Current Options for Determining Fracture Union

Determining whether a bone fracture is healed is one of the most important and fundamental clinical determinations made in orthopaedics. However, there are currently no standardized methods of assessing fracture union, which in turn has created significant disagreement among orthopaedic surgeons in both clinical and research settings. An extensive amount of research has been dedicated to finding novel and reliable ways of determining healing with some promising results. Recent advancements in imaging techniques and introduction of new radiographic scores have helped decrease the amount of disagreement on this topic among physicians. The knowledge gained from biomechanical studies of bone healing has helped us refine our tools and create more efficient and practical research instruments. Additionally, a deeper understanding of the molecular pathways involved in the bone healing process has led to emergence of serologic markers as possible candidates in assessment of fracture union. In addition to our current physician centered methods, patient-centered approaches assessing quality of life and function are gaining popularity in assessment of fracture union. Despite these advances, assessment of union remains an imperfect practice in the clinical setting. Therefore, clinicians need to draw on multiple modalities that directly and indirectly measure or correlate with bone healing when counseling patients. 1. Introduction There are about 6 million fractures in the United States annually and 5–10% of these fractures proceed to nonunion [1]. The risk of nonunion is increased based on certain patient factors such as smoking habit or diabetes and varies by location of fracture with those of the scaphoid waist, neck of femur, and open fractures of the tibia being especially susceptible [2–6]. Nonunions are associated with significantly higher rate of healthcare resource use, drastically higher per patient cost, and use of stronger opioid medications [7–10]. Infection can present as a delay or failure of fracture repair, and the clinician should always consider this in the differential diagnosis. Determining when a fracture is healed is a routine part of orthopaedic clinical care. It is crucial to making the right clinical decision for patients including determining their weight-bearing status, appropriate time for hardware removal, and diagnosis and treatment of nonunions. It is also tremendously important in interpreting research studies on treatment and therapeutics of fracture repair. Therefore, a valid and standard definition of fracture union should be an