 Introduction/Background Stress fractures occur in 2 varieties: 1) fatigue fractures resulting from repetitive submaximal stress on normal bone, resulting in a region of accelerated bone remodeling [1] and 2) insufficiency fractures due to normal activity on bones that are deficient in microstructure and/or mineralization [2]. At the microscopic level, repetitive overloading leads to increased osteoclastic activity that exceeds the rate of osteoblastic new bone formation. This results in bone weakening and microtrabecular disruption (stress injury) and eventually may lead to a cortical break (stress fracture). Stress fractures are encountered frequently and account for up to 20% of all injuries seen in sports medicine clinics [1,3-6]. The fatigue variation of stress fractures are particularly common in athletes participating in activities that require running and jumping, as well as in ballet dancers and military recruits [7-9]. Certain medical interventions such as radiation therapy and long-term osteoporosis treatment with bisphosphonates predispose patients to the insufficiency variation of stress fractures [10-12]. OR Discussion of Procedures by Variant Variant 1: Adult. Suspect stress fracture, excluding vertebrae. Initial imaging. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. In the setting of new or repetitive athletic activity, fatigue fractures can develop in patients with normal bone. Furthermore, certain athletic activities often result in specific sites of fatigue fracture, such as olecranon process fractures in javelin throwers and baseball pitchers, proximal femur and tibial stress fractures in runners, and tarsal navicular stress fractures in basketball players [13-15]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis or irradiated bone, as typical examples.
Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs.  Introduction/Background Stress fractures occur in 2 varieties: 1) fatigue fractures resulting from repetitive submaximal stress on normal bone, resulting in a region of accelerated bone remodeling [1] and 2) insufficiency fractures due to normal activity on bones that are deficient in microstructure and/or mineralization [2]. At the microscopic level, repetitive overloading leads to increased osteoclastic activity that exceeds the rate of osteoblastic new bone formation. This results in bone weakening and microtrabecular disruption (stress injury) and eventually may lead to a cortical break (stress fracture). Stress fractures are encountered frequently and account for up to 20% of all injuries seen in sports medicine clinics [1,3-6]. The fatigue variation of stress fractures are particularly common in athletes participating in activities that require running and jumping, as well as in ballet dancers and military recruits [7-9]. Certain medical interventions such as radiation therapy and long-term osteoporosis treatment with bisphosphonates predispose patients to the insufficiency variation of stress fractures [10-12]. OR Discussion of Procedures by Variant Variant 1: Adult. Suspect stress fracture, excluding vertebrae. Initial imaging. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. In the setting of new or repetitive athletic activity, fatigue fractures can develop in patients with normal bone. Furthermore, certain athletic activities often result in specific sites of fatigue fracture, such as olecranon process fractures in javelin throwers and baseball pitchers, proximal femur and tibial stress fractures in runners, and tarsal navicular stress fractures in basketball players [13-15]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis or irradiated bone, as typical examples.