Orthopaedic braces for pectus carinatum and vacuum bell therapy for pectus excavatum are conservative therapies for chest wall deformities and have become the preferred treatment options for patients with pectus excavatum and pectus carinatum owing to their advantages, including non-invasiveness, no surgical scarring, and low treatment cost[9]. However, the outcomes are often unsatisfactory for complex chest wall deformities with combined deformities. Eleven paediatric patients in this group, in whom orthopaedic braces for pectus carinatum or vacuum bell therapy for pectus excavatum had failed, underwent surgery. The reasons for the failure of conservative treatment are summarised as follows: a) low compliance with medical advice during the use of the orthopaedic braces and vacuum bell on the part of the parents at home, and insufficient wearing time or irregular wearing due to aversion and resistance of the paediatric patients to the treatment, which ultimately led to treatment failure; b) poor thoracic compliance such as poor thoracic compliance and stiffness and poor elasticity of the bones resulting in failure of conservative treatment in older paediatric patients or adults[6].
Both the minimally invasive sternal compression procedure and the Nuss procedure are established procedures for the treatment of pectus carinatum and pectus excavatum that have been validated worldwide[10, 11]. When a minimally invasive sternal compression procedure is used to treat pectus carinatum, additional indentation may occur around the site of sternal compression[12]. For pectus carinatum combined with Harrison sulcus, the Harrison sulcus is exacerbated when the sternum is compressed during treatment. This not only results in failure to improve external appearance but also a reduction in thoracic volume. This double-plate technique is an effective surgical method with plate supports under the sternum, which to some extent avoids excessive compression of the anterior chest wall with the plate above the sternum leading to pectus excavatum; moreover, the stability of the thoracic cage is maintained, the volume of the thoracic cage is increased, and lung function is improved, thereby overcoming the limitations of a pure sternal compression procedure[13]. At the same time, this surgical approach has the advantages of less trauma, less intraoperative blood loss, fast postoperative recovery, and pleasing postoperative external appearance of the chest wall.
The length of the steel plate, the distance between the two plates, the selection of the entrance and exit points, and the location of the incisions need to be carefully designed. The selection of the length of the pressing steel plate is centred on the highest point of the sternum prominence. The lengths of both the mid-axillary line and the anterior axillary line are measured using a skin ruler. The steel plate's length falls within this range. Based on the rib position where the steel plate will be secured, the final length of the steel plate is determined. The two plates should not be too close to each other to allow adequate space for the fixing pieces. In two cases in this group, the plates were placed too close to each other; hence, the fixing pieces could not be placed, and thus the plates were tied directly with stainless-steel wires, which resulted in the loosening of wires and plate displacement after surgery. The fixing pieces were also not placed in another case with incision dehiscence and plate exposure. The causes of complications were analysed and were as follows: 1) the plate was placed under the fat layer, and the patient was thin with a thin subcutaneous fat layer and a lack of a chest muscular layer to protect the plate; 2) the patient was in adolescence with rapid growth in height and the thoracic cage, which caused the plate to exert more tension on the skin from the inside out, eventually leading to skin abrasion by the plate and plate exposure. Based on the lessons learned, we placed the plates under the muscular layer in the subsequent surgeries. The placement of two plates often causes high skin tension, and the plates are prone to exposure once infection or rejection occurs, which leads to the risk of premature removal of the plates. The thicker muscular and fat layers wrap the plates and fixing pieces tightly, and it is easier to heal after regular dressing changes in case of infection. As the intersection of the lowest point of indentation and the sternum is often located at the xiphoid process, the separation of the tissues behind the sternum by the introducer needs to be performed under direct thoracoscopic view to avoid damage to the diaphragm.
After the minimally invasive sternal compression procedure combined with the Nuss procedure, paediatric patients often feel severe pain that can cause postoperative complications such as insomnia, fear of excreting sputum by coughing due to the fear of pain, which leads to postoperative pneumonia and atelectasis, and scoliosis due to the long-term protective posture of paediatric patients. Therefore, effective surgical analgesia is extremely important for the postoperative recovery of paediatric patients. All cases in our group received multimodal analgesia[14], where ropivacaine was used for a regional block during anaesthesia, sufentanil combined with non-steroidal anti-inflammatory drugs was administered intravenously for 2–3 days after the surgery for analgesia, and additional intravenous or oral analgesics, such as acetaminophen, ibuprofen, and diclofenac, were administered in cases of severe pain.
Although this double-plate technique is minimally invasive and effective, the age and indications for surgery need to be strictly controlled. The authors specified the age of enrolment as 8–18 years. For prepubertal paediatric patients with pectus carinatum, their bones are still soft, the thoraxes are easily shaped, and the treatment outcomes are satisfactory with orthopaedic braces. Undergoing surgery before puberty is associated with a risk of recurrence and can affect the growth of the ribs of paediatric patients. However, in adulthood, the patients have stiff bones and poor thoracic elasticity, and more support is required to lift the thoraxes forward, which can easily lead to unsatisfactory orthopaedic correction outcomes. Therefore, the authors believe that early adolescence is the best time to perform this surgery. One case in this group was operated on at the age of 8 years due to the strong desire of the patient and parents for surgery, and the rest of the paediatric patients were operated on at the age of 10 years or above. For some congenital cardiopulmonary diseases, such as congenital diaphragmatic hernia, retrosternal hernia, and lobar emphysema, secondary pectus carinatum formed by forward extrusion of the sternum can be initially treated with braces after treating the primary disease.