Abstract
Purpose
To evaluate the use of cutaneous marking of the sacrum for percutaneous iliosacral screw fixation. Iliosacral screw placement is dependent upon spatial perception, multiplanar fluoroscopic imaging, and an appreciation of pelvic anatomy which often makes learning the technique difficult for residents. Cutaneous marking of the sacrum may facilitate iliosacral screw insertion by providing additional cues to the orientation of the sacrum.
Method
A cross-over study design was used for placing iliosacral screws in whole cadaver specimens using standardized operative and imaging techniques with and without cutaneous sacral markings. Lateral fluoroscopic imaging and a radio-opaque straight edge were used to trace the lateral profile of the sacrum with a marking pen. Total procedure time and fluoroscopy time were recorded. A total of 14 residents (6 seniors and 8 juniors) each placed two iliosacral screw guide-wires in a total of seven whole cadavers (14 SI joints). Group 1 performed the procedure first with no markings and then with markings. Group 2 performed the procedure first with markings and then without markings. Statistical analysis included T test, Wilcoxon Rank Sum Test, and Signed-Rank Test for Difference (p = 0.05). Participants also reported their opinions on each technique.
Results
Mean procedure time for Group 1 was 8.83 minutes (3.77 17.17) and mean fluoroscopy time was 0.77 minutes (0.4 1.2) for the no-marking attempt and 10.33 min (5.88 15.25) and 1.06 min (0.6 2.3) respectively for the marking attempt. Mean procedure time for Group 2 was 11.3 min (6.33 16.5) and mean fluoroscopy time was 1.19 min (0.6 2.3) for the marking attempt and 7.22 min (2.83 17.27) and 0.97 min (0.4 1.8) respectively for the no-marking attempt. There were no significant differences between groups. T test analysis of all marking vs. no marking showed no significant difference for total procedure time (p= O.7020) or fluoroscopy time (p= 0.8297). Wilcoxon Rank Sum Test analysis showed no significant difference for total procedure time (p= 0.4415) or fluoroscopy time (p=0.7486) and Signed-Rank Test for Difference showed no significant difference for total procedure time (p=0.0625) or fluoroscopy time (p=0.1459). Senior residents reported they found the cutaneous marking helpful and would use it again whereas junior residents had mixed feelings on its utility.
Conclusion
Cutaneous marking of the sacrum did not significantly impact total procedure time or fluoroscopy time but was generally reported to be helpful for residents learning percutaneous iliosacral screw fixation.
