Biomechanical Study for Treatment of Unstable Trochanteric Fractures with Osteoporotic Bone-Comparison between a PMMA Cemented DHS and an Intramedullary Device

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details

Abstract

In elderly patients, the aim of treatment of interochanteric fractures is to restore the previous level of independence and function. To achieve this goal, stable fracture fixation followed by early ambulation is a fundamental requirement. But it remains a considerable challenge as these fractures are often associated with severe osteoporosis and comminution. The standard treatment of these fractures is osteosynthesis with a dynamic hip screw (DHS). For stable fractures, sliding of the lag screw usually facilitates bone healing by means of impaction between fragments and controllable settling of the fracture. However, in unstable intertrochanteric fractures, complications of cut-put and excessive sliding of the lag screw occurred frequently. Although polymethylmethacrylate (PMMA) bone cement has been widely as a secondary fixation to facilitate fracture stability, there has been no biomechanical study regarding the significance of bone cement to prevent these two complications (cut-out and excessive sliding of the lag screw) in unstable fracture patterns with osteoporotic bone. Another device frequently used to treat these unstable intertrochanteric fractures is the use of a second generation intramedullary nail (e.g. Russell-Taylor reconstruction nail). With two proximal screws fixed to the femoral head, the intramedullary devices had been used in an attempt to improve treatment results of a conventional DHS. Theoretically, the intramedullary devices provide more effective control over screw sliding by acting as a lateral buttress. However, most reports have shown no significant differences between the DHS and intramedullary devices in failure of fixation. Furthermore, the intramedullary devices for fixation of unstable intertrochanteric fractures have the disadvantages of difficult reduction, intraoperative splintering as a result of bulky proximal part of the nails. To prevent the common surgical complications of unstable intertrochanteric fractures in elderly patients, this study aims to compare the biomechanical performance between a PMMA cemented DHS and an intramedullary device using osteoporotic bone. Theoretically, PMMA bone cement augmentation may enhance the fixation stability of a conventional DHS, and lower the incidence of screw cutout from the femoral head in osteoporotic bone. We propose to perform this study within two years. By using MTS hydraulic test machine, a biomechanical study is performed to compare the fixation stability of the two currently used fixation methods. Twenty four (24) synthetic femora will be used and divided into two groups (cemented DHD and intramedullary nail). By using MTS testing machine, biomechanical experiments including: (1) Measurement of displacement of the femoral head; (2) Static compressive failure test; and (3) Dynamic cyclic test, will be performed. The biomechanical performance between a cemented DHS and an intramedullary device in the treatment of unstable trochanteric fractures with osteoporotic bone will be compared accordingly.

Project IDs

Project ID:PB10007-2289
External Project ID:NSC100-2221-E182-023
StatusFinished
Effective start/end date01/08/1131/07/12

Keywords

  • Unstable intertrochanteric fracture
  • osteoporosis
  • Dynamic Hip Screw
  • reconstruction nail
  • Finite element analysis

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