Table 4: Cobb Angle, Kyphotic Deformation and Beck Index Preoperatively, Postoperatively and at the Latest Follow-Up, for Short-Segment and Long-Segment Instrumentation Group. The Change of the Variables is Compared Between the Two Groups of Patients

	Cobb Angle			Kyphotic Deformation			Beck Index
	Mean	SD	p-Value	Mean	SD	p-Value	Mean	SD	p-Value
Pre-op
Short-segment	17.0	7.0	N.S	4	9	N.S	0.6	0.1	N.S
Long-segment	17.5	6.8		4.5	8		0.6	0.1
poST-op
Short-segment	5.0	3.5	0,051	-9	4	N.S	0.92	0.2	N.S
Long-segment	3.0	2.0		-8	4		0.94	0.2
follow-up
Short-segment	8.5	6.0	Ν.S	4.5	4	< 0.0005	0.90	0.2	N.S
Long-segment	6.0	4.0		40	15		0.92	0.2
	Cobb angle			Kyphotic deformation			Beck index
	Median (%)		p-Value	Median (%)		p-Value	Median (%)		p-Value
Comparison between pre-op and post-op
Short-segment	-70,6%		Ν.S	-330%		Ν.S	-53%		Ν.S
Long-segment	-82,9%			-277%			-56%
Comparison between pre-op and follow-up
Short-segment	-50%		0.03	11%		< 0.0005	-50%		Ν.S
Long-segment	-65,7%			788%			-49%