While the pathogenic mechanisms for PC remain unclear, the disease has a lower incidence rate than pectus excavatum and accounts for 6-22% of all chest wall deformities [2, 11]. It is more common in males with a male-female ratio of 4:1, and typically presents during childhood and aggravates dramatically during pubertal growth . There are different types of PC according to the maximum point of the deformity: the chondrogladiolar form is the most common variety (involving the lower sternum) with symmetric or asymmetric protrusion, while the chondromanubrial form is much less common (involving the upper sternum) . In contrast to pectus excavatum, pectus carinatum deformities are more evident and difficult to conceal with clothing or posture. As a result, the patients with PC suffer from poor self-confidence, feelings of inferiority, and are hesitant or refuse to participate in sports or social activities, which are all harmful to the patient's psychological health.
Treatment options for PC include nonoperative treatment and operative treatment. Nonoperative treatment for PC employs a specially designed orthotic chest brace to apply compression on the protruding sternum to achieve the correction of the deformity. This technique has been proven to be effective and associated with advantages of non-invasiveness and low morbidity [14, 15]. However, as it requires long-term application of the brace and does not immediately present a satisfactory result, non-compliance is frequent .
The conventional Ravitch operation and its modified procedures for PC [17,18], consisting of open incision and resection of costal cartilages, are substantially invasive and associated with considerable postoperative pain and an obviously visible scar. The minimally invasive procedure for repair of PC, introduced by Abramson, has been performed widely with good cosmetic results and less postoperative complications. However, at least 4 ribs are involved in the fixation system, and postoperative wire breakage is difficult to avoid as the entire force working against the sternum is sustained by the wires. Although various modifications to the Abramson procedure have been applied, the essential principle of the surgery is still the same. Early wire breakage is the primary cause of bar displacement that results in orthopedic failure and re-operation. In addition, since both ends of the metal bars are fixed to the chest wall, the growth and development of the chest may be restricted.
In our technique, the pectus bar is placed over the sternum through the subcutaneous tunnel, with both ends passing through the intercostal spaces of the selected rib at the anterior axillary line. The protruding sternum is depressed by force being exerted by the selected ribs onto the bar. Since the intra- and extra-thorax placement of the bar results in an “autologous” force and stability, neither manual compression nor special wire fixation is needed. Furthermore, due to the exemption from the fixation of the bar to the bilateral ribs, this procedure can eliminate the restriction on the growth of the chest. Meanwhile, this procedure has an added advantage as the bar corrects the chest contour and simultaneously expands the chest laterally which produces a better cosmetic result. Finally, this operation can be performed with the conventional Nuss pectus bar and instrument, without any specially designed apparatus.
The most significant characteristic of our technique is that the bar passes through the thorax 4 times (2 intra- and 2 extra-thorax). The technique in principle is similar to the method proposed by Kálmán and Hock and their colleagues [19, 20], in which the bar is passed into or out of the chest parasternal using the finger for blind guidance. In contrast to this method, our procedure presented here is simpler and safer and does not entail a risk of injury to the heart or the great vessels, since the bar is passed through the thorax under direct vision. Compared with Tarhan’s technique , our procedure further simplifies the operation in the same safety setting and does not require a thoracoscope or presternal incision.
Unlike pectus excavatum, which is characterized by progressive aggravation before adolescence, the deformity of PC is not apparent in childhood but will be rapidly aggravated and reach its physically and psychologically disturbing peak during puberty. According to our experience, the best candidates for the minimally invasive correction are 12-18 years old. However, the decision of surgery is based on the flexibility of the chest wall rather than the age. Preoperative evaluation of the chest wall flexibility, by compression of the protruding area with the examiner’s hand, while the patient is taking a supine position or leaning against a wall, should be routinely performed for judging whether if a thorax is flexible enough to be corrected. The contraindications for a bar correction are non-malleable, rigid thoraces, as the chondromanubrial type of PC or very asymmetric deformities are more suitable for treatment with the open techniques [4, 19].
Eight patients with asymmetric deformity of chondrogladiolar type underwent a correction in our procedure and received good cosmetic results. Therefore, besides symmetric PC, we believe that this technique could also be considered a valid method for the correction of asymmetric PC in selected patients.
There was 1 case of uncontrolled wound infection, which ultimately resulted in the failure of the correction due to the removal of the pectus bar and stabilizers prior to the planned date. This should be ascribed to the insufficient coverage of the bar and stabilizer. The implants should be placed under and well covered by the muscle tissue to avoid subcutaneous exudate. Overall, we consider the morbidity of postoperative complications to be lower. The risk of wire breakage and bar displacement, as frequently observed in the Abramson technique, is avoided due to the fact that the implant is not fixed to the ribs.
Taken together, compared with Abramson procedure and other techniques, the advantages of our procedure are that there are (ⅰ) no complications with wire breakage or bar displacement, (ⅱ) no potential restriction on the growth of the chest wall, (ⅲ) no risk of injury to the heart or great vessels; and that (ⅳ) the chest wall can be expanded laterally for a better appearance.
This study has several limitations. First, this is a retrospective study from a single center, which is limited by the small sample size. Surgical skill level needs to be considered in a study of this nature. However, this new minimally invasive technique for 42 patients with PC in our hospital was performed by 3 different skilled surgeons with excellent technique. Given that satisfactory cosmetic results were obtained in all the patients, we believe it is worth spreading this safe and feasible technique for chondrogladiolar PC in other centers. Second, all the patients enrolled in the study were chondrogladiolar PC and only 20 patients underwent the removal of the bar, further experience with more patients is necessary to evaluate the long-term results and to study whether this technique is applicable to other forms of PC.