Pulmonary function improvement in patients with ankylosing spondylitis kyphosis after pedicle subtraction osteotomy.

STUDY

DESIGN

A prospective clinical study.

OBJECTIVE

To observe postoperative change in pulmonary function in patients with ankylosing spondylitis (AS) kyphosis after pedicle subtraction osteotomy (PSO).

SUMMARY OF BACKGROUND DATA: The preoperative pulmonary dysfunction in patients with AS has been reported in several literatures, whereas few research about postoperative changes in pulmonary function with AS kyphosis was published.

METHODS

A total of 32 (27 males and 5 females) patients with AS were eligibly involved. Twenty-nine (25 males and 4 females) patients completed the follow-up and 3 (2 males and 1 females) patients were lost. Pulmonary function tests, breath-holding time (BHT), and full-length spine radiographs in natural standing position were followed postoperatively.

RESULTS

The global kyphosis significantly decreased from 63.0°± 20.3° preoperatively to 15.3°± 10.3° postoperatively and 17.1°± 10.9° at the 2-year follow-up. The BHT before surgery was 32.5 ± 10.1 s, whereas the postoperative BHT had increased to 43.1 ± 8.6 s (P < 0.05). Two patients with AS underwent normal pulmonary function test before operation, whereas there were 19 patients at 2-year follow-up. The clinical improvement rate was 85.2% (23/27). The percent-predicted vital capacity had increased from 68.4% ± 9.5% to 79.4% ± 6.1% at 2-year follow-up (P < 0.05). The percent-predicted forced vital capacity before PSO was 75.5% ± 6.4% and it was 81.0% ± 6.9% at 2-year follow-up (P < 0.05). The improved percent-predicted vital capacity and predicted forced vital capacity had a positive correlation with the correction of global kyphosis (r = 0.6328 and 0.8612, respectively).

CONCLUSION

The postoperative pulmonary function including pulmonary volume and ventilatory function in patients with AS with kyphosis had significantly improved at 2-year follow-up. And, the improved pulmonary function had a positive correlation with the kyphosis correction.

LEVEL OF EVIDENCE: 3.