Thesis (M.S. in mechanical engineering)--Washington State University, December 2006. / Includes bibliographical references (p. 79).

Background: A number of treatment options are available for diaphyseal non-unions of the tibia, including intramedullary (IM) nailing. An infrapatellar entry point with the knee in deep flexion can make this procedure challenging, especially with associated deformity or an obliterated canal. The suprapatellar approach allows nail insertion with the knee extended, which facilitates correction of malalignment in the sagittal and coronal planes. The aim of our study was to review the outcome of diaphyseal tibia non-unions, treated with an intramedullary nail, using the suprapatellar approach. Method: We retrospectively reviewed consecutive cases with non-union of the tibial shaft, treated with a suprapatellar entry nail between May 2016 and January 2018. Patients who were previously managed with a nail or who had active sepsis were excluded. The rate and time to union, as well as complications were assessed. Results: Thirteen cases were included and followed up until union at a mean of 5.8 months. All were performed percutaneously, without opening of the non-union site. Two patients developed complications, although bony union was still achieved. Conclusion: A suprapatellar entry tibial nail is an acceptable treatment option for tibial non-unions not previously treated with a nail.

No description available.

Each year, thousands of femoral and tibial internal fracture repairs are performed by orthopedic surgeons in the United States. Internal fixation of long bones using intramedullary nails (IMN) has decreased incidence of non-union, allowed shorter hospitalization time, and earlier weight bearing for the patient compared to other fixation methods. Orthopedic surgeons have expressed that one of the most difficult parts of this intramedullary nailing of long bones, is locating and drilling the interlocking screw holes. IMN interlocking requires the surgeon to locate the holes in the nail, center the drill, and advance the bit through the bone to meet them. Many novel procedures and devices have been developed to assist the surgeon in distal locking of intramedullary nails, but have some disadvantages. These can include the need for extensive x-ray exposure, expensive x-ray equipment, high power consumption, active electronics in vivo, soft tissue damage, which all lead to inaccurate screw placement. For these reasons, a new prototype device for locating and drilling IMN distal interlocking holes has been developed. This prototype device uses magnetic sensors to locate a permanent magnet placed at a know distance from the IMN interlocking hole. A drill sleeve may be attached to the targeting sensors so that when they are aligned with the target magnet, the drill sleeve is aligned with the axis of the interlocking hole to be drilled. This new prototype device has significant advantages over existing devices, including the following. It has no active or passive electronics in vivo, no x-ray imaging is needed for targeting, while allowing real time feedback of alignment. It is a percutaneous technique, which can be adapted for use with existing IMN's. The new prototype also has low power requirements allowing battery operation, a single target magnet with unique axisymmetric field and novel magnet orientation, and adjustable sensitivity. Additionally, the new device allows visual, audible, or tactile positioning feedback. This prototype magnetic targeting device can improve orthopedic surgeons' ability to target and drill distal IMN interlocking screw holes. This device may allow shorter surgery, decreased x-ray exposure, and fewer complications for the surgeon and patient. / Master of Science

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / The (Surgical Implant Generation Network) SIGN Intramedullary (IM) nail is designed to fix long bone fractures without using a costly C‐arm imaging device. It is distributed for free to countries in need, allowing for elevation of care from the standard, lengthy traction treatment in those countries to clinically superior IM nailing. This paper compares the clinical outcomes of the SIGN IM nail to those of the IM nails used in developed countries with use of a C‐arm. The terms “Surgical Implant Generation Network” and “union” were searched in four databases. Primary studies of SIGN IM nails were included and their outcomes, including union rate, time to union, and complications, were recorded and compared to historical data of IM nails used in developed countries. Overall, there is a similar union rate in bones fixed with SIGN IM nails (94.6%) versus bones fixed with IM nails in developed countries (92.3%) (p = 0.009, OR = 1.67), while some bone types (tibia and femur) demonstrated a lower union rate when individually stratified (p = 0.008, OR = 0.26 and p = 0.002 and OR = 0.15, respectively). Mean time to union for all bone types combined showed no significant difference between SIGN IM nails and IM nails used in developed countries (p = 0.26). Complications rates were similar between SIGN IM nails and IM nails used in developed countries. It is possible for the SIGN IM nail to be used to fix long bone fractures in developing countries with outcomes comparable to the IM nail used in developed countries.

M.Med., Orthopaedic Surgery, Faculty of Health Sciences, University of the Witwatersrand, 2010

Στην παρούσα εργασία μελετάμε την εφαρμογή ενός ρομποτικού βραχίονα στην διαδικασία της ενδομυελικής ήλωσης, η οποία είναι η συνήθης τεχνική που χρησιμοποιείται σε διαδικασίες ρουτίνας, για την ανακατασκευή των καταγμάτων του μηριαίου οστού και της κνήμης. Πιο συγκεκριμένα, αρχικά γίνεται προσπάθεια ανίχνευσης των οπών του ενδομυελικού ήλου, οι οποίες λαμβάνονται μέσω ενός C-arm, στον τρισδιάστατο χώρο. Στις οπές αυτές τοποθετούνται ειδικά μεταλλικά καρφιά που στοχεύουν στη συγκράτηση του ενδομυελικού ήλου με το οστό του ασθενούς. Από τη στιγμή που έχει προσδιοριστεί ο άξονας που συνδέει δύο οπές στον ήλο, οδηγείται ρομποτικός βραχίονας προκειμένου να τρυπηθεί το οστό του ασθενούς, κατά μήκος αυτού του άξονα. Η όλη διαδικασία μελετάται μέσω προσομοίωσης στην παρούσα εργασία. / The summary is not available.

No description available.

An intramedullary nail is a trauma treatment device used for fracture fixation of long bones. These devices are subject to failure, including lag screw cut-out and failure at the lag screw insertion hole from high stress concentrations in that region. Clinical developments for such devices are frequently based on a trial and error method, which often results in failure before improvement. However, the finite element method can be used for the development of trauma treatment devices, and their interaction with bone, by providing a large data set at a relatively low cost. Also, parameters can be changed to assess the relative benefits of one device to another. A novel finite element model has been developed that can be used for the analysis of intramedullary nails inserted into long bones. A commercially available finite element package, ANSYS, has been used to implement the modelling strategy. The finite element modelling technique has been applied to fractures of the proximal femur, but the model is generic, and can be developed to deal with any form of intramedullary device where contact between the bone and implant is important. The finite element strategy can be used in pre-clinical trials to test a new device, or for the design optimisation of existing devices. The finite element model consists of the device surrounded by a thin layer of bone, which forms a 'base' model component that is re-usable. This 'base' component can be mathematically connected to any long bone model, forming an integrated implant and bone construct. The construct can be used to assess which device is best suited to a particular fracture, for example. Contact elements have been used to allow stresses to develop as contact is achieved within the implant and bone construct. Pre-assignment of contact points is not required. Verification of the finite element model is achieved by comparison to available data from experiments carried out on constructs of bone and device that use intramedullary femoral nails. In this thesis the finite element model has been applied to two areas of proximal femoral nailing. The finite element model is used to analyse the distal end of a Gamma nail, and shows that analyses that do not consider contact may not lead to accurate predictions of stresses. The model has been developed for using configurations with one and two distal locking screws. The most distal locking screw is more critical under axial loading, and the more proximal screw is more important for bending loads. The use of 'softer' screws distributes the load more evenly between them. The finite element model has been used to investigate the mechanical environment of a fracture callus for a femoral neck fracture, and a subtrochanteric fracture. The use of one and two lag screws, fracture gap size and material properties of the nail have been investigated for a stiffening callus. Results show that the use of two lag screws for a neck fracture provides a more rigid support at the early stages of fracture healing, and minimises stress-shielding once the callus has healed. For subtrochanteric fractures there is a critical point at which the fracture callus is able to carry any load. A Titanium nail significantly reduces the peak stress at the lag screw insertion hole, and titanium lag screws share the load more evenly between them. Each two-lag-screw configuration used transfers a similar load into the fracture callus. A configuration using a larger lag screw above a smaller has a significantly higher stress at the upper lag screw insertion hole. Critically, the load shared between two lag screws changes as the fracture callus stiffens and an assessment should be made at different stages of fracture healing to optimise the use of a device.

Implants such as intramedullary nails or cancellous screws are used to mechanically stabilize fractures in bone. They provide reinforcement to the bone if they find good purchase in cancellous bone. Not all implants hold enough loads for mechanical stability and pull-out or cut-out may happen in some cases. This is linked to the interface between the bone and the implant. Computer modelling techniques are used to investigate both the effects of cut-out in a femur model, and the pull-out forces of cancellous bone screws. The bone geometry was based on CT scanned cancellous bone and converted using Mimics® software. The finite element models were produced in ANSYS®. Simple bone models were used to examine a fractured femur under standard gait loading. These models were continuum models and idealised the screw to bone interface in order to ease computational demand. The models were used to investigate the ideal positions of intramedullary devices lag screws on an anterior-posterior view of the implant location. In accordance with literature, an inferior-central or central-central position was the best position of the lag screw, while a superior-anterior or inferior-anterior position was adverse. The introduction of multi-scale modelling in order to investigate cut-out with a discrete bone model was not achieved. Discrete cancellous bone models were used to examine some of the cancellous screw characteristics, including pitch, inner diameter and proximal half angle, while a cancellous screw was also studied using a model of cancellous bone with a range of bone densities. The calculated reaction force for a pull-out of 0.2mm shows the influence of some parameters. Change in the proximal half angle increased the stiffness and strength by about 15% in line with the experimental findings of others, while apparent density changes of 2.5% increased the forces threefold. A significant reduction in reaction force was observed when a particular screw geometry in lower apparent density bone was modelled and rotated through 180° on a plane. Examination of the geometry of the bone/screw interface shows that in certain positions there is very little cancellous bone to support the implant. This will lead to low strength and is very difficult to predict. The same models were used to examine the effect of increasing bone stiffness adjacent to the implant and the use of a cement layer to augment the screw model. The increasing stiffness concluded that an increase in pull-out stiffness can be achieved, even in low quality bone, while the cement augmentation showed a significant increase in pull-out strength, though it was idealised as bonded to the bone and screw.