Application of SRS-Schwab grade IV osteotomy in the treatment of type I congenital kyphosis

Objective To evaluate the radiographic and clinical outcomes of Scoliosis Research Society(SRS)-Schwab Grade IV osteotomy in type I congenital kyphosis. Methods All of 28 patients with type I congenital kyphosis who underwent SRS-Schwab Grade 4 osteotomy from June 2015 to June 2017 were retrospectively reviewed,including 21 males and 7 females aged 10 to 28 years old, with an average of 13.6±8.5 years. On standing wholespinal X-rays at pre-operation, post-operation and each follow-up, global kyphosis(GK), thoracic kyphosis(TK), lumbar lordosis(LL) and sagittal vertical axis(SVA) were measured. The intra-operative and post-operative complications were recorded for each patient. The Scoliosis Research Society-22 questionnaires(SRS-22) and visual analog scale(VAS) for back pain were collected from patients elder than 12 years old at pre-operation and last follow-up. The comparison analysiswasperformed by paired samples t test. Results At pre-operation, the GK, TK, LL and SVA were 47.0°±4.9°, 16.8°±3.7°, 36.6°±7.7°, (-31.9±13.6) mm, respectively. At 3 months post-operation, the average values improved to 3.7°±2.3°, 36.8°±4.0°, 46.5°±4.4°, 4.0±19.1 mm, respectively. Significant differences were found in all parametersbetween pre- and post-operation. The post-operative follow-up was 12 to 24 months, with an average of 13.2±5.2 months. At the last follow-up, the GK, TK, LL and SVA were 4.0°±2.4°, 38.0°±6.0°, 45.9°±5.4°, 7.6±15.3 mm, and no significant correction loss was found during follow-up. The scores of each domain of SRS-22 questionnaire improved at different level during follow-up, of which the improvement in self-imagewas statistically significant (P<0.001). The scores of VAS for back pain improved significantly after operation (P<0.001). One patient hadabnormal intra-operative monitoringwhile no neurological defectwas detected at post-opera tion. Proximal junctional kyphosis occurred in 2 patients at 3 months follow-up while no patients needed revision surgery. There wereno implant-related complicationsduring follow-up. Conclusion The SRS-Schwab Grade 4 osteotomycould provide satisfying correction with relatively low rates of complications in type I congenital kyphosis. Thus, the SRS-Schwab Grade IV osteotomy is a safe strategy for type I congenital kyphosis. Key words: Thoracic vertebrae; Lumbar vertebrae; Congenital Abnormalities; Kyphosis; Osteotomy; Quality of life