Tutorial
Brixia system of screws: a titanium modular system with wide applicability for reinforced sternal closure in cardiac and thoracic surgery
The use of cannulated screws and titanium plates to reinforce the sternal closure or to treat sternal dehiscence after median sternotomy has already been suggested in several articles. The system proposed here has some important advantages over those already described. Moreover, thanks to its characteristics, this system can also be used to treat pathologies affecting the entire rib cage. The system consists of a first threaded cannulated screw that is inserted in the bone or chondral cartilage and accommodates a cap screw that is tightened into the first screw and fixes a plate according to the following scheme: a threaded cannulated screw/plate/cap screw (Brixia system of screws). This system allows the plates to be fixed on the anterior face of the ribs and/or sternum without the need to enlarge dissection of the tissue, thereby lowering the danger of haemorrhage and injury to the thoracic organs. For this reason, it is particularly suitable for treating post-sternotomy sternal dehiscence, but it can be used to reinforce the primary sternal closure (after median or transversal sternotomy) in high-risk patients with sternal dehiscence. Owing to the modular nature of the system, singular components can also be utilized independently.
A median sternotomy is the incision of choice for the majority of cardiac operations. The sternum is usually closed by wiring with stainless steel wires, typically in a simple six-wire interrupted pattern. Sternal dehiscence, with or without infection, is the most serious issue associated with sternal closure and a major cause of morbidity and mortality, with a frequency ranging from 0.5% to 5% [1]. In this video tutorial, we present our experience treating noninfected sternal dehiscence with rigid sternal fixation using transverse or longitudinal titanium plates in combination with threaded cannulated screws and threaded cap screws [Brixia system of screws (B-SOS); IESS Group srl, Pozzuolo del Friuli (UD), Italy] in patients with three or more of the sternal dehiscence risk factors indicated in Table 1. Figure 1 shows a simplification of the B-SOS.
Figure 1. Brixia system of screws, simplified illustration.
1 - System features (0:12)
Two screw types and one plate comprise the system. All components are composed of pure titanium. The first screw, known as a cap screw, has a head diameter of 3.7 mm and a length between 9 and 10 mm. The second screw, known as a threaded cannulated screw, has a 7 mm head, a cannulated tract diameter of 1.2 mm and a length between 10 and 16 mm. The length of the threaded tract is 10 mm. The plate is 180 mm long, 80 mm wide and 2.5 mm thick, with 18 holes. When all components of the B-SOS are in place, at least two threaded cannulated screws (one on each side) will be tightened into the rib bone or rib cartilage, with the plate positioned above the head of the threaded cannulated screws and fixed to them with cap screws (one per each threaded cannulated screw). A pair of bicortical screws (one on each side) are then tightened alongside the threaded cannulated screws to prevent the plate from tilting.
2 - Patient characteristics (1:39)
The patient was a 72-year-old male who underwent aortic valve replacement, replacement of the ascending aorta and myocardial revascularization with the left internal thoracic artery on the anterior descending and the left internal thoracic vein on the posterior descending 10 years prior. The operation was complicated by bleeding that necessitated a surgical revision that resulted in sternal dehiscence and mediastinitis. When the patient was brought to our attention, he had a BMI of 32 kg/m2 and a pseudoaneurysm (of the distal anastomosis) that had eroded the sternum on the CT scan.
3 - Insertion of two threaded cannulated screws to be used with steel wire (2:24)
After three steel wires were passed through the manubrium, the surgical procedure for reinforcing the sternal closure with the B-SOS commenced with the insertion of a couple of threaded cannulated screws into the third costal cartilage. The cartilage was exposed using electrocautery, beginning on the left side. The cartilage was drilled completely using a cannulated drill after exposure. This operation was conducted with a manual drill; it is essential that the instrument remain as perpendicular to the cartilage as possible. Step by step, the identical operation was conducted on the right third costal cartilage. Then, a No. 5 steel wire was inserted through the holes created in the costal cartilage, and its two ends were trimmed to a length of about 20 cm from the cartilage.
4 - Insertion of the steel wire and closure of the sternum (3:40)
The thickness of the sternum was evaluated with a tape measure. The thickness suggested the length of the threaded cannulated screws. If the measurements were odd numbers, we undersized the screw: for instance, if the sternal thickness was 15 mm, we would select a 14-mm threaded cannulated screw. We chose a couple of 16-mm threaded cannulated screws for this patient. The left screw was threaded in the left end of the cut steel wire and tightened with a cannulated Torx screwdriver. The same procedure was performed step by step to fix the right threaded cannulated screw. After the steel wire was crossed, the sternum was closed.
5 - Shaping the plate and inserting the left threaded cannulated screw (4:32)
The steel wires were twisted and cut after two nitinol thermoreactive clips were placed in the third and fourth intercostal spaces. The sixth costal cartilage was exposed using electrocautery. Then, a titanium 18-hole plate measuring 180 mm in length, 8 mm in width and 2.5 mm in thickness was cut and moulded using the appropriate bending pliers to conform with the arch that the seventh costal cartilage forms by articulating with the sixth costal cartilage. Using the contoured plate as a template, a dot was marked in the middle of the sixth or seventh cartilage on the left side of the costal arch. The cartilage was then drilled using a standard drill, and a 16 mm-long threaded cannulated screw was tightened into the cartilage using a cannulated Torx screwdriver.
6 - Insertion of the right threaded cannulated screw and fixation of the plate (5:35)
After placing the arch-shaped plate above the head of the threaded cannulated screw, a cap screw was put into the threaded cannulated screw through a hole in the plate using a smaller cannulated Torx screwdriver. The cap screw was not completely tightened so that the plate could be used as a stencil to designate the contralateral dot in the middle of the cartilage on the right side of the costal arch. The cartilage was then drilled completely using a standard drill, and a 16 mm-long threaded cannulated screw was tightened using a cannulated Torx screwdriver. The right end of the arch-shaped plate was placed above the head of the threaded cannulated screw, and a cap screw was driven into the threaded cannulated screw using a smaller cannulated Torx screwdriver, as previously described. Then, the cap screws were securely tightened. At this point, the B-SOS was complete. To increase the stability of the system, two bicortical screws, one for each side, were tightened into the plate hole next to the cap screws. To achieve this, a smaller drill was utilized to pierce the cartilage, and a 16-mm bicortical screw was then tightened, first in the right side of the plate and then in the left. The final result can be seen on the video.
From November 2017 until May 2022, primary chest closure with the B-SOS was performed on 5 men and 1 woman, whereas sternal resynthesis for dehiscence was performed on 10 men and 3 women. The average age of the patients was 73.6 years (range, 56–88 years). The two most frequent operative risk factors were chronic obstructive pulmonary disease and the use of bilateral internal thoracic arteries (BITA). The average number of risk factors was 2.4 (range, 2–4). The most common cardiac procedure was coronary artery bypass grafting (CABG) with BITA. There were no perioperative deaths. Two patients developed superficial skin dehiscence, but sternal dehiscence did not occur in any case. The superficial skin dehiscences happened in two patients who underwent CABG and had BMI >30 kg/m2 and diabetes. The time taken to insert the B-SOS (1 plate+2 threaded cannulated screws+2 cap screws+2 bicortical screws), after an initial learning curve, was approximately 20 minutes longer than the time required for a standard six-wire sternal closure. There were apparently no intraoperative complications connected to implanting the screws.
Instability of sternal closure after a median sternotomy has been demonstrated to affect sternal wound integrity, leading to complications such dehiscence and mediastinitis as well as prolonged incisional pain. However, surgeons disagree regarding the most effective technique for sternal closure. Presumably for this reason, steel wiring remains the conventional method for sternal closure, despite the fact that it frequently fails to provide the stable sternal fixation necessary for successful bone healing. Therefore, we focused on designing an easy-to-use sternal closure approach with minimal influence on tissue dissection.
Therefore, we developed the B-SOS by taking an idea from the field of dental implants. The B-SOS offers two advantages compared with the other suggested systems. The first is that the threaded cortical screws are inserted into the rib cartilage/bone, which enables the system to be used even in cases of a paramedian sternotomy or destructive processes with partial or complete loosening of the sternal bone between the ribs. In these instances, it is almost impossible to use devices in the intercostal spaces. Therefore, the only option is to use threaded cannulated screws, which are more solid than sternal wiring and simpler than sternal plating that requires a large number of bicortical screws. The second advantage is that B-SOS requires only one threaded cannulated screw and one bicortical screw to stabilize each hemisternum. As previously stated, these advantages imply that the dissection of the tissues for the allocation of the threaded cannulated and bicortical screws is minimal with a reduced chance of causing damage to the lungs and mammary arteries when these are not used for surgery. Moreover, in the event of reopening in response to bleeding, it is sufficient to unscrew the two cap screws and two bicortical screws, and the entire process takes only a few minutes. In our experience, the only contraindication to sternal closure with B-SOS is osteomyelitis of the sternum and/or mediastinitis, and the only recommendation is to pay more attention to haemostasis in patients with a high risk of postoperative bleeding.
Casha and colleagues have provided the rationale for enhancing the closure of the lower part of the sternum [2]. In particular, these authors discovered that dehiscence of a typical six-wire sternal closure begins at the xiphoid and spreads cranially like a domino effect. They outlined the three mechanisms that contribute to sternal dehiscence: (i) the tension of the chest wall is proportional to the tangential radius at the relative level of the chest; (ii) there is a concentration of stresses in the lower portion of the sternum because the fifth, sixth and seventh ribs attach to about the same location on the sternum; (iii) the seventh rib receives extra stresses from the eighth, ninth and tenth ribs, which are linked to its inferior costal margin. Based on these findings, we have had experience with sternal closure reinforcement since 2014. Since that time, we have reinforced primary sternal closure in patients with at least two of the risk factors for sternal dehiscence shown in Table 1 by passing a steel wire through a couple of cannulated screws implanted in the cartilage of the fifth or sixth rib [3]. More recently (November 2017), we adopted the B-SOS for reinforcing sternal closure in very high-risk patients for sternal dehiscence (at least three risk factors) such as the patient described here who presented with obesity (BMI>30 kg/m2), sternal eruption, redo sternotomy, a history of sternal dehiscence and CPB time >2 h. Because the B-SOS is a modular system, it offers a range of sternal closure combinations, with a minimum armamentarium, as shown in Figure 2.
Figure 2. (1) Screw box; (2) screwdriver handle, 20 mm (3) anteroposterior bending pliers; (4) craniocaudal bending pliers; (5) titanium plates; (6) cannulated drill 2.8×90 mm, working length 18 mm; and (7) screwdriver with cannulated blade for 5.5-mm Torax screws.
In other words, the B-SOS expands the alternatives for an appropriate sternal closure strategy, as represented in Figure 3.
Figure 3. (A,B) The most frequently used combinations of sternal resynthesis for sternal dehiscence after a median full sternotomy. (C) Use of the Brixia system of screws for sternal resynthesis for sternal dehiscence after a clamshell sternotomy (double-lung transplant). (D–F) The most used combinations of sternal closure in case of a redo operation or in a patient with a very high risk of development of sternal dehiscence. The screws with the red asterisks above belong to the Brixia System of Screws; the screws without a red asterisk are common bicortical screws.
Finally, after testing various sternal closure combinations, as shown in Figure 4, we have determined that the one described in this video is the most stable and the least expensive in terms of benefits, costs, risks and usage flexibility.
Figure 4. (A–I) Some intraoperative pictures that demonstrate the versatility of the Brixia system of screws. (L) Illustration of the sternum to orient the reader.
1. Losanoff JE, Richman BW, Jones JW. Disruption and infection of median sternotomy: a comprehensive review. Eur J Cardiothorac Surg 2002;21:831–839.
PubMed Abstract | Publisher Full Text
2. Casha AR, Manché A, Gatt R, Duca E, Gauci M, Schembri-Wismayer P, et al. Mechanism of sternotomy dehiscence. Interact Cardiovasc Thorac Surg 2014;19:617-621
PubMed Abstract | Publisher Full Text
3. De Cicco G, Tosi D, Crisci R, Bortolami A, Aquino TM, Prencipe A, et al. Use of new cannulated screws for primary sternal closure in high risk patients for sternal dehiscence. J Thorac Dis. 2019;11:4538-4543.
The author(s) received no financial support for the research, authorship, and/or publication of this article.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Authors
Giuseppe De Cicco1, Gerardo Di Matteo1, Rosati Fabrizio1, Francesco Rattenni1, Taulant Bregova1, Davide Tosi2, Lorenzo Rosso2 & Stefano Benussi1
Affiliations
1Unit of Cardiac Surgery, Spedali Civili di Brescia, Brescia, Italy
2Unit of Thoracic Surgery and Lung Transplantation, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico di Milano, Milano, Italy
Corresponding Author
Giuseppe De Cicco
Unit of Cardiac Surgery
Spedali Civili di Brescia
Brescia
Italy
Email: decicco.giuseppe@yahoo.it
Keywords
© The Author 2023. Published by MMCTS on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
