Posterior correction of thoracic adolescent idiopathic scoliosis with pedicle screw instrumentation: results of 48 patients with minimal 10-year follow-up

Abstract

Purpose Since early 1990s pedicle screws in thoracic spine have been used in posterior correction of adolescent idiopathic scoliosis (AIS). Long-term results are scarce. We report clinical, radiological and pulmonary function results of 48 consecutive patients with 10-year minimal follow-up. Methods Forty-eight consecutive patients (42 females, 6 males) with 41 Lenke 1 (lumbar modifier A = 19, B = 8, C = 14), 7 Lenke 2 (lumbar modifier A = 2, B = 4, C = 1) were operated for AIS from posterior with pedicle screw alone instrumentation. Risser stage at the time of operation was 0-3 in 24, more than 3 in 24 patients. Mean age was 15.3 years. The data were prospectively collected preoperatively, at 6 weeks, 2 years and 10 years postoperatively. Cobb angle, sagittal and coronal balance, distal adjacent disc angle and lowest fused vertebral tilt were documented at all time-points. Choice of fusion levels is described. Not every vertebra was instrumented with pedicle screws. The implant density was average one pedicle screw per vertebra or 50 %. Derotation and translation of apical vertebrae on the concave side were performed for correction. The overall outcome and the outcome of different curve types were analyzed statistically. Results Lowest instrumented vertebra (LIV) was distal end vertebra in two-thirds of the patients and was one below distal end vertebra in one-third of the patients. The main thoracic curve correction was 63 %, from 58°± 12°p reoperative to 21°± 9°at 6 weeks. The Cobb angle was 23°± 10°at 2 years and 26°± 10°at 10 years. The apical vertebral rotation improved 35 %, the non-instrumented lumbar curves improved 47 %, the distal adjacent disc angle decreased from 6°± 3°preoperatively to -2°± 4°p ostoperatively and the last instrumented vertebral tilt decreased from 23°± 8°preoperatively to 5°± 5°post-operatively. All these parameters remained stable up to 10-year follow-up. The scoliosis correction was not associated with any change in the preoperative thoracic kyphosis and lumbar lordosis. The % FVC remained unchanged with 74 ± 21 % preoperatively to 74 ± 11 % at 2 years and 75 ± 10 % at 10 years. The SRS-24 score was 93 ± 18 points at 2 years and 95 ± 22 points at 10 years. There were no neurological complications, no pedicle screw-related complications. Conclusion Posterior correction of thoracic AIS with pedicle screw instrumentation is safe and produces a longterm stable correction and high patient satisfaction. An implant density of 50 % is sufficient to achieve these results. LIV can be the distal end vertebra or one below the distal end vertebra depending on the position of the distal end vertebra to the centre sacral line. The preoperative pulmonary function does not change on long term.Keywords Adolescent idiopathic scoliosis Á Selective posterior correction with pedicle screw instrumentation Á Choice of fusion levels Á Long-term operative results Á Long-term pulmonary function

Optimal surgical care for adolescent idiopathic scoliosis: an international consensus

“…A recent prospective cohort study with 10-year follow-up conducted by Min et al [44] has shown good correction with a pedicle screw implant density of 50 %. High implant density has not shown improvement in patient reported outcomes [38][39][40][41][42][43][44] or cosmesis [39], and has contributed to less thoracic kyphosis [38,40,41], and high costs [42,45]. In contrast to what might be expected, it was shown through a finite element analysis and computational study that high implant density does not improve the distribution of forces and correction [46,47].…”

“…Some studies have shown slightly larger radiographic correction with high implant density [38][39][40], while others have shown no correlation between implant density and curve correction [41][42][43]. A recent prospective cohort study with 10-year follow-up conducted by Min et al [44] has shown good correction with a pedicle screw implant density of 50 %. High implant density has not shown improvement in patient reported outcomes [38][39][40][41][42][43][44] or cosmesis [39], and has contributed to less thoracic kyphosis [38,40,41], and high costs [42,45].…”

Treatment of severe scoliosis with posterior-only approach arthrodesis and all-pedicle screw instrumentation

“…The use of pedicle screws at all vertebral levels led to the reassessment of the role of posterior-only arthrodesis as treatment for severe scoliosis [16,17]. Recent studies [18] have shown a correction rate in severe scoliosis treated by all-screw posterior instrumentation to be around 50 %, which is similar to the correction rate obtained by combined approach surgery. Di Silvestre et al [19] compared two similar series of patients with severe thoracic idiopathic scoliosis (main curve over 80°Cobb), the first treated by posterior hybrid instrumentation fusion and the second by posterior all-screw instrumentation fusion, with a mean follow-up of 6.7 years.…”

Implant and spinal mobility influence on the spinal curvature correction in adolescent idiopathic Lenke I type scoliosis

“…To compare the preoperative stiffness of the curves, the flexibility % was calculated, with no difference in the groups (p > 0.05). The mean postoperative thoracic Cobb curve angle was 15.81º (±5.28), 21.63º (±6.89), and 27.55º (±8.25), respectively. The mean correction of the thoracic curve was 68.87% in the screw group, 58.76% in the hybrid and 50.27% in the hook group.…”