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Gravity line necessary consideration when considering surgery in patients with ASD
Researchers found the prevalence of discordance between the gravity line and the C7 plumb line in patients with adult spinal deformity was significantly correlated with thoracic kyphosis and global sagittal alignment, concluding that discordance between the ground reaction forces and gravity line must be taken into account when surgical treatment is considered in this population.
The researchers retrospectively studied 300 consecutive patients with adult spinal deformity (ASD). Patients had to be older than 50 years of age, have a Cobb angle of the main curve of more than 20° and a C7 plumb line (C7PL) of more than 5 cm for inclusion in the study.
The patients were categorized into two groups: an occiput-trunk (O-T) concordance (C group, gravity line-C7PL < 3 cm) or an O-T discordance (D group, gravity line-C7PL more than 3 cm) group. Demographic, radiographic and clinical outcome data were then compared between the two groups.
The researchers noted 24% of patients were categorized in the D group. Between the two groups, no significant differences in demographic data were observed.
Patients with a gravity line of more than 10 cm had significantly higher Scoliosis Research Society 22 and Oswestry Disability Index scores compared with patients whose gravity line was less than 10 cm, according to the researchers.
Significantly higher T5–T12 values were observed in the D group through a comparison of regional sagittal alignment, according to the researchers. Additionally, multiple regression analysis revealed significant correlations among T2-T5, T5-T12 and GL-C7PL. However, the T2 sagittal tilt was significantly larger in the D group compared with the C group. – by Robert Linnehan
Disclosure: Yagi reports speaking/teaching arrangements from DePuy Synthes, research support from K2M and grants from Surgical Spine. Please see the full study for a list of all other authors’ relevant financial disclosures.