Thoracic kyphosis in light of lumbosacral alignment in thoracic adolescent idiopathic scoliosis: recognition of thoracic hypokyphosis and therapeutic implications

Table 1 Radiographic parameters

Parameter	mean	SD
Cobb angle of thoracic scoliosis	40.9˚	16.5˚
Cobb angle of lumbar scoliosis (L1-S1)	16.3˚	8.6˚
Thoracic Kyphosis (TK)	16.1˚	9.1˚
Lumbar Lordosis (LL)	53.0˚	11.0˚
Max-LL^a	56.4˚	10.8˚
C7 sagittal vertical axis (C7 SVA)	-15.4 mm	24.1 mm
Pelvic Incidence (PI)	48.5˚	11.6˚
Pelvic Tilt (PT)	8.8˚	7.2˚
Sacral Slope (SS)	39.5˚	8.8˚
Inflection Point^b	-0.5	1.3
Inflection Point SVA (IP SVA)^c	5.5 mm	17.0 mm

^amax-LL was defined as the maximum lordotic Cobb angle from S1, which is measured from the upper end plate of S1 to the upper endplate of the vertebra at the inflection point between thoracic kyphosis and lumbar lordosis
^bInflection point was defined as the junction between the kyphosis and lordosis, and was denominated 0 when this point was at L1, and positive number was given when this goes down caudally (i.e., +1 at L2, +2 at L3, -1 at T12)
^cIP SVA is SVA of the inflection point, measured as the horizontal distance from the posterosuperior corner of S1 vertebral body to the inflection point

ISSN: 1471-2474