Novel index to estimate the cephalocaudal extent of the excavation in pectus excavatum - JPS article

Why Another Index

Pectus excavatum is the most common congenital chest wall deformity, and for decades surgeons have relied on CT-based measurements to quantify severity and guide operative planning 0:11. The Haller index and correction index are the currently primarily used indices for pectus excavatum and tell us about the severity of the deformity 0:11 — essentially, how deep the depression goes. But severity is only part of the picture. A narrow, deep defect presents differently than a broad, shallow one that spans most of the sternum. The Titanic index addresses this gap: it takes into account the extent of the pectus excavatum deformity 0:19, measuring how much of the sternum is involved rather than how far it sinks.

The Core Problem

Minimally invasive repair of pectus excavatum (MIRPE, or the Nuss procedure) involves placing one or more substernal bars to elevate the depressed sternum 0:35. The number of bars required correlates with operative complexity, anesthesia time, and postoperative pain. Existing indices tell you whether the deformity is severe enough to warrant surgery, but they do not reliably predict how many bars you will need 0:46. A patient with a high Haller index but a short segment of involvement might need only one bar; a patient with moderate depth but extensive cephalocaudal involvement might need three. Preoperative planning would benefit from a measure that captures this dimension 0:19.

How the Titanic Index Works

The Titanic index is calculated as the percentage of the sternum that lies behind the anterior costal line as seen on CT scans 0:25. The anterior costal line is drawn connecting the most anterior points of the ribs on a sagittal reconstruction 0:25. Any portion of the sternum posterior to this line is considered involved. The calculation yields a percentage reflecting the extent of sternal involvement 0:25. The measurement is straightforward and reproducible on standard preoperative CT imaging 0:25.

A retrospective review of patients at an institution in Argentina who had undergone minimally invasive repair of pectus excavatum 0:35 tested whether the Titanic index added information beyond the Haller and correction indices. The study found a weak correlation between the Titanic index and the other indices 0:46, which is precisely the point — it is measuring something different. More importantly, the Titanic index might be more helpful for helping determine how many bars a patient is going to need for repair 0:46. The threshold established was 66.5%, meaning that patients with a higher Titanic index than that probably needed more than 2 bars 0:57.

What This Means for Referral and Planning

For the surgeon planning a Nuss procedure, the Titanic index offers a quantitative estimate of cephalocaudal extent that complements existing severity measures 0:19. A patient with a lower Titanic index is a different operative case than one with a higher Titanic index 0:46. The former might be managed with a single bar; the latter will almost certainly require two or more 0:57. Knowing this preoperatively allows for more accurate consent discussions, appropriate operative time allocation, and advance planning for bar inventory and sizing.

For the referring clinician, the practical implication is modest but real: if your institution adopts the Titanic index, you may see it reported alongside the Haller index on radiology reads 0:25. A high Titanic index (above 66.5%) flags a case that will likely require more extensive repair 0:57, which may influence timing, surgeon selection, or discussion of expectations with the family.

Where Uncertainty Remains

This is a single-center retrospective study from one institution 0:35. The 66.5% threshold is derived from that cohort and will need validation in other populations 0:57. Operative technique varies — some surgeons prefer longer bars, some use stabilizers differently, some have lower thresholds for adding a third bar — and these practice patterns will affect whether the index proves broadly useful. More study is needed for this index 1:06. The weak correlation with existing indices is encouraging because it suggests the Titanic index captures independent information 0:46, but it also means we do not yet know how to integrate all three measures into a unified decision algorithm.

The index also does not account for asymmetry, rotation, or the position of the deepest point relative to the xiphoid — all factors that influence bar placement. It is a one-dimensional measure of a three-dimensional problem. Still, one-dimensional measures are useful when they are reproducible, easy to obtain, and answer a specific question 0:25. The Titanic index does that: it tells you how much sternum is involved 0:19, and in doing so, it gives you a better sense of how much hardware you will need to fix it 0:46.

Why Another Pectus Index Exists

Pectus excavatum is the most common congenital chest wall deformity, and for decades surgeons have relied on CT-based measurements to quantify severity and guide operative planning 0:35. The Haller index and correction index are the currently primarily used indices for pectus excavatum and tell us about the severity of the deformity 0:11 — essentially, how deep the depression goes. But severity is only part of the surgical problem. A narrow, deep defect behaves differently than a broad, shallow one that spans most of the sternum. The Titanic index addresses this gap by measuring something the existing indices do not: the cephalocaudal extent of the deformity 0:19.

The Core Clinical Problem

When planning minimally invasive repair of pectus excavatum (MIRPE), the surgeon must decide how many substernal bars to place 0:46. Too few bars leave portions of the deformity uncorrected; too many increase operative time, cost, and potential complications. The decision hinges not just on depth but on how much of the sternum is involved. A patient with a focal depression at the xiphoid needs different hardware than one whose entire lower sternum sits posterior to the costal margin. Until now, no standardized measurement captured this dimension 0:19.

How the Titanic Index Works

The Titanic index is calculated as the percentage of the sternum that lies behind the anterior costal line as seen on CT scans 0:25. The anterior costal line is drawn connecting the most anterior points of the ribs on a sagittal reconstruction 0:25. Any portion of the sternum posterior to this line is considered excavated 0:25. The index is simply the length of excavated sternum divided by total sternal length, expressed as a percentage 0:25.

This is a fundamentally different measurement than the Haller index, which compares transverse chest diameter to anteroposterior diameter at the deepest point of the defect 0:11. The Haller index tells you the cross-sectional severity at one slice; the Titanic index tells you how many slices are involved 0:19 0:25.

What the Validation Study Found

The study was a retrospective review of patients at an institution in Argentina who had undergone minimally invasive repair of pectus excavatum 0:35. The authors calculated the Titanic index alongside the traditional severity indices for each patient and correlated these measurements with operative findings — specifically, how many bars were required 0:35 0:46.

The study found a weak correlation between the Titanic index and the other indices (Haller and correction index) 0:46. This weak correlation is actually the point: the Titanic index is measuring something orthogonal to severity 0:46. A patient can have a severe but focal defect or a mild but extensive one. The indices are complementary, not redundant 0:11 0:19.

More importantly, the Titanic index might be more helpful for helping determine how many bars a patient is going to need for repair 0:46. The threshold established was 66.5%, meaning that patients with a higher Titanic index than that probably needed more than 2 bars 0:57. This gives the operating surgeon a preoperative data point that directly informs a concrete intraoperative decision 0:46 0:57.

Where Practice Remains Uncertain

This is a single-center retrospective study from one surgical team 0:35. The 66.5% threshold reflects that group's technique, bar selection, and repair philosophy 0:57. A team that routinely uses longer bars or a different bar configuration might find a different threshold. The study does not address whether the Titanic index predicts outcomes beyond bar number — recurrence rates, patient satisfaction, or complication profiles are not reported 0:35.

More study is needed for this index 1:06. Prospective validation across multiple centers with varying surgical approaches would establish whether the threshold generalizes 1:06. It would also clarify whether the Titanic index adds value beyond experienced surgical judgment, which already incorporates an informal assessment of deformity extent.

When to Use This Measurement

For the referring clinician, the Titanic index does not change the indications for pectus repair or the timing of referral. Those decisions still rest on symptomatology, cardiopulmonary testing, and patient preference, with severity indices like the Haller playing a supporting role 0:11.

For the thoracic or pediatric surgeon planning MIRPE, the Titanic index offers a structured way to quantify something you were already eyeballing on the CT: how much of the sternum needs lifting 0:19 0:25. If your practice includes patients who require multiple bars, calculating the Titanic index preoperatively might help you anticipate that need, adjust your operative plan, and counsel families more accurately about what the repair will entail 0:46 0:57. Whether it becomes standard practice will depend on whether subsequent studies confirm its predictive value and whether the calculation proves practical to incorporate into routine imaging review 1:06.