Sternal elevation in pectus excavatum repair: comparison of a unilateral versus bilateral frame crane system

Instability in the conventional, unilateral frame crane system occurs when greater sternal elevation forces are required, which potentially limits optimal sternal elevation during Nuss repair of the pectus excavatum. A bilateral frame setup was subsequently developed. We hypothesized that increasing the retractor's stability with the bilateral frame crane system would yield superior sternal elevation, as reflected by a greater lift of the anterior chest wall.

Pectus excavatum patients who underwent the Nuss procedure utilizing sternal elevation between November 2022 and October 2023 were included in this crossover study. Three-dimensional surface imaging was used to evaluate differences in established maximum and average combined chest wall elevation, comparing unilateral to bilateral frame crane systems. The results were also compared to the effect of bar implantation on the deepest point of the deformity.

The 30 patients included in the final analysis were predominantly male (83%) with a median age of 16.0 years (interquartile range 14.3-17.0) and median Haller index of 3.3 (interquartile range 2.9-3.8). The bilateral frame crane system achieved maximum combined chest wall elevation comparable to the effect of definitive bar placement (33 mm vs 38 mm, P = 0.06) and provided significantly greater elevation than the unilateral frame crane system (33 mm vs 24 mm, P < 0.001). Both systems, however, showed similar results for average combined chest wall elevation (4 mm vs 5 mm, P = 0.16).

The bilateral frame crane system demonstrates superiority in achieving sternal elevation at the deepest point of the deformity, which may theoretically facilitate safer and more optimal bar placement.