Freehand distal interlocking of intramedullary nails remains a challenging task. If not performed correctly it can be a time consuming and radiation expensive procedure. Recently, the AO Research Institute developed a new training device for Digitally Enhanced Hands-on Surgical Training (DEHST) that features practical skills training augmented with digital technologies, potentially improving surgical skills needed for distal interlocking. Aim of the study: To evaluate weather training with DEHST enhances the performance of novices without surgical experience in free-hand distal nail interlocking compared to a non-trained group of novices.

20 novices were assigned in two groups and performed distal interlocking of a tibia nail in an artificial bone model. Group 1: DEHST trained novices (virtual locking of five nail holes during one hour of training). Group 2: untrained novices without DEHST training. Time, number of x-rays, nail hole roundness, critical events and success rates were compared between the groups.

Time to complete the task (sec.) and x-ray exposure (µGcm2) were significantly lower in Group1 414.7 (290–615) and 17.8 (9.8–26.4) compared to Group2 623.4 (339–1215) and 32.6 (16.1–55.3); p=0.041 and 0.003. Perfect circle roundness (%) was 95.0 (91.1–98.0) in Group 1 and 80.8 (70.1–88.9) in Group 2; p<0.001. In Group 1 90% of the participants achieved successful completion of the task (hit the nail with the drill), whereas only 60% of the participants in group 2 achieved this; p=0.121.

Training with DEHST significantly enhances the performance of novices without surgical experience in distal interlocking of intramedullary nails. Besides radiation exposure and operation time the com-plication rate during the operation can be significantly reduced.

Freehand distal interlocking of intramedullary nails is technical demanding and prone to handling issues. It requires the surgeon to precisely place a screw through the nail under x-ray. If not performed accurately it can be a time consuming and radiation expensive procedure. The aims of this study were to assess construct and face validity of a new training device for distal interlocking of intramedullary nails.

53 participants (29 novices and 24 experts) were included. Construct validity was evaluated by comparing simulator metrics (number of x-rays, nail hole roundness, drill tip position and accuracy of the drilled hole) between experts and novices. Face validity was evaluated by means of a questionnaire concerning training potential and quality of simulated reality using a 7-point Likert scale (range 1-7).

Mean realism of the training device was rated 6.3 (range 4-7) and mean training potential as well as need for distal interlocking training was rated 6.5 (range 5-7) with no significant differences between experts and novices, p≥0.236. All participants stated that the simulator is useful for procedural training of distal nail interlocking, 96% would like to have it at their institution and 98% would recommend it to their colleagues. Total number of x-rays were significantly higher for novices (20.9±6.4 vs. 15.5±5.3), p=0.003. Successful task completion (hit the virtual nail hole with the drill) was significantly higher in experts (p=0.04; novices hit: n=12; 44,4%; experts hit: n=19; 83%).

The evaluated training device for distal interlocking of intramedullary nails yielded high scores in terms of training capability and realism. Furthermore, construct validity was established as it reliably discriminates between experts and novices. Participants see a high further training potential as the system may be easily adapted to other surgical task requiring screw or pin position with the help of x-rays.