Radiographic Correction and Functional Outcomes After Spinal Osteotomy

Uri M. Ahn MD,
Nicholas U. Ahn MD,
Khalid Kebaish MD,
J. Buchowski MS,
Mesfin A. Lemma MD,
Edward Song, MD,
David Cohen MD,
Ann Sieber RN,
and John P. Kostuik MD
Johns Hopkins Hospital Department of Orthopaedic Surgery, Baltimore, Maryland, USA

INTRODUCTION:
Flatback deformity and adult scoliosis are serious problems which are cosmetically displeasing and a potential source of severe pain. There is current interest in the use of osteotomy of the lumbar spine to help correct sagittal and/or coronal deformity. The efficacy of osteotomy in providing functional improvement has previously been shown. However, no prospective studies exist to examine whether correction of specific radiographic parameters obtained via osteotomy is associated with improved functional outcomes. Such information would help the spine surgeon in determining which deformities are most important to correct.

MATERIALS AND METHODS:
Eighty–two patients with fixed sagittal and/or coronal deformity of the lumbar spine were evaluated and treated surgically with a spinal osteotomy by the senior author over a six year period (1993–1998). Mean age was 54.4 years. Minimum follow–up was 2 years. All patients complained of deformity and/or pain, and all had failed traditional conservative treatment. All patients were evaluated clinically and radiographically in the pre– and postoperative periods. Each patient also completed a questionnaire preoperatively and at latest follow–up. The questionnaire contained questions from the AAOS Modems instrument, and the SF–36 Health Survey. Spearman correlation analysis was used to determine if an association existed between amount of correction of specific radiographic parameters and outcomes.

RESULTS:
A significant association was found between the amount of angular correction of sagittal lordosis of the lumbar spine and SPF–36 outcomes physical function (p=0.03) and role physical (p=0.01) for patients in whom the postoperative lumbar lordosis was greater than 25 degrees. A significant association was also found between the amount of plumb coronal correction and SPF–36 outcomes physical function (p=0.04), vitality (p=0.05), and social function (p=0.04) for patients in whom the postoperative plumb coronal alignment was less than 2.5 cm.

CONCLUSION:
Correction of both sagittal and coronal deformities are important in the surgical treatment of spinal deformities. A significant association was found between outcomes and radiographic correction of coronal and/or sagittal deformity if postoperative sagittal lordosis was greater than 25 degrees and if postoperative plumb coronal alignment was less than 2.5 cm. Thus, correction of deformity with postoperative sagittal lordosis > 25 degrees and plumb coronal alignment < 2.5 cm lead to better functional outcomes, and should be the goal of spinal osteotomy.