Effects of Fracture Fixation Stability on Ossification in Healing Fractures

Mark, Hans; Nilsson, Anders; Nannmark, F. Ulf; Rydevik, Björn

doi:10.1097/00003086-200402000-00040

Cited by 46 publications

(41 citation statements)

References 16 publications

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“…Our histologic data from the rat concur with studies in large-animal models [1,16,22,23] and small-animal models [25,36,43] also showing a prolonged chondral phase and delayed healing resulted from increased IFM during the early phase of healing. It has been proposed early higher-magnitude mechanical stimulation may influence stem cell proliferation and promote differentiation into a cartilage phenotype, thereby altering regenerative processes [5,19].…”

Section: Discussionsupporting

confidence: 86%

“…Histologically, larger IFM leads to the predominance of endochondral ossification with a prolonged chondral phase and later bone formation [16,22,23,25,36,43] and may cause bone resorption at the fragment ends [31]. The bridging of the periosteal and intracortical fracture gaps Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.…”

Section: Introductionmentioning

confidence: 99%

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Temporal Variation in Fixation Stiffness Affects Healing by Differential Cartilage Formation in a Rat Osteotomy Model

Willie

Blakytny

Glöckelmann

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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Background Dynamization involves a reduction in fixation construct stiffness during bone healing, allowing increased interfragmentary movement of the fracture through physiologic weightbearing and muscle contraction. Within some optimal range, interfragmentary movement stimulates healing, but this range likely varies across stages of bone healing. Questions/purposes How does the time of dynamization affect the cartilage formation, bony bridging, and bone resorption in a rat fracture-healing model? Methods Unilateral external fixators, stabilizing a 1-mm gap, were dynamized at 1 (D1 group, n = 10), 3 (D3 group, n = 11), or 4 (D4 group, n = 11) weeks postoperatively. Continuously 5 weeks stiff (S group, n = 10) and flexible (F group, n = 11) fixation were included for comparison. After 5 weeks, healing was evaluated by histomorphometric methods.

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Section: Discussionsupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Temporal Variation in Fixation Stiffness Affects Healing by Differential Cartilage Formation in a Rat Osteotomy Model

Willie

Blakytny

Glöckelmann

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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“…5,25 Similar uncertainty exists concerning load magnitude. For example, a wide range of load and strain magnitudes have been studied in sheep models, 7,13,26,27 but the effects of different peak loads on healing have not been examined.…”

Section: Introductionmentioning

confidence: 99%

In vivo cyclic axial compression affects bone healing in the mouse tibia

Gardner

Meulen

Demetrakopoulos

et al. 2006

Journal Orthopaedic Research

128

113

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Abundant evidence exists that fracture healing can be influenced by mechanical loading. However, the specific loading parameters that are osteogenic remain unknown. We hypothesized that the bone healing response in mouse tibial osteotomies would be different with a short delay before loading compared to immediate load application, as well as with higher and lower load magnitudes applied. Eighty 12-week-old mice underwent osteotomy of the left tibia followed by intramedullary nailing. Mice were divided into six groups based on days delayed until application of load (0 days or 4 days) and amplitude of cyclic load (0.5N, 1N, or 2N). Loading regimens were applied at 1 Hz for 100 cycles per day, 5 days per week for 2 weeks, using an external device that applied axial compression to the tibia. Bone healing was assessed by both microcomputed tomography (CT) and four-point bend testing. A short delay followed by cyclic application of a relatively low load led to improved fracture healing, as determined by increased callus strength, but this enhancement disappeared as load amplitudes increased. Load initiation immediately following fracture inhibited healing, regardless of the magnitude of load applied. MicroCT measurements of calluses in the early healing stage did not predict the mechanical strength of the fractures. These findings confirm that controlled, noninvasive cyclic loading can improve the strength of healing callus. However, application of load immediately after fracture appears to be detrimental to healing. Load magnitude also plays a critical role, and must be taken into account in future studies and clinical applications. As the loading parameters necessary to enhance fracture healing become refined, external compression may be used as a potent stimulus for treating fractures with decreased biological capacity. ß

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“…Several studies examined the influence of fixation stiffness in a rat femoral fracture model by comparing noninterlocking and interlocking nails [13][14][15] or comparing intramedullary nails made of different materials. [16][17][18][19][20] Only half of these studies 14,15,17,18 reported in vitro axial stiffness data for their intramedullary nailing devices.External unilateral fixation devices used for fracture fixation, [21][22][23][24][25][26][27] segmental bone defect models, 28-32 and distraction osteogenesis [33][34][35][36][37][38][39][40][41] can provide rotational stability, thus allowing controlled, reproducible axial and shear IFM in a rat femoral fracture model. Unfortunately, only three previous studies using external fixators in this model 21,23,24 attempted to mechanically characterize in vitro fixation stiffness and its effect on subsequent axial and shear IFM.…”

mentioning

confidence: 99%

“…They also reported that offsets of 4 to 8 mm were linearly related to the axial and transverse stiffness. Both the Harrison et al 23 and Mark et al [24][25][26] studies allowed complete closure of the osteotomy gap. Once contact between the two bone fragments occurred, the stiffness of the bone-fixator construct dramatically increased, becoming much higher than that for the fixator alone.…”

mentioning

confidence: 99%

Mechanical characterization of external fixator stiffness for a rat femoral fracture model

Willie

Adkins

Zheng

et al. 2008

Journal Orthopaedic Research

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Clinical and experimental studies have shown that several mechanical factors influence the fracture healing process. One such factor, interfragmentary movement, is affected by loading and the stiffness of the fixation device. This study evaluated the stiffness of different external fixation devices for a rat femoral fracture model, using in vitro and analytical methods. The contribution to the stiffness of the fixation construct was dominated by the flexibility of the pins in relation to their offset, diameter, and material properties. The axial stiffness increased with decreasing offset and increasing pin diameter. Titanium pins resulted in significantly lower axial stiffness compared to stainless steel pins of the same design. The fixator body material and fixator length had a less pronounced influence on fixation stiffness. Mechanically characterized external fixation devices will allow in vivo study of the fracture healing process utilizing pre-calculated fracture fixation stiffness. These characterized fixation devices will allow controlled manipulation of the axial and shear interfragmentary movement to achieve a flexible fixation resulting in callus formation compared to a more rigid fixation limiting callus formation in a rat femoral fracture model. Keywords: fracture healing; external fixators; biomechanics Blood supply, fracture gap size, and mechanical factors influence the fracture healing process.1-4 The most important mechanical factors are the axial 1,4 and shear interfragmentary movements (IFMs) in the plane of the fracture surface. 5,6 These movements are influenced by the load applied to the fracture fixation device (weightbearing and muscle forces) and the stiffness of the device.1,7-10 More flexible fixators stimulate callus formation and endochondral ossification, while more rigid fixators limit IFM and subsequent callus formation. 1,6,7,11,12 The reproducibility and manipulation of axial and shear IFM in the rat femoral fracture model have not been adequately described. Several studies examined the influence of fixation stiffness in a rat femoral fracture model by comparing noninterlocking and interlocking nails [13][14][15] or comparing intramedullary nails made of different materials. [16][17][18][19][20] Only half of these studies 14,15,17,18 reported in vitro axial stiffness data for their intramedullary nailing devices.External unilateral fixation devices used for fracture fixation, [21][22][23][24][25][26][27] segmental bone defect models, 28-32 and distraction osteogenesis [33][34][35][36][37][38][39][40][41] can provide rotational stability, thus allowing controlled, reproducible axial and shear IFM in a rat femoral fracture model. Unfortunately, only three previous studies using external fixators in this model 21,23,24 attempted to mechanically characterize in vitro fixation stiffness and its effect on subsequent axial and shear IFM.Harrison et al. 23 reported no significant difference in axial stiffness between aluminum and titanium fixator bar materials, using an 8-mm o...

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Effects of Fracture Fixation Stability on Ossification in Healing Fractures

Cited by 46 publications

References 16 publications

Temporal Variation in Fixation Stiffness Affects Healing by Differential Cartilage Formation in a Rat Osteotomy Model

Temporal Variation in Fixation Stiffness Affects Healing by Differential Cartilage Formation in a Rat Osteotomy Model

In vivo cyclic axial compression affects bone healing in the mouse tibia

Mechanical characterization of external fixator stiffness for a rat femoral fracture model

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