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. 2024 Jun 18;29(1):336.
doi: 10.1186/s40001-024-01892-7.

Changes in nail position and antirotation blade angles on the risk of femoral head varus in PFNA fixed patients: a clinical review and comprehensive biomechanical research

Chenyi Huang #  1 , Wenqiang Xu #  2 , Xiong Ye  1 , Wanying Hong  2 , Yue Xu  3 , Zongchao Liu  4 , Jingchi Li  5
Affiliations

Changes in nail position and antirotation blade angles on the risk of femoral head varus in PFNA fixed patients: a clinical review and comprehensive biomechanical research

Chenyi Huang et al. Eur J Med Res. .

Abstract

Background: Femoral head varus triggers poor clinical prognosis in intertrochanteric fracture patients with proximal femoral nail antirotation (PFNA) fixation. Studies present that changes in nail position and screw insertion angles will affect fixation stability, but the biomechanical significance of these factors on the risk of femoral head varus has yet to be identified in PFNA fixed patients.

Methods: Clinical data in PFNA fixed intertrochanteric fracture patients have been reviewed, the relative position of intermedullary nail has been judged in the instant postoperative lateral radiography. Regression analyses have been performed to identify the effect of this factor on femoral head varus. Corresponding biomechanical mechanism has been identified by numerical mechanical simulations.

Results: A clinical review revealed that ventral side nail insertion can trigger higher risk of femoral head varus, corresponding numerical mechanical simulations also recorded poor fixation stability in models with ventral side nail insertion, and changes in the trajectory of anti-rotation blade will not obviously affect this tendency.

Conclusions: Ventral side insertion of intramedullary nail can trigger higher risk of femoral head varus in PFNA fixed patients by deteriorating the instant postoperative biomechanical environment, and changes in blade trajectory cannot change this tendency biomechanically. Therefore, this nail position should be adjusted to optimize patients' prognosis.

Keywords: Femoral head varus; Fixation stability; Intertrochanteric fracture; Intramedullary nail position changes; Proximal femoral nail anti-rotation.

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Conflict of interest statement

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

Figures

Fig. 1
Fig. 1
Schematic of patient inclusion and exclusion and measurement of imaging-based parameters
Fig. 2
Fig. 2
Schematic for the construction of PFNA fixed AO 3.1 A 2.3 type of intertrochanteric fracture models with different nail positions and anti-rotation blade trajectories
Fig. 3
Fig. 3
Typical case with ventral shifted intramedullary nail position, and obvious femoral head varus during the 6 month follow-up period
Fig. 4
Fig. 4
Boundary and loading conditions of numerical simulations and computational results obtained using different models
Fig. 5
Fig. 5
Nephograms of stress distributions on the anti-rotation blade under 2100N compressive load
See this image and copyright information in PMC

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