[Application of self-designed adjustable operation frame in treatment of severe kyphosis secondary to ankylosing spondylitis with posterior osteotomy].

Objective: To introduce a self-designed adjustable operation frame and explore the feasibility and safety in the treatment of severe kyphosis secondary to ankylosing spondylitis with posterior osteotomy.

Methods: Between March 2016 and May 2018, 7 cases of severe kyphosis secondary to ankylosing spondylitis were treated with posterior osteotomy using self-designed adjustable operation frame with prone position. There were 5 males and 2 females with an average age of 49.4 years (range, 40-55 years). The disease duration was 10-21 years (mean, 16.7 years). The apical vertebrae of kyphosis were located at T in 2 cases, T in 1 case, L in 1 case, and L in 3 cases. Among the 7 cases, 2 were classified as typeⅠ, 4 as type ⅡB, and 1 as type ⅢA according to 301 classification system. There was no neurological deficit of all cases; but 1 case suffered bilateral hip joints ankylosed in non-functional position. The parameters of chin-brow vertical angle (CBVA), global kyphosis (GK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), sagittal vertical axis (SVA) were measured; and the operation time, the intraoperative blood loss, and the complications were also collected and analyzed.

Results: All operations completed successfully. The operation time was 310-545 minutes (mean, 409.7 minutes) and the intraoperative blood loss was 1 500-2 500 mL (mean, 1 642.9 mL). There were 2 cases treated with one-level osteotomy of sagittal translation, 1 case of radiculopathy symptom of L , and 3 cases of tension of abdominal skin. All patients were followed up 20-35 months (mean, 27.9 months). There were significant differences in CBVA, GK, TLK, LL, and SVA between pre- and post-operation ( <0.05); but no significant difference between 1 week after operation and last follow-up ( >0.05). All the osteotomies and bone grafts fused well and no complications of loosening and breakage of internal fixator occurred during the follow-up.

Conclusion: In the posterior osteotomy for correction of severe kyphosis secondary to ankylosing spondylitis, the self-designed adjustable operation frame is convenient for the patient to be placed in prone position. It is safe, feasible, and effective to perform osteotomy correction with the aid of the self-designed adjustable operation frame.