Mylène Jansen

User-friendliness of a dedicated KJD device 139 7 The shortened surgical procedure (21% time reduction) is considered not only beneficial for the surgeon, but also for the patient (shorter sedation, reducing risks for complications, e.g. surgical wound infection) and reduces healthcare costs by shortening the operating room occupation. The time difference is not considered attributable to a learning curve from the CD device as the surgeon performing the surgeries with the DD device already had extensive experience with the CD device following a similar surgical procedure. As such, the time difference is considered to result from improved user-friendliness for the DD device. It was noticeable that the incidence of pin tract infections was lower in the DD device group, although the difference was statistically significant only in patients who filled out the user- friendliness questionnaire and not in the whole group. The total number of complications seemed somewhat less in the DD group as well, although because of the low occurrence of complications other than pin tract infections and limited sample size this outcome could be influenced by coincidence. Pin tract infections are considered a significant and well-known burden of treatment with external fixator devices, as is the case in KJD. 18 The reduced number of patients with pin tract infections in the DD group fits with the patients’ experience that pin tract care is easier in the DD device compared to the CD device , which means the DD device seems to be successful in making pin tracts are accessible for pin tract care. This might indicate that difficulties in performing pin care increase the risk of pin tract infection development. On the other hand, the effect is could be related to differences in patient instructions for performing pin tract care as well. However, despite the reduction, the incidence is still high and extra attention in future developments towards improvement of treatment is demanded. In general, all parameters related to patient user-friendliness were in favor of the DD device, some reaching statistically significance. For the 3 aspects that patients reported as most relevant for user-friendliness, the questions concerning harm to the contralateral leg and the pin tract care showed statistically significant improvement for the DD device, while the 22% improvement regarding the aspect of catching clothes was not statistically significant on group level. The latter aspect is likely inherent to the use of any externally fixated distraction device, regardless of minimization of protruding parts. Still, like the question concerning harm to the other leg, the significantly improved scores of finding suitable/fitting clothes and damage to bedding seen for the DD device are likely the result of the fact that no protruding parts are present above the most proximal and below the most distal bone pin and protruding bone pins are shielded. The fact that patients using the DD device indicated they could better resume daily activities seems to be the result of a combination of improvements in device characteristics as described in Table 1. Further improvement of the system should involve critical analysis of the defined device characteristics including clinical experiences from this study. Specifically, characteristics that may have high impact on patients during treatment should be carefully considered for evolvement of the device. In this respect, especially the items ‘providing pin