A stress fracture is more accurately termed a “bone stress injury”, as there are different degrees of injury that can occur to a bone. A bone stress injury (BSI) is exactly what it sounds like – with load, the bone can become stressed, and eventually will form a small crack.
Most BSIs occur in the lower extremities, in athletes who participate in sports with repetitive impact. They occur most commonly in distance runners and cross country/track athletes, but also in basketball players, soccer players, and lacrosse players. More rarely, BSI’s can occur in the upper extremity in overhead athletes such as baseball pitchers and swimmers. Upper extremity BSI’s are much more common in adolescent athletes, whose growth plates have not closed yet.
BSI’s occur in two ways: when there is abnormal amounts of stress on a normal bone, or a normal amount of stress on an abnormal bone. The former method of injury typically occurs when the athlete does “too much, too soon”; such as a basketball athlete going into their preseason training with no base fitness, or a runner increasing their mileage drastically in preparation for a race. On the other hand, stress fractures can occur without drastic increases in training. This method of injury typically occurs in female athletes who are not eating enough to support their activity and may or may not have disruption of their menstrual cycle. As such, stress fractures as a whole occur more commonly in females than in males. Common sites for bone stress injuries of the lower extremity include the femoral neck, femoral shaft, tibia, fibula, cuboid, navicular, and metatarsals. Common sites for BSI’s of the upper extremity include the proximal humeral epiphysis, and the epicondyles of the humerus. BSI can also occur in the lumbar spine, the sacrum, and the pelvis.
Most BSI’s require an MRI as the gold-standard diagnosis, though older injuries may show up on an X-Ray. Clinical tests can raise suspicion of a BSI, but cannot be used for definitive diagnosis. All BSIs should be managed and monitored by a physician (MD or DO), in addition to your physical therapy care, as serial X-Rays are usually used to ensure the bone is healing. Treatment of BSI begins with relative rest, or unloading of the bone. THe degree of unloading depends on the degree of injury. For a lower extremity BSI, you may be utilizing crutches or a CAM boot for 6-12 weeks. Many athletes will be allowed to cross-train with a BSI; swimming and pool running can be good options for maintaining cardiovascular fitness without more stress on the bone. Again, this depends on the location and severity of the injury. Physical therapy is crucial to management of BSI’s. Early PT management of BSIs includes educating the patient on how to protect the healing bone, providing options for maintaining strength while protecting the injury, and then gradually introducing load to the bone in a way that stimulates healing. Your physical therapist will guide you through a return-to-sport progression, to ensure that your healing bone – and the rest of your body – can handle the load of your sport to prevent a re-injury.