A biomechanical study of median sternotomy closure techniques 1 (original) (raw)
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European Journal of Cardio-thoracic Surgery, 1999
Objective: Sternal dehiscence is a complication of median sternotomy incisions with high mortality and morbidity. Different techniques of sternal closure have been described. Rigid fixation of the sternum results in earlier union. We measured the rigidity of sternotomy fixation using a mechanical model in order to differentiate different techniques of sternal closure using their biomechanical characteristics. Methods: We measured the force-displacement curves of six different fixation techniques using a metal sternal model using a computerized materials-testing machine. We tested straight wires (the most commonly used surgical technique), figure-of-8 wires, 'repair' technique (used when a wire breaks), Ethibond, Sterna-band and a 'multitwist' closure described for the first time. Results: At 20 kg force, twisted wires used for sternotomy closures start to untwist. The most rigid closure was a multitwist closure that displaced only 0.37 mm at a force of 20 kg. Straight wires displaced 0.78 mm, figure-of-8 wires 1.20 mm, Sterna-band 1.37 mm, repair wires 5.08 mm, Ethibond 9.37 mm. The single factor Anova test for the rigidity of the different closures had P-values Ͻ0.0001. Conclusions: We applied a mathematical model to calculate chest wall forces during coughing, in order to determine the force placed upon a sternotomy closure. We conclude that severe coughing may cause wires to untwist. We discuss potential applications of different wire closures based on their characteristics.
Biomechanical comparison of median sternotomy closures
The Annals of Thoracic Surgery, 2004
Background. Poor healing of median sternotomy can significantly increase morbidity, mortality, and hospital costs. Effective union requires reliable sternal fixation. Although wire has proven the most reliable and widely used sternotomy closure material, no experimental studies have compared a large variety of wiring techniques in a human model. We developed an easily reproducible experimental model using cadaveric human sterna and compared several wiring methods to assess closure strength and stability. Methods. Fifty-three fresh adult human cadaveric sternal plates with adjacent ribs were fixed with specially designed spiked stainless steel clamps and attached to a texture analyzer. Single peristernal and transsternal, alternating single peristernal and transsternal, figure-eight peristernal, figure-eight pericostal, and Robicsek closures using no. 5 stainless steel wires were tested. We evaluated bone density, stiffness, and displacement using perpendicular, repetitive variable force loads of 800 Newtons cycling at a rate of 0.5 mm/s. Results. There were no significant differences in age, sex, or bone density in outcome measures of the sternal groups. No clamp failures or clamp damage to the specimens occurred. The single peristernal and alternating peristernal and transsternal closures proved superior in strength and stability (p < 0.001). The figure-eight peristernal, then the single transsternal, then the Robicsek were next stablest groups in decreasing order. The figureeight pericostal closure had the highest failure rate (p < 0.001). Conclusions. This novel model of sternotomy closure testing was reliable, inexpensive, and easily reproducible. The mechanical stability of peristernal and alternating peristernal and transsternal wires was significantly greater than that of the other tested methods. Pericostal figure-eight closures were not sufficiently stable to be considered a reliable method of primary sternotomy repair.
Mechanical analysis of midline sternotomy wound closure
The Journal of Thoracic and Cardiovascular Surgery, 1999
Median sternotomy wound complications range from prolonged incisional pain to dehiscence and mediastinitis. These problems are often preceded by sternal instability, which has been shown to compromise wound integrity and promote bacterial infection. This study presents a comprehensive analysis of the stability of human sternal closure when subjected to mechanical distracting forces and to increases in intrathoracic pressure. The goal is to elucidate the mechanisms for sternal dehiscence so that improved methods for sternal closure can be developed.
Effect of sternal wire twisting on sternotomy closure rigidity
Indian Journal of Thoracic and Cardiovascular Surgery
Introduction Wire twisting is the commonest method of median sternotomy closure. However, wire twisting weakens the wire and fracture may occur at the base of the twisted portion. We investigated how wire twisting affects the physical characteristics of sternotomy closure since rigid fixation promotes quicker primary bone healing. Methodology The maximum strength and rigidity of wire closure were tested in a steel sternal model, with varying number of twists, ranging from none to ten twists. Pearson correlation coefficient was used to investigate the relationship between the number of twists versus the maximum closure strength and rigidity. Regression analysis was used to relate closure rigidity with test load and number of wire twists. Results Maximum rigidity occurred at two-twists, and decreased from three to ten-twists. Pearson correlation coefficient showed a strong relationship between the number of twists versus maximum closure strength (r = 0.833, p = 0.003) and rigidity (r = 0.819, p = 0.004). The regression model identified load (p < 0.001) and number of twists as significant (p < 0.001), explaining 88.9% of the total variance in displacement. The maximum strength of all twisted closures far exceeded the threshold for wire cutting through bone; suggesting that maximum closure strength is clinically not an important parameter as closure rigidity. Conclusions In order to maximize rigidity in the wound closure and optimize primary bone healing, the optimal number of wire twists should be kept low. Excessive number of twists should be avoided as this weakens the closure and increases the amount of foreign material in the wound, theoretically increasing the risk of wound sepsis.
A biomechanical study of 4 different sternum closure techniques under different deformation modes
Interactive CardioVascular and Thoracic Surgery
OBJECTIVES: This study experimentally compares the efficiency of the 4 most preferred sternal closure tehniques, in 3 different deformation modes of the chest. METHODS: Polyurethane sternum models fixed by conventional wiring, steel band, ZipFix band and figure-8 wiring are tested statically under lateral distraction, longitudinal shear and torsional deformation modes. As a result, load-deformation curves are obtained. The closure efficiency of the techniques is then compared with respect to allowable load (corresponding to 2 mm displacement), rigidity, rupture load and rupture displacement. A comparison in terms of cost and ease of application has also been presented. RESULTS: The highest allowable load and rigidity values in simple tension and longitudinal shear are obtained by the steel and ZipFix band techniques, respectively. In torsion mode, the highest allowable load is provided by the ZipFix band and the highest rigidty is attained by the steel band technique. The highest rupture loads under simple tension, longitudinal shear and torsion modes are observed in ZipFix, steel band and conventional wiring, respectively. Steel band closure provides the least rupture displacement in simple tension as well as torsion, whereas ZipFix bands give the smallest rupture displacements in longitudinal shear. However, in every loading mode there were no statistically significant differences in allowable load, rigidity and rupture load values between the closure methods, and only rupture displacement values were statistically different for each method. CONCLUSIONS: Our results showed that conventional wiring is the most advantageous closing method when compared to the others.
Improvement of sternal closure stability with reinforced steel wires
The Annals of Thoracic Surgery, 2003
Background. Sternal dehiscence occurs when steel wires pull through sternal bone. This study tests the hypothesis that closure stability can be improved by jacketing sternal wires with stainless steel coils, which distribute the force exerted on the bone over a larger area. Methods. Midline sternotomies were performed in 6 human cadavers (4 male). Two sternal closure techniques were tested: (1) approximation with six interrupted wires, and (2) the same closure technique reinforced with 3.0mm-diameter stainless steel coils that jacket wires at the lateral and posterior aspects of the sternum. Intrathoracic pressure was increased with an inflatable rubber bladder placed beneath the anterior chest wall, and sternal separation was measured by means of sonomicrometry crystals. In each trial, intrathoracic pressure was increased until 2.0 mm of motion was detected. Differences in displacement pressures between groups were examined at 0.25-mm intervals using the paired Student's t test. Results. The use of coil-reinforced closures produced significant improvement in sternal stability at all eight displacement levels examined (p < 0.03). Mean pressure required to cause displacement increased 140% (15.5 to 37.3 mm Hg) at 0.25 mm of separation, 103% (34.3 to 69.8 mm Hg) at 1.0 mm of separation, and 122% (46.8 to 103.8 mm Hg) at 2.0 mm of separation. Conclusions. Reinforcement of sternal wires with stainless steel coils substantially improves stability of sternotomy closure in a human cadaver model.
In Vitro Comparison of Wire and Plate Fixation for Midline Sternotomies
The Annals of Thoracic Surgery, 2005
Background. The incidence of severe sternal wound complications in high-risk cardiac patients presents a significant need for more stabile sternal fixation techniques after median sternotomy procedures. Rigid metal plates, a potential alternative to wire fixation, are thought to promote faster sternal healing by reducing motion at the wound site. The goal of this study was to compare the stability provided by commercially available sternal plates with standard wires using an in vitro model.
A review of sternal closure techniques
Sternotomy and sternal closure occur prior to and post cardiac surgery, respectively. Although post-operative complications associated with poor sternal fixation can result in morbidity, mortality, and considerable resource utilization, sternotomy is preferred over other methods such as lateral thoracotomy. Rigid sternal fixation is associated with stability and reduced incidence of post-operative complications. This is a comprehensive review of the literature evaluating in vivo, in vitro, and clinical responses to applying commercial and experimental surgical tools for sternal fixation after median sternotomy. Wiring, interlocking, plate-screw, and cementation techniques have been examined for closure, but none have experienced widespread adoption. Although all techniques have their advantages, serious post-operative complications were associated with the use of wiring and/or plating techniques in high-risk patients. A fraction of studies have analyzed the use of sternal interlocking systems and only a single study analyzed the effect of using kryptonite cement with wires. Plating and interlocking techniques are superior to wiring in terms of stability and reduced rate of post-operative complications; however, further clinical studies and long-term follow-up are required. The ideal sternal closure should ensure stability, reduced rate of post-operative complications, and a short hospitalization period, alongside cost-effectiveness.
The Heart Surgery Forum, 2021
Background: Although closure of a sternotomy incision is usually a simple procedure, failure to do so (sternal dehiscence) is a serious complication and is an independent factor that poses a high degree of morbidity or mortality after open heart surgery. Instability of the bone fragments can lead to complete sternal breakdown, sternal wound infection, and mediastinitis. The stainless-steel encircling wire used as either interrupted simple sutures or as figure of eight sutures is the current standard method of median sternotomy closure. Interlocking multi-twisted sternal wire closure is an alternative that provides rigid sternal fixation. We aim to identify the best method of sternal closure in order to implement it as a standardised protocol for our department. Methods: Two-hundred patients aged 18-70 years were undergoing cardiac surgeries at Ain Shams University hospitals. They were divided into two groups: Group I included 100 patients with sternal closure using simple wire, and ...