Indications for surgery in so-called "regular" thoracic and thoracolumbar kyphosis

Idiopathic thoracic, thoracolumbar, and Scheuermann's kyphosis do not figure in the same global entity. We propose a classification for so-called "regular" kyphosis. This classification is based on the location of the most rigid curvature segment. Segmental kyphosis may be short, in which case we can distinguish between four types: high kyphosis (type I), middle kyphosis (type II), low or thoracolumbar kyphosis (type III), and segmental kyphosis, which can extend along the entire thoracic spine (type IV). The symptomatology and therapeutic indications are different for each type. We report a series of 15 patients (6 female, 9 male), aged between 18 and 33 years (average age 24 years). The mean kyphosis angle (Cobb angle) in type I patients (n = 3) was 75 degrees in type II patients (n = 3) it was 82 degrees, and in type III patients (n = 9) it was 78 degrees. The pain was greater in type III patients. All patients were operated on using a double approach. As the first step, we performed an anterior approach, disc excision, and bone graft. Ten days later, a posterior approach with CD instrumentation was carried out on ten levels. The mean follow-up is 4 years (range 9 months in 7 years). We noticed no neurological complications and one case of late sepsis. Mean angular loss of correction was 6 degrees. The correction obtained depended on the type of kyphosis. We obtained a mean postoperative Cobb angle of 63 degrees in type I curves, 55 degrees in type II, and 45 degrees in type III. The new classification allows a better understanding of regular kyphosis and helps to define clinical and therapeutic approaches. An analysis of the resulting surgical correction can also be made by comparing homogeneous groups of patients.