ANALYSIS OF AN INTERNAL FIXATION OF A LONG BONE FRACTURE

2005 ◽  
Vol 05 (01) ◽  
pp. 89-103 ◽  
Author(s):  
K. RAMAKRISHNA ◽  
I. SRIDHAR ◽  
S. SIVASHANKER ◽  
V. K. GANESH ◽  
D. N. GHISTA
Keyword(s):  
Stress Shielding ◽  
Axial Loading ◽  
Bending Moment ◽  
Fracture Site ◽  
Long Bone ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Long Bone Fracture ◽  
Fracture Interface ◽  
Tensile Surface

A major concern when a fractured bone is fastened by stiff-plates to the bone on its tensile surface is excessive stress shielding of the bone. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays bone healing. Likewise, the tensile stress shielding of the healed bone underneath the plate also does not enable it to recover its tensile strength. Initially, the effect of a uniaxial load and a bending moment on the assembly of bone and plate is investigated analytically. The calculations showed that the screws near the fracture site transfers more load than the screws away from the fracture site in axial loading and it is found that less force is required when the screw is placed near to fracture site than the screw placed away from the fracture site to make the bone and plate bend with same radius of curvature when subjected to bending moment. Finally, the viability of using a stiffness graded bone-plate as a fixator is studied using finite element analysis (FEA): the stiffness-graded plate cause less stress-shielding than stainless steel plate.

Development of a Bioabsorbable Glass-Reinforced-Glass Intra-Osseous Scaffold for Fracture Healing

2011 ◽  
Vol 9 ◽  
pp. 81-91
Author(s):  
Philip Boughton ◽  
Y. Chen ◽  
C. Thompson ◽  
G. Roger ◽  
Jari Hyvarinen ◽  
...  
Keyword(s):  
Fracture Healing ◽  
Bone Fractures ◽  
Stress Shielding ◽  
Long Bone ◽  
Hematopoietic Tissue ◽  
Shear Tests ◽  
Intramedullary Canal ◽  
Long Bone Fracture ◽  
Torsional Loads ◽  
Mechanically Stabilized

Intramedullary (IM) nails are routinely used to stabilize long bone fractures. They can however lead to stress shielding, pain, migration, obstruct hematopoietic tissue, become a loci for infection, and require subsequent surgical retrieval. Novel intra-osseous scaffold (IOS™) prototypes for fracture healing have been developed to function as a regenerative scaffold to enhance callous formation under mechanically stabilized conditions then resorb. Prototype fixation pins and rod systems were formed from glass-reinforced-glass. Flexion, torsion and shear tests were performed to evaluate the composite pins and rods. A modular rod design was successfully deployed and dilated while in a deformable state. When fitted and gripping the intramedullary canal then set in a rigid state. An obliquely sectioned ovine femur was used as a long bone fracture model for deployment and mechanical verification. Flexural support provided by the intramedullary scaffold was superior to multiple k-wire fixation, while the k-wire approach was more stabilizing under torsional loads. Glass reinforced glass samples were mechanically tested after soaking for up to 4 weeks in saline. Strength and modulus of the composite was reduced to approximately 25% of initial values after 2 weeks.

Deformation in Multilayer Stacked Assemblies

1990 ◽  
Vol 112 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Tsung-Yu Pan ◽  
Yi-Hsin Pao
Keyword(s):  
Thermal Loading ◽  
Bending Moment ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
First Order ◽  
Strain Behavior ◽  
Linear Elastic ◽  
Nonlinear Stress ◽  
Order Polynomial ◽  
Vertical Displacements

A linear-elastic analytical model has been developed to describe the deformed geometry of a multi-layered stack assembly subject to thermal loading. The model is based on Timoshenko’s bimetal thermostat analysis [1] and consists of a series of first-order polynomial equations. The radius of curvature, bending moment, force, horizontal and vertical displacements can be determined numerically. These quantities match well with finite element analysis. Calculations for silicon power transistor stacks are presented in order to demonstrate the model capability. The results from this analyitcal model have been found to correlate well with experimental measurements when an appropriate secant modulus is used to represent the nonlinear stress-strain behavior of solder.

Enhancement of Long Bone Fracture Healing by Local Soft Tissue Compression1

2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Ernest C. Chisena ◽  
Jahangir S. Rastegar ◽  
Robert S. Chisena
Keyword(s):  
Blood Flow ◽  
Fracture Healing ◽  
Soft Tissues ◽  
Fracture Site ◽  
Long Bone ◽  
Bony Union ◽  
Bone Fracture Healing ◽  
Mechanical Pressure ◽  
Long Bone Fracture ◽  
Local Oxygen

Endochondral fracture healing, the process in which callus bridges a fracture, can be enhanced using a brace with a deforming element. This deforming element acts to locally increase pressure at the fracture site. In this paper, we describe a bracing device, which has the capability of controlling blood flow in targeted regions of an extremity. Controlling the blood flow around a fracture site induces a mechanism that enhances fracture healing. We hypothesize that, since local oxygen tension is lowered by means of controlling the blood flow at the fracture site, fracture healing is accelerated and bony union is more likely. Using the results of several previous studies, we will show that increased mechanical pressure in the soft tissues over the fracture site enhances fracture healing.

scholarly journals Biomechanical assessment of composite versus metallic intramedullary nailing system in femoral shaft fractures: A finite element study

2021 ◽  
Author(s):  
Saeid Samiezadeh ◽  
Pouria Tavakkoli Avval ◽  
Zouheir Fawaz ◽  
Habiba Bougherara
Keyword(s):  
Mechanical Performance ◽  
Bone Fractures ◽  
Stress Shielding ◽  
Femoral Shaft ◽  
Delayed Union ◽  
Fracture Site ◽  
Long Bone ◽  
Fe Model ◽  
Non Union ◽  
Shaft Fractures

Background: Intramedullary nails are the primary choice for treating long bone fractures. However, complications following nail surgery including non-union, delayed union, and fracture of the bone or the implant still exist. Reducing nail stiffness while still maintaining sufficient stability seems to be the ideal solution to overcome the above mentioned complications. Methods: In this study, a new hybrid concept for nails made of carbon fibers/ fl ax/epoxy was developed in order to reduce stress shielding. The mechanical performance of this new implant in terms of fracture stability and load sharing was assessed using a comprehensive non-linear FE model. This model considers several mechanical factors in nine fracture configurations at immediately post-operative, and in the healed bone stages. Results: Post-operative results showed that the hybrid composite nail increases the average normal force at the fracture site by 319.23 N ( P b 0.05), and the mean stress in the vicinity of fracture by 2.11 MPa ( P b 0.05) at 45% gait cycle, while only 0.33 mm and 0.39 mm ( P b 0.05) increases in the fracture opening and the fragments' shear movement were observed. The healed bone results revealed that implantation of the titanium nail caused 20.2% reduction in bone stiffness, while the composite nail lowered the stiffness by 11.8% as compared to an intact femur. Interpretation: Our results suggest that the composite nail can provide a preferred mechanical environment for healing, particularly in transverse shaft fractures. This may help bioengineers better understand the biomechanics of fracture healing, and aid in the design of effective implants.

scholarly journals Biomechanical assessment of composite versus metallic intramedullary nailing system in femoral shaft fractures: A finite element study

2021 ◽  
Author(s):  
Saeid Samiezadeh ◽  
Pouria Tavakkoli Avval ◽  
Zouheir Fawaz ◽  
Habiba Bougherara
Keyword(s):  
Mechanical Performance ◽  
Bone Fractures ◽  
Stress Shielding ◽  
Femoral Shaft ◽  
Delayed Union ◽  
Fracture Site ◽  
Long Bone ◽  
Fe Model ◽  
Non Union ◽  
Shaft Fractures

Background: Intramedullary nails are the primary choice for treating long bone fractures. However, complications following nail surgery including non-union, delayed union, and fracture of the bone or the implant still exist. Reducing nail stiffness while still maintaining sufficient stability seems to be the ideal solution to overcome the above mentioned complications. Methods: In this study, a new hybrid concept for nails made of carbon fibers/ fl ax/epoxy was developed in order to reduce stress shielding. The mechanical performance of this new implant in terms of fracture stability and load sharing was assessed using a comprehensive non-linear FE model. This model considers several mechanical factors in nine fracture configurations at immediately post-operative, and in the healed bone stages. Results: Post-operative results showed that the hybrid composite nail increases the average normal force at the fracture site by 319.23 N ( P b 0.05), and the mean stress in the vicinity of fracture by 2.11 MPa ( P b 0.05) at 45% gait cycle, while only 0.33 mm and 0.39 mm ( P b 0.05) increases in the fracture opening and the fragments' shear movement were observed. The healed bone results revealed that implantation of the titanium nail caused 20.2% reduction in bone stiffness, while the composite nail lowered the stiffness by 11.8% as compared to an intact femur. Interpretation: Our results suggest that the composite nail can provide a preferred mechanical environment for healing, particularly in transverse shaft fractures. This may help bioengineers better understand the biomechanics of fracture healing, and aid in the design of effective implants.

Effect of Intramedullary Nailing Patterns On Interfragmentary Strain in a Mouse Femur Fracture: a Parametric Finite Element Analysis

2021 ◽  
Author(s):  
Gregory Lowen ◽  
Katherine Garrett ◽  
Moore-Lotridge Stephanie ◽  
Sasidhar Uppuganti ◽  
Scott A. Guelcher ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Healing ◽  
Bone Repair ◽  
Bone Fractures ◽  
Fracture Site ◽  
Fracture Repair ◽  
Long Bone ◽  
Design Parameters ◽  
Element Analysis

Abstract Delayed long bone fracture healing and nonunion continue to be a significant socioeconomic burden. While mechanical stimulation is known to be an important determinant of the bone repair process, understanding how the magnitude, mode, and commencement of interfragmentary strain (IFS) affect fracture healing can guide new therapeutic strategies to prevent delayed healing or non-union. Mouse models provide a means to investigate the molecular and cellular aspects of fracture repair, yet there is only one commercially available, clinically-relevant, locking intramedullary nail (IMN) currently available for studying long bone fractures in rodents. Having access to alternative IMNs would allow a variety of mechanical environments at the fracture site to be evaluated, and the purpose of this proof-of-concept finite element analysis study is to identify which IMN design parameters have the largest impact on IFS in a murine transverse femoral osteotomy model. Using the dimensions of the clinically relevant IMN as a guide, the nail material, distance between interlocking screws, and clearance between the nail and endosteal surface were varied between simulations. Of these parameters, changing the nail material from stainless steel (SS) to polyetheretherketone (PEEK) had the largest impact on IFS. Reducing the distance between the proximal and distal interlocking screws substantially affected IFS only when nail modulus was low. Therefore, IMNs with low modulus (e.g., PEEK) can be used alongside commercially available SS nails to investigate the effect of initial IFS or stability on fracture healing with respect to different biological conditions of repair in rodents.

scholarly journals Prospective study of managing long bone fracture nonunion: is bone graft needed in every case?

2018 ◽  
Vol 4 (4) ◽  
pp. 556
Author(s):  
Srinivas Balagani
Keyword(s):  
Prospective Study ◽  
Bone Graft ◽  
Bone Fracture ◽  
Fracture Site ◽  
Long Bone ◽  
Segmental Defect ◽  
Long Bones ◽  
Non Union ◽  
Number Of Patients ◽  
Long Bone Fracture

<p class="abstract"><strong>Background:</strong> Increased road traffic accidents lead to increased incidence of fracture of long bones. It has a tendency of non-union. Infection is very common in these cases which are an important cause of nonunion of long bone fractures. The objective of the study was to study the incidence and patterns of non-union of long bone fracture.</p><p class="abstract"><strong>Methods:</strong> Hospital based prospective study was carried out at Department of Orthopedics, from June 2017 to March 2018. Patients admitted to wards of Department of Orthopedics with nonunion of long bones were included. During the study period a total of 20 cases were eligible for the present study as per the inclusion and exclusion criteria.<strong></strong></p><p class="abstract"><strong>Results:</strong> Males were more affected than females. Most commonly affected age group was 41-50 years and 61-70 years (25% each). Most commonly affected long bone was femur in 35% of the cases. Most common type of non-union was hypertrophic (50%). Most common cause of non-union was broken implant in 35% of the cases. Maximum number of patients had union in 4-6 months in 60% of the cases after surgery of previous non-union of long bones. Only four patients developed complications like shortening of the limb or persistent non-union.</p><p class="abstract"><strong>Conclusions:</strong> Hypertrophic non unions doesn’t require bone graft, they require only stable fixation. For removal of broken implant in hypertrophic non-union if we open the fracture site, then even the gap after debridement of fracture site shows partial segmental defect it doesn’t require bone grafting.</p>

↵​Efficacy of Multi-ion Doped Plasma Spray Nano-hydroxyapatite Coated Titanium Implants in Long Bone Fracture Repair in Dogs- Radiographical and Bone Markers Evaluation

2021 ◽  
Author(s):  
G. Vani ◽  
P. Veena ◽  
R.V. Suresh Kumar ◽  
M. Santhi Lashmi ◽  
D. Rani Prameela ◽  
...  
Keyword(s):  
Plasma Spray ◽  
Bone Fracture ◽  
Bone Markers ◽  
Fracture Site ◽  
Fracture Repair ◽  
Titanium Implants ◽  
Long Bone ◽  
Tissue Remodelling ◽  
Long Bone Fracture ◽  
Intramedullary Implants

Background: Fracture of long bones is a common orthopaedic condition noticed in dogs and its primary goal is to completely restore the function of the injured limb as early as possible. Osteo-conductivity of hydroxyapatite can be improved further by decreasing the particle size to nanometre range and incorporation of inorganic materials in hydroxyapatite can enhance osteoblast cell material interactions. Strontium, Zinc, Silver and Fluorine are known to play an important role in the bone formation and also affect bone material characteristics such as crystallinity, degradation behaviour and mechanical properties. When doped with plasma spray nanohydroxyapatite, these multi-ions cause no harm to the physical environment during the degradation process of hydroxyapatite as these are nontoxic and play significant role in bone metabolism, growth and nourishment. Bone markers have tremendous potential as a rapid and sensitive method for assessing the response of the skeleton to medical or surgical interventions providing valuable information regarding bone turn over in animals. Hence, the current study was undertaken to evaluate the potential of multi-ion doped nano-hydroxyapatite coated intramedullary titanium implants in long bone fracture repair in dogs compared to the conventional intramedullary titanium implants through radiographical studies and evaluation of bone markers. Methods: Radiographical evaluation, Sandwich ELISA kits developed by Bioassay technology laboratory. Result: Plasma spray nano-hydroxyapatite coated titanium intramedullary implants have shown excellent osteo-conductivity when doped with multi-ions of Strontium, Zinc, Silver and Fluorine facilitating rapid osteoblastic activity and rapid bone turnover at the fracture site and complete fracture healing by 3rd week post-operatively as evidenced by radiographic scores and a peak BALP (Canine Bone Alkaline Phosphatase) values and early limb usage. Bone reabsorption and bone tissue remodelling due to osteoclastic action at the fracture site was quicker when the multi-ion doped nano-hydroxyapatite coated titanium intramedullary implants were used which is evidenced by the radiographic scores and highest CTX (Canine C-telopeptide of Type 1 Collagen) values indicating completion of fracture healing and near completion of bone tissue remodelling by 9th post-operative week in long bone fracture repair in dogs.

scholarly journals Comparison of Outcome of Bone Autograft and Allograft in Union of Long Bone Fractures

2021 ◽  
Vol 48 (2) ◽  
pp. 13-18
Author(s):  
H. Valiyollahpoor-Amiri ◽  
S. M. Esmaeilnejad-Ganji ◽  
R. Jokar ◽  
B. Baghianimoghadam ◽  
S. Kamali-Ahangar ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Bone Fractures ◽  
Bone Allograft ◽  
Fracture Site ◽  
Lower Limbs ◽  
Long Bone ◽  
Long Bone Fractures ◽  
Surgical Methods ◽  
Long Bone Fracture ◽  
Bone Autograft

Abstract Background and Purpose There are few studies addressing the rate of application of bone allograft and its use; hence, the present study aimed to compare the clinical outcomes of using bone allograft and autograft in patients with long bone fracture. Method In this clinical trial study, all patients who underwent bone graft surgery with the diagnosed long bone fractures of upper and lower limbs at Shahid Beheshti Hospital were included in the research. Patients were divided into two groups, autograft and allograft, according to type of treatment. They were evaluated for their union, complications, and range of motion. Results In the present study, 124 people were studied. Among them, 100 patients were eligible and included in the study. The allograft and autograft groups did not have any statistical significant differences in terms of age, sex, location, causes of fracture, and surgical methods. Results of the present research on patients in terms of fracture site indicated that there was no significant relationship between the two groups in rate of union (P = 0.18). Allograft and autograft had no difference in terms of complications. Studied range of motion indicated that patients were not different in terms of their ranges of motion. Conclusion Based on findings of the present study, allograft could be a suitable substitute for the autograft. The two graft methods were similar in terms of complications, union, and ranges of motion.

scholarly journals Soft Tissue Reconstruction for Open Tibia Fractures

2020 ◽  
Vol 25 (3) ◽  
pp. 207-218
Author(s):  
Young-Woo Kim ◽  
Ho-Youn Park ◽  
Yoo-Joon Sur
Keyword(s):  
Soft Tissue ◽  
Free Flaps ◽  
Fracture Site ◽  
Open Fractures ◽  
Long Bone ◽  
Soft Tissue Reconstruction ◽  
Long Bone Fracture ◽  
Tissue Reconstruction ◽  
Tibia Fractures ◽  
Radical Debridement

Tibia fractures are the most common long bone fracture and about 24% of them are open fractures. Open fractures accompany disruption of the soft tissue around the fracture site and the fractures are exposed to the external environment. Contamination of the fracture site and devitalization of the injured soft tissue greatly increase the risk of infection, nonunion, and other complications. The first and most important treatment goal of open fractures is prevention of infection. To accomplish this objective, immediate radical debridement and irrigation, second-look operation, and subsequent soft tissue reconstruction should be performed as soon as possible. However, early soft tissue reconstruction is not always possible and when it should be delayed, negative pressure wound therapy is recommended. Among various reconstructive armamentarium including skin graft, local flaps, pedicled flaps, and free flaps, the best method need to be chosen based on patient’s general condition, size of defect, neurovascular status, range of injury zone, and cosmetic and functional perspectives. Preoperative in-depth evaluation of vascular structures is mandatory and free flaps are preferred when the range of injury zone is wide.

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