Conversion from external fixator to intramedullary nail causes a second hit and impairs fracture healing in a severe trauma model

Center of Musculoskeletal Research Ulm, University of Ulm, Ulm, Germany.
Journal of Orthopaedic Research (Impact Factor: 2.99). 03/2013; 31(3). DOI: 10.1002/jor.22242
Source: PubMed


In poly-traumatic patients, second hits are known to potentiate the posttraumatic systemic inflammatory response, thus increasing the risk of multi-organ dysfunction. In accordance with "damage control orthopaedic surgery" principles, fractures are initially treated with external fixators, which are replaced by internal osteosynthesis once the immunological status of the patient is considered stable. Recently, we demonstrated that a severe trauma impaired the healing of fractures stabilized by external fixation during the entire healing period. The question arose, whether switching to intramedullary nailing increases the inflammatory response in terms of a second hit, leading to a further impairment of bone healing. Wistar rats received a femoral osteotomy stabilized by an external fixator. Simultaneously half of the rats underwent an additional thoracic trauma. After 4 days, the external fixator was replaced by an intramedullary nail in half of the rats of the two groups. The inflammatory response was evaluated by measuring serum C5a levels. Fracture healing was determined by three-point-bending, µCT, and histomorphometry. The thoracic trauma significantly increased C5a concentrations 6, 24, and 72 h after the second surgical intervention. After 40 days, conversion to intramedullary nailing considerably decreased the flexural rigidity of the callus, with no significant differences between rats with or without thoracic trauma. After 47 days, flexural rigidity in rats subjected to conversion remained decreased compared to animals solely treated by external fixation, particularly in combination with blunt chest trauma. The results indicate that accumulation of second hits after multiple injuries could lead to aggravation of the fracture healing outcome. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

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Available from: Tim Wehner, Feb 28, 2015
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    • "Additional trauma due to IMN could push the 'borderline' stable patient towards decompensation [8]. Other open questions are the influence of injury severity and damage control external fixation (EF) on the outcome of femoral shaft fracture treatment [10] [11] [12]. "
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    ABSTRACT: Intramedullary nailing (IMN) is the preferred treatment for femoral shaft fractures in adults. Although previous studies published good outcomes, some controversies remain. The purpose of this retrospective study was to identify factors that influence outcome after IMN for femoral shaft fractures. Between July 1998 and July 2013, we treated 230 patients with 248 femoral shaft fractures. Statistical analyses were performed to determine predictors of nonunion. The following set of variables was selected based on the speculation that they would contribute to the outcome: sex (male or female), smoking, obesity, polytrauma, fracture type, open fractures, Gustilo type, primary external fixation (EF) and reaming. Initial fracture stabilization was performed by IMN in 161 (64.9%) and by EF in 87 (35.1%) fractures. There were no documented cases of deep infection. Nonunion was diagnosed in 27 patients with 28 fractures (11.3%). Factors affecting nonunion in the univariate analysis were Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) fracture type (odds ratio [OR] 25.0; p<0.0001), Gustilo type (OR 0.64; p=0.0358), and EF (OR 0.42; p=0.0401). Multiple logistic regression analysis only identified AO/OTA fracture type (OR 22.0; p<0.0001) as a risk factor for nonunion. Fracture reaming did not change the outcome (OR 0.80; p=0.6073). A separate analysis showed that damage control EF was not a risk factor in polytrauma patients (OR 0.76; p=0.5825). Fracture stabilisation with IMN is a good treatment option for femoral shaft fractures in adults. The purpose of this study was to evaluate risk factors of poor outcome after IMN of femoral shaft fractures. The present analysis revealed that there was no difference in the outcome whether the fracture was reamed or not. Univariate and multivariate analysis could only correlate AO/OTA fracture type with the occurrence of nonunion. Therefore, in this study, unreamed nailing and damage control EF were not associated with a negative outcome. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Injury 05/2015; 17(8). DOI:10.1016/j.injury.2015.05.007 · 2.14 Impact Factor
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    ABSTRACT: For ex vivo measurements of fracture callus stiffness in small animals, different test methods, such as torsion or bending tests, are established. Each method provides advantages and disadvantages, and it is still debated which of those is most sensitive to experimental conditions (i.e. specimen alignment, directional dependency, asymmetric behavior). The aim of this study was to experimentally compare six different testing methods regarding their robustness against experimental errors. Therefore, standardized specimens were created by selective laser sintering (SLS), mimicking size, directional behavior, and embedding variations of respective rat long bone specimens. For the latter, five different geometries were created which show shifted or tilted specimen alignments. The mechanical tests included three-point bending, four-point bending, cantilever bending, axial compression, constrained torsion, and unconstrained torsion. All three different bending tests showed the same principal behavior. They were highly dependent on the rotational direction of the maximum fracture callus expansion relative to the loading direction (creating experimental errors of more than 60%), however small angular deviations (<15°) were negligible. Differences in the experimental results between the bending tests originate in their respective location of maximal bending moment induction. Compared to four-point bending, three-point bending is easier to apply on small rat and mouse bones under realistic testing conditions and yields robust measurements, provided low variation of the callus shape among the tested specimens. Axial compressive testing was highly sensitive to embedding variations, and therefore cannot be recommended. Although it is experimentally difficult to realize, unconstrained torsion testing was found to be the most robust method, since it was independent of both rotational alignment and embedding uncertainties. Constrained torsional testing showed small errors (up to 16.8%, compared to corresponding alignment under unconstrained torsion) due to a parallel offset between the specimens' axis of gravity and the torsional axis of rotation.
    PLoS ONE 03/2015; 10(3):e0119603. DOI:10.1371/journal.pone.0119603 · 3.23 Impact Factor
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    ABSTRACT: Background: Numerous experimental studies have been performed to investigate the adverse effects of reamed versus unreamed nailing in isolated or combined trauma models. However, the translational relevance is still discussed controversially. Methods and results: A systemic review of the literature was performed. An increase of intramedullary pressure with liberation of emboli to the venous and systemic circulation associated with reamed and unreamed nailing has been well described. Reamed nailing, however, seems to have superior clinical results in terms of fracture healing. Conclusion: The pathophysiologic effects, optimal timing, and technique of reamed nailing particularly in patients with multiple injuries continue to be controversial topics. Therefore, further experimental studies should focus on these topics as well as on the interaction of local and systemic processes particularly in the context of different surgical treatment strategies (Early Total Care vs. Damage Control Orthopaedics) to improve our understanding and approach to intramedullary nailing.
    Journal of Trauma and Acute Care Surgery 06/2014; 76(6):1495-506. DOI:10.1097/TA.0000000000000236 · 2.74 Impact Factor
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