A mRUS Validation Study for Nail-treated Fractures of Long Bones and a TUS Exploratory Study for Nail and Plate-treated Fractures of Long Bones

Early intervention attempts to shorten protracted delayed union (DU) or prevent non-union (NU) fractures are hampered by lack of validated quantitative assessment tools for bone fracture healing during normal and delayed healing processes. In actual practice, sequential X-rays usually follow a pre-determined time interval in patients with fractures.They constitute the best available state of the art used by surgeons to assess the fracture healing course. In an attempt to improve between raters reliability of radiographic assessment of healing, studies have explored a novel radiographic assessment for tibial shaft fractures, the Radiographic Union Scale for Tibial Fractures (RUST). The RUST assesses the presence of bridging callus and a fracture line on each of four cortices (seen on anterior-posterior and lateral views). This callus based scoring system has been since extended to other bones than the tibia in a retrospective case series. It has been renamed modified radiological union score (mRUS) and has shown potential value in bone healing measurement. Based on an initial retrospective study in nail-treated fractures, the first objective of the present investigation is to prospectively validate mRUS as a tool to identify patients at increased risk of DU and NU within the first 75-110 days after fracture occurrence. This prospective validation will be performed on a retrospective cohort of patients having sustained long bone fractures, including both upper and lower extremities. A further objective of the present investigation is to apply the scoring system to tomographic imaging in case of nail/plate treated fractures, deriving a tomographic union score (TUS) and first assess its potential value in bone healing for fractures treated by nails/plates.