Chao-Jan Wang

Preliminary analysis of the forces on the thoracic cage of patients with pectus excavatum after the Nuss procedure

BACKGROUND The Nuss procedure corrects pectus excavatum using a pre-bent bar that generates stress on the chest wall. To investigate the biomechanical effects after the Nuss procedure, we designed a three-dimensional finite element analysis model to analyze the distribution of stress and strain induced in the chest wall. METHODS Three patients with pectus excavatum aged 8, 7, and 7 years, were enrolled in this study. The greatest upward displacements of their sternums after the operation were measured from computed tomography images and chest X-ray films. Based on these displacements, we constructed three finite element analysis models for analyzing biomechanical changes in the thoracic cage after the Nuss procedure. FINDINGS The simulation results indicated that greatest strain occurred at the third through seventh cartilages, especially where they join the sternum and ribs. A high bilateral stress distribution was also found over the backs of the third to the seventh ribs near the vertebral column. INTERPRETATION The stress and strain induced by the Nuss procedure can be analyzed using our finite element analysis model. Although the stress and strain may have some influence on chest and spine development, a more detailed finite element analysis model is recommended for future study to improve the accuracy of our simulation results.

Costochondral changes in the chest wall after the Nuss procedure: ultrasonographic findings

PURPOSE The Nuss procedure is one of the most popular surgeries for correcting pectus excavatum. However, little is known regarding stress and strain on the deformed ribs after inserting the pectus bar. We used ultrasonography to investigate costochondral changes before and after the Nuss procedure. METHODS Ninety-five patients underwent the Nuss procedure between July 2007 and February 2008 at 2 institutions. Chest ultrasonography, specifically of the bones and cartilage, was performed 1 day before and 1 week after the operation. RESULTS Postoperatively, all patients showed various degrees of deformation from the second to sixth cartilages bilaterally. The cartilages were not fractured. Of these patients, 28 (29.5%) had significant changes, including acute angulation of the costochondral junction and rib fractures near the pectus bar. These changes were associated with increased age (P < .01) and the degree of postoperative sternum elevation (P < .01). The pectus index and sex were not significant predictors of rib damage. CONCLUSIONS The Nuss procedure created significant stress and strain over the deformed cartilages. Approximately 29% of the patients showed localized, self-limited costochondral changes via chest ultrasonography.

The measurement and designation of the pectus bar by computed tomography

PURPOSE The length of the bar used for the Nuss procedure is typically determined by measuring the distance between the 2 midaxillary lines and subtracting 2.5 cm. However, this may not be accurate for all patients. Measurements of the chest using computed tomography (CT) were developed for better determination of bar length. METHODS Seventy-five patients underwent the Nuss procedure between 2005 and 2008. The length and curve of the pectus bar were determined using both the traditional method (TM) and CT. RESULTS Twelve patients (16%) had length differences (LD) with the methods. The LD and non-LD patients were 18.8 +/- 2.4 and 11.3 +/- 0.6 years old, respectively (P = .005). The proportion of females in the groups was 58.3% (7/12) and 28.6% (18/63), respectively (P = .046). The TM gave a longer bar estimation in all but one patient with a high sternal angulation. Slight bar protrusion was noted in 3 of the 12 patients with LD using TM and 0 of the 9 patients using CT. CONCLUSIONS Computed tomography measurement is a precise means for determining length, especially in older patients, females with developed breasts, or patients with high sternal angulation. It also allows for better curvature design, preventing multiple intraoperative adjustments.

Intussusception and intestinal malrotation in an infant: a case report

Abstract.An abnormal cecum position is usually found in patients with intestinal malrotation. We report one case with intussusception and intestinal malrotation in a 10-month-old infant. An unusual radiologic imaging feature and also abnormal intussusception mass location are discussed.

Rapid increase in the height and width of the upper chest in adolescents with primary spontaneous pneumothorax.

BACKGROUND We determined the chest height in a cohort of patients with primary spontaneous pneumothorax (PSP) who had received chest radiographic examinations prior to the attack. The aim of this study was to determine when their chest height began to change and how this was related to the PSP. METHODS From June 2009 to February 2012, the chest posteroanterior radiographs of 156 patients with PSP (Group 1) were reviewed. Among another 3134 patients with PSP, we identified 52 patients who had a chest posteroanterior radiograph prior to the attack (Group 2). We also recruited 196 controls for comparison (Group 3). The chest height and chest width at different levels were measured and analyzed. RESULTS Before 14 years of age, the chest height of patients in Group 2 was no different from that of patients in Group 3. By the age of 14 years, however, the chest height and upper chest width of patients with PSP was significantly higher than that of the normal controls. The difference from normal chest height did not increase at adulthood. CONCLUSION The rapid increase in chest height and upper chest width is a unique finding in patients with PSP. It might be attributable to the occurrence of PSP. This finding may also help to identify patients who are at risk of PSP.

Three-dimensional computed tomography reveals different donor-site deformities in adult and growing microtia patients despite total subperichondrial costal cartilage harvest and donor-site reconstruction.

Background: Donor-site deformity may complicate autologous costal cartilage harvest for microtia reconstruction. This is reportedly prevented by total subperichondrial costal cartilage harvest, costochondral growth center preservation, donor-site reconstitution with morselized leftover costal cartilage, and perichondrial repair (Kawanabe-Nagata method). However, no quantitative assessment of preoperative versus postoperative thoracic morphology exists following use of this method. Methods: Twenty-five consecutive patients (11 adult and 14 growing patients) who received radiographic donor-site evaluation for autologous unilateral primary microtia reconstruction were studied. Each underwent thoracic three-dimensional computed tomography preoperatively and 6 months postoperatively. The authors quantified (1) donor-site skeletal deformation with respect to the sixth to ninth costochondral junctions (2) and distortion in thoracic/hemithoracic Haller indices. The contralateral unoperated hemithorax provided intrapatient control data. Results: Statistically significant deformations occurred in the sagittal and transverse planes in growing patients and in the transverse plane in adults, with respect to most costochondral junctions on operated versus unoperated sides. Importantly, in growing patients, the sixth to ninth costochondral junctions on the operated side failed to descend postoperatively with normal growth in the vertical plane, unlike on the unoperated side. However, no gross distortions in thoracic/hemithoracic proportions occurred according to Haller indices. Conclusions: Despite meticulous donor-site management and reconstruction according to the Kawanabe-Nagata method, patients sustained significant localized skeletal deformations, as quantified by three-dimensional computed tomography, the configurations of which differed according to whether patients were adult or growing when operated on. Whether these improve or worsen in the long term, particularly in growing patients, requires confirmation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Mediastinal and Retropharyngeal Abscesses in a Neonate

Mediastinal abscess following retropharyngeal abscess is a rare entity. We report the first neonate presenting with a large mediastinal abscess as a complication of a retropharyngeal abscess. The initial manifestations of this newborn were fever and stridor. The chest sonography revealed a mediastinal mass, and the neck and chest computed tomography showed multiple abscesses in the retropharyngeal space, parapharyngeal space, and superior mediastinum. The mediastinal cystic mass was excised, and antibiotic treatment was completed for 7 weeks. She did well without any sequelae at follow-up clinic. Pediatricians should consider retropharyngeal and mediastinal abscesses among the differential diagnoses when confronting a newborn with fever and stridor.

A cross-sectional study of lung volume development in pectus excavatum patients: estimating the total lung volume from chest computed tomograph using 3-dimensional volumetric reconstruction

BACKGROUND/PURPOSE This study quantified the lung volume development of pectus excavatum (PE) patients using chest computed tomography (CT) 3-dimensional volumetric reconstructions. The technique permits current and retrospective analyses of data from different institutions. PATIENTS AND METHODS We analyzed the records of PE patients who underwent chest CT preoperatively between 2005 and 2009 at 3 institutions. All patients were Chinese. A window of -992 to -198 Hounsfield units was chosen for calculating the CT total lung volume (TLV). The data were compared with the data for 73 microtia and other chest-wall tumor patients studied during the same period as a control group. RESULTS In total, 377 PE patients with Haller pectus index (PI) of at least 3.2 were identified for this study. Compared with the reported TLV data for 1050 healthy children and our control group, we found little evidence of a decreased TLV in PE patients at any age for either sex. The mean PI did not change significantly between the ages of 3 and 27 years. The PI was inversely correlated with the TLV (P < .001). CONCLUSION Our cross-sectional study provides evidence that the TLV of PE patients is within the reference range in children and adolescents.

Chest Wall Constriction after the Nuss Procedure Identified from Chest Radiograph and Multislice Computed Tomography Shortly after Removal of the Bar.

BACKGROUND This study radiographically examined the changes in the chest walls of patients with pectus excavatum (PE) after Nuss bar removal, to define the deformation caused by the bar and stabilizer. In the first part of the study, we compared the changes in chest radiographs of patients with PE to a preoperation PE control group. In the second part, we used multislice computed tomography (CT) scans to provide three-dimensional reconstructions with which to evaluate the changes to the thoracic wall. METHODS Part 1 From June 2006 to August 2011, 1,125 patients with PE who had posteroanterior chest radiographs taken before undergoing the Nuss procedure at four hospitals were enrolled as a preoperative control group. At the same time, 203 patients who had the bar removed were enrolled as the study group. The maximum dimensions of the outer boundary of the first to ninth rib pairs (R1-R9, rib pair width), chest height, and chest width were measured. Part 2 Thirty-one consecutive patients with PE (20 males and 11 females) who underwent Nuss bar removal were evaluated 7 to 30 days after operation. During this period, a further 34 patients with PE who had undergone CT imaging before bar insertion were evaluated and compared with the postoperative group. RESULTS Part 1 The width of the lower ribs (R4-R9) after bar removal was significantly less than in the age-matched controls. The ribs adjacent to the bar (R5-R7) showed the greatest restriction. The width of the upper ribs (R1-R3) 2 to 3 years after bar placement did not differ significantly from the controls. Patients who were operated on after 10 years of age had less of a restrictive effect. Three years of bar placement resulted in more restriction than a 2-year period, particularly in patients younger than 10 years old. Part 2: A significant constriction of the chest wall was observed in 13 patients after removal of the Nuss bar. Constriction at ribs 5 to 8 was found to be present adjacent to the site of bar insertion. However, constriction of the chest wall was found in only 3 of the 34 patients in the preoperative group. The severity of constriction (as graded by the spline model) also increased in the postoperative group. CONCLUSION The growth of the chest wall was restricted after placement of the Nuss bar for PE correction. Long-term follow-up of chest wall growth is needed to clarify whether such constriction resolves with time.

Congenital tuberculosis: case report and review of the literature

Abstract Congenital tuberculosis is rare, even where tuberculosis (TB) is endemic. A 14-day-old girl presented with a 3-day history of fever and respiratory distress. Her mother was diagnosed with a disseminated TB infection immediately after the delivery which was confirmed by a positive TB-polymerase chain reaction (TB-PCR) and subsequent culture from ascites and sputum. The infant was separated from her mother at birth. Her chest radiograph showed bilateral miliary nodules. Congenital TB was strongly suspected because of the symptoms, signs and maternal TB history, and was confirmed by TB-PCR and culture from the gastric lavage. Timely administration of standard anti-TB therapy resulted in a good outcome. The case highlights the importance of maternal TB history and typical miliary pattern on chest radiography for early diagnosis of congenital or neonatal TB which in turn facilitates prompt treatment and the prognosis.