Hand injuries, meanwhile, were more likely to be caused by struggling prey. Stress fractures in dinosaur bones can be identified by looking for bulges on the shafts of bones that face toward the front of the animal. When X-rayed, these bulges often show lines of clear space where the X-rays have a harder time traveling through the bone. Rothschild and the other researchers noted that this "zone of attenuation" seen under the X-ray typically cannot be seen with the naked eye.The researchers described theropod phalanges as being "pathognomonic" for stress fractures, this means they are "characteristic and unequivocal diagnostically." Rothschild and the other researchers examined and dismissed other kinds of injury and sickness as causes of the lesions they found on the dinosaurs bones. Lesions left by stress fractures can be distinguished from osteomyelitis without difficulty because of a lack of bone destruction in stress fracture lesions. They can be distinguished from benign bone tumors like osteoid osteoma by the lack of a sclerotic perimeter. No disturbance of the internal bony architecture of the sort caused by malignant bone tumors was encountered among the stress fracture candidates. No evidence of metabolic disorders like hyperparathyroidism or hyperthyroidism was found in the specimens, either.After examining the bones of many kinds of dinosaur the researchers noted that Allosaurus had a significantly greater number of bulges on the shafts of its hand and foot bones than the tyrannosaur Albertosaurus, or the ostrich dinosaurs Ornithomimus and Archaeornithomimus.
A stress fracture is a fatigue-induced bone fracture caused by repeated stress over time. Instead of resulting from a single severe impact, stress fractures are the result of accumulated injury from repeated submaximal loading, such as running or jumping. Because of this mechanism, stress fractures are common overuse injuries in athletes.Stress fractures can be described as small cracks in the bone, or hairline fractures. Stress fractures of the foot are sometimes called "march fractures" because of the injurys prevalence among heavily marching soldiers. Stress fractures most frequently occur in weight-bearing bones of the lower extremities, such as the tibia and fibula (bones of the lower leg), metatarsal and navicular bones (bones of the foot). Less common are stress fractures to the femur, pelvis, and sacrum. Treatment usually consists of rest followed by a gradual return to exercise over a period of months. Signs and symptoms
Stress fractures are typically discovered after a rapid increase in exercise. Symptoms usually have a gradual onset, with complaints that include isolated pain along the shaft of the bone and during activity, decreased muscular strength and cramping. In cases of fibular stress fractures, pain occurs proximal to the lateral malleolus, that increases with activity and subsides with rest. If pain is constantly present it may indicate a more serious bone injury. There is usually an area of localized tenderness on or near the bone and generalized swelling in the area. Pressure applied to the bone may reproduce symptoms and reveal crepitus in well-developed stress fractures.