ORIGINAL ARTICLE Serum level of cartilage oligomeric matrix protein is lower in children with idiopathic scoliosis than in non-scoliotic controls P. Gerdhem • C. Topalis • A. Grauers • J. Stubendorff • A. Ohlin • K. M. Karlsson Received: 28 June 2014 / Revised: 14 November 2014 / Accepted: 16 November 2014 / Published online: 27 November 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Purpose The etiology of idiopathic scoliosis remains unknown, but growth is a risk factor for progression. Growth pattern differs in children with and without scoli- osis. Cartilage oligomeric matrix protein (COMP) may be associated with scoliosis and growth. We, therefore, stud- ied COMP in children with and without idiopathic scoliosis. Methods We included 105 children, with mean age 14.4 years (range 10–16), under observation or treatment for idiopathic scoliosis, and 103 children from an age- matched population-based cohort. COMP was measured in serum at the time of inclusion. Growth velocity was esti- mated from repeated height measurements. T tests, analysis of covariance or linear regression were used for statistical comparisons. Results COMP was mean (SD) 11 (5) units/liter (U/L) in children with scoliosis and 13 (5) U/L in the control cohort (p = 0.005, adjusted for sex and sampling time of the day). When patients and controls were analyzed together, high COMP was correlated with high growth velocity (b = 0.19, p = 0.003). When patients and controls were analyzed separately, COMP was correlated with growth velocity in children with scoliosis (b = 0.27, p = 0.007), but not in children without scoliosis (b = 0.02, p = 0.83) (all analyses adjusted for age, sex and sampling time). Low COMP was significantly correlated with large curve size in children with scoliosis (b =-0.29, p = 0.003), but not after adjustment for age, sex and sampling time (b = -0.16; p = 0.14). Conclusion COMP was lower in children with idiopathic scoliosis than in a control cohort. In children with scoliosis, high COMP was modestly correlated with high growth velocity, but not with curve severity. Keywords Cartilage oligomeric matrix protein Á Idiopathic scoliosis Á Children Á Growth velocity Introduction Idiopathic scoliosis is characterized by an abnormal three- dimensional curvature of the spine, involving both the skeleton and the intervertebral discs. Idiopathic scoliosis is seen in about 3 % of otherwise healthy children and ado- lescents and is often detected at the time of the prepubertal growth spurt [1]. Growth in that period is faster in children with idiopathic scoliosis than in non-scoliotic children [2, 3]. Around one-tenth of the affected individuals will pro- gress to a more severe form and may be subjected to treatment with bracing or surgery. However, it is difficult P. Gerdhem Á C. Topalis Á A. Grauers Department of Clinical Sciences, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden P. Gerdhem (&) Á A. Grauers Department of Orthopaedics, K54, Karolinska University Hospital, Huddinge, SE 141 86 Stockholm, Sweden e-mail: paul.gerdhem@karolinska.se A. Grauers Department of Orthopaedics, Sundsvall and Ha ¨rno ¨sand County Hospital, Sundsvall, Sweden J. Stubendorff Department of Orthopaedics, Skaraborg Hospital, Sko ¨vde, Sweden A. Ohlin Á K. M. Karlsson Department of Orthopaedics and Clinical Sciences, Ska ˚ne University Hospital, Lund University, Malmo ¨, Sweden 123 Eur Spine J (2015) 24:256–261 DOI 10.1007/s00586-014-3691-2