Five days of inpatient scoliosis-specific exercises improve preoperative spinal flexibility and facilitate curve correction of patients with rigid idiopathic scoliosis

Preoperative spine flexibility plays a key role in the intraoperative treatment course of severe scoliosis. In this cohort study, we examined the effects of 5 day inpatient scoliosis-specific exercise (SSE) on the spinal flexibility of patients with adolescent idiopathic scoliosis before surgery. A total of 65 patients were analyzed. These patients were divided into a prospective cohort (n = 43, age: 15 +/- 1.6 years, 36 girls and 7 boys, Lenke class 1 and 2, Cobb angle: 64 +/- 11 degrees) who underwent spinal fusion in 2020, and a retrospective cohort (n = 22, age: 15 +/- 1.5 years, 17 girls and 5 boys, Lenke class 1 or 2, Cobb angle: 63 +/- 10 degrees), who underwent surgery between 2018 and 2019 and did not receive preoperative SSE. Rigid scoliosis was defined as a reduction of less than 50% in Cobb angle between the preoperative fulcrum bending and initial standing curve magnitude. In the prospective cohort, 21 patients (Cobb angle: 65 +/- 11 degrees) presented with rigid thoracic scoliosis (pre-SSE fulcrum bending: 40 +/- 9 degrees, 39% reduction), and therefore received 5-day SSE to improve their preoperative spinal flexibility (SSE group), whereas 22 patients (Cobb angle: 63 +/- 12 degrees) presented with flexible thoracic scoliosis (pre-SSE fulcrum bending: 27 +/- 8 degrees, 58% reduction), and therefore underwent surgery without preoperative SSE (non-SSE group). For patients who received 5-day preoperative SSE for 4 h every day, the International Schroth Three-Dimensional Scoliosis Therapy technique was implemented with an inpatient model. After 5 days of SSE, improvements in Cobb angle with post-SSE fulcrum-bending radiography (23 +/- 7 degrees, 66% reduction) and pulmonary function (forced expiratory volume in 1 s/forced expiratory volume: 87% before SSE and 92% after SSE, p < 0.01) were observed. At the postoperative day 5, the degree of scoliosis had reduced from 44 +/- 6.6 degrees to 22 +/- 6 degrees in the SSE group, which is 1 degrees less than the Cobb angle obtained on post-SSE fulcrum-bending radiography. In the non-SSE group, the degree of scoliosis decreased to 26 +/- 5.7 degrees. In the retrospective cohort, the degree of scoliosis decreased to 35 +/- 5 degrees, with the group also having higher postoperative pain (Visual Analog Scale score = 7, range = 5-10) and an extended hospitalization duration (11 +/- 3 days). At 2-year follow-up, curve correction was found to be maintained without adding-on or proximal junctional kyphosis. Compared with the non-SSE group, the SSE group exhibited a greater curve correction (66%) with a shorter hospitalization duration (5 +/- 1 days) and a lower degree of postoperative pain (Visual Analog Scale score = 4, range = 3-8). Taken together, our findings indicate that 5 day SSE improves preoperative spinal flexibility and facilitates curve correction.