Posterior fusion only for thoracic adolescent idiopathic scoliosis of more than 80°: pedicle screws versus hybrid instrumentation

Abstract

The treatment of thoracic adolescent idiopathic scoliosis (AIS) of more than 80°traditionally consisted of a combined procedure, an anterior release performed through an open thoracotomy followed by a posterior fusion. Recently, some studies have reassessed the role of posterior fusion only as treatment for severe thoracic AIS; the correction rate of the thoracic curves was comparable to most series of combined anterior and posterior surgery, with shorter surgery time and without the negative effect on pulmonary function of anterior transthoracic exposure. Compared with other studies published so far on the use of posterior fusion alone for severe thoracic AIS, the present study examines a larger group of patients (52 cases) reviewed at a longer follow-up (average 6.7 years, range 4.5-8.5 years). The aim of the study was to evaluate the clinical and radiographic outcome of surgical treatment for severe thoracic ([80°) AIS treated with posterior spinal fusion alone, and compare comprehensively the results of posterior fusion with a hybrid construct (proximal hooks and distal pedicle screws) versus a pedicle screw instrumentation. All patients (n = 52) with main thoracic AIS curves greater than 80°(Lenke type 1, 2, 3, and 4), surgically treated between 1996 and 2000 at one institution, by posterior spinal fusion either with hybrid instrumentation (PSF-H group; n = 27 patients), or with pedicle screw-only construct (PSF-S group; n = 25 patients) were reviewed. There were no differences between the two groups in terms of age, Risser's sign, Cobb preoperative main thoracic (MT) curve magnitude (PSF-H: 92°vs. PSF-S: 88°), or flexibility on bending films (PSF-H: 27% vs. PSF-S: 25%). Statistical analysis was performed using the t test (paired and unpaired), Wilcoxon test for nonparametric paired analysis, and the Mann-Whitney test for non-parametric unpaired analysis. At the last follow-up, the PSF-S group, when compared to the PSF-H group had a final MT correction rate of 52.4 versus 44.52% (P = 0.001), with a loss of -1.9°versus -11.3°( P = 0.0005), a TL/L correction of 50 versus 43% (ns), a greater correction of the lowest instrumented vertebra translation (-1.00 vs. -0.54 cm; P = 0.04), and tilt (-19°vs. -10°; P = 0.005) on the coronal plane. There were no statistically significant differences in sagittal and global coronal alignment between the two groups (C7-S1 offset: PSF-H = 0.5 cm vs. PSF-S = 0 cm). In the hybrid series (27 patients) surgery-related complications necessitated three revision surgeries, whereas in the screw group (25 patients) one revision surgery was performed. No neurological complications or deep wound infection occurred in this series. In conclusion, posterior spinal fusion for severe thoracic AIS with pedicle screws only, when compared to hybrid construct, allowed a greater coronal correction of both main thoracic and secondary lumbar curves, less loss of the postoperative correction achieved, and fewer revision surgeries. Posterior-only fusion with pedicle screws enabled a good and...

Five-year clinical and radiographic outcomes using pedicle screw only constructs in the treatment of adolescent idiopathic scoliosis

“…Hwang et al [30] assessed skipped pedicle screw fixation in 57 patients with 5-year follow-up and noted minimal loss of correction from the immediate post-op (2 %), but did not remark on any changes at the 2-year interval. Di Silvestre et al [11] compared hybrid and pedicle screw constructs with a mean follow-up of 6.7 years and found better maintenance of correction with screws. They noted a mean loss of 11.3°with hybrid constructs as compared to 1.9°using screws (p = 0.0005).…”

“…In 1995, Suk et al [5] reported outcomes in 78 patients and noted improved coronal correction and less loss of correction at 2 years using screws when compared to hybrid constructs. Subsequently, other studies have shown pedicle screw constructs to provide greater immediate postoperative correction of coronal curvature, axial translation, and axial rotation [11][12][13]. Better maintenance of correction at 2 years has been reported in both fused and compensatory curves, as well as a reduction in the number of segments fused and a lower revision rate associated with pedicle screw constructs [12,15,16].…”

“…The development of CD instrumentation improved upon Harrington rod constructs, but correction of axial rotation remained suboptimal [3][4][5][6]. Most recently, the application of thoracic pedicle screws has improved upon many of the limitations from earlier constructs while providing maintenance of correction in the short-term [10][11][12][13][14][15].…”

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

“…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. They reported a thoracic curve correction rate of 44.52 % in patients treated by hybrid instrumentation versus 52.4 % in patients treated by all-screw instrumentation.…”

Simultaneous translation on two rods is an effective method for correction of hypokyphosis in AIS: radiographic results of 24 hypokyphotic thoracic scoliosis with 2 years minimum follow-up

“…Authors stated that all-screw constructs result in a negligible loss of correction at follow-up compared with that observed with hybrid constructs and especially with hook constructs [6,7,32,33]. It is speculated that this loss of reduction is due, in great part, to the instability of the anchorages.…”