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Biomechanical comparison of semi-rigid pediatric locking nail versus titanium elastic nails in a femur fracture model.

Flinck M, von Heideken J, Janarv PM, Wåtz V, Riad J - J Child Orthop (2014)

Bottom Line: No difference was found in shortening between the PLN and the four 3.0-mm TEN [by 7.0 (3.3-8.4) mm; p = 0.065].The two 3.0-mm TEN did not withstand the maximum shortening of 10.0 mm.PLN provides the greatest stability in all planes compared to TEN models with end caps, even though the difference from the two 4.0-mm or four 3.0-mm TEN models was small.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, Skaraborg Hospital, Skövde, Sweden.

ABSTRACT

Background: The treatment for length-unstable diaphyseal femur fractures among school-age children is commonly intramedullary elastic nails, with or without end caps. Another possible treatment is the semi-rigid pediatric locking nail (PLN). The purpose of this biomechanical study was to assess the stability of a length-unstable oblique midshaft fracture in a synthetic femur model stabilized with different combinations of intramedullary elastic nails and with a PLN.

Methods: Twenty-four femur models with an intramedullary canal diameter of 10.0 mm were used. Three groups with various combinations of titanium elastic nails (TEN) with end caps and one group with a PLN were tested. An oblique midshaft fracture was created, and the models underwent compression, rotation, flexion/extension, and a varus/valgus test, with 50 and 100 % of the forces generated during walking in corresponding planes.

Results: We present the results [median (range)] from 100 % loading during walking. In axial compression, the PLN was less shortened than the combination with two 4.0-mm TEN [by 4.4 (3.4-5.4) mm vs. 5.2 (4.8-6.6) mm, respectively; p = 0.030]. No difference was found in shortening between the PLN and the four 3.0-mm TEN [by 7.0 (3.3-8.4) mm; p = 0.065]. The two 3.0-mm TEN did not withstand the maximum shortening of 10.0 mm. In external rotation, the PLN rotated 12.0° (7.0-16.4°) while the TEN models displaced more than the maximum of 20.0°. No model withstood a maximal rotation of 20.0° internal rotation. In the four-point bending test, in the coronal and the sagittal plane, all combinations except the two 3.0-mm TEN in extension withstood the maximum angulation of 20.0°.

Conclusions: PLN provides the greatest stability in all planes compared to TEN models with end caps, even though the difference from the two 4.0-mm or four 3.0-mm TEN models was small.

No MeSH data available.


Related in: MedlinePlus

Illustration of how seven circles (elastic nails) with a diameter of 3.0 mm fit into a larger circle (medullary canal) with a diameter of 10.0 mm
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Fig2: Illustration of how seven circles (elastic nails) with a diameter of 3.0 mm fit into a larger circle (medullary canal) with a diameter of 10.0 mm

Mentions: Theoretically, several (seven) 3.0-mm nails fit in a canal with an inner diameter of 10 mm; however, closer to a clinical situation, we applied a maximum of four nails to fit inside a femur model with a 10.0-mm intramedullary canal (Fig. 2) [26]. It did not require any significant extra force to insert four nails, compared to two, in the femur models. All femur models were assessed with radiographs to ensure correct nail placement and there was no destruction of the intramedullary canal or splitting of the cortex.Fig. 2


Biomechanical comparison of semi-rigid pediatric locking nail versus titanium elastic nails in a femur fracture model.

Flinck M, von Heideken J, Janarv PM, Wåtz V, Riad J - J Child Orthop (2014)

Illustration of how seven circles (elastic nails) with a diameter of 3.0 mm fit into a larger circle (medullary canal) with a diameter of 10.0 mm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4340854&req=5

Fig2: Illustration of how seven circles (elastic nails) with a diameter of 3.0 mm fit into a larger circle (medullary canal) with a diameter of 10.0 mm
Mentions: Theoretically, several (seven) 3.0-mm nails fit in a canal with an inner diameter of 10 mm; however, closer to a clinical situation, we applied a maximum of four nails to fit inside a femur model with a 10.0-mm intramedullary canal (Fig. 2) [26]. It did not require any significant extra force to insert four nails, compared to two, in the femur models. All femur models were assessed with radiographs to ensure correct nail placement and there was no destruction of the intramedullary canal or splitting of the cortex.Fig. 2

Bottom Line: No difference was found in shortening between the PLN and the four 3.0-mm TEN [by 7.0 (3.3-8.4) mm; p = 0.065].The two 3.0-mm TEN did not withstand the maximum shortening of 10.0 mm.PLN provides the greatest stability in all planes compared to TEN models with end caps, even though the difference from the two 4.0-mm or four 3.0-mm TEN models was small.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics, Skaraborg Hospital, Skövde, Sweden.

ABSTRACT

Background: The treatment for length-unstable diaphyseal femur fractures among school-age children is commonly intramedullary elastic nails, with or without end caps. Another possible treatment is the semi-rigid pediatric locking nail (PLN). The purpose of this biomechanical study was to assess the stability of a length-unstable oblique midshaft fracture in a synthetic femur model stabilized with different combinations of intramedullary elastic nails and with a PLN.

Methods: Twenty-four femur models with an intramedullary canal diameter of 10.0 mm were used. Three groups with various combinations of titanium elastic nails (TEN) with end caps and one group with a PLN were tested. An oblique midshaft fracture was created, and the models underwent compression, rotation, flexion/extension, and a varus/valgus test, with 50 and 100 % of the forces generated during walking in corresponding planes.

Results: We present the results [median (range)] from 100 % loading during walking. In axial compression, the PLN was less shortened than the combination with two 4.0-mm TEN [by 4.4 (3.4-5.4) mm vs. 5.2 (4.8-6.6) mm, respectively; p = 0.030]. No difference was found in shortening between the PLN and the four 3.0-mm TEN [by 7.0 (3.3-8.4) mm; p = 0.065]. The two 3.0-mm TEN did not withstand the maximum shortening of 10.0 mm. In external rotation, the PLN rotated 12.0° (7.0-16.4°) while the TEN models displaced more than the maximum of 20.0°. No model withstood a maximal rotation of 20.0° internal rotation. In the four-point bending test, in the coronal and the sagittal plane, all combinations except the two 3.0-mm TEN in extension withstood the maximum angulation of 20.0°.

Conclusions: PLN provides the greatest stability in all planes compared to TEN models with end caps, even though the difference from the two 4.0-mm or four 3.0-mm TEN models was small.

No MeSH data available.


Related in: MedlinePlus