Persistent low-normal bone mineral density in adolescent idiopathic scoliosis with different curve severity: A longitudinal study from presentation to beyond skeletal maturity and peak bone mass.
OBJECTIVES
Low bone mineral status has been reported in patients first presented with adolescent idiopathic scoliosis (AIS). We aimed to study whether low-normal bone mineral density (BMD) is persistent among AIS girls during puberty and at peak bone mass, and whether if such persistence is associated with curve severity and differed from healthy controls.


METHOD
This prospective longitudinal study comprised 550 AIS girls and 194 healthy control subjects followed from 1997 till 2016. Low-normal BMD was defined as z-standardized bone mineral density (z-BMD) of bilateral femoral neck ≤ -1. Markov Chain 2-stages analysis was conducted to investigate the low-normal BMD transition rate. Linear mixed-effects model and Bland-Altman plot were used to investigate whether low-normal BMD is persistent among a subgroup of AIS patients that reached peak bone mass.


RESULTS
The average z-BMD were comparable between AIS cohort and controls at 11 years old (-0.532 vs -0.602), but at 19 years old z-BMD worsened among AIS subjects (-0.860) while controls z-BMD improved (-0.455). During growth period until skeletal maturity, persistence of low-normal BMD was high in both cohorts (>80%) and the AIS group with severe curve presented 100% persistence. Subgroup analysis revealed that z-BMD of AIS patients at skeletal maturity and peak bone mass were highly correlated (r2 = 0.905) and with good agreement.


CONCLUSION
AIS patients had poorer BMD that is associated with curve severity and more likely to persist beyond peripubertal period and at peak bone mass when compared to controls.
['Li|Xue|X|', 'Hung|Vivian Wing Yin|VWY|', 'Yu|Fiona Wai Ping|FWP|', 'Hung|Alec Lik Hang|ALH|', 'Ng|Bobby Kin Wah|BKW|', 'Cheng|Jack Chun Yiu|JCY|', 'Lam|Tsz Ping|TP|', 'Yip|Benjamin Hon Kei|BHK|']
D000293:Adolescent D000328:Adult D015519:Bone Density D001851:Bone Diseases, Metabolic D002648:Child D005260:Female D006801:Humans D008137:Longitudinal Studies D011446:Prospective Studies D012600:Scoliosis D055815:Young Adult
Bone mineral density Adolescent idiopathic scoliosis Low-normal BMD Low bone mass