[Osteotomy for severe thoracolumbar kyphosis in advanced ankylosing spondylitis: skipping two-level pedicle subtraction osteotomy].

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.