Transverse sternal nonunion is a rare but a disabling complication, occurring mainly after traumatic sternal fractures or after a rarely performed transverse sternotomy [1]. The rate of nonunion is less than 1% after sternal fractures, while the condition becomes more common and is considered an important chronic complication after a transverse sternotomy, with the rate of 6.8% [4,6]. A transverse thoracosternotomy (known as a Clamshell incision) is typically used in double-lung transplantations, offering an excellent exposure to the heart, lungs and the great vessels [6,7]. Due to multidirectional movements with tension and compression forces acting in all planes, fixation of the transverse sternotomy, sternal fracture or transverse nonunion remains a challenge [1,5]. There is very limited data published on transverse sternal nonunion, especially after a sternotomy, mostly being case reports or small case series [1,8,9]. Different fixation materials and techniques were described to fix transverse fractures, osteotomies or nonunions, with tension wiring and plating being the most commonly performed [4,5,8]. Tension wires, which are still typically used to close a median sternotomy, often fail when used for a transverse sternotomy closure, which also occurred in our patient in the early postoperative period. When using cerclage wires, the crossed wiring closure technique reduced the incidence of sternal dehiscence compared to the uncrossed technique [10]. In their comparative study Qin-Yun Ma with co-workers showed a significantly higher sternal healing rate in the plated group compared to the tension-wired group after a transverse sternotomy [11]. Biomechanical advantages of sternal plating were previously shown in a cadaveric study [12]. Other authors also reported good functional outcome of sternal plating, with a high rate of union mainly after the usage of the one or two parallel locking plates [3,5–7,9,13,14]. Locking implants, with screws that are angular stable locked in the plate, in contrast to conventional plating better resist continuous multidirectional forces that act on the construct during breathing. Additionally, monocortical locking screws could be used as a safer option to prevent an iatrogenic injury to the retrosternal vital structures. But on the other hand, they provide less purchase than bicortical locking screws, especially in a weaker bone [3,9]. A review of the published literature done by Schulz et al. in 2015 showed good results for the most locking plate systems that were used, and a review from Klei et al. from 2018 confirmed that plating was the most common type of fixation after sternal fractures (83%), with a good consolidation rate and low complications [8,15]. In our case, the patient had a symptomatic postoperative chest wall defect because of transverse sternal nonunion in combination with a rib resection. Nonunion was previously unsuccessfully treated by tension wiring and one-third tubular plate fixed with conventional, non-locking screws. In accordance with available published data, we fixed the nonunion with a locking plate. Due to the anatomical conditions, we did not use one or two regular longitudinal 3.5 mm locking plates. We decided to use a single stronger locking plate that is normally used to fix distal tibial fractures, which we shaped to the bone. As the patient was tall and obese, the plate appeared to be well sized. The broad ending of the plate with multiple locking screws that were applied in different directions provided a really strong purchase in a deformed proximal fragment. The sternal defect was also bone grafted with a tricortical iliac crest autograft. Bone grafting was also advocated for and performed in some other published cases of transverse sternal nonunion with a bone defect [1,5,16,17]. Important late complications of the sternal plating are pain and irritation, caused by the prominent material, requiring removal of the plate in 15.4% and in 27% of the patients, respectively [2,9]. In our case there were no implant-related problems and therefore, there were no indications for plate removal.
A Gore-Tex Dual mesh membrane was additionally used in our patient, to cover the chest wall defect after rib resection. Gore-Tex dual mesh membranes were shown to be a good option for reconstruction of chest wall defects, especially after wide surgical resections [18–20]. By using the membranes, we successfully closed the remaining defects and treated the lung herniation. Besides that, we believe that membranes also diminished loads applied on the plate during continuous chest movements and possibly contributed to prevention of an early plate failure.
We reviewed the literature for similar cases and could only find a few small series and case reports describing a successful combination of titanium plates with Gore-Tex dual mesh membranes to achieve a stable chest that allows the complete range of respiratory movements, most of them being used after wide surgical resection of the thorax [19,21]. However, we could not find any reports of a similar treatment in such an extensive postoperatively deformed chest, resulting from widely displaced sternal nonunion and rib resection. To our knowledge this is also the first time that a specific tibial plate being successfully used to fix transverse sternal nonunion is reported.
In conclusion, we present a rare case of a patient with a symptomatic postoperative chest wall defect resulting from transverse sternal nonunion after a transverse thoracosternotomy (clamshell incision) and concomitant rib resection. We believe that addressing both, the transverse sternal nonunion by a properly sized and shaped locking plate with bone grafting and the chest wall defect after rib resection by a dual mesh membrane, was important for a good outcome in our patient.