Long-term outcome after surgical treatment of Scheuermann's Kyphosis (SK)

Study design A retrospective observational cohort study with a minimum follow-up of 10 years of patients who underwent surgery for Scheurmann Kyphosis (SK). Objective Evaluate the long-term clinical and radiological outcome of patients with SK who either underwent combined anterior-posterior surgery or posterior instrumented fusion alone. Summary of background data There is paucity of literature for long-term outcome studies on SK. The current trend is towards only posterior (PSF) surgical correction for SK. The combined strategy of anterior release, fusion and posterior spinal fusion (AF/PSF) for kyphosis correction has become historic relic. Long-term outcome studies comparing the two procedures are lacking in literature. Methods 51 patients (30 M: 21F) who underwent surgery for SK at a single centre were reviewed. Nineteen had posterior instrumentation alone (PSF) (Group 1) and 32 underwent combined anterior release, fusion with posterior instrumentation (AF/PSF) (Group 2). The clinical data included age at surgery, gender, flexibility of spine, instrumented spinal levels, use of cages and morcellised rib grafts (in cases where anterior release was done), posterior osteotomies and instrumentation, complications and indications for revision surgery. Preoperative flexibility was determined by hyperextension radiographs. The radiological indices were evaluated in the pre-operative, 2-year post-operative and final follow-up [Thoracic Kyphosis (TK), Lumbar lordosis (LL), Voustinas index (VI), Sacral inclination (SI) and Sagittal vertical axis (SVA)]. The loss of correction and incidence of JK (Junctional Kyphosis) and its relation to fusion levels were assessed. Complications and difference in outcome between the two groups were analyzed. Results The mean age at surgery for 51 patients was 20.6 years who were followed up for a minimum of 10 years (mean: 14 years; range 10-16 years). The mean age was 18.5 +/- 2.2 years and 21.9 +/- 4.8 years in groups 1 and 2, respectively. The mean pre- and 2-year post-operative ODIs were 32.6 +/- 12.8 and 8.4 +/- 5.4, respectively, in group 1 (p < 0.0001) and 30.7 +/- 11.7 and 6.4 +/- 5.7, respectively, in group 2 (p < 0.0001). The final SRS-22 scores in group 1 and 2 were 4.1 +/- 0.4 and 4.0 +/- 0.35, respectively (p = 0.88). The preoperative flexibility index was 49.2 +/- 4.2 and 43 +/- 5.6 in groups 1 and 2, respectively (p < 0.0001). The mean TKs were 81.4 degrees +/- 3.8 degrees and 86.1 degrees +/- 6.0 degrees for groups 1 and 2, respectively, which corrected to 45.1 degrees +/- 2.6 degrees and 47.3 degrees +/- 4.8 degrees, respectively, at final follow-up (p < 0.0001). The mean pre-operative LL angle was 60.0 degrees +/- 5.0 degrees and 62.4 degrees +/- 7.6 degrees in groups 1 and 2, respectively, which at final follow-up was 45.1 degrees +/- 4.4 degrees and 48.1 degrees +/- 4.8 degrees, respectively (p < 0.0001). The mean pre-operative and final follow-up Voustinas index (VI) in group 1 were 22.9 +/- 2.9 and 11.2 +/- 1.2, respectively, and in group 2 was 25.9 +/- 3.5 and 14.0 +/- 2.3, respectively. The mean pre-operative and final follow-up SI angle were 43.6 degrees +/- 3.3 degrees and 31.2 degrees +/- 2.5 degrees in group 1, respectively, and 44.3 degrees +/- 3.5 degrees and 32.1 degrees +/- 3.5 degrees in group 2, respectively (p < 0.0001). The pre-operative and final follow-up SVA in group 1 were - 3.3 +/- 1.0 cms and - 1.3 +/- 0.5 cms, respectively, and in group 2 was - 4.0 +/- 1.3cms and - 1. 9 +/- 1.1cms, respectively (p < 0.0001). Though the magnitude of curve correction in the groups 1 and 2 was significant 36 degrees vs 39 degrees (p = 0.05), there was no significant difference in correction between the two groups. Proximal JK was seen in seven and distal JK in five patients were observed in the whole cohort. Conclusion The long-term clinical outcomes for both PSF and AF/PSF are comparable with reproducible results. No difference was noted in loss of correction and outcome scores between the two groups. The correction of thoracic kyphosis (TK) had a good correlation with ODI. AF/PSF had much higher complications than PSF group. The objective of correcting the sagittal profile and balancing the whole spinal segment on the pelvis can be achieved through single posterior approach with fewer complications.