Pulmonary function before and after anterior spinal surgery in adult idiopathic scoliosis

Background - Little is known about the long term effects of anterior spinal surgery on pulmonary function in adult patients with idiopathic scoliosis. A study was therefore undertaken of pulmonary function before and after anterior spinal surgery in this group of patients. Methods - Fourteen patients (12 women) of mean age 26.5 years (range 17-50, 10 greater than or equal to 20 years) were studied. All 14 patients underwent thoracotomy and anterior arthrodesis, and five also underwent posterior arthrodesis. Scoliosis curves and lung volumes were measured preoperatively and at a mean follow up of 32 months (range 14-49) after surgery. Results - At long term follow up after surgery the mean (SD) Cobb angle of the thoracic curve improved from 59 degrees (25 degrees) to 39 degrees (18 degrees), a correction of 31%. Despite this there was a fall in mean forced vital capacity (FVC) of 0.31 litres (95% confidence interval 0.04 to 0.38). In the patients who underwent anterior surgery without posterior surgery (n = 9) there was a fall in mean FVC of 0.31 litres (95% confidence interval 0.12 to 0.50); mean forced expiratory volume in one second and total lung capacity were also reduced and there was an increase in mean residual volume. Conclusions - Forced vital capacity is reduced at long term follow up in adult patients with idiopathic scoliosis who undergo anterior spinal surgery. The fall in FVC is small and is unlikely to be of clinical significance in patients with reasonable lung function in whom surgery is planned for prevention of curve progression or improvement of cosmetic appearance and pain. However, surgical intervention should not be undertaken in an attempt to improve pulmonary function.