The effectiveness of double-bar correction for pectus excavatum: A comparison between the parallel bar and cross-bar techniques

Pectus Disorders: Excavatum, Carinatum and Arcuatum

This article reviews pectus excavatum, carinatum, and arcuatum. Topics covered include etiology, epidemiology, associated syndromes, physiologic impact, workup, indications for treatment, surgical and nonsurgical therapy, results, complications, and emerging therapies. Pectus excavatum is an inward deformation of the sternum and/or anterior chest wall. Pectus carinatum is ether an outward protrusion or tilt of the sternum with potential psychological impact, but no demonstrated physiologic impact. Nonoperative compression bracing is successful in carinatum patients with chest wall flexibility who are compliant with a bracing program. Pectus arcuatum is an abnormally short, fully fused sternum with a high anterior protrusion.

'Short Bars Crossed' to Remodel the Entire Chest Wall in Children and Adolescents with Pectus Excavatum

BACKGROUND

The cross-bar technique of minimally invasive pectus excavatum (PE) correction remains underreported, which is especially true of pediatric patients. We therefore reviewed the experience of a Turkish and an Austrian center. An additional novelty characterizing both pediatric cohorts was the use of short bars.

METHODS

In a retrospective study, pediatric PE corrections involving 'short bars crossed' were analyzed for complications and intra-/postoperative outcomes. Cases with two or three bars were included, given that a horizontal third bar was placed whenever considered useful for upper-chest elevation. All bars were fitted with a single stabilizer near the surgical entry point. In the Austrian center, intercostal nerve cryoablation was used for pain management. Descriptive statistics are presented.

RESULTS

Seventy-eight patients ≤18 years old were evaluable at the Turkish (n = 56) and Austrian (n = 22) centers. Total median values were 16.2 (IQR: 15.1-17.4) years for age and 4.60 (IQR: 3.50-6.11) for Haller index. Ten mild or moderate complications (12.8%) were observed, including just one revision requirement due to bar migration (1.28%). Intercostal nerve cryoablation (n = 13) was associated with longer surgical procedures at 150 (IQR: 137-171) versus 80 (IQR: 60-100) minutes but with shorter hospital stays, given an IQR of 3-4 days versus 4-5 days.

CONCLUSION

'Short bars crossed'-with a single stabilizer in a ventral position close to the surgical entry point-ensure a wide distribution of forces, protect against bar migration, are safe and effective, and offer stability at an age characterized by growth and physical activity.

LEVEL OF EVIDENCE

IV.

Biomechanical Effectivity Evaluation of Single- and Double-Metal-Bar Methods with Rotation and Equilibrium Displacements in Nuss Procedure Simulations

Surgical treatment of the pectus excavatum has led to the introduction of the Nuss procedure, a minimally invasive surgical procedure that involves inserting a metal bar under the sternum through a small lateral thoracic incision. An additional metal bar was inserted in patients with pectus excavatum to improve the retention of the restored chest wall after the Nuss procedure. However, a need still exists to analyze the mechanistic advantages and disadvantages of the double-bar method owing to the increased surgical time and proficiency. The purpose of this study is to compare and evaluate the efficiency of single- and double-bar methods using rotational and equilibrium displacement simulations of the Nuss procedure. A finite-element model was constructed for two types of metal bars inserted into the chest wall. Boundary conditions for the rotation and equilibrium displacements were set for the metal bar. The anterior sternal translation, Haller index and maximum equivalent stress and strain owing to the behavior of the metal bar were estimated and compared with the single-bar method and postoperatively acquired patient data. The simulation results showed that the influences of the intercostal muscle and equilibrium after rotation displacement were significant. The stresses and strains were distributed across the two metal bars, and the upper-metal bar was heavily loaded. The double-bar method was advantageous regarding the load distribution effects of the two metal bars on the chest wall. However, mechanical assessments are also important because an excessive load is typically applied to the upper-metal bar.

A novel in silico Nuss procedure for pectus excavatum patients

The purpose of this study is to suggest a novel in silico Nuss procedure that can predict the results of chest wall deformity correction. Three-dimensional (3D) geometric and finite element model of the chest wall were built from the 15-year-old male adolescent patient's computed tomography (CT) image with pectus excavatum of the mild deformity. A simulation of anterior translating the metal bar (T) and a simulation of maintaining equilibrium after 180-degree rotation (RE) were performed respectively. A RE simulation using the chest wall finite element model with intercostal muscles (REM) was also performed. Finally, the quantitative results of each in silico Nuss procedure were compared with those of postoperative patient. Furthermore, various mechanical indicators were compared between simulations. This confirmed that the REM simulation results were most similar to the actual patient's results. Through two clinical indicators that can be compared with postoperative patient and mechanical indicators, the authors consider that the REM of silico Nuss procedure proposed in this study is best simulated the actual surgery.

Modification of the Nuss procedure: the crossed bar technique for new subtypes of pectus excavatum

BACKGROUND

We aim to describe four new subtypes of PE in detail and represent modification of the Nuss procedure called crossed bar technique for their optimum correction with good results.

METHODS

101 patients who underwent crossed bar technique between August 2005 and February 2022 were included into the study.

RESULTS

The mean age of the patient series was 21.1 (range 15-38 years) years. Mean Haller index was 3.87. Mean operation duration was 86.84 min. 2 bars were used in 74 (73.3%) of the patients whereas 3 bars were preferred in 27 (26.7%) of them. Mean hospital stay was 4.1 (2-8) days, and all the patients were seen routinely on postoperative follow-up at 1st, 6th, and 18th months. Quality of life questionnaires revealed satisfaction.

CONCLUSIONS

Cross bar technique yields satisfactory results for these new subtypes and can be performed safely with good results in these selected group of patients.

The Cross-Bar Technique for Pectus Excavatum Repair: A Key Element for Remodeling of the Entire Chest Wall

INTRODUCTION

 The multiple bar approach was developed to cover broader and heavier teenager/adult chest wall deformities. We designed the cross-bar technique to achieve remodeling of the entire chest wall. This study aimed to demonstrate the role of cross-bar and its benefits over the parallel bar.

MATERIALS AND METHODS

 The cross-bar technique involves placing two bars diagonally and then cross on the target. The primary purposes are to double the lifting forces by making two bars converge on a single target to lift inflexible heavy chest wall depressions or cover lower lateral areas. The results of the cross-bar and parallel bar are compared for the indications, postrepair outcomes, and complications.

RESULTS

 From 2016 to 2019, 247 patients who underwent multiple bar pectus excavatum (PE) repair were enrolled in the study: 157 with cross-bar and 90 with parallel bar. In the cross-bar group, 33% (51/157) received three bars in XI fashion to cover the upper depression. The cross-bar group was older (18.0 ± 6.1 vs. 15.7 ± 5.0), had higher depression index (1.9 ± 0.7 vs. 1.8 ± 0.3), and was less asymmetric (45% vs. 71%) than those in the parallel bar group. The overall complication rates were not different between the two groups (9.6% vs. 10%, p = 1.0), although the cross-bar group was more rigid and complex. There was no bar displacement or reoperation in both groups.

CONCLUSION

 The cross-bar technique is as safe and effective as the parallel-bar technique, even though it was selected to correct more complexities. The cross-bar technique could be a method for complex PE deformities for remodeling of the entire chest wall.

Pushing the boundaries of minimally invasive repair of pectus excavatum: first experience with a 4-bar technique

Several modifications to minimally invasive repair of pectus excavatum have been reported to date. Of these, the use of multiple bars was a major development. At present, there are 2 established techniques: cross-bar and parallel bar placement. We used a combination of both parallel and cross-bar techniques in a 25-year-old male patient with deep, Grand-Canyon type pectus excavatum, placing a total of 4 bars and 4 stabilizers. The patient had no complications during the 7 months of postoperative follow-up. We share this case report as the first experience using this modified technique in the literature.

Current Development of Minimally Invasive Repair of Pectus Excavatum (MIRPE)

For decades, open surgical repair was the only available method to treat congenital and acquired chest wall deformities (CWDs). In 1998, D. Nuss described a minimally invasive procedure for surgical repair of Pectus excavatum (PE). Today, the Nuss procedure is performed with increasing frequency worldwide and considered as the “gold standard”. After its introduction, the method experienced numerous modifications such as routine thoracoscopy and/or sternal elevation, increasing safety of the procedure. Placement of multiple bars and/or the so called cross-bar technique were introduced to correct complex CWDs. Standardized pain management, the introduction of cryo-analgesia and a standardized postoperative physiotherapy program including deep breathing exercises facilitate the establishment of an enhanced recovery after surgery (ERAS) process. However, the widespread use of the minimally invasive repair of pectus excavatum (MIRPE) procedure has been associated with a significant number of serious complications. Furthermore, several studies report near-fatal complications, not only during bar placement, but also during bar removal. This review focuses upon the most relevant modifications, including recent published surgical techniques of MIRPE, in order to describe current developments in the field.