Lumbo-pelvic lordosis and the pelvic radius technique in the assessment of spinal sagittal balance: strengths and caveats.

INTRODUCTION: The two main methodologies described for the assessment of spinal sagittal alignment are the pelvic radius (PR) technique and that based on measures of the Pelvic Incidence (PI) and Spino-Sacral Angle (SSA). Both methods stress the fundamental relationship between the anatomical position and orientation of the sacrum within the pelvis and the spinal curves above. The aim of the current study was to assess the strengths and potential weaknesses of the PR technique. The PR technique uses measures based on a line (the PR), drawn between the hip axis and the posterior corner of the S1 endplate. The angle formed between the PR line and the sacral endplate, PRS1, is a developmental measure of sacropelvic morphology. Geometrically, PI and PRS1 are approximately complementary angles and both reflect reciprocal alterations in pelvic tilt (for PI) or angulation (for PRS1) and the slope of the S1 endplate. The angle formed between PR and T12, the PR-T12, reflects a combined measure of pelvic morphology and lumbar lordosis. It appears to be a useful measure, which provides a simple and rapid assessment of lumbopelvic sagittal balance, but only in the presence of a congruent thoracic curvature. MATERIALS AND METHODS: After reviewing the literature, published measures made using the PR technique were compared to measures taken from a substantial patient population (479 adult patients). CONCLUSIONS: Errors can occur using the PR technique if the PRT12 is viewed in isolation from the thoracic kyphosis. We found the ratio of the thoracic kyphosis to lumbar lordosis (T4-T12/T12-S1) to be a useful predictor of congruent sagittal alignment, which may alert the clinician to situations where use of the PR-T12 in isolation may be misleading.

Health-related quality of life: a comparison of outcomes after lumbar fusion for degenerative spondylolisthesis with large joint replacement surgery and population norms.

BACKGROUND CONTEXT: Degenerative spine disease will become an increasing health problem, and a significant number of patients will be considered for surgery. Spinal surgeries have evolved since the last decades, and there is a positive impact on the clinical outcomes. Few works in the literature have reviewed the outcome compared with large joint replacement surgery, which is considered a benchmark for operative restoration of patients' quality of life. PURPOSE: The purpose of this study was to investigate if spinal fusion can return patients' health-related quality of life to that of age-matched population norms and yield outcomes comparable with those of total hip and knee joint replacement. STUDY DESIGN: This is a prospective cohort study. PATIENT SAMPLE: The sample consists of 100 consecutive patients who were enrolled between December 1997 and January 2007. OUTCOME MEASURES: The 12-item Short Form Health Survey (SF-12) was chosen for outcome measurement. METHODS: All patients underwent wide decompressive laminectomy and single-level posterior lumbar interbody fusion for spinal stenosis associated with degenerative spondylolisthesis. RESULTS: The preoperative and postoperative physical component summary (PCS)-12 scores of the spinal fusion patients were comparable with those of both the total knee and hip replacement patients. The mean improvement in PCS-12 scores after spine surgery was 11 (95% confidence interval [CI]: 9-14, p<.0001). It was equal to that after total hip replacement surgery, which was 11 (95% CI: 9-13), and higher than that of total knee replacement patients, which had an improvement of 8 (95% CI: 7-9). The postoperative mean and 95% CI of the PCS-12 scores for the three surgical procedures approached the population norm value of 44 (95% CI: 43-46).There was no statistical difference between the postoperative mental component summary-12 score among all the three surgical groups, which approached similar to the population norm value of 54 (95% CI: 53-54). CONCLUSIONS: The current study demonstrated that spinal surgery can return patients' HRQL to that of age-matched population norms and yield outcomes comparable with those of total hip and knee joint replacement patients.