Implant holding power of the femoral head

Benterud, Jan G; Husby, Torstein; Graadahl, øivind; Alho, A

doi:10.3109/17453679209154848

Cited by 25 publications

(3 citation statements)

References 7 publications

(8 reference statements)

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“…Selvan et al [7] demonstrated that triangular configurations had biomechanical advantage for the fixation of Pauwels type III fractures using synthetic bone models. But mechanical tests performed by Crowell et al [24] and Benterud et al [25] concluded that configuration of inverted triangle and diamond patterns provides better fixation of femoral head. And Yang et al [8] reported that the inverted triangle configuration of screws increased the union rate when compared with triangle configuration.…”

Section: Discussionmentioning

confidence: 99%

“…First, the two most distal screws of triangle configuration inevitably pass through the Ward triangle within the femoral neck, which leads to the decrease of bone density because of the absence of trabeculation [26]. Second, the dense trabeculae on the central and superior portion of the femoral head could provide greater bone anchorage [24, 25]. The two screws of inverted triangle configuration inserted into the dense trabeculae area exhibit greater holding strength than the only one screw of triangle configuration.…”

Section: Discussionmentioning

confidence: 99%

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Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation

Wang

Zhou

et al. 2018

BioMed Research International

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Objectives In the present study, we evaluated the mechanical outcome of different configurations of cannulated compression screws for the fixation of Pauwels type III femoral neck fracture and the stress distribution around the holes corresponding to fixation protocol after screws removal. Methods The Pauwels type III of femoral neck fracture was created in 3-matic software and the models of cannulated compression screws were constructed using UG-NX software. Five fixation systems were assembled to the fracture models. Abaqus software was used to perform the process of finite element analysis. Values of stress distribution, maximum stress, model principal strains of proximal fragment, and stress distribution around the holes of femur model were recorded. Results Stress of cannulated compression screws was intensely focused on the middle area of the screw near the fragment of each group. Inverted triangle model showed the highest peak stress on screws under different phases of load. Each screw dispersed some stresses, but at least one underwent the peak stress. Fracture model fixed by inverted triangle configuration showed the lowest volume of yielding strain in the proximal fragment. The area of higher stress around the holes was largest after triangle screws removal when compared with other four models. Conclusions Our study indicated that different cannulated compression screws fixation configurations for the unstable femoral neck fractures showed the different mechanical efficiency. Inverted triangular configuration showed the mechanical advantage and being less likely to cutout. The fixation strategy of triangle configuration was least recommended if patients tended to remove the implants.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation

Wang

Zhou

et al. 2018

BioMed Research International

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“…14 Perren 25 stated that cancellous screws are designed to have greater thread depth and decreased thread cross-sectional thickness in comparison to cortical bone screws, to provide more holding power in porous material such as cancellous bone. Other factors which have been found experimentally to increase the holding power of cancellous bone screws include: increasing the major diameter of the screw, 24 increasing the length of engaged screw thread, 12 inserting the screw in cancellous bone of greater apparent density and shear strength 6 and decreasing the thread pitch. 13 The holding power of a screw in bone is a function of both the design of the screw and the properties of the bone into which it is inserted.…”

Section: Cancellous Screwsmentioning

confidence: 99%

A modified operative technique for enhanced compression of medial malleolar non-union

Madhu

Morgan–Jones

2005

Injury Extra

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Mechanical performance of standard and cannulated 4.0‐mm cancellous bone screws

Brown

McCarthy

Bourgeault

et al. 2000

Journal Orthopaedic Research

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The mechanical performance of bone screws is determined by their pull-out strength (holding power), compressive force, stripping torque, yield bending moment, ultimate bending moment, and fatigue strength. These parameters are related to the parameters of the screw design, including major thread diameter, minor thread diameter, thread length, pitch, shaft diameter, cannulation diameter, and material properties. The goal of the study was to theoretically predict the static performance of five 4.0-mm, 45-46-mm-long, cancellous, partially threaded standard and cannulated bone screws and compare the predictions with experimental measurements. A secondary goal was to determine if cannulation of the bone screw diminished its mechanical performance. The predicted values for pull-out force, compressive force, and stripping torque were determined by the thread length, major thread diameter, and thread shape factor. The screws with the largest major thread diameter and longest thread length had the greatest pull-out force, compressive strength, and stripping torque. However, when correcting for the thread length, a higher thread shape factor compensated for a smaller major diameter. The coefficient of determination (r2) for the correlation between the predicted and measured pull-out force improved from 0.75 to 0.90 when the theoretical model included the thread shape factor. The yield and ultimate bending moments are a function of the section modulus and material properties of the screw. The Ace solid screw had the greatest section modulus and yield and ultimate bending moments. The experimental data support the theoretical models for predicting the mechanical performance of bone screws. The design of the bone screws can be optimized on the basis of theoretical modeling. The strong correlation between the predicted and measured parameters allows comparison between bone screws without repeated experimental tests. Theoretical and experimental results show that cannulation of the bone screw did not inherently diminish its mechanical performance.

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Implant holding power of the femoral head

Cited by 25 publications

References 7 publications

Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation

Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation

A modified operative technique for enhanced compression of medial malleolar non-union

Mechanical performance of standard and cannulated 4.0‐mm cancellous bone screws

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