Adolescent Idiopathic Scoliosis with Excessive Thoracic Kyphosis: Comparison of Anterior Versus Posterior Instrumentation for Maintaining Correction

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David H. Clements, MD*.
Randal R. Betz, MD*;
Thomas G. Lowe, MD,
Lawrence G. Lenke, MD;
Peter 0. Newton, MD ·
* (a – DePuy AcroMed Corporation)
Shriners Hospitals for Children. Philadelphia, PA, USA

PURPOSE:
To prospectively analyze the sagittal and coronal correction initially achieved compared to two–year follow–up results in patients with excessive thoracic kyphosis and scoliosis treated with anterior rigid rod versus posterior segmental instrumentation.

METHOD:
Surgically treated patients with adolescent thoracic idiopathic scoliosis with minimum two–year follow–up and excessive thoracic kyphosis defined as pre–op sagittal contour of greater than 40° measured from T2 to T12 were included. Analysis included evaluation of lateral radiographs of T2 to T 12 at first erect, 1 year, and 2 year post–op and the degree of scoliosis. 20 patients had anterior instrumentation and 18 patients had posterior instrumentation.

RESULTS:
Sagittal correction of anterior group: Mean pre–op 50° kyphosis corrected initially to 45° (10% improvement), but returned to 49° (2% improvement) at two years. In 11 patients kyphosis increased greater than 5°, was unchanged in 3, and decreased greater than 5° in 6 at 2 years. Sagittal correction of posterior group: Mean 49° kyphosis corrected initially 35% to 32° and at two years measured 36°, for a 27% improvement. Kyphosis decreased greater than 5° in all 18 patients. In the anterior group, mean 55° scoliosis initially corrected to 24° and ended at 27° at two years. In the posterior group, mean 57° scoliosis initially corrected to 20° and ended at 25° at two years.

CONCLUSION:
In patients with excessive thoracic kyphosis and scoliosis, anterior rigid instrumentation initially improved the kyphosis 10%, but by two years the sagittal contour had returned to close to its initial measurement. Posterior segmental instrumentation corrected the excessive kyphosis 35% initially and maintained a 27% correction at 2 years. Maintenance of scoliosis correction at two–year follow–up was similar in both groups. If excessive progressive kyphosis (> 40°) is present with thoracic scoliosis, posterior instrumentation is recommended.

* · If noted, the author indicates something of value received. The codes are identified as: a–research or institutional support, b–miscellaneous funding, c–royalties, d–stock options, e–consultant or employee.