Objective: To explore the feasibility of single-stage skipping two-level pedicle subtraction osteotomy (PSO) for severe thoracolumbar kyphosis (Cobb > 100°) in advanced ankylosing spondylitis (AS).
Methods: Ten AS patients with thoracolumbar kyphosis undergoing skipping two-level PSO were retrospectively reviewed. The most frequent levels of osteotomy was L1 and L4 (n = 7), followed by T12 and L3 (n = 2) and L2 and L5 (n = 1). All patients were males with a mean age of 28.5 ± 9.1 years (range: 17 - 47). The pre- and post-operative values of thoracic kyphosis (TK), lumbar lordosis (LL), globe kyphosis (GK), local kyphosis of osteotomized vertebra (LK1, LK2) and sagittal imbalance (SVA) were measured.
Results: Significant differences were observed with respects to the improvements of LL, GK, LK1, LK2 and SVA (P < 0.01). LL, GK, LK1, LK2 and SVA improved from 41.9°, 113.4°, 40.5°, -0.3° and 25.2 cm preoperatively to -44.1°, 71.6°, 13.5°,-26.8° and 5.8 cm postoperatively respectively. The mean operative duration was 370 minutes (range: 290 - 420) and the estimated volume of blood loss 2600 ml (range: 1700 - 3800). Dural tear occurred intra-operatively in 1 patient. One had a transient brachial plexus paralysis and resolved after 1 week postoperatively. One had transient radiculopathy in right lower extremity and recovered completely 3 weeks postoperatively.
Conclusion: As a safe and effective technique for correction of severe thoracolumbar kyphosis (Cobb > 100°) secondary to AS, single-stage skipping two-level PSO osteotomy can achieve larger correction and better sagittal alignment with a mean correction of 86°in terms of LL.