Three-dimensional load measurements in an external fixator

Seide, K.; Weinrich, N.; Wenzl, M; Wolter, D.; Jürgens, Christian

doi:10.1016/j.jbiomech.2003.12.025

Cited by 48 publications

(33 citation statements)

References 17 publications

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“…Data were recorded for three testing cycles for each construct configuration. Physiologic loading was considered to consist of 500 N axial loading, 20 Nm bending, and 5 Nm torsional load, being analogous to loads shown to be supported by a tibial frame during normal gait at 30 days postoperatively [8,32].…”

Section: Methodsmentioning

confidence: 99%

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

Henderson

Rushbrook

Harwood

et al. 2017

Clinical Orthopaedics &Amp; Related Research

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Section: Methodsmentioning

confidence: 99%

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

Henderson

Rushbrook

Harwood

et al. 2017

Clinical Orthopaedics &Amp; Related Research

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“…Loading was applied to a maximum of 700 N axially, 20 Nm bending, and 20 Nm torsion. A previous study [7] showed that by 30 days postoperatively the majority of patients with tibial circular fixation are placing full body weight through their affected limb, and a clinical study [28], using instrumented frames, showed that in severely comminuted fractures up to 70% of ground reaction force is supported by the frame as axial load, 2.5% (Nm/N) as bending load, and 0.75% (Nm/N) as torsion. On the basis of an 80-kg patient therefore, physiologic loading was considered to consist of 500-N axial loading, 20-Nm bending, and 6-Nm torsional load, rounded to 5-Nm for testing.…”

Section: Methodsmentioning

confidence: 99%

What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames?

Henderson

Rushbrook

Stewart

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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Background Fine-wire circular frame (Ilizarov) fixators are hypothesized to generate favorable biomechanical conditions for fracture healing, allowing axial micromotion while limiting interfragmentary shear. Use of half-pins increases fixation options and may improve patient comfort by reducing muscle irritation, but they are thought to induce interfragmentary shear, converting beam-to-cantilever loading. Little evidence exists regarding the magnitude and type of strain in such constructs during weightbearing. Questions/purposes This biomechanical study was designed to investigate the levels of interfragmentary strain occurring during physiologic loading of an Ilizarov frame and the effect on this of substituting half-pins for finewires. Methods The ''control'' construct was comprised of a four-ring all fine-wire construct with plain wires at 90°-crossing angles in an entirely unstable acrylic pipe synthetic fracture model. Various configurations, substituting half-pins for wires, were tested under levels of axial compression, cantilever bending, and rotational torque simulating loading during gait. In total three frames were tested for each of five constructs, from all fine-wire to all half-pin. Results Substitution of half-pins for wires was associated with increased overall construct rigidity and reduced planar interfragmentary motion, most markedly between all-wire and all-pin frames (axial: 5.9 mm ± 0.7 vs 4.2 mm ± 0.1, mean difference, 1.7 mm, 95% CI, 0.8-2.6 mm, p \ 0.001; torsional: 1.4% ± 0.1 vs 1.1% ± 0.0 rotational shear, mean difference, 0.3%, 95% CI, 0.1%-0.5%, p = 0.011; bending: 7.5°± 0.1 vs 3.4°± 0.1, mean difference, À4.1°, 95% CI, À4.4°to À3.8°, p \ 0.001). Although greater transverse shear strain was observed during axial loading (0.4% ± 0.2 vs 1.9% ± 0.1, mean difference, 1.4%, 95% CI, 1.0%-1.9%, p \ 0.001), this increase is unlikely to be of clinical relevance given the current body of evidence showing bone healing under shear strains of up to 25%. The greatest transverse shear was observed under bending loads in all fine-wire frames, approaching 30% (29% ± 1.9). This was reduced to 8% (±0.2) by incorporation of sagittal plane half-pins and 7% (±0.2) in all half-pin frames (mean difference, À13.2% and À14.0%, 95% CI, À16.6% to 9.7% and À17.5% to À10.

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“…Although new technologies improve not only the treatment of broken bones, but also our ability to monitor the progression of healing experimentally (Roberts and Steele, 2000;Hente et al, 2003;Thorey et al, 2008) and in clinical practice (Richardson et al, 1994;Seide et al, 2004), it is still not possible to differentiate in vivo the early effects on healing of either mechanical or biological stimuli. Even though there are many methods available for monitoring the progress of tissue regeneration at the molecular, cellular, structural and biomechanical levels, many investigations focus on the molecular and radiographic evaluation of bone healing.…”

Section: Defect Healing Characterised By In Vivo Mechanicsmentioning

confidence: 99%

Time kinetics of bone defect healing in response to BMP-2 and GDF-5 characterised by in vivo biomechanics

Wulsten

Glatt

Ellinghaus

et al. 2011

eCM

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This study reports that treatment of osseous defects with different growth factors initiates distinct rates of repair. We developed a new method for monitoring the progression of repair, based upon measuring the in vivo mechanical properties of healing bone. Two different members of the bone morphogenetic protein (BMP) family were chosen to initiate defect healing: BMP-2 to induce osteogenesis, and growth-and-differentiation factor (GDF)-5 to induce chondrogenesis. To evaluate bone healing, BMPs were implanted into stabilised 5 mm bone defects in rat femurs and compared to controls. During the first two weeks, in vivo biomechanical measurements showed similar values regardless of the treatment used. However, 2 weeks after surgery, the rhBMP-2 group had a substantial increase in stiffness, which was supported by the imaging modalities. Although the rhGDF-5 group showed comparable mechanical properties at 6 weeks as the rhBMP-2 group, the temporal development of regenerating tissues appeared different with rhGDF-5, resulting in a smaller callus and delayed tissue mineralisation. Moreover, histology showed the presence of cartilage in the rhGDF-5 group whereas the rhBMP-2 group had no cartilaginous tissue.Therefore, this study shows that rhBMP-2 and rhGDF-5 treated defects, under the same conditions, use distinct rates of bone healing as shown by the tissue mechanical properties. Furthermore, results showed that in vivo biomechanical method is capable of detecting differences in healing rate by means of change in callus stiffness due to tissue mineralisation.

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Three-dimensional load measurements in an external fixator

Cited by 48 publications

References 17 publications

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

What Are the Biomechanical Properties of the Taylor Spatial Frame™?

What Are the Biomechanical Effects of Half-pin and Fine-wire Configurations on Fracture Site Movement in Circular Frames?

Time kinetics of bone defect healing in response to BMP-2 and GDF-5 characterised by in vivo biomechanics

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