Pectus carinatum

In 1987 Donald Nuss introduced a minimally invasive procedure, entitled the Nuss procedure, which transformed the treatment of pectus excavatum (PE). The operation involved inserting a stainless steel bar to correct any deformity of the anterior wall of the chest. After further research and trials spanning seven years, the procedures involved in PE were effectively transferred to PC. This approach was based on the assumption that both pectus excavatum and carinatum share common characteristics and require similar therapeutic strategies. However, is that true? As we know, both deformities of the anterior chest wall are frequent, and boys are more often affected than girls. It is also a known fact that both entities can concomitantly occur together with scoliosis, whereas it is unclear whether one or the other deformity induces or interferes with the other, or if they are distinct phenomena. Similarly to PE, a genetic predisposition of PC is likely, although the onset of the latter corresponds more frequently to the beginning of puberty. Research in the associated symptoms, such as dyspnea, palpitations, etc. are inconsistent in PC, while both deformities are concomitant features in patients with Marfan and Noonan Syndrome. For the sake of completeness, it should be noted that many chest wall deformities, including PC, can also occur as a result of a surgical procedure to correct a congenital disease, e.g. diaphragmatic hernia, or following sternotomy, which is mostly performed in cardiosurgical procedures.

In terms of the developmental process, a similar pathomechanism is suggested for both kinds of sternal dislocation. Researchers agree that the inappropriate growth of the costosternal cartilage can result in sternal shifting. However, it remains unclear as to which factor determines whether the sternum moves to a position above or below the ideal line, and why these osteochondral deformities occur either symmetrically or asymmetrically. It is also enigmatic whether additional pathologic angulations of the sternum are due to the abovementioned mechanism, or if another factor solely targets the osseous malformation. Another unanswered question concerns the onset of chest wall deformities, because PE, more often than PC, occurs in early infancy and remains stable over years before a rapid dislodgment of the sternum progresses as puberty starts. 

Therapeutic concepts for the surgical repair of PC date from the early 1950s, when Ravitch published his technique for the correction of both pectus excavatum and carinatum. However, this topic received very little attention from researchers and scientists and, over the course of 50 years following the introduction of Ravitch’s technique, just three papers per year on average were published that examined PE and PC. The majority of those studies that were published described an individual’s experience with surgery in PC, but the operative concept remained largely rare.

This situation did not change until 2005, at which point Abramson demonstrated the inverse use of the Nuss pectus bar. His concept spurred the community as a whole to pay more attention to the use of surgical concepts to correct PC, and research into the modification of instruments and implants commenced. Stimulated by this discussion, promoters of the open repair of PC reappeared on the field, advocating for the open approach and refining their technique and implants. From that point onwards, the frequency of PC-related publications increased to up to 17 papers on average per year. However, in contrast to the treatment of pectus excavatum, for which the Nuss procedure had already become state of the art, the diverging concepts on how to best treat PC remained open to debate. In the meantime, the conservative approach to treating PC, which was first proposed in the mid-1970s, experienced renaissance. Pediatric surgeons from Argentin] and Canada introduced their newly developed devices, protocols and study results. They demonstrated that bracing PC patients during puberty had a high success rate. However, treatment strategies for pectus carinatum remain under debate to this day. 

The crucial and most diverging point about the treatment of chest wall deformities is to define the right indication, particularly for major procedures, including the risks and side effects of radiation, anesthesia and surgery. Despite the fact that recent studies demonstrate a slight improvement in cardiopulmonary function following PE repair, it is still the patients with PC and PE who indicate the time and mode of the procedure. In other words, we are experiencing a paradigm shift through which the affected young people do not visit cosmetic surgeons but requiring surgery that is predominantly not medically indicated from thoracic and pediatric surgeons. All the more, it remains the surgeon’s responsibility to decide whether or not to follow the patient’s desire. However, those adolescents who suffer from conspicuous thoracic deformities, or who suffer greatly from an impairment of self-image, should be considered candidates for surgery, even when the indication is primarily not medical. In consequence, the outcome measures also have to be newly defined. Meeting the patients’ expectations is the main goal to be achieved, and success rates of either procedure have to be measured against the satisfaction of the patient and the improvement of his or her self-esteem.

Taking into account the fact that patients with PC do not suffer from physical limitations, further medical investigation depends on the therapeutic concept. Planning a surgical procedure requires appropriate diagnostic work, while scanning the thoracic surface without radiation and photographic documentation are sufficient for bracing therapy. Unnecessary exposure to radiation has to be avoided whenever possible.

Most open procedures for PC repair follow the principle of Ravitch`s technique. The key steps in this approach involve the dissection of the pectoralis muscles, resection of the costosternal cartilages, osteotomy of the sternum, if necessary, and intermediate fixation of the lifted sternum with variable devices and material. Several authors have published methods that incorporate slight modifications to the technique, the majority of which involve shortening the skin incision, minimizing the surgical trauma and avoiding secondary interventions for the removal of implants. The overall results of open surgery for PC are good according to the abovementioned parameters.

The inverse use of the pectus bars for PC was introduced by Abramson. He showed how the protruding sternum could be pressed down into a normal position and fixed by use of an individually bent bar, which was subcutaneously introduced. The principle of this procedure was adopted by other authors, whereby they developed different solutions as to how to fix the bars to the ribs. However, the flexibility of the sternum is a crucial precondition for the use of this approach.

The flexibility of the thorax is also essential for the conservative approach to PC. Herein, thoracic plasticity can be tested by slow, but forced, manual pressure on the prominent sternum. When the sternum can be replaced into a normal position, bracing is a promising option. Several studies have already shown that the effect of this treatment can be observed within a few weeks, and complete reposition is a question of months [5]. The most striking argument for this orthopedic approach is that no side effects are threatening, except for skin irritation and general discomfort when using the device. On the other hand, no evidence is given when diverging concepts are recommended concerning the design of the brace, minimal and maximal pressure rates and the appropriate time of use. Another advantage is that, in case of a relapse, the same treatment can be started once again with a reasonable chance of success.

 

In contrast to PE patients, where surgical correction should preferably be scheduled for late adolescence, the orthopedic approach to PC has to be started as soon as the deformity becomes evident. This alleged contradiction has to be passed to the pediatricians, orthopedics and surgeons who see those patients first.The challenge for the upcoming years will be to optimize the treatment modality of the non-operative approach to PC and to elucidate the complexity of thoracic and concomitant spinal deformities.   

 

Excerpt  from 

C. Petersen, C. Fortmann in “Thoracic Surgery in Children and Adolescents”, Claus Petersen, Benno M. Ure (Eds.), 2016 Walter de Gruyter GmbH, Berlin/Boston

Claus Petersen | Department of Pediatric Surgery | Hannover Medical School | Carl-Neuberg-Strasse 1 | 30625 Hannover, Germany
Tel.: +49-(0)511-532-9040 | Fax: +49-(0)511-532-8052 | www.chestwall.org | chestwall@mh-hannover.de