Role of thoracoscopy for the sagittal correction of hypokyphotic adolescent idiopathic scoliosis patients

Thoracic adolescent idiopathic scoliosis (AIS) curves (Lenke 1-4) are often characterized by hypokyphosis. Sagittal alignment remains challenging to correct, even with recent posterior segmental instrumentation. Some authors recommend anterior endoscopic release (AER) to reduce anterior column height, and facilitate thoracic kyphosis correction. The aim of this study was to assess the contribution of AER to sagittal correction in hypokyphotic AIS. Fifty-six hypokyphotic (T4T12 < 20A degrees) AIS patients were included. In group 1 (28 patients), patients first underwent AER, followed by posterior instrumentation and correction 5-7 days later. In group 2 (28 patients), patients underwent the same posterior procedure without AER. Posterior correction was performed in all cases using posteromedial translation and hybrid constructs consisting of lumbar pedicle screws and thoracic sublaminar bands. From radiological measurements performed using low-dose EOS radiographs, the correction of thoracic kyphosis was compared between the two groups. Groups 1 and 2 were comparable regarding demographic data and preoperative thoracic kyphosis (group 1: 11.7A degrees A A +/- A 6.9A degrees vs group 2: 12.1A degrees A A +/- A 6.3A degrees, p = 0.89). Postoperative thoracic kyphosis increase averaged 18.3A degrees A A +/- A 13.6A degrees in group 1 and 15.2A degrees A A +/- A 9.0A degrees in group 2. The benefit of anterior release was not statistically significant (p = 0.35). Although previous studies have suggested that thoracoscopic release improved correction compared to posterior surgery alone, the current study did not confirm this finding. Moreover, results of the current series showed that no significant benefit can be expected from AER in terms of sagittal plane improvement when the posteromedial translation technique is used, even in challenging hypokyphotic patients.