Forces to be overcome in correction of pectus excavatum.

OBJECTIVE: The Erlangen technique of funnel chest correction is carried out through an anterior incision, and an essential step is retrosternal mobilization. After elevation of the funnel, the chest wall is stabilized with a lightweight transsternal metal implant. Forces necessary to elevate the chest wall were measured at defined intervals during the operation to prospectively assess the effect of peristernal and retrosternal dissection.

METHODS: Over a 3-year period, systematic tension measurements were carried out on 100 consecutive patients with symmetric funnel chest to assess the effect of individual steps in mobilization of the sternum.

RESULTS: Whereas in adolescents the extraction force is about 175 N, in adults it is not possible to elevate the sternum to the desired level without surgical mobilization because the force required is, on average, more than 200 N. Only about 50% of this tension can be eliminated by costal chondrotomy. To reduce the tension further and achieve a stable result without the need for heavy-duty internal fixation, we carry out a retrosternal dissection, including removal of the slips of the diaphragm and the insertions of the transversus thoracis muscle. The mean tension at the end of the procedure is 25 N.

CONCLUSIONS: Our measurements show that retrosternal dissection is the decisive step in the Erlangen technique, which might explain the low relapse rate and allow for a less extensive anterolateral mobilization.