Correlates of the Peak Height Velocity (PHV) in Girls with Idiopathic Scoliosis

Summary: 24 girls, Risser 0 or 1 at enrollment, with idiopathic scoliosis were followed prospectively until after their PHV with clinical, radiographic, and serological evaluations. These measurements were correlated to PHV timing. At the PHV, all girls were Risser 0 with open triradiate cartilages (TRC). When the TRC's are open, other useful maturity indicators include Tanner staging and specific aspects of the skeletal age. Serologically, higher IGF-1 and estradiol levels occur post PHV.

Purpose: In idiopathic scoliosis, the most important known prognostic factor is the timing of the PHV combined with curve magnitude. Because PHV can only be verified well after the fact using serial height measurements, clinically useful correlates are needed to determine PHV status while meaningful decisions can still be made.

Methods: 24 girls, Risser 0 or 1 at enrollment, with idiopathic scoliosis were followed every six months until after their PHV. Standing and sitting height, arm spans, Tanner sexual staging, skeletal age (Tanner-Whiteside III), spinal radiographs, and serologic markers IGF-1, IGFBP-3, DHEA-S, estradiol, bone-specific alkaline phosphatase, and osteocalcin were obtained at each visit and correlated to PHV timing.

Results: Of the 24 girls enrolled, 14 had identifiable growth peaks. Of the others, two were lost to follow-up, and eight were either at (4) or beyond (4) their PHV at enrollment. The average PHV was 10.5 ±1.8 cm/yr at age 11.7 ± 1 years. Correlates with PHV timing: Risser sign: At the PHV, all girls were Risser 0 with open triradiate cartilages (TRC). Skeletal Age: Uncapped phalangeal epiphyses were indicative of prePHV and fused epiphyses of postPHV. Capped but unfused epiphyses were indeterminate. Tanner Staging: Tanner stage 1 for breast strongly indicates prePHV. Stage 3 for breast and pubic hair never occurred before the PHV, and stage 4 always occurred postPHV. Chemistries: All of the serologies showed changes over time, but the only ones with discriminatory potential were IGF-1 and estradiol.

Significance: The PHV occurs during Risser 0 with open TRC's. If the TRC's are open, other useful maturity indicators include Tanner staging and specific aspects of the skeletal age. PrePHV indicators include Tanner 1 breast and uncapped phalangeal epiphyses. Tanner 3 occurs at or post PHV while Tanner 4 occurs postPHV. Serologically, higher IGF-1 and estradiol levels occur post PHV.