bone-building cells called osteoblasts while old bone is being absorbed by cells called osteoclasts. In fact, an adult skeleton turns over every 7 years, and a child’s skeleton turns over even more rapidly. Stress fractures can occur when normal force is applied to bone at a time when it is remodeling. Overworked and overstressed, the bone gives way, resulting in microscopic cracks. The only symptom of a stress fracture is pain and tenderness to the touch. Most people have had stress fractures at one time or another and may not have even have realized it. The pain may be here one day and gone the next, and all is forgotten. However, if the pain persists—and sometimes it does—it may warrant an examination by a physician, mostly to rule out other potential problems.
Physical Examination. The only positive finding on a physical examination is localized tenderness at the site of the stress fracture. Occasionally, there might be associated swelling. The stress fracture is rarely, if ever, intraarticular (within the joint) but more characteristically on the tibia (shinbone).
An MRI or Bone Scan. Because it is so small, a stress fracture cannot be detected on plain X rays until the bone begins to heal, and the body lays down a callus, a layer of new bone over the crack. A normal X ray may not be able to pick up an early stress fracture, but a bone scan or an MRI will note the increased vascularity, which will have a characteristic pattern for stress fractures.
Stress fractures normally heal by the themselves within 3 to 6 weeks. Ice and over-the-counter analgesics can help to relieve pain. Any activity that causes a great deal of discomfort during this healing period should be avoided, otherwise, you can pursue your usual activities.