The effect of growing rod lengthening technique on the sagittal spinal and the spinopelvic parameters

The aim of this retrospective clinical study is to evaluate the effect of growing rod lengthening technique on sagittal balance in relationship with the spinopelvic parameters, in early onset scoliosis (EOS).

Twenty-three patients (18 female, 5 male), with a mean age of 8.3 years during the operation (range 3.2-12.2), with EOS due to various etiologies were operated using growing rod (8 single, 15 dual) technique, between the years 2007 and 2011. The patients were operated in two different institutions and were evaluated retrospectively via the parameters on the radiographic charts including the mean curve angle, T1-S1 distance, cervical lordosis, thoracic kyphosis, lumbar lordosis, sagittal and coronal balance, pelvic tilt, sacral slope and pelvic incidence. The parameters were measured in the preoperative and the early postoperative periods and during the last follow-up. The data obtained from the measurements were evaluated statistically. Complications were also noted.

The mean follow-up period was 34.2 months (range 24-57.6). The mean thoracic kyphosis angle was 53.6° (range 25°-119°) preoperatively, 39.6° (range 20°-61°) early postoperatively (p < 0.05) and 39.9° (range 21°-65°) during the last follow-up (p < 0.05). The mean lumbar lordosis angle was -46.1° (range -67° to -13°) preoperatively, -41° (range -64° to -11°) early postoperatively (p > 0.05) and -39.7° (range -62° to -16°) during the last follow-up (p > 0.05). Average sagittal balance was measured as 0.2 cm (range -7 to 24.7 cm) preoperatively, -0.1 cm (range -6.6 to 8.5 cm) initial postoperatively (p > 0.05) and -0.2 cm (range -7.3 to 13.5 cm) during the last follow-up (p > 0.05). The average pelvic incidence was found as 46.4° (range 27°-83°) preoperatively, 45.2° (range 28°-78°) (p > 0.05) early postoperatively and 45.7° (range 28°-82°) during the last follow-up (p > 0.05). We have encountered complications in 14 patients. These consisted of eight rod fractures, seven screw pull-outs, four hook dislodgements, three proximal junctional kyphosis, two screw nut loosening, one lamina fracture, one skin slough, one superficial wound infection and one deep wound infection.

Significant improvement was found in the global thoracic kyphosis angle, by comparing the preoperative, the early postoperative and the last follow-up parameters statistically (p < 0.05). There was no statistically significant improvement in the spinopelvic parameters (p > 0.05). We claim that growing rod technique doesn't provide statistically significant improvement, in the sagittal spinal and the spinopelvic parameters, except for the kyphosis, in the treatment of EOS patients.