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. 2023 Mar 17:10:1142135.
doi: 10.3389/fsurg.2023.1142135. eCollection 2023.

A new posterosuperior screw placement strategy to avoid in-out-in screws in femoral neck fractures

Shi-Jie Li  1 , Shou-Chao Du  1 , Sun-Jun Hu  1 , Shi-Min Chang  1 , Ying-Qi Zhang  1   2
Affiliations

A new posterosuperior screw placement strategy to avoid in-out-in screws in femoral neck fractures

Shi-Jie Li et al. Front Surg. .

Abstract

Objective: The inverted triangle configuration of the three cannulated screws is the classic fixation method most commonly performed for undisplaced femoral neck fractures in young and geriatric patients. However, the posterosuperior screw has a high incidence of cortical breach, known as an in-out-in (IOI) screw. In this study, we present a novel posterosuperior screw placement strategy to prevent the screw from becoming IOI.

Methods: Using computed tomography data and image-processing software, 91 undisplaced femoral neck fractures were reconstructed. The anteroposterior (AP), lateral, and axial radiographs were simulated. To simulate the intraoperative screw placement process, participants used three screw insertion angles (0°, 10°, and 20°) to place the screw on the AP and lateral views of the radiograph according to the three established strategies. On the AP radiograph, a screw was placed abutting (strategy 1), 3.25 mm away from (strategy 2), or 6.5 mm away from (strategy 3) the superior border of the femoral neck. On the lateral radiograph, all the screws were placed abutting the posterior border of the femoral neck. Axial radiographs were used to evaluate the screw position.

Results: In strategy 1, all the placed screws were IOI regardless of the screw insertion angle. In strategy 2, 48.3% (44/91) of IOI screws occurred at a 0° screw insertion angle, 41.7% (38/91) of IOI screws occurred at a 10° screw insertion angle, and 42.9% (39/91) of IOI screws occurred at a 20° screw insertion angle situation. In strategy 3, no IOI screw occurred, and the screw insertion angles did not affect the safety and accuracy of screw placement.

Conclusions: Screws placed according to strategy 3 are safe. The reliability of this screw placement strategy is unaffected by a screw insertion angle of less than 20 degrees.

Keywords: femoral neck fracture; femoral neck safe zone; in-out-in; insertion angle; screw placement strategy.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Simulated (A) AP, (B) lateral, and (C) axial views of the radiograph.
Figure 2
Figure 2
Three insertion angles of the screw including (A) 0°, (B) 10°, and (C) 20°.
Figure 3
Figure 3
Three screw placement strategies and corresponding axis radiographs.
Figure 4
Figure 4
Typical (A) excellent, (B) poor, and (C) acceptable screw positions in the axial radiograph.
See this image and copyright information in PMC

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