Nerve Reconstruction: Improving outcome using allografts and stem cells in motor nerve repair

The overarching aim of this thesis is to improve nerve reconstruction using an off the shelf peripheral nerve allograft that is unlimited in supply and can be individualized to each patient using stem cells, providing functional recovery comparable to autograft nerve. In the first part, studies on the current clinical use of nerve grafts are presented. The clinical focus of this part is on brachial plexus injury, as these injuries typically require large amounts of donor nerve material that is frequently not available. The availability of an off the shelf alternative would be very beneficial in this field. Before implementing new nerve reconstruction strategies in vivo in animal models, we recognized there was a need for non-invasive follow-up methods. Therefore, in the second part of this thesis, we aimed to develop an ultrasound based evaluation technique to measure muscle recovery after nerve reconstruction in animal models. In the third part of this thesis, studies are presented that focus on the implementation and further improvement of the processed nerve allograft. Our previously optimized nerve allograft was implemented in different animal models. Results were promising, but did show there was further room for improvement. We hypothesized the need for a source of supportive and stimulating growth factors since allografts are devoid of cells that would provide this stimulus in autografts. We hypothesized that patient own adipose derived stem cells (MSCs) added to the nerve allograft could potentially produce these growth factors to further improve outcomes. A simple technique to deliver stem cells to the nerve allograft was developed. Finally, the interaction between MSCs and our optimized nerve allograft was evaluated with regard to growth factor production and gene expression. With this work, we have taken a promising path by using allografts and stem cells on our mission to improve nerve reconstruction

Can I handle the scalpel?:Different views on critical subtask assessment between residents and expert surgeons

Background: Success of surgical procedures largely depends on good judgment and decision making and these skills are mostly taught implicitly in the OR. Cognitive task analysis (CTA) has been used successful to elicit tacit expert knowledge to determine the decision points in a medical procedure and then use this in medical skill instructions. For instructions to be effective, it is also important that they are timed properly, that is, during low mental workload in the resident. Aim(s): As a start for further research, we therefore asked residents to indicate their mental workload during the steps of an orthopaedic procedure. Because in the OR, residents are commonly guided by supervisors, we also investigated which steps supervisors find mentally demanding. Methods: A task analysis of a total hip replacement procedure was constructed. Subsequently we asked both 17 orthopedic surgeons (supervisors) and 21 residents to rate (5-point scale) how much mental effort they invest in each subtask. They were asked to explain ratings above average (>3). Results: Although there were subtasks where supervisors and residents disagreed on the level of attention required, overall, supervisors and residents agreed for most subtasks. High attention was related to subtasks that require decision making skills. However, the reasons were different. In residents, high ratings were associated with subtasks that they found difficult, or where they were anxious about doing it accurately. Supervisors’ ratings were more correlated with the evaluation of crucial, i.e., point-of-no-return steps where quality of execution has important consequences for later steps, end result or complications. Discussion/Conclusion: Supervisors pay more attention to steps that will become important later in the procedure, whereas residents are more anxious about their own performance in crucial steps. It may be useful for supervisors and residents to be aware of this difference in interpretation of “important steps”