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. Significance This first-in-kind, perfused, and amputated human limb model allows for the collection of human data in preclinical selection of lead fluorescent agents. The model facilitates more accurate selection and testing of fluorophores with human-specific physiology, such as differential uptake and signal in fat between animal and human models with zero risk to human patients. Preclinical testing using this approach may also allow for the determination of tissue toxicity, clearance time of fluorophores, and the production of harmful metabolites. Aim This study was conducted to determine the fluorescence intensity values and tissue specificity of a preclinical, nerve tissue targeted fluorophore, as well as the capacity of this first-in-kind model to be used for lead fluorescent agent selection in the future. Approach Freshly amputated human limbs were perfused for 30 min prior to in situ and ex vivo imaging of nerves with both open-field and closed-field commercial fluorescence imaging systems. Results In situ , open-field imaging demonstrated a signal-to-background ratio (SBR) of 4.7 when comparing the nerve with adjacent muscle tissue. Closed-field imaging demonstrated an SBR of 3.8 when the nerve was compared with adipose tissue and 4.8 when the nerve was compared with muscle. Conclusions This model demonstrates an opportunity for preclinical testing, evaluation, and selection of fluorophores for use in clinical trials as well as an opportunity to study peripheral pathologies in a controlled environment.

Importance Chronic, non-cancer pain affects approximately 20–30% of the population in North America, Europe, and Australia, with surgery and trauma frequently cited as inciting events. Prospective studies of fracture patients have demonstrated an association between somatic pre-occupation, poor coping, and low recovery expectations following surgery with persistent pain, functional limitations, and lower rates of return to work. Psychological interventions, such as cognitive behavioural therapy (CBT), that are designed to modify unhelpful beliefs and behaviours have the potential to reduce persistent post-surgical pain and its associated effects among trauma patients. Objective To determine whether online CBT, versus usual care, reduces the prevalence of moderate to severe persistent post-surgical pain among participants with an open or closed fracture of the appendicular skeleton. Design, setting, and participants The Cognitive Behavioural Therapy to Optimize Post-Operative Fracture Recovery (COPE) protocol will be followed to conduct a multi-centre randomized controlled trial. Participants undergoing surgical repair of a long bone fracture will be randomized to receive either (1) online CBT modules with asynchronous therapist feedback or (2) usual care. The primary outcome will be the prevalence of moderate to severe persistent post-surgical pain over 12 months post-fracture. Secondary outcomes include the Short Form-36 Physical and Mental Component Summary scores, return to function, pain severity and pain interference over 12 months post-fracture, and the proportion of patients prescribed opioid class medications (and average dose) at 6 and 12 months post-fracture. The COPE trial will enroll 1000 participants with open and closed fractures of the appendicular skeleton from approximately 10 hospitals in North America. Discussion If CBT is effective in improving outcomes among patients with traumatic fractures, our findings will promote a new model of care that incorporates psychological barriers to recovery. Trial registration ClinicalTrials.gov Identifier: NCT04274530. Registered on 14 February 2020.

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Indocyanine green (ICG)-based dynamic contrast-enhanced fluorescence imaging (DCE-FI) can objectively assess bone perfusion intraoperatively. However, it is susceptible to motion artifacts due to patient’s involuntary respiration during the 4.5-minute DCE-FI data acquisition. An automated motion correction approach based on mutual information (MI) frame-by-frame was developed to overcome this problem. In this approach, MIs were calculated between the reference and the adjacent frame translated and the maximal MI corresponded to the optimal translation. The images obtained from eighteen amputation cases were utilized to validate the approach and the results show that this correction can significantly reduce the motion artifacts and can improve the accuracy of bone perfusion assessment.