A Targeting Arm for Interlocking Screws Reduces Radiation Exposure: Results of a Prospective Randomized Controlled Trial.

Abstract

Objectives: To compare time, fluoroscopic utilization, and number of misses for placement of far interlocking screws in tibial and femoral nails using a targeting arm (Targeter) versus perfect circle technique (Control).

Methods design: Prospective randomized controlled trial.

Setting: Single-center, large, urban, level 1 trauma center.

Patient selection criteria: Patients ≥ 18 years old with a tibia or femur fracture (AO/OTA 31A, 32, or 42) treated with an intramedullary nail from November 2022 to December 2023 were included.Outcome Measures and Comparisons: The main outcome measures were number of fluoroscopy images taken and average time elapsed to place each far interlocking screw. The far interlocking screws were defined as the screws farthest from the insertion handle. Comparisons were made between the Targeter and Control cohorts in terms of number of fluoroscopy images taken and average time elapsed to place each far interlocking screw, and the number of misses.

Results: 31 patients were randomized to Targeter and 31 to Control. There were no significant differences between the Targeter and Control cohorts in patient sex (58.6% vs 54.5% female, p=0.75), age (range (20-90 vs 18-91, mean 52.7 vs 54.2, p=0.81), BMI (mean 25.9 vs 26.2, p=0.66), AO classification (13.8% vs 36.4% 31A, 37.9% vs 21.2% 32, 48.2% vs 42.4% 42, p= 0.20), or number of open fractures (13.8% vs 7.1%, p= 0.67) between the two cohorts. For the Targeter group, fewer images were used compared to Controls for the first (15.0 vs 22.5, p= 0.002), second (11.5 vs 18.0, p= 0.006), and combined first and second (25.0 vs 39.0, p = 0.001) screws. There was no difference between the Targeter and Control cohorts in the time it took to place the first (6.3 vs 7.3 min, p= 0.31), second (5.8 vs 6.2 min, p= 0.63), or combined first and second (11.9 vs 13.7 min, p= 0.63) screws. In the Control cohort, there was one missed screw (1.4%, n=69). In the Targeter cohort, there were three missed screws (5.4%, n=56), a 4-fold increase that did not reach statistical significance (p=0.31).

Conclusions: In this prospective randomized controlled trial, a targeting arm decreased the number of fluoroscopic images used for all far interlocking screws as compared to the perfect circle technique without a reduction in time. There was a trend towards increased misses in the Targeter cohort (p=0.31). While the reduction in radiation exposure may have a cumulative beneficial effect over the course of a surgeon's career, the trend of increased misses with the Targeter should be taken into account.

Level of evidence: level I.