P96. Moderate scoliosis continues to progress at 30-year followup. A call for concern?

Abstract

BACKGROUND CONTEXT A study with 50-year follow-up of untreated patients with AIS found that curves 50° increase and may progress to the point of causing decreased pulmonary functions. In addition, significant deformity may alter body satisfaction and overall contentment with life. Based on this information, small curves of less than 30° with minimal deformity at skeletal maturity are rarely surgically treated. Curves of 50°or more with significant deformity may be candidates for surgical treatment. What about the middle group of patients with curves between 30° and 50°at skeletal maturity? What is the curve progression of these patients? What is the functional status of the patients? Is there a need for surgery for changes in the spine, and how common is it? PURPOSE Describe the natural history of moderate AIS curves at skeletal maturity. STUDY DESIGN/SETTING This is an IRB-approved natural history study, Level 3. PATIENT SAMPLE AIS patients with moderate curves (30 to 50°) and no history of spine fusion surgery prior to skeletal maturity. OUTCOME MEASURES Radiographic parameters (ie, thoracic cobb angle, thoracic kyphosis, lumbar cobb angle, lumbar lordosis) and patient-reported outcomes (Oswestry Disability Index, SF-36, and Roland-Morris). METHODS Radiographs and charts at 20- and 30-years’ follow-up were compared to status at skeletal maturity. We hypothesize that AIS curves between 30 and 50°at skeletal maturity tend to progress. RESULTS We followed 31 patients. Average age was 17±2y at skeletal maturity. Mean follow-ups were 22±6y and 34±6y. Average ages at these time points were 39±7y and 51±7y. At skeletal maturity, thoracic cobb=35±5°, thoracic kyphosis=20±11°, lumbar cobb=33±7°, and lumbar lordosis=42±8°. At first follow-up, thoracic cobb=43±10, thoracic kyphosis=32±13, lumbar cobb=42±15, and lumbar lordosis=51±17. At second follow-up, thoracic cobb=47±12, thoracic kyphosis=33±13, lumbar cobb=40±17 and lumbar lordosis=46±8. Thoracic curves changed more rapidly the first 20 years and slower over the next 10 years. The opposite was true for lumbar curves. From 0-20y, thoracic kyphosis and thoracic cobb progressed 0.5 and 0.4°/y; from 20-30y, these angles changed 0.2 and 0.1°/y. From 0-20y, lumbar lordosis and lumbar cobb progressed 0.1 and 0.3°/y; from 20-30y, these angles changed -0.7 and 0.5°/y. The average change was less than 1°/y in all patients. Functional outcomes were good at 20 and 30y follow-up. ODI scores were 7 at 20y and 8 at 30y. SF-36 domains improved 1% on average between 20 and 30y. The average Roland-Morris scores were 2.6 at 20y and 2.7 at 30y. Pain scores did not change: VAS-B and VAS-L scores were 2 and 0 at 20y and 2 and 1 at 30y. CONCLUSIONS Moderate AIS curves at skeletal maturity tend to progress. Thoracic curves progress more than lumbar curves during the first 20 years and then slow down. The opposite happens with lumbar curves, in addition to loss of lordosis. ODI, SF-36, and Roland-Morris scores suggest patients are functionally good at 20 and 30y follow-up despite curve changes. More follow-up is needed to define the true outcome of moderate curves at maturity. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.