Growth friendly surgeries increase 3D true spine length at two-years post-operative.

Abstract

Traditional coronal-plane vertical spine height measurements, such as T1-T12 and T1-S1 spine height, are influenced by 3-dimensional spinal deformity. Therefore, they are unreliable indicators of true spine growth. The novel 3D true spine length (3D-TSL) technique assesses spine growth regardless of the presence of 3D spinal deformity. This study evaluates the effect of growth friendly surgery on spine growth using the 3D-TSL technique at two years follow-up. Radiographs of early onset scoliosis (EOS) participants undergoing growth friendly surgery at a single institution were evaluated at pre-index, post-index, and at 2-year follow-up. Scoliosis, kyphosis, traditional coronal height and 3D-TSL were measured. Twenty-four EOS patients (14 female) with a mean age of 6.3 years were included. Scoliosis improved from 77.8 ± 18.7° pre-index to 56.0 ± 17.8° post-index (p < 0.001); but increased at 2 years to 65.9 ± 20.1° (p < 0.05). Kyphosis improved from 56.0 ± 20.7° pre-index to 39.3 ± 13.8° post-index (p < 0.001); and increased again at 2 years to 48.6 ± 16.4° (p < 0.05). Traditional T1-S1 height increased from pre-index to post-index, to 2-year follow-up (245.5 ± 37.2 mm to 275.8 ± 42.7 mm; p < 0.001, to 288.0 ± 41.7 mm; p = 0.005). As expected, T1-S1 3D-TSL did not change from pre to immediately post-index (305.6 ± 43.9 mm vs 306.5 ± 44.0 mm); there was a significant change from post-index to 2-year follow-up (334.1 ± 48.0 mm; p < 0.001). Out of plane changes in scoliosis and kyphosis over time justify the use of the 3D-TSL for this cohort of patients. There was no significant change in 3D-TSL from pre-index to post-operatively; however, during the growth phase of treatment 3D-TSL increased significantly by 27.6 mm.