TY - JOUR
T1 - Retrograde Stainless Steel Flexible Nails Have Superior Resistance to Bending in Distal Third Femoral Shaft Fractures
AU - Hubbard, Elizabeth W.
AU - Thompson, Rachel M.
AU - Jo, Chan Hee
AU - Pierce, William A.
AU - Riccio, Anthony Ian
AU - Wimberly, Robert L
N1 - Funding Information:
From the *Duke University Medical Center, Durham NC; †University of California Los Angeles, Orthopaedic Institute for Children, Los Angeles, CA; and ‡Texas Scottish Rite Hospital for Children, Dallas, TX. No financial support was provided for this study but implants were donated by OrthoPediatrics and Smith and Nephew. The authors declare no conflicts of interest. Reprints: Elizabeth W. Hubbard, MD, 3000 Erwin Road, Rm 100, Durham, NC 27705. E-mail: Elizabeth.hubbard@duke.edu. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/BPO.0000000000001301
Publisher Copyright:
© Copyright 2018 Wolters Kluwer Health, Inc. All rights reserved.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
PY - 2019/4/1
Y1 - 2019/4/1
N2 - Background: It has been shown that retrograde titanium flexible intramedullary nails (Ti FIN) provide superior resistance to bending compared to antegrade Ti FIN in distal femur fractures. The purpose of this study was to compare resistance to torsional and bending forces of stainless steel (SS) FIN, with or without a locking screw, and Ti FIN in distal third femoral shaft fractures. We hypothesize that locked retrograde SS FIN will demonstrate greater resistance to both bending and torsional forces. Methods: Thirty adolescent synthetic femur models were used to simulate transverse distal femoral fractures at either 60 mm or 90 mm proximal to the distal femoral physis. The femurs were instrumented with antegrade Ti FIN, antegrade SS FIN, retrograde Ti FIN, retrograde SS FIN, or retrograde locked SS FIN. Three models for each construct at both osteotomy levels were tested. Models were analyzed to determine maximum resistance to bending and torsion. Results: In fractures 60 mm from the physis, retrograde SS FIN demonstrated statistically superior resistance to bending when compared with both antegrade and retrograde Ti FIN (P=0.001 and 0.008, respectively) and antegrade SS FIN (P=0.0001). Locked SS constructs showed a trend towards greater resistance to bending forces when compared with unlocked constructs (P>0.05). No significant difference was seen in resistance to bending when fractures were 90 mm proximal to the distal femoral physis between the five groups. No significant differences were observed in resistance to torsion in either the proximal or distal fracture models, regardless of construct type. Conclusions: Retrograde SS FIN confer significantly greater resistance to bending forces for fractures 60 mm proximal to the distal femoral physis compared with Ti FIN or antegrade entry SS FIN. In fractures 90 mm from the physis, no differences were noted in our model. Our results support the use of retrograde SS nails in the pediatric patient with distal femoral shaft fractures. Level of Evidence: Level II-comparative biomechanical study.
AB - Background: It has been shown that retrograde titanium flexible intramedullary nails (Ti FIN) provide superior resistance to bending compared to antegrade Ti FIN in distal femur fractures. The purpose of this study was to compare resistance to torsional and bending forces of stainless steel (SS) FIN, with or without a locking screw, and Ti FIN in distal third femoral shaft fractures. We hypothesize that locked retrograde SS FIN will demonstrate greater resistance to both bending and torsional forces. Methods: Thirty adolescent synthetic femur models were used to simulate transverse distal femoral fractures at either 60 mm or 90 mm proximal to the distal femoral physis. The femurs were instrumented with antegrade Ti FIN, antegrade SS FIN, retrograde Ti FIN, retrograde SS FIN, or retrograde locked SS FIN. Three models for each construct at both osteotomy levels were tested. Models were analyzed to determine maximum resistance to bending and torsion. Results: In fractures 60 mm from the physis, retrograde SS FIN demonstrated statistically superior resistance to bending when compared with both antegrade and retrograde Ti FIN (P=0.001 and 0.008, respectively) and antegrade SS FIN (P=0.0001). Locked SS constructs showed a trend towards greater resistance to bending forces when compared with unlocked constructs (P>0.05). No significant difference was seen in resistance to bending when fractures were 90 mm proximal to the distal femoral physis between the five groups. No significant differences were observed in resistance to torsion in either the proximal or distal fracture models, regardless of construct type. Conclusions: Retrograde SS FIN confer significantly greater resistance to bending forces for fractures 60 mm proximal to the distal femoral physis compared with Ti FIN or antegrade entry SS FIN. In fractures 90 mm from the physis, no differences were noted in our model. Our results support the use of retrograde SS nails in the pediatric patient with distal femoral shaft fractures. Level of Evidence: Level II-comparative biomechanical study.
KW - distal femur fracture
KW - pediatric
KW - retrograde flexible intramedullary nail
KW - stainless steel flexible nail
KW - titanium flexible nail
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U2 - 10.1097/BPO.0000000000001301
DO - 10.1097/BPO.0000000000001301
M3 - Article
C2 - 30451812
AN - SCOPUS:85056896407
SN - 0271-6798
VL - 39
SP - E258-E263
JO - Journal of Pediatric Orthopaedics
JF - Journal of Pediatric Orthopaedics
IS - 4
ER -