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Erschienen in:
01.11.2012 | Basic Research
Establishment of Parameters for Congenital Thoracic Stenosis: A Study of 700 Postmortem Specimens
Erschienen in: Clinical Orthopaedics and Related Research® | Ausgabe 11/2012
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Background
Congenital thoracic stenosis (CTS) occurs when the bony anatomy of the canal is smaller than expected in the general population. The diagnosis currently is made based on the clinical impression from subjective radiographic studies, and the normal values for CTS have not been established.
Questions/purposes
We provided a statistical definition for CTS based on objective measurements of thoracic spine specimens and explored parameters that might predict CTS.
Methods
We selected 700 adult skeletal specimens from the Hamann-Todd Collection in the Cleveland Museum of Natural History (Cleveland, OH, USA). We used calipers to measure the sagittal canal diameter (SCD), interpedicle distance (IPD), and pedicle length (PL). At each level, canal area was calculated using a geometric formula, a standard distribution was created, and values two SDs below the mean were considered congenitally stenotic. Corresponding values of SCD and IPD of the stenotic specimens were studied. The values of SCD and IPD predicting CTS with highest sensitivity and specificity were tabulated.
Results
At each level, CTS was defined as: T1, 160 mm2; T2, 135 mm2; T3, 131 mm2; T4, 130 mm2, T5, 129 mm2, T6, 127 mm2; T7, 127 mm2; T8, 129 mm2; T9, 130 mm2; T10, 132 mm2; T11, 140 mm2; and T12, 173 mm2. A SCD less than 15 mm and an IPD less than 18.5 mm were predictive of CTS at each level with sensitivities and specificities of 80% to 100%.
Conclusions
We statistically defined CTS at each level. A SCD less than 15 mm or IPD less than 18.5 mm predicted the presence of CTS at all levels.
Clinical Relevance
In a symptomatic patient, on routine radiologic examination, a physician should suspect stenosis of the thoracic canal if the SCD and IPD are less than 15 and 18.5 mm respectively. As a spinal deformity surgeon, the canal area is especially relevant when considering a possible canal intrusion by implants.