Radiographically occult and subtle fractures are a diagnostic challenge. They may be divided into (1) “high energy trauma fracture,” (2) “fatigue fracture” from cyclical and sustained mechanical stress, and (3) “insufficiency fracture” occurring in weakened bone (e.g., in osteoporosis and postradiotherapy). Independently of the cause, the initial radiographic examination can be negative either because the findings seem normal or are too subtle. Early detection of these fractures is crucial to explain the patient’s symptoms and prevent further complications. Advanced imaging tools such as computed tomography, magnetic resonance imaging, and scintigraphy are highly valuable in this context. Our aim is to raise the awareness of radiologists and clinicians in these cases by presenting illustrative cases and a discussion of the relevant literature. 1. Introduction Radiographically occult and subtle fractures are a common diagnostic challenge in daily practice. Indeed, fractures represent up to 80% of the missed diagnoses in the emergency department [1]. Failure to recognize the subtle signs of osseous injury is one of the reasons behind this major diagnostic challenge [2]. While occult fractures present no radiographic findings, radiographically subtle fractures are easily overlooked on initial radiographs. In both cases, a negative radiographic diagnosis with prominent clinical suspicion of osseous injury will prompt advanced imaging examination such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine to confirm or exclude the clinically suspected diagnosis. The burden entailed in missing these fractures includes prolonged pain with a loss of function, and disability. Early detection, on the other hand, enables more effective treatment, a shorter hospitalization period if necessary, and decreased medical costs in the long run. It will also prevent inherent complications such as nonunion, malunion, premature osteoarthritis, and avascular osteonecrosis (as in scaphoid fracture) [3]. Occult and subtle fractures may be divided into: (1) fractures associated with high energy trauma; (2) fatigue fracture secondary to repetitive and unusual stress being applied to bone with normal elastic resistance; and (3) insufficiency fracture resulting from normal or minimal stress on a bone with decreased elastic resistance [4]. The term “stress fracture” is more general and encompasses both of the latter two entities [5]. Pediatric and microtrabecular fractures—known as bone bruises and contusions—are outside the scope of this
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