Material and Methods:
This retrospective study was approved by the local ethics committee and
have been performed in accordance with the ethical standards laid down
in Declaration of Helsinki. Between December 2009 and January 2020, a
total of 21,357 median sternotomies were performed, with an incidence of
NISD of 1.32% (283/21,357). The incidence of infectious sternal
dehiscence during the same period was 2.1% (432/21,357). Sternal
instability was determined at hospital and was defined as the presence
of mobility when pressing both sternal halves separately. Treatment
failure was defined as the need for reintervention for sternal closure.
Institutional protective measures against major wound infection and
sternal dehiscence included: a bath with chlorhexidine soap the night
before the operation, surgical site antisepsis with 10% povidone-iodine
solution, whole body shaving two days before the operation, antibiotic
prophylaxis with 1 g cefazolin (2 g in patients >80 kg),
and use of a chest brace and activity restriction for 6 to 8 weeks after
the surgery. Bone wax was not used during the procedures. Sternal
closure included the placement of 6–8 stainless steel wire U-sutures
one-by-one, without crossing.
We considered three principal categories for the classification of
sternal wound complications: mechanical NISD, sternal dehiscence with
superficial wound sternal infection, and sternal dehiscence with deep
sternal wound infection [5]. Patients who experienced infectious
complications of the sternal wound after sternotomy (n=432) were
excluded from the study. Of 283 patients with NISD who underwent
refixation, we mainly studied 34 cases who received TRNC treatment. We
divided these 34 cases into two groups: patients who had a previous
Robicsek repair before TRNC treatment (group A, n=11) and patients who
had been directly referred to TRCN treatment (group B, n= 23). In
addition, we compared the results of those who underwent TRCN treatment
(group B, n=23) with all 260 patients who underwent Robicsek repair
(group C, n=260) as the first sternal refixation procedure (Figure1).
Demographic, preoperative, intraoperative and postoperative parameters
were analyzed.
Nitinol thermoreactive clips (IAWA Bioscience Engineering Company,
Jiangsu, China) were used. Operation time was defined as the time
interval between the introduction of anesthesia and the end of the
surgical procedure. Routine preoperative echocardiography examinations
were performed. All patients were cultured for infection at the time of
reoperation and received standard antibiotic prophylaxis, which included
24-hour administration of a first-generation cephalosporin. Before
repair treatment, all cultures were verified to be negative for
infective microorganisms. Computerized data of the patients were
reviewed for reassessment of those in whom refixation was performed.
High-risk patients were defined as those having three or more risk
factors, including comorbidities and surgical complications which
predisposed them to sternal dehiscence. All reported comorbidities were
established by attending physicians.
Comorbidities included: severe or morbid obesity (body mass index
>35 kg/m2), old age (> 75 years), chronic
obstructive pulmonary disease (COPD) (forced expiratory volume less than
70% in 1 second, and/or need for bronchodilatatory therapy for more
than 6 months), congestive heart failure (New York Heart Association
functional classes III-IV), peripheral vascular disease (Fontaine
classification stages IIB-IV), chest irradiation, diabetes (insulin
dependent or non-insulin dependent therapy longer than 12 months),
severe osteoporosis (therapy for more than 6 months), chronic steroid
use (therapy more than 6 months), renal insufficiency (creatinine
>2 mg/dL), and prolonged ventilation (more than 7 days)
[6].
Surgical complications included: use of bilateral internal mammary
artery grafts, cardio-pulmonary bypass run longer than 5 hours, an
asymmetric off-center sternotomy, transverse fractures of the sternum,
rewiring for post-operative bleeding, and repeated sternal reopening
[7].
Out of 283 patients with NISD; 260 underwent Robicsek repair, of which
17 were reported as high-risk patients. Of these 17 high-risk patients,
11 still had sternal instability after Robicsek treatment. There was no
reported failure in the remaining Robicsek cases. Failed cases were
referred to the thoracic surgery clinic for TRNC treatment.
The Robicsek method consists of placing continuous wire sutures
parasternally. First, substernal tissues or adhesions were dissected.
Each half of the sternum was fastened by continuous parasternal wire
sutures. The suture began at the upper end of the sternum and passed
down to the xiphoid process, alternating anteriorly and posteriorly
between the costal cartilages. The suturing was then reversed toward the
cranial direction, passing through the cartilages posteriorly where it
had been anterior, and vice versa. At the upper end of the first rib,
adequate reinforcement was provided and the two ends of the suture were
tied together. Stainless steel wires were placed parasternally. The
first wire was then passed through the manubrium through the second
intercostal space and twisted to form a ring. The second wire was placed
through the second and third intercostal spaces in an interlocking
fashion until the end of the sternum was reached. The interlocking
created a chain on both sides of the sternum [8]. The Robicsek
technique was performed in the cardiovascular surgery clinic.
The TRNC method includes placement of nitinol clips either with or
without the dissection of the substernal tissues. The pectoral muscle
was completely bilaterally mobilized from the thoracic wall to
facilitate approximation. Granulation tissues at both sternal ends were
carefully removed and the bone tissue was exposed. Using electrocautery,
parasternal holes were opened through the intercostal muscles close to
the parasternal edges. When dissection of the substernal tissues or
adhesions was required, they were dissected close to the costochondral
junction using a right angle instrument. Both hemi-sternums were joined
and stabilized with two Backhaus forceps. The sternal horizontal
diameters were measured with the sizing tool provided, and
appropriately-sized nitinol clips were used. The clips were put into
refrigerated (<5° C) sterile saline solution. They became
forgeable in minutes and were adequately enlarged by bending. The clips
were inserted into the parasternal holes, from superior to inferior
direction, and at least four horizontal placements were made for each
patient. The clips were then heated with warm water (>45°
C). After the clips resumed their original shapes and regained
stiffness, the forceps were removed. The TRNCs were placed at the
intercostal spaces without using steel wires. Pectoral muscle flaps were
closed at the midline using absorbable sutures. Small suction drains
were left in the central defect and under both pectoral muscle flaps and
the substernum. The TRNC technique was performed at the thoracic surgery
clinic (Figure 2). In both reoperations, mediastinal tissue and fluid
cultures were collected in patients with suspected infections.
All statistical analyses were performed using SPSS version 21.0 software
(SPSS, Inc., Chicago, IL, USA). Continuous parameters are presented as
mean standard deviations. Categorical data are presented as numbers and
percentages, and proportions between the two groups were compared using
the chi-square test or Fisher’s exact test. The Mann–Whitney U test was
used for comparison of nonparametric variables, and the independent
samples t test was used for comparison of parametric variables. A p
value <0.05 was considered significant.