Abstract
BackgroundThe 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.MethodsTwenty-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.ResultsWe 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°.ConclusionsPLN 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.
Highlights
The treatment for length-unstable diaphyseal femur fractures among school-age children is commonly intramedullary elastic nails, with or without end caps
The pediatric locking nail (PLN) was less shortened than the combination with two 4.0mm titanium elastic nails (TEN) [by 4.4 (3.4–5.4) mm vs. 5.2 (4.8–6.6) mm, respectively; p = 0.030]
The PLN rotated 12.0° (7.0–16.4°) while the TEN models displaced more than the maximum of 20.0°
Summary
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). J Child Orthop (2015) 9:77–84 most common surgical treatment for children aged 4–14 years in our clinic is titanium elastic nails (TEN) inserted in the distal femur in a proximal direction This stabilization is based on the principle of creating a six-point fixation using two C-shaped nails [2]. From biomechanical studies and clinical experience, we have learned that end caps prevent the nails from sliding back through the insertion site, and increase the axial stabilization in femur fractures [5, 6] Another treatment option, beside external fixation and submuscular plating [7, 8], is the more recently introduced semi-rigid pediatric locking nail (PLN) [9]. There are limited reports on the semi-rigid pediatric interlocking nail regarding stability [10, 11]
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