Modified cannulated screw fixation in the treatment of Pauwels type III femoral neck fractures: A biomechanical study

Objective: Pediatric femoral neck fractures are uncommon injuries. Accurate early reduction and fixation is recommended to avoid serious long-term complications. The aim of this study was to analyze the clinical and radiological outcomes of 12 children with femoral neck fractures who were treated with closed reduction and cannulated screw fixation. Method: Between November 2015 and December 2019, 12 children (4 males,8 females) with an average age of 9.7 were operated by closed reduction and cannulated screw fixation for femoral neck fractures. We evaluated the medical records of all patients, including age, gender, injury mechanism, fracture type, initial displacement, postoperative reduction, follow-up roentgenograms and Ratliff’s scores. Results: The mean follow-up was 22.3 months (range 12–47 months). Six Delbett type 2, five Delbett type 3 and one Delbett type 4 fractures were operated with an avarage time to surgery of 12.5 (range: 1-75 hours). Satisfactory outcomes according to Ratliff’s criteria were obtained in 10 (%83.3) children. Coxa vara occurred in 2 cases. Any avascular necrosis was not seen during the follow-up period. Conclusion: Early closed reduction and cannulated screw fixation may be effective to avoid long-term complications in pediatric femoral neck fractures. Keywords: Femoral neck fracture, Pediatric, Closed reduction

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Modified F Configuration in the Treatment of Pauwels Type III Femoral Neck Fracture: a Finite Element Analysis

10.21203/rs.3.rs-135954/v1 ◽

2021 ◽

Author(s):

Shiyuan Lin ◽

Huizi Li ◽

Kai Tong ◽

Zihang Feng ◽

Gang Wang ◽

...

Keyword(s):

Finite Element ◽

Stress Distribution ◽

Femoral Neck ◽

Femoral Neck Fracture ◽

Femoral Neck Fractures ◽

Cannulated Screw ◽

Type Iii ◽

Neck Fracture ◽

Maximum Crack ◽

Hip Screw

Abstract Background: The optimal treatment of Pauwels type III femoral neck fracture in young patients remains a worldwide challenge in orthopedic surgery. Methods: Finite element models of four internal fixations were developed to treat Pauwels type III Femoral neck fracture: a: the traditional inverted triangular cannulated screw model, b: the F-technique cannulated screw model, c: the modified F-technique cannulated screw model using a fully threaded screw instead of a partially threaded distally, d: the dynamic hip screw coupled with anti-rotational screw model. Under the same conditions, finite element analyses were carried out to compare the displacement and von Mises stress distribution of four internal fixations and femurs, the maximum crack distances of the fracture surfaces, Z axis displacements of four models as well as the stress distribution in the subtrochanteric region. Results: The modified F-technique configuration resulted in a more stable fixation as compared to the other three approaches, with respect to the maximum displacement and stress peaks of femur and internal fixations, the maximum crack distances of the fracture surfaces, Z axis displacements of four configurations as well as the stress distribution in the subtrochanteric region.Conclusions: Our results suggested that modified F-technique configuration show a better performance in resisting shearing and rotational forces in treating Pauwels type III femoral neck fractures compared to those using traditional inverted triangular, the F-technique configuration or dynamic hip screw coupled with anti-rotational screw, providing a new choice for the treatment of femoral neck fractures.

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