Predicting Kyphosis Correction during Posterior-Only Vertebral Column Resection by the Amount of Spinal Column Shortening

Woojin Cho, Lawrence G. Lenke, Kathy M. Blanke, Brian A. O'Shaughnessy, Ian G. Dorward, Linda A. Koester, Brenda A. Sides, Christine R. Baldus

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Study Design: Retrospective. Objective: To investigate the relationship between the amount of correction achieved (K°) and extent of vertebral column shortening (mm) with posterior vertebral column resection (PVCR). Summary of background data: There is no scientific reference to the correlation between K° and column shortening (mm) with PVCR. Methods: Based on simple geometry, we tested the hypothesis that we could predict the amount of actual kyphosis correction (K°) by calculation on 26 kyphotic PVCR patients. Using multiple linear measurements (mm), two angular approximations (°) were calculated: the geometric approximation (G°) using the geometric calculation (G-cal), and the rough approximation (R°) by more simplistic calculation (Rcal). Both G° and R° were compared against K° as measured on the pre- and postoperative radiographs. If calculated G° and R° is close to measured K°, we can use the calculations (G-cal and R-cal) in the clinical situation. Results: The mean correction of K° was 38°. K°°G° and K°°R° were not significantly greater than 3° and 6°, respectively. As K° was very close to G° and R°,K° can replace G° and R°. Therefore, we can use G-cal and R-cal in the clinical setting and we can determine how much posterior shortening and what cage size is required to obtain a certain amount of K°. Conclusions: With two calculations (G-cal & R-cal), we can determine how much vertebral column shortening (mm) we need during PVCR to obtain the amount of kyphosis correction desired (K°). In order to obtain K°, using the formula deduced from G-cal and R-cal, we can determine the shortening between the upper and lower pedicle screws and cage size.

Original languageEnglish (US)
Pages (from-to)65-72
Number of pages8
JournalSpine deformity
Issue number1
StatePublished - 2015


  • Correlation formula
  • Kyphosis correction
  • Posterior vertebral column resection
  • Vertebral column shortening

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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