The Biomechanical Evaluation Of Hydroxyapatite-chitosan-calcium Sulfate Hemihydrate To Enhance Effect Of Osteoporotic Intertrochanteric Fracture Fixation

ObjectiveTo compare and evaluate the biomechanical properties of bone reinforcing material enhancing proximal femur nail anti-rotation(PFNA) or Gamma nail fixation of femoral intertrochanteric fracture fixation by biomechanics experiments, and provide scientific basis for clinical application of bone reinforcing material.Materials and Method36 formalin-soaked bodies of osteoporotic proximal femur specimens are made to simulate the unstable intertrochanteric fracture(Evans-Jensen V type), and they are fixed by proximal femoral nail antirotation(PFNA) or Gamma nail, respectively with hydroxyapatite-chitosan-calcium sulfate hemihydrate(HA/CS/CSHA) and calcium phosphate cement(CPC).36 specimens of the proximal femur are divided into six groups: HA/CS/CSHA+PFNA group(A1 group), HA/CS/CSHA+Gamma nail group(A2 group), CPC+PFNA group(B1 group), CPC+Gamma nail group(B2 group), PFNA(C1 group), Gamma nail(C2group), the former four group as the experimental group, the later two as control group. The compression test is performed by biomechanical testing machine, and firstly each specimen is loaded by 300 N to eliminate elastic creeping, then reloaded, and the experimenter records thedisplacement, the maximum load values in 300 N, 600 N, 1200 N and the load-displacement curve,observes changes in specimen when the maximum load is added and the distribution of material surrouding bone screw and tissue section figure in cross-sectional view, and compare the fixed performance difference the stability in HA/CS/CSHA with CPC to evaluate the biomechanical effects of the material of HA/CS/CSHA strenthening stability in treating osteoporosis intertrochanteric fracture.ResultsCompression test results showed that:(1) the load displacement of intertrochanteric fracture increases with the load after internal fixation;(2) on 300 N, 600 N, 1200 N load, when material types are different and internal fixation is the same, at different materials group and control group, the displacement are significant difference(P <0.05) between the groups, and material group(HA/CS/CSHA materials group, CPC material group) is smaller than the non-material group(control group), HA /CS/CSHA material group than CPC material group load displacement small; on 300 N, 600 N, 1200 N load, when internal fixation different and the material same, the load displacement of PFNA group and Gamma nail group were statistically different(P <0.05), PFNA fixation group smaller than the Gamma nail group in displacement;(3)when material types are different and internal fixation is the same, the maximum load between different materials and control groups is significant difference(P <0.05), and the maximum load of material group(HA/CS/CSHA material group, CPC material group) is greater than the non-material group(control group), HA/CS/CSHA material group is larger than the CPC material group on maximum load; when internal fixation different and the material same, PFNA fixation group and the Gamma nail on group largest load were statistically different(P <0.05),the maximum load of PFNA fixation group is larger than Gamma nail group.ConclusionBone reinforcing material is beneficial to strengthen the stability of fixation amang osteoporotic intertrochanteric fracture. the stability effect of calcium phosphate-chitosan-calcium sulfate hemihydrate composite bone cement is better than CPC, and the biomechanical advantages of PFNA exceeds to gamma nail betwwen unstable osteoporotic intertrochanteric fracture treatment.