An exploration of familial associations in spinal posture defined using a clinical grouping method

The primary aim of this study was to examine familial associations in spinal posture, defined using postural angles and a clinical classification method. A secondary aim was to investigate the reliability of clinical postural classification. Postural angles were calculated from sagittal photographs, while two experienced clinicians made use of standing sagittal images to classify participants into one of four postural groups (sway, flat, hyperlordotic, neutral). Parent-child associations in postural angles and postural groups were evaluated using Pearson's correlation and Fisher's exact test, respectively. Inter-rater reliability was expressed using percentage agreement and Kappa coefficients (K). Daughters whose father or mother had a hyperlordotic posture were 4.0 or 3.5 times, respectively, more likely to have a hyperlordotic posture than daughters whose parents did not have a hyperlordotic posture. These participants in the hyperlorotic group had a significantly higher body mass index than members of the other postural groups (p < 0.03). Percentage agreement between clinicians was 63.5% (K = 0.48). These results provide preliminary evidence of a familial association in the hyperlordotic posture and support the use of postural classification.