Introduction: Lumbar spine morphology is well described in healthy children but has not been described in children with Osteogenesis Imperfecta (OI).

Aims: To look at lumbar bony morphometry in OI children and to consider the importance of these factors in spinal surgery in these children.

Methods: 21 lumbar vertebrae (from L3–5) of 7 OI (6 OI type 3 and 1 OI type 4) children with scoliosis were analysed using Reformatted Computer Tomographic scans. The following measurements obtained: Spinal canal diameters, Transverse pedicle width, Total pedicle length, Pedicle root length, Transverse pedicle angle and Sagittal pedicle angle. Results are compared with previously published data of normal age-matched lumbar spine measurements.

Results: The mean age was 12 years (range 7–18 years). 6 females and 1 male. All had spondylolisthesis at L5-S1. Results were analysed by Wilcoxon Signed Rank test (nonparametric test). The transverse pedicle width was significantly narrower at all 3 levels (p< 0.01). Transverse pedicle angle was significantly less angled at all 3 levels (L3 p=0.04, L4 & L5 p< 0.01) whilst the sagittal pedicle angle was significantly more angled at all 3 levels (p< 0.01). Spinal canal diameter (AP) was significantly increased at all 3 levels (L3 & L5 p< 0.01, L4 p=0.02). And no significant differences in spinal canal transverse diameter and total pedicle length. Pedicle root length Significantly longer at all 3 levels (L3 & L4 p< 0.05, L5 p< 0.01). All children had grade-I spondylolisthesis at L5/S1.

Conclusions: A longer pedicle root with a narrower transverse diameter (and thinner cortices) and a reduced transverse angle is essential knowledge when passing pedicle screws in the lumbar spine in children with OI. This is a difficult technique and its safety requires further evaluation.