Overgrowth Of Costal Cartilages Research Articles

The etiology of pectus carinatum involves overgrowth of costal cartilage and undergrowth of ribs

PurposeWe compared the length of costal cartilage and rib between patients with symmetric pectus carinatum and controls without anterior chest wall protrusion, using a 3-dimensional (3D) computed tomography (CT) to evaluate whether the overgrowth of costal cartilage exists in patients with pectus carinatum. Subjects and methodsTwenty-six patients with symmetric pectus carinatum and matched twenty-six controls without chest wall protrusion were enrolled. We measured the full lengths of the 4th–6th ribs and costal cartilages using 3-D volume rendering CT images and the curved multiplanar reformatted (MPR) techniques. The lengths of ribs and costal cartilages, the summation of rib and costal cartilage lengths, and the costal index [length of cartilage/length of rib * 100 (%)] were compared between the patients group and the control group at 4th–6th levels. ResultsThe lengths of costal cartilage in patient group were significantly longer than those of control group at 4th, 5th and 6th rib level. The lengths of ribs in patient group were significantly shorter than those of control group at 4th, 5th and 6th rib level. The summations of rib and costal cartilage lengths were not longer in patients group than in control group. The costal indices were significantly larger in patients group than in control groups at 4th, 5th and 6th rib level. ConclusionIn patients with symmetric pectus carinatum, the lengths of costal cartilage were longer but the lengths of rib were shorter than those of controls. These findings may supports that the overgrowth of costal cartilage was not the only factor responsible for pectus carinatum.

EComment. Is overgrowth of costal cartilages the unique cause of pectus deformities?

In their recent article, Park and coworkers hypothesized that 'if overgrowth of the costal cartilage is the cause of the outward protrusion of the anterior chest wall seen in pectus carinatum (PCar), the costal cartilage lengths on the more protruded side would be greater than that on the opposite side'. By studying the length of three paired rib/costal cartilages in 22 patients with asymmetric PCar, Park and coworkers discovered no statistically significant differences between the two sides and concluded 'overgrowth of the costal cartilage might not be the responsible factor in PCar' [1]. This is an interesting and meticulous study, which, however, raises some issues, as they outlined in their article. First, a rather small number of patients were enrolled. Second, only three paired rib/cartilages (fourth to sixth) were measured while either the third to seven paired rib/cartilages are involved in the standard form of PCar deformities; and second to fourth/five in the upper form (pouter pigeon breast) [2]. Last, no data are provided regarding the morphology/distortion of costal cartilages. Upon re-examining Figure 1 of the article (thoracic CT, axial view of an asymmetric PCar) it appears to us that the right cartilage area (more protruded side) is convex-shaped, while the contralateral cartilage area is concave, leading to sternum rotation, volume reduction of the rib cage on the left and, consequently, asymmetric deformity. Therefore this issue impedes a clear demonstration of the authors' hypothesis. In fact, the pathogenesis of anterior chest wall deformities remains elusive so far. Apart from connective tissue disorders or severe scoliosis, the cause of pectus deformities has been thought to be abnormal elongation of the ribs [3], and then costal cartilages [4], while Park and coworkers, and others [1, 5] claim that overgrowth of costal cartilages is not responsible, since there is no significant change in the costal cartilage length/rib length ratio (C/R ratio). In our opinion, this latter finding might be suggestive of a developmental cartilage dysfunction including the growth centre at the costochondral junction, leading to proportionate overgrowth of both cartilage and adjacent rib (thus with no change of C/T ratio) as shown bilaterally in patients with symmetric pectus deformities, and only on the more protruded side in patients with severe asymmetric pectus excavatum (PEx); or, on the contrary, proportionate hypoplasia of both cartilage and adjacent rib on the more depressed side (generally on the right) in patients with severe asymmetric PEx. Furthermore, this developmental cartilage dysfunction might be responsible for cartilage distortion and/or enlargement as shown in patients with protruding lowermost costal cartilage in a PEx context. Finally, overgrowth of costal cartilages is not the unique cause of pectus deformities but this cartilage structure plays a key role in the pathophysiologic and clinical features of the disease. Conflict of interest: none declared

Does overgrowth of costal cartilage cause pectus carinatum? A three-dimensional computed tomography evaluation of rib length and costal cartilage length in patients with asymmetric pectus carinatum

To evaluate whether the overgrowth of costal cartilage may cause pectus carinatum using three-dimensional (3D) computed tomography (CT). Twenty-two patients with asymmetric pectus carinatum were included. The fourth, fifth and sixth ribs and costal cartilages were semi-automatically traced, and their full lengths were measured on three-dimensional CT images using curved multi-planar reformatted (MPR) techniques. The rib length and costal cartilage length, the total combined length of the rib and costal cartilage and the ratio of the cartilage and rib lengths (C/R ratio) in each patient were compared between the protruding side and the opposite side at the levels of the fourth, fifth and sixth ribs. The length of the costal cartilage was not different between the more protruded side and the contralateral side (55.8 ± 9.8 mm vs 55.9 ± 9.3 mm at the fourth, 70 ± 10.8 mm vs 71.6 ± 10.8 mm at the fifth and 97.8 ± 13.2 mm vs 99.8 ± 15.5 mm at the sixth; P > 0.05). There were also no significant differences between the lengths of ribs. (265.8 ± 34.9 mm vs 266.3 ± 32.9 mm at the fourth, 279.7 ± 32.7 mm vs 280.6 ± 32.4 mm at the fifth and 283.8 ± 33.9 mm vs 283.9 ± 32.3 mm at the sixth; P > 0.05). There was no statistically significant difference in either the total length of rib and costal cartilage or the C/R ratio according to side of the chest (P > 0.05). In patients with asymmetric pectus carinatum, the lengths of the fourth, fifth and sixth costal cartilage on the more protruded side were not different from those on the contralateral side. These findings suggest that overgrowth of costal cartilage cannot explain the asymmetric protrusion of anterior chest wall and may not be the main cause of pectus carinatum.

Overgrowth of costal cartilage is not the etiology of pectus excavatum

PurposeThe etiology of pectus excavatum (PE) has not been clarified. In 1944, Sweet (Sweet RH. Pectus excavatum. Ann Surg 1944;119:922-934) mentioned about the possibility of the overgrowth of costal cartilage being involved. However, no additional report that supports his hypothesis is available. In this study, we investigated whether the overgrowth of costal cartilage was an actual cause of PE through measurement of the costal cartilage length in PE patients and healthy controls. Materials and MethodsWe investigated the length of the fifth and sixth costal cartilages and ribs in PE patients from reconstructed images of 3-dimensional computed tomography. To examine the relative costal cartilage length, we calculated the C/R ratio, defined as the quotient of the costal cartilage length divided by the adjacent rib length, and compared it between PE patients and healthy controls. ResultsIn PE patients, the C/R ratios were not larger than in healthy controls at any level. At the left sixth, the C/R ratio was significantly smaller in patients than in the healthy control group. DiscussionThe results revealed that, in PE patients, relative costal cartilage lengths were not longer than in healthy controls. We conclude that the overgrowth of costal cartilage is not the etiology of PE.

Does overgrowth of costal cartilage cause pectus excavatum? A study on the lengths of ribs and costal cartilages in asymmetric patients

Purpose The cause of pectus excavatum has been hypothesized to be overgrowth of the costal cartilage. According to this theory, the length of costal cartilages must be longer in the side of deep depression in asymmetric patients. To challenge this hypothesis, we measured the lengths of ribs and costal cartilages and investigated lateral differences. Subjects and methods Twenty-four adolescent and adult patients with asymmetric pectus excavatum (14-30 years of age) with no history of surgery were investigated in this study. The fifth and sixth ribs and costal cartilages were individually traced to measure their full lengths on 3-dimensional computed tomographic (CT) images. As an index of asymmetry, sternal rotation angle was measured in the chest CT images. Patients with a 21° or greater angle of sternal twist were designated as an asymmetric group and those with an angle of smaller than 20° as a symmetric group. Lateral differences in the fifth and sixth costal and costal cartilage lengths were compared between the groups. Results On comparison of the costal and costal cartilage lengths in the asymmetric group, the right fifth ribs and costal cartilages were significantly shorter than the left ( P = .02 and .03, respectively), and right sixth ribs were also significantly shorter than the left ( P = .004), but right sixth costal cartilages were not ( P = .31). In the symmetric group, the lengths of the left and right fifth ribs and costal cartilages were showing no significant difference ( P = .20 and P = .80, respectively), and those of the sixth ribs and costal cartilage were also showing no significant difference ( P = .97 and P = .64, respectively). Discussion The ribs and costal cartilages on the right side with severer depression were significantly shorter or not different than those on the contralateral side. Based on these findings, the theory of costal cartilage overgrowth is contradictory. The etiology of asymmetric chest deformity should be reevaluated.