CORD Conference
June 15, 2013
A Novel Approach to Teaching Visual-spatial Skills in Wire Navigated Procedures
Jenniefer Y. Kho, MD, JL Marsh, MD, Geb Thomas, PhD, Brian Johns, MS, Don Anderson, PhD
University of Iowa Hospitals and Clinics, Iowa City, IA
Purpose - Fluoroscopic-guided wire navigation, or the ability to drive a wire from one precise location to another, is a
fundamental skill in orthopaedic surgery. We propose that a radiation free electromagnetic sensor-based wire navigation
simulator in a proximal femur model will 1) improve novice surgeons’ (PGY-1 residents) performance in actual fluoroscopic
navigation of a wire in a Sawbones model, and will 2) differentiate expert surgeons from novice surgeons.
Methods - We developed a surgical simulator that targets wire navigation
into the femoral head for hip fracture fixation. Electromagnetic sensors
were used to detect the position of a wire in relation to an osseous femur
model. A real-time 3D projection of the proximal femur and position of
the wire was projected onto a computer screen (Figure 1). As a baseline,
six PGY-1 residents (novice group)
were tested on ability to place a
wire using fluoroscopic guidance
into the center-center position of
an osseous femoral head model,
Figure 1.
which was encased in synthetic
soft tissue (Figure 2). The residents then had three practice sessions on the
electromagnetic simulator, and were re-tested on the fluoroscopic simulation the
same day. Pre- and post-test assessments included tip-apex-distance (TAD), number of
fluoroscopy shots, number of attempts (wire repositioning), and time to completion.
TAD measurements were calculated from saved fluoroscopic anteroposterior and
lateral shots of the final wire position. Expert surgeons (five PGY-4, 1 PGY-3 residents
and four attending surgeons) were assessed on simulator performance as well, and
Figure 2. compared to the novice group.
Results – In the novice group, the mean post-test TAD increased by 5.6mm (p=0.23), while all other parameters decreased
with training (Table 1). There was a statistically significant decrease in mean number of fluoroscopy shots (-9.8, p=0.045) and
time to completion (2 minutes 50 seconds, p=0.012). Number of attempts was also reduced (-3.67, p=0.08). Expert surgeons
had decreased TAD on the simulator compared to novice surgeons (p=0.006) (Table 2). There was decreased fluoroscopic
shots (p=0.05) and time (p=0.0012) with simulator practice, although TAD remained unchanged (p=0.96) (Figure 3).
Table 1. Pretest vs posttest (PGY-1)
Tip-apex distance, mm (TAD)
Number of fluoroscopy shots
Number of attempts
Time (mins)
Pre-test (Mean+SD)
19.46+2.15
36.85+13.73
5.83+4.16
8:00
Post-test (Mean+SD)
25.02+8.79
27+9.27
2.16+1.83
5:11
p-value
0.23
0.045
0.08
0.012
Table 2. Novice versus expert surgeons
Pre-test (Mean+SD)
21.46+7.11
33+13.78
3:16
Tip-apex distance, mm (TAD)
Number of fluoroscopy shots
Time (mins)
Post-test (Mean+SD)
12.69+3.9
29.6+12.30
2:32
p-value
0.006
0.62
0.17
Figure 3.
PGY-4
50
45
40
35
30
25
20
15
10
5
0
4:48
Staff
Time (min)
# fluoro shots
PGY-1
3:36
2:24
1:12
Trial 1
Trial 2
Trial 3
0:00
Trial 1
Trial 2
Trial 3
25
TAD (mm)
20
15
10
5
0
Trial 1
Trial 2
Trial 3
Conclusion - We developed a novel electromagnetic-based radiation free wire navigation simulator in a proximal femur
model that targets basic skills needed for hip fracture fixation. Expert surgeons had decreased TAD on the simulator
compared to novice surgeons. Novice surgeons who trained on the simulator had decreased number of attempts, less
fluoroscopic shots, and improved speed when tested on ability to place a wire into the femoral head in a soft-tissue
Sawbones model. Interestingly, TAD increased post-training, which may be due to residents accepting more error in trade of
speed and efficiency. Further studies would need to include a control group, a larger cohort, and validation studies that test
more experienced surgeons and assess skill retention and transfer of skills to the actual operating room.
This project was funded in part by National Board of Medical Examiners Edward J. Stemmler, MD Medical Education Research
Fund Grant. Grants from the Orthopaedic Research and Education Foundation and from the Orthopaedic Trauma Association
provided additional support.