Introduction: One of the important goals of scoliosis surgery is to improve or to prevent deterioration of pulmonary function. There have been many reports on this subject, yet there are a few reports on cases that had surgery by modern multi-hook system. Modern instrumentation can provide better correction; therefore better results on pulmonary function can be expected.

The purpose of this study is to analyse post-operative pulmonary function in cases that underwent Isola instrumentarion to scoliosis.

Method and Results: There are 130 cases (Male 23, Female 107) who underwent Isola instrumentation to scoliosis from December 1991 to December 1998 and had pulmonary function test pre-operatively and at the time of two-years follow-up. Aetiologies were Idiopathic 119, Congenital 3, Neurofibromatosis 2, Marfan 4, and Others 2. Average age is 15 at the time of operation ranging 10 to 26. One hundred and twenty-six cases had single operation and four cases had two-staged anterior-posterior surgery.

VC, %VC, Fev.l.0, % Fev.1.0 were measured pre-operatively and two years post-operatively. Body height correction was done using Kohno’ s equation to obtain % VC.

The pre-operative average VC, %VC, Fev.l.0, and %Fev.l.0 were 2.4l, 84.2%. 2.1l, and 85.5% respectively. They were 2.6l, 83.0%. 2.3l, and 87.2% at 2 years postoperatively. Cases were diagnosed according to the change of % VC using a threshold of 10% change. If the change of the %VC is less than 10%. it is diagnosed as unchanged. Thirty cases (23.1%) had decreased %VC, 70 cases (53.8%) unchanged and 21 cases (16.1%) had increased %VC.

The cases were divided into four groups according to the pre-operative % VC. Group 1; the pre-operative %VC was less than 60%. Group 2; 60% to 69%, Group3; 70% to 79%. and Group 4; 80% or more. The average pre- and post-operative %VC were 50% and 54% in Group 1, 65.5% and 67.5% in Group 2, 75.4% and 80.5% in Group 3, 94.8% and 90.6% in Group 4.

Conclusion: The results showed that a patient can expect to have normal or almost normal VC post-operatively when the pre-operative % VC is larger than 70%. On the other hand, if the pre-operative % VC is less than 60% the chance to have normal or almost normal VC . post-operatively is very little. Therefore, surgery must be done before % VC deteriorates to less than 60%. The goal of scoliosis treatment is three fold; 1) to restore stable, balanced, and stable spine, 2) to have normal pulmonary function, 3) to be emotionally stable. In 61% of the cases the surgical technique applied was conventional method which gave average % correction of 68%. From 1997, a new correction technique using Isola system has been applied. Results at one-year follow-up showed better results. It is my opinion that the treatment of scoliosis should be focused not only to the correction of coronal and sagittal curvature but to the correction of thoracic cage deformity.