## 13 Discussion
Younger patients are at risk for re-deformation of the chest wall, and approximately 25% of patients develop significant changes in the ribs, such as step deformities in the costal cartilage of greenstick fractures [2]. These complications particularly affect patients who are older than 10 years at the time of surgery. In adults, the Nuss procedure is usually modified, for example, by an additional anterior chest wall incision or extensive endoscopic mobilization to reduce tension. The total length of the incisions in these cases can therefore be significantly longer than in the Hummer procedure. In preoperative diagnostic testing, more than 20% of patients in general and more than 40% of patients undergoing surgery have restrictive pulmonary function or abnormal cardiac findings (such as mitral valve prolapse). Postoperatively, these functions almost always return to normal [13]. Functional back complaints usually improve as well. Consistent with the literature, our patient cohort showed no correlation between the severity of the deformity and pulmonary function test and ECG findings [2; 30; 31; 32]. Approximately 70% of our patients felt that their physical fitness had improved after corrective surgery. Some studies suggest that there is no improvement in pulmonary function after the Nuss procedure [33], while others have found opposite results, even postulating better results after the Nuss procedure than after the Ravitch procedure [34]. Studies after the Nuss procedure have not shown any improvement in lung function or physical fitness [35; 36]. During the long period (routinely 3 years) that the Nuss implant is in place, thoracic compliance is inevitably compromised. Long-term objective improvement in lung function is expected only in severe cases [37]. Echocardiography shows improvement in the motion of both ventricles [35; 37]. The Hummer procedure has an average operating time of 89.5 min (including a large number of procedures in adults), which is slightly longer than in the MIRPE procedure, which takes an average of 68 min in children and adolescents [38]. It is difficult to compare the figures from samples with such different patient ages. Larger adults require longer operating times than children, regardless of the technique used. The average incision length for the Hummer method is 8.9 cm. In children, a 5 cm incision is usually sufficient. Intraoperative tensiometry shows that the important step in overcoming retraction forces is the retrosternal dissection. This can be performed endoscopically; but in our experience, this is time consuming. Direct access to the deformity--either through a longitudinal incision over the sternum or through a submammary transverse incision--allows for correction of both symmetrical and asymmetrical deformities. The Nuss MIRPE procedure typically involves bilateral longitudinal incisions with an average of 6.8 cm in length and a much longer and stronger metal implant (the _\"petus bar\"_), that is inserted retrosternally and stabilized with reinforcing plates--a total of approximately 200 g of metal. Chondrotomy and dissection and direct access to the deformity are avoided in the original procedure but are required in the modified adult procedure. The original method is suitable for the malleable tissues of the chest wall in children and for symmetrical deformities. Modifications are required for adults, with an already rigid chest wall, and for asymmetric deformities. This usually involves additional incisions [39]. Lateral stabilization is almost always required to prevent displacement of the pectorus bar, making removal of the implant a major undertaking [40]. In our study, 64.6% of the patients were not satisfied, mainly because of the scar in the middle of the chest. According to other authors [41], 95.6% of the patients were either satisfied or very satisfied after the Nuss procedure and 87.0% of patients stated that they would undergo the procedure again, which is higher than in our cohort.