Abstract
Introduction
We prospectively examined the effect of pedicle screw placement at a young age (<5 years) for early-onset spinal deformity on the growth and development of pedicles and the spinal canal.
Methods
Patients with early-onset deformity who received pedicle screw placement before the age of 5 years and had preoperative and final follow-up axial imaging were included. To increase sample size, patients who had the same criteria but with no preoperative axial images were also included. Anteroposterior and transverse diameters of the canal and pedicle length were measured on axial images cutting through the middle of the pedicle (figures 1 and 2).
Results
13 patients (five male, eight female) met inclusion criteria. Average age at surgery was 46·6 months (29–60), and average follow-up 49·8 months (24–82). 77 instrumented and 32 non-instrumented levels were studied. The table summarises measurements. In the nine patients without preoperative axial imaging, pedicle lengths and canal diameters seemed to accord with previously published normative morphological data for this age group.
Conclusions
Animal studies have shown the potential slowing of pedicle and canal growth in immature spines with pedicle screws. This is the first study to examine the behaviour of instrumented immature human vertebrae prospectively. Early application of pedicle screws does not seem to cause adverse effects on pedicle and canal growth in young patients. This discordance between human and animal studies may have three explanations: (1) although the neurocentral cartilage is still visible it may not be physiologically active in this age group; (2) a single screw across may not exert sufficient compression; (3) or the canal may have means of remodelling that is yet not known.
