Load transmission through the callus site with external fixation systems: Theoretical and experimental analysis

Prat, Jaime; Juan, J.A.; Vera, P.; Hoyos, J.V.; Dejoz, Ricardo; Peris, José Luis Aguilar; Sánchez-Lacuesta, J.; Comín, Mario

doi:10.1016/0021-9290(94)90022-1

Cited by 23 publications

(15 citation statements)

References 25 publications

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“…Vera et al [22] pointed out a significant load transmission through callus even using a highly rigid external fixation system. For Prat et al [19], rabbit calluses with minimum elastic characteristics (less than 1/ 100 of those values for normal cortical bone) provide a drastic change on load transmission patterns of healing bone. From an initial situation, when the fixator supports the total applied load, it changes to another in which callus assumes a part of the function.…”

Section: Discussionmentioning

confidence: 96%

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Effect of callus development on the deformation of external fixation frames

Burny

Donkerwolcke

et al. 2012

International Orthopaedics (SICOT)

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Purpose We designed a sensor that measures the bending moments at the articulations and the torque of the rod of a Hoffmann II® external fixation. We considered the effect of the callus formation in the stabilisation of a "fracture-fixation system." Methods Four Hoffmann II® frame configurations were mechanically tested. Two carbon fibre tubes represent the bone fragments (length 180 mm, outer diameter 25 mm, inner diameter 19 mm). The callus is represented by the interposition of springs of different rigidity (10-405 N/mm) in the fracture gap between the tubes. Results The deformation of the frame is in inverse proportion to the stiffness of the callus; the slope of the curve drops rapidly during early development of the callus, to reach a plateau after some 50 % of recovery of the normal mechanical characteristics of the bone. This simulation supports the theoretical approach, i.e. the external frame resists larger stresses at the start of the fracture healing. Over a callus stiffness of some 200 N/mm the pattern of the curves remains similar, regardless of the frame configuration. Conclusion An optimisation of the frame is possible, adapted to the actual mechanical situation of the callus. A monitoring system is deemed reliable after making sure that the elementary components behave the same way in the clinical condition as in the laboratory. In an experimental set up we confirmed its reliability in a clinical-like situation.

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Section: Discussionmentioning

confidence: 96%

“…However, data from mechanical behaviour, considering callus evolution in external fixation systems, are scarce [1,2,4,5,[7][8][9][10][11][12][13][14][15][17][18][19][20][21][22].…”

Section: Discussionmentioning

confidence: 99%

Effect of callus development on the deformation of external fixation frames

Burny

Donkerwolcke

et al. 2012

International Orthopaedics (SICOT)

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“…In such a model any geometric or material variations can be easily made in order to perform parametric analyses (1,4,5,7,8,12,17,20,21,22). The validity of the numerical results of stresses, strains and displacements yielded by finite element analysis of bone-ESF constructs has been demonstrated in previous studies (19,20).…”

mentioning

confidence: 89%

“…Material properties of the different ESF components (18,19). All materials were assumed to be homogeneous, isotropic and linearly elastic.…”

Section: Tablementioning

confidence: 99%

Fracture stabilization with type II external fixator vs. type I external fixator with IM pin

Shahar¹,

Shani²

2004

Vet Comp Orthop Traumatol

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SummaryBilateral external fixator frames are frequently preferred over unilateral frames due to their superior rigidity. The objective of this study was to compare the biomechanical features of bilateral external fixators with those of unilateral external fixators that are combined with an intra-medullary pin. Three-dimensional, solid models were created of several unilateral and bilateral external fixator frames. The callus in the fracture gap was also modeled. Biomechanical analyses of all constructs were performed by the finite element method. This modeling approach allows the determination of stresses, displacements, and strains in the components of the various constructs, and thus the calculation of their relative stiffness. In addition, local shear strain values in the fracture gap, currently thought to be one of the deciding factors in the process of bone healing, can also be determined. The concept of equivalent stiffness modulus, which represents a weighed average stiffness of a construct to various loads, was defined. Using this concept, it was shown that when the intramedullary pin is well seated in the epiphyseal bone, the various unilateral frames have an equivalent stiffness modulus that is similar or even greater than that of bilateral frames with a similar arrangement of transcortical pins.

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“…Fractures with surrounding soft tissue and good vascularization heal rapidly even while bone fragments remain mobile [Buckwalter et al, 1996]. Most evidence suggests that fixation devices allowing partial loading and slight fracture motion improve healing [Aro and Chao, 1993;Goodman and Aspenberg, 1993;Goodship et al, 1993;Goodman et al, 1994;Hedstrom et al, 1994;Kostopoulos et al, 1994;O'Sullivan et al, 1994;Prat et al, 1994;Noordeen et al, 1995;Augat et al, 1996;van Laarhoven et al, 1996].…”

Section: Fracture Healingmentioning

confidence: 99%

Assessing Behavior in Extinct Animals: Was <i>Smilodon</i> Social?

2003

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It has been suggested that saber-tooth species such as Smilodon fatalis were social because partially healed skeletal injuries were found at Rancho La Brea, California. This conclusion assumes injured animals would die without help. This paper will rebut assertions of sociality. First, cats use metabolic reserves to heal quickly without feeding. Second, dehydration is a more profound limitation than starvation as prey carcasses only provide a quarter of necessary water. Injured animals must be mobile enough to find water or die of dehydration. Their presence in a tar pit also strongly suggests locomotion. Finally, the relatively small brain found in Smilodon is not consistent with sociality. Another argument for sociality has been the large ratio of Smilodon to other species in the La Brea tar pits. However, the remains of a non-social species, the Golden eagle (Aquila chrysaetus), are about as common as Smilodon. Contrariwise, the highly social grey wolf (Canis lupus) and coyote (Canis latrans) are extremely rare. Available evidence does not support sociality in Smilodon.

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Load transmission through the callus site with external fixation systems: Theoretical and experimental analysis

Cited by 23 publications

References 25 publications

Effect of callus development on the deformation of external fixation frames

Effect of callus development on the deformation of external fixation frames

Fracture stabilization with type II external fixator vs. type I external fixator with IM pin

Assessing Behavior in Extinct Animals: Was <i>Smilodon</i> Social?

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