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Review
. 2024 May 23;25(1):405.
doi: 10.1186/s12891-024-07334-z.

Extending the intermedullary nail will not reduce the potential risk of femoral head varus in PFNA patients biomechanically: a clinical review and corresponding numerical simulation

Xiaofeng Cha  1 , Qin Zhou  1 , Jujie Li  1 , Hong Xu  1 , Wenqiang Xu  2 , Jingchi Li  3
Affiliations
Review

Extending the intermedullary nail will not reduce the potential risk of femoral head varus in PFNA patients biomechanically: a clinical review and corresponding numerical simulation

Xiaofeng Cha et al. BMC Musculoskelet Disord. .

Abstract

Femoral head varus is an important complication in intertrochanteric fracture patients treated with proximal femoral nail anti-rotation (PFNA) fixation. Theoretically, extending the length of the intramedullary nail could optimize fixation stability by lengthening the force arm. However, whether extending the nail length can optimize patient prognosis is unclear. In this study, a review of imaging data from intertrochanteric fracture patients with PFNA fixation was performed, and the length of the intramedullary nail in the femoral trunk and the distance between the lesser trochanter and the distal locking screw were measured. The femoral neck varus status was judged at the 6-month follow-up. The correlation coefficients between nail length and femoral neck varus angle were computed, and linear regression analysis was used to determine whether a change in nail length was an independent risk factor for femoral neck varus. Moreover, the biomechanical effects of different nail lengths on PFNA fixation stability and local stress distribution have also been verified by numerical mechanical simulations. Clinical review revealed that changes in nail length were not significantly correlated with femoral head varus and were also not an independent risk factor for this complication. In addition, only slight biomechanical changes can be observed in the numerical simulation results. Therefore, commonly used intramedullary nails should be able to meet the needs of PFNA-fixed patients, and additional procedures for longer nail insertion may be unnecessary.

Keywords: Case-comparative study; Femoral head varus; Finite element analysis; Intermedullary nail length; PFNA.

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Conflict of interest statement

The authors have no conflicts of interest to disclose in relation to this article.

Figures

Fig. 1
Fig. 1
Schematic for patient inclusion and exclusion
Fig. 2
Fig. 2
The measurement of imaging parameters: The length of the intramedullary nail in the femoral trunk (D1), the distance between the lesser trochanter and the distal locking screw (D2), and the femoral head varus values, TAD in the anterior-posterior radiography (D3), and the distance between femoral calcar and the anti-rotation blade (D4)
Fig. 3
Fig. 3
Schematic for numerical model construction, and surgical simulations in models with different length of the intramedullary nail in the femoral trunk, and different distances between the lesser trochanter and the distal locking screw
Fig. 4
Fig. 4
Boundary and loading conditions for numerical simulation, computational results in different models
Fig. 5
Fig. 5
Nephograms for anti-rotation blade stress distributions: Slight difference in stress distribution can be observed in different numerical models
See this image and copyright information in PMC

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