The Biomechanic And Clinical Studies Of Titanium Elastic Nail Combined With End Caps And Wire Fixation In Children With Unstable Femoral Shaft Fractures

PART ?The stiffness test of titanium elastic nail combined with end caps and wire fixation in cadaver with long oblique femoral shaft fracturesObjective To provide the theoretical basis for rational selection of internal fixation,biomechanical in vitro testing was performed to determine whether twomodified osteosyntheses with end caps or a wire could significantly improve the stability in comparison toclassical elastic stable intramedullary nailing in a length-unstable obliquemidshaft fracturecadaver model.Methods An identical length obliquemidshaft fracture was created in eightsmall adult cadaveric femurs harvested from four donors.Two 3.5-mm titanium elastic nails(TEN)wereintroduced intramedullary into all femur models,then eight osteosyntheses were modified by using end caps and wire.According to the different fracture fixations,all models were divided into four groups(group A: TEN,group B: TEN+wire,group C: TEN+caps,group D: TEN+wire+caps).Nondestructive axial compression,four-point bending and torsion tests were conducted.Stiffness,displacement and torque were analyzed usingthe T-test for paired samples.Results In the axial compression tests,the TEN+cap combination was 509% stiffer and 74% less displacement than TEN alone(P<0.01);The TEN+wire combination showed a significant positive influence on the stability in four-pointbendings as well as in torsion comparing to the group A: mean values of stiffness were significantlyhigher in the sagittal plane and coronal plane bending tests(29.26± 1.78 /41.19± 1.59 vs.11.13± 2.59 / 16.65± 3.18 N/mm,p< 0.01)and duringtorsion(0.34± 0.052 vs.0.18± 0.047 Nm/deg,p < 0.01).mean displacements were fewer in both bending tests(3.57± 0.37/2.83±0.47 vs.9.56± 1.28 / 9.09± 1.42 mm,p<0.01).The modification with end caps and wire in group D improved the stiffness significantly inall direction.Conclusions These findings indicate that end caps fitted toelastic nails may contribute to the stabilization of fractures thatour length obliquemodel mimics.The TEN+wire combination shows a significant positive influence on the stability in four-pointbendings as well as in torsion.modified osteosyntheses with end caps and wire remain a viable alternative in the treatment of length-unstablepediatric femur fracture patterns.PART ? The failure load test of the fracture of long oblique femoral shaft with different diameter of elastic nails and end caps in synthetic modelObjective To assess the failure load of a length-unstable oblique midshaft fracture in a synthetic femur model stabilized with two different diameters of intramedullary elastic nails and to observe whether titanium elastic nail combined with end caps could significantly increase the failure load.Methods An identical length oblique midshaft fracture was created using 24 synthetic adolescent-sized composite femoral models.The femur models were divided into four groups with six femur models in each group.All groups received two different diameters of TEN with and without end caps.According to the different fracture fixations,all models were divided into four groups(group A: 3.0 mm TEN,group B: 3.0 mm TEN with end caps,group C: 3.5 mm TEN,group D: 3.5 mm TEN with end caps).Biomechanical testing was performed with axial compression until failure.The load were analyzed using the T-test for paired samples.Results On a synthetic bone model,the TEN with end caps(group D and B)had a greater failure load in the axial compression test than TEN alone(2180N± 196 /1470 N ± 163 vs.390 N ± 119;P<0.01).The larger diameter elastic nail(group C)showed a significant positive influence on the stability comparing to the group A.Push-out force was significantly higher(1240N±102 vs.390N±119;P<0.01).Conclusions These findings indicate that end caps and larger diameter elastic nails may contribute to the construct stability under axial compression and that the risk of elastic stable intramedullary nailing push–out can be effectively reduced by the use of end caps.PART ? The clinical study of limited open reduction and titanium elastic nailcombined with end caps fixation in children with unstable femoral shaft fracturesObjective To compare the clinical and radiological results in unstable pediatric femoral shaft fractures treated with either limited open reduction or closed reduction and titanium elastic nailing combined with end caps.Methods Retrospectively analyze the data of total 54 cases of 5-14 years children with unstable femoral shaft fractures,from January 2012 to June 2016,were treated with titanium elastic nail and end caps.24 cases were treated with limited open reduction(16 males and 8 females,mean age of 8.4±2.1 years;12 long oblique fractures,8 long spiral fractures and 4 comminuted fractures)and 30 cases were treated with closed reduction(22 males and 8 females,mean age of 8.1±1.8 years;13 long oblique fractures,11 long spiral fractures and 6 comminuted fractures).The intraoperative indexes and postoperative radiological results,clinical outcomes and complications of the two groups were assessed.Results Both surgical and fluoroscopy time were significantly longer in group B.The cases of intraoperative fracture and postoperative plaster immobilization were fewer in group A.There were no significant differences between intraoperative estimated blood loss,length of stay,fracture healing time,partial weight bearing time and complications.Applying Beaty imaging result to group A,satisfactory results were documented in 22 cases,unsatisfactory results in 2 cases.In group B,satisfactory were seen in 16 cases,unsatisfactory in 14 cases.According to the TEN outcome scoring system,group A was excellent in 15 cases,good in 9 cases.In group B,excellent were seen in 5 cases,good in 22 cases,poor in 3 cases.The results of early Beaty imaging and TEN scoring system were statistically different between the two groups.At the last follow-up,there was no significant difference between the two groups in terms of clinical and radiological results.Conclusions Limited open reduction provides the same satisfactory clinical results as closed reduction.It is an superior method of limited open reduction to gain better reduction fixation and to decrease complications,the time of surgical and fluoroscopy.