Pelvic parameters in the prediction of anterior sagittal spine collapse.  — ASN Events
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Pelvic parameters in the prediction of anterior sagittal spine collapse.  (#151)

Larry I Cohen 1 , Sarah Dennis , Milena Simic 1 , Kathryn Refshauge 1 , Evangelos Pappas 1
  1. Faculty of Health Sciences, Sydney University, Sydney, NSW, Australia

Anterior sagittal balance (ASB), defined by the Scolisis Research Society (SRS) adult spine deformity classification as a minimum 40mm sagittal vertical axis1 (SVA - anterior displacement of C7 over the posterior sacral border) may be more prevalent in the osteoporotic population2 and  is associated with increased falls3, increased pain, reduced function and reduced quality of life. The SRS have also identified lumbo-pelvic compensatory thresholds (LPCP) of 20° pelvic retroversion (PT) and 10 pelvic incidence- lumbar lordosis mismatch (PILL)1. 

EOS full spine radiographic data from 49 adults with scoliosis (coronal Cobb > 10°; 48 ±20 years) stratified into younger (n=24) and older (n=25) groups above and below the mean age of 48 years was retrospectively analysed. Group characteristics, normal and anterior sagittal balance classification and LPCP variables were analysed by T tests and Fisher’s exact tests.  Unless detailed, resultant group proportions are reported as (younger% vs older%).

A greater proportion of older participants exceeding the SVA threshold of 40mm (9% vs 58%, p<.001) were classified as anterior sagittaly imbalanced. Similarly, a greater proportion of older adults exceeded the 20° pelvic retroversion threshold (8% vs 79%, p<.001) and 10°PILL mismatch threshold (20% vs 58%, p=0.008). There was no difference in the proportion of older and younger participants with SVA below 40mm exceeding LPCP thresholds (29% vs 24%, p=0.99) and exceeding the 40mm SVA threshold without exceeding LPCP thresholds (4% vs 8%, p=0.99).

This study confirms a higher prevalence of anterior sagittal balance in older participants and using LPCP thresholds identifies a sub-group, within the remaining normally balanced older and younger participants, who can be classified as compensated balanced.  This sub-group might be considered, especially if accompanied by low bone quality, at risk for future anterior collapse and warrant closer clinical monitoring, intensive clinical intervention and ongoing clinical research.  

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  1. 1. Smith JS, Klineberg E, Schwab F, Shaffrey CI, Moal B, Ames CP, Hostin R, Fu KM, Burton D, Akbarnia B, Gupta M, Hart R, Bess S, Lafage V, International Spine Study G (2013) Change in classification grade by the SRS-Schwab Adult Spinal Deformity Classification predicts impact on health-related quality of life measures: prospective analysis of operative and nonoperative treatment. Spine 38 (19):1663-1671.
  2. 2. Lee JS, Lee HS, Shin JK, Goh TS, Son SM (2013) Prediction of sagittal balance in patients with osteoporosis using spinopelvic parameters. Eur Spine J 22 (5):1053-1058.
  3. 3. Imagama S, Ito Z, Wakao N, Seki T, Hirano K, Muramoto A, Sakai Y, Matsuyama Y, Hamajima N, Ishiguro N, Hasegawa Y (2013) Influence of spinal sagittal alignment, body balance, muscle strength, and physical ability on falling of middle-aged and elderly males. Eur Spine J 22 (6):1346-1353.